Germany (1943) Experimental Circular Wing Aircraft – 1 Prototype Built
The unusual Sack AS-6 circular-wing aircraft [falkeeins.blogspot.com]In the history of aviation there were many designers who had ambitious ideas and concepts for new designs, but never had the chance to bring their ideas to fruition. On the other hand, there were those who had radical or even completely impractical designs that did manage, at least to some extent, to be built. Germany had a fair share of such individuals, especially during the later stages of the Second World War. These designers may have proposed their projects out of desperation to save their country or in fear of being sent to the front. There were also those that were simply enthusiasts in aircraft development but lacked a better understanding of how aerodynamics actually work. One such person was Arthur Sack (1900-1964), who prior to the war came up with the idea of building a circular-wing aircraft known simply as the Sack AS-6.
History
Prior to the war, Germans were prohibited from developing and building military aircraft. The Germans simply bypassed this prohibition by instead focusing on gliders, but also on civilian aircraft which if needed would be quickly converted for military use and conducted secret experiments. They especially took great care in the development and investment of manned gliders, but also scale model-building competitions and organizations. While this may seem like a waste of time and money, it actually helped gain initial and valuable experience in aircraft development which proved vital for the later Luftwaffe.
One such model competition was the National Contest of Aero Models with combustion engines, held in late June 1939 at Leipzig-Mockau. Here, aviation enthusiast Arthur Sack presented his model of an unusually circular-wing-shaped aircraft named AS-1. It is sadly unclear why Sack pursued the design of such an unusual aircraft design. Due to engine problems, the AS-1 was unable to take off from the ground, so the small model had to be launched by hand instead. The Air Minister (Reichsluftfahrtministerium RLM) Ernst Udet, who was present at the event, seemed to be impressed with this design and advised Sack to continue its development.
Arthur Sack and his AS-1 model. [lvz.de]Thanks to financial support from the RLM, Sack was able to proceed with the development and even the construction of a few scale models, a process that lasted some three years. In 1943 he submitted a fully operational model SA-5 to the RLM. The presentation went well for Sack and the RLM commission provided the necessary funds for the construction of a fully operational prototype. Interestingly, at some point Sack came into contact with another unusual aircraft designer Dr. Alexander Lippisch. While not completely clear, it appears that Sack received some design tips from Lippisch, to better improved his work.
With the order secured, Sack initiated the construction of a prototype. He named this aircraft the AS-6 V1 (Versuchs – version). As he had no proper workshop to build the aircraft himself, the glider manufacturer Mitteldeutsche Metallwerke was tasked with this instead. The initial work for the assembly of the aircraft began in the autumn of 1943. It took nearly half a year to complete the working prototype. Interestingly, due to the general shortage of materials, the AS-6 was constructed by utilizing a considerable amount of salvaged components from other damaged aircraft. For example, the cockpit canopy and parts of the interior were taken from a Bf 109B. Once the prototype was ready, it was allocated to the Luftwaffe for initial tests in early 1944.
AS-6 side view. [lvz.de]
Technical Characteristics
A good view of the AS-6 internal wooden frame construction.[all-aero.com]The AS-6 was designed as an experimental prototype to test the idea of using circular-wing design. Sadly, this aircraft is quite obscure and poorly documented so not much is known about its overall design. It was a single-seater aircraft that was mostly built out of wood. It did not have a classical fuselage, instead, the majority of the aircraft consisted of two large circular wings. The internal design is more or less conventional with a wooden construction frame being covered with canvas. Two large elevators were installed on the rear of the wings. The tail assembly is a conventional design as well, consisting of one vertical stabilizer and two horizontal stabilizers.
The AS-6 rearview. The two elevators were too small, poorly designed, and did not provide adequate control during initially limited test flights. [all-aero.com]The AS-6 was powered by an Argus As 10C-3 engine, which ultimately proved to be inadequate [all-aero.com]The AS-6 was powered by a 240 hp Argus As 10C-3 engine driving a two-blade wooden propeller. The engine was housed in a metal frame, which was then bolted to the AS-6 fuselage. The engine was salvaged from a Bf 108 aircraft.
The cockpit canopy and its interior, as already mentioned, were taken from a Bf 109B. The cockpit was slightly elevated above the fuselage and provided the pilot with an excellent all-around view. The landing gear was also salvaged from a Bf 109B, but in the case of the AS-6, it was fixed. Initially, a landing skid was used on the rear, which was later replaced with a landing wheel instead.
The canopy and landing gear was taken from a damaged Bf 109 aircraft [ufxufo.org]
Testing the Prototype
Initial evaluation tests of the AS-6 prototype were conducted at the Luftwaffe Brandis Airbase. The flight tests were conducted by Rolf Baltabol Junkers test pilot. While several short take-offs were made, there were no attempts to actually take the aircraft to the sky. The test pilot noted that the aircraft had an overall poor design and was difficult to control. He urged that the control surfaces and rudder be completely redesigned. The engine was also deemed too weak. During the last short take-off, one of the two landing gear assemblies was damaged.
The AS-6, following its unsuccessful start, spent several weeks in repairs and received a number of modifications in an attempt to improve its performance. These included adding an additional 70 kg of weight to the rear, installation of brakes taken from a Ju 88, and repositioning the landing wheels to the rear by about 20 cm. Sack proposed moving the landing wheels further back, but the test pilot Rolf simply refused to fly it if this change was implemented. He argued that placing the landing gear to the rear would imbalance the aircraft potentially leading to tipping forward during a take-off. For this reason, the modification was not implemented. While the engine was underpowered, there were simply no alternatives available at that time.
The AS-6 during testing [falkeeins.blogspot.com]The next test was scheduled for April 1944. During these tests, Rolf tried to take it to the sky, but failed again to do so. This time it was noted that the wings were simply too short. Further tests were canceled, the AS-6 was to await more modifications, and was to be tested in a wind tunnel; if possible with a completely new engine.
The fate of the AS-6
Following the unsuccessful testing, the AS-6 was stored at the Brandis airfield. In the summer of 1944, this airfield became the main operational base for the experimental Me 163 rocket-powered aircraft. The pilots of the I./JG 400 (charged with testing the Me 163) found the AS-6. One of its pilots, Franz Rossle, expressed a desire to attempt flying the unusual plane. But when the ground crew was preparing the aircraft for take-off, one of its landing gear units simply broke due to rough terrain, effectively preventing the test flight to be conducted. After this, it was once again stored at Brandis. It would remain there until early 1945 when it was lost in an Allied bombing raid.
The AS-7 project
While not clear when (possibly during early 1945), Sack approached Messerschmitt company with a proposal to use his circular-wing design on the Bf 109K-4 aircraft. The aircraft marked as SA-7 would be powered by a DB 605 2,000 hp engine. Fitted with circular wings it was theorized that it would be capable of carrying more armament inside the wings. It is believed (but not clear) that Messerschmitt was interested in this proposal and designated the project Me 600. Due to the war’s end, nothing really came from this project.
Conclusion
While certainly an unusual and interesting design, due to poor quality and salvaged materials used during its construction, the AS-6 performed poorly and never actually achieved flight. We will never know if the AS-6 circular-wing design offered any major advantage over more conventional wing designs. It appears that Arthur Sack did not continue with his idea after the war and passed away in the mid-1960’s. While his work was never implemented in mass production, his unusual design was often mistakenly taken as some advanced and secret German World War II project, which ironically, it never was.
Germany (1944) Rocket-Powered Interceptor Prototype – 1 Built
The Me 163D prototype [luftwaffephotos.com]The Me 163 showed to have great potential as a fast rocket-powered interceptor, but its design had some shortcomings. These included a limited view from the cockpit, lacking of landing gear, increased fuel storage, etc. The German companies Messerschmitt and later Junkers tried to resolve this by implementing a number of improvements to its design leading to the Me 163D of which only a few prototypes were built given the late start of the program.
History
The Me 163 small size, while reducing the overall cost of the aircraft, enforced limitation of the fuel that could be stored inside which in turn led to a limited operational powered flight time of fewer than 8 minutes. In combat operations, this proved to be insufficient but no auxiliary tanks could be added to the Me 163 wings not inside of it. Another issue was the lack of proper landing gear. The Me 163 was instead forced to use a two-wheel dolly. Once the aircraft was in the air, the dolly was jettisoned. On occasion, there were accidents regarding this system when for example the dolly refused to be detached from the aircraft or even worse when it bounced off the ground and hit the aircraft from below. On the landing, the Me 163 were to use a simple retractable landing skid, placed beneath the fuselage. After landing the aircraft was immobile and essentially an easy target for enemy crafts. For this reason, a normal retracting landing gear unit was desirable but once again due to Me 163 small size impossible to install.
To redress the previously mentioned issues engineers at Messerschmitt began working on an improved version named Me 163C. It incorporated a longer fuselage, extended cockpit, having an engine with two combustion chambers, and other modifications. The work on this version was rather slow and by war end not much was done on it besides a few incomplete airframes.
Illustration of a Me 163C aircraft, which was to replace the Me 163B. [walterwerke.co.uk]One or two Me 163B prototypes had their fuselage extended in order if such modification was possible. [walterwerke.co.uk]Parallel with the Me 163C development another project was carried out in early 1944 once again by Messerschmitt. This project was initially designated as Me 163D and was to have substantial numbers of improvements mostly regarding the overall shape of the aircraft, engine use, weaponry etc. For testing this new concept of substantially extending the aircraft fuselage if it was feasible at all. One or two (depending on the source) Me 163 (BV13 and BV18) was to be experimentally modified with an extended fuselage. In addition, experimental landing gear was also to be added. The testing of this rebuilt aircraft proved to be feasible and so the work on a fully built prototype began in earnest.
Name
The Me 163D project, due to Messerschmitt being simply overburdened with the Me 262 production, would instead be given to Junkers company. Once in their hands, the project was renamed Ju 248. The Me 163D obviously had an identity crisis as in late 1944 it was once again given back to Messerschmitt. Once back to its original designers, the project once again changed its name, this time to Me 263. As all three designations are basically correct for this aircraft, this article will use the original Me 163D designation for the sake of simplicity and to avoid any possible confusion.
First Prototype
Despite being originally designed by Messerschmitt, it was actually assembled in Junkers factories sometime during August 1944 or in early 1945 (the sources are not clear here). After that it would be returned to Messerschmitt where it was planned to examine and test its overall performance. While it was intended to have an increase in fuel capacity and an improved engine, the first prototype had actually no engine installed at that time. The Me 163D V1 (DV-PA) prototype was also provided with a new retractable tricycle landing gear which was to help with the mobility during the ground drive.
Given that no engine was fitted to the Me 163D, first flight testing was done as a glider, in late 1944. After these were conducted the prototype was in a series of wind-tunnel testings. The results of these two test trials (flight and wind tunnel) showed that the Me 163D was not capable of safely achieving dive speeds that were greater than its normal flight speed. In this regard, it was inferior to the original Me 163 aircraft which could achieve extensive dive speed but still managed to preserve good flight controls. The Messerschmitt engineers at this phase even considered redesigning the rear tail unit, but nothing came of it. The tricycle landing gear units did not offer good mobility on the ground, this was mainly due to it being too narrow. The Germans had plans to test using a parachute that was to be released during landing to help reduce the need for a long airfield. If this was tested or even installed on a Me 163D is unknown.
Technical characteristics
The Me 163D like its predecessor was designed as a high-speed, rocket-powered, swept-wing tailless aircraft. Given its experimental nature and its late development into the war, not much is known about its precise technical characteristics. Its overall construction would probably be similar to the previous versions, with a fuselage being built of metal and wooden wings.
The semi-monocoque construction fuselage was longer and was now 7.88 m ( 25 ft 10 in) compared to the original 5.84 m (9 ft 2 in) length. It had a good overall aerodynamic shape. The wings were swept to the back at a 19° angle, compared to the Me 163B 23.3° angle.
The Me 163D like its predecessor had wings that were swept to the back at a 19° angle. The fuselage had an excellent aerodynamic shape. [forum.warthunder.com]The pilot cockpit received a new ‘bubble-shaped canopy. This provided the pilot with a much greater field of view. Given that it was intended to operate at great heights, the Me 163 D cockpit was to be pressurized and for this was bolted to the fuselage.
The Me 163D received a much better canopy which offered a much better all-around view. It was also completely pressurized so that the pilot could effectively fly it, on great heights. [forum.warthunder.com]Interior of the Me 163D pilot cockpit. [forum.warthunder.com]The Me 163D was to be powered by an improved Walter 109-509C rocket engine. It was provided by two combustion chambers. While the sources are not clear if this engine was ever installed in the Me 163D, the estimated maximum speed was noted to be 950 km/h (590 mph) or up to 1,000 km/h (620 mph) depending on the source. It should also provide more economical consumption of fuel providing an operational range of some 160-220 km (100-140 mile) once again depending on the source. The operational flight endurance was increased from 7 minutes and 30 seconds to 15 minutes.
To overcome the previous Me 163B version’s lack of proper landing gear, the Me 163D was provided with the retractable tricycle landing gear. It consisted of a forward smaller and two larger wheels in the rear, just below the wing roots. All three of these retracted to the rear into the fuselage.
The fuel load consisted of 1040 liters (229 gallons) of T-Stoff and 492 liters of C-Stoff. The Me 163 was notorious for having only a limited endurance flight ofOnce the fuel was spent the pilots were to simply glide the aircraft back to the base.
The armament consisted of two 30 mm (1.18 in) MK 108 cannons, which were placed in the wing roots. Depending on the source the ammunition storage for each cannon ranged between 40 to 75 rounds.
Production
It is often mentioned in the sources that one complete and one partially complete prototype were built, by the war’s end. According to M. Griehl (Jet Planes of the Third Reich) on the other hand, mentioned that at least three prototypes were built with less than 20 aircraft being in various states of construction when these were captured by the Allies in 1945.
Service
The limited operational test use of the Me 163D and the German plans for it is not clear. Once again depending on the sources, there are mostly two versions. It appears that despite some faults in its design the Germans were willing to proceed with its further development. Given the end of the war, it should not be surprising that this was ever achieved. In another version, the work on the Me163D after some testing flight in February 1945 was officially terminated by the Luftwaffe officials. Mostly due to the fact that production of its unique and dangerous fuel is no longer possible.
The fate of these aircraft is not clear, given either information that these were either destroyed or captured by the Soviets. The latter option seems more likely as some sources suggest that the Soviets based on the Me 163D after the war developed their own version of it, the I-270. The project led nowhere and it would be abandoned.
Me 163D V1 – Completed prototype
Me 163D V2 – Incomplete second prototype
Me 163D V3 – Possible third prototype being built with additional 18 airframes
Conclusion
Given its experimental nature and its late introduction, it is quite difficult to make the final decision on the general properties of this aircraft. While it introduced some improvements in comparison to the previous version it also had issues regarding its reaching speed during dive flights. Despite offering the Germans a relatively cheap aircraft the whole Me 163 project by 1945 was essentially over given the general impossibility of production of its unique fuel. Nevertheless despite its downsides, the Me 163 whole series was certainly an interesting concept that had some merits that unfortunately for the Germans were never completely implemented.
Me 163D V1 Specifications
Wingspans
31 ft 2 in / 9.5 m
Length
25 ft 10 in / 7.88m
Height
ft in / 3.17 m
Wing Area
192.6 ft² / 17.91 m²
Engine
HWL 509 rocket engine
Empty Weight
4,400 lbs / 2,000 kg
Maximum Takeoff Weight
11,660 lbs / 5.300 kg
Maximum Speed
590 mph / 950 km/h
Operational range
100 mil / 160 km
Engine endurance
15 minutes
Maximum Service Ceiling
52,480 ft / 16,000 m
Crew
One pilot
Armament
Two 30 mm MK108 cannons
Gallery
Artist Conception of the Me 163C – by Carpaticus
Artist Conception of the Me 263 – by Carpaticus
Credits
Written by Marko P.
Edited by Henry H. & Ed J.
Illustrated by Carpaticus
Source:
D. Nešić (2008) Naoružanje Drugog Svetsko Rata-Nemcaka. Beograd.
E. T. Maloney and U. Feist (1968) Messerschmitt Me 163, Fallbrook
M. Emmerling and J. Dressel (1992) Messerschmitt Me 163 “Komet” Vol.II, Schiffer Military History
J.R. Smith and A. L. Kay (1990) German AIrcraft of the Second World War, Putham
United Kingdom (1917)
Heavy Bomber Prototype – 1 Built / 1 Incomplete
The completed Kennedy Giant (Flickr)
The Kennedy Giant was a very large heavy bomber prototype developed by the United Kingdom, and designed by Chessborough J. H. Mackenzie-Kennedy during World War I. The type was meant to be similar to the Russian Ilya Muromets series of heavy bombers. Development was plagued with issues due to the large size of the aircraft, and after a failed attempt at a first flight, the prototype was left to rot. A smaller redesign was in the works, but the program would be canceled in 1920.
The Man
Chessborough J H Mackenzie-Kennedy in front of the Kennedy Giant in 1917. (The Imperial War Musuem Footage)
In 1904, at the age of 18, Chessborough J. H. Mackenzie-Kennedy would leave his home country of Britain and move to Russia. The allure of developing his own aircraft firm in a place where very few firms were located was his main reason to move to the country. Only a few years after moving, Kennedy was able to design and build his own aircraft in 1908, and a year later would establish his own aircraft company, the Kennedy Aeronautic Firm, in 1909. In 1911, Kennedy would become acquainted with Igor Sikorsky, the premier aircraft designer of the Russian Empire. Kennedy would assist Sikorsky on several occasions with the design of several aircraft, but none of these would be as important as Kennedy’s work on the Sikorsky Russky Vityaz. The Russky Vityaz would be the world’s first 4-engined airplane and was one of the biggest aircraft built at the time. The aircraft would first fly in 1913. Kennedy would continue to help Sikorsky work on other aircraft, among them the successor to the Vityaz, the Ilya Muromets, until 1914.
On July 28th, 1914, Europe would be plunged into the First World War, with Britain entering the war on August 4th. After Britain entered the conflict, Kennedy would return to his home country to help with their war effort. Using the knowledge he gained while in Russia working with Sikorsky, Kennedy was confident Britain could use his expertise in aircraft design. Kennedy wanted to create a large bomber, akin to the Muromets. Upon his return to England, he would establish a design office at 102 Cromwell Road, South Kensington in London.
The Machine
Kennedy would begin talks with the British War Council discerning the creation of a large four engine bomber aircraft, similar to projects he had worked on with Sikorsky. Interestingly enough, Igor Sikorsky would convert the Ilya Muromets civilian aircraft Kennedy was familiar with into Russia’s first 4-engine strategic bomber. Kennedy was able to convince the War Council of his idea, and he was given funding to create his heavy bomber. The aircraft would become known as the Kennedy Giant.
The incomplete Giant being worked on. The wings are outside of the hangar while the tail is still inside. (The Imperial War Musuem Footage)
Construction of the Giant began soon afterwards at an unknown date. The manufacture of the components of the aircraft were undertaken by two companies, Gramophone Company Ltd and Fairey Aviation Co Ltd, both located in Hayes, Middlesex. When all of the components were finished, they were shipped to the Hendon Aerodrome for final construction of the massive aircraft. The sheer size of this aircraft would end up being the source of many problems during its development, and the first one would happen upon the arrival of the disassembled plane. Due to its large size, no hangar at the aerodrome was able to house the Giant, so the actual construction of the aircraft was done completely outdoors, on the airfield. The completed aircraft was impressive, possessing an 80ft (24.4m) fuselage and 142ft (43.3m) long wings. The Giant would heavily resemble the Russky Vityaz and Ilya Muromets that Kennedy had worked on in Russia. Due to the large size of the aircraft, the airplane was stored with its tail inside the hangar, whilst its wings and nose protruded outside. Moving the aircraft required two trucks and 70 men, and in one attempt, the fuselage was damaged from this action. The fuselage3 was redesigned to be 10ft (3m) shorter after this. Originally, Kennedy requested the aircraft to have 4 Sunbeam engines for power, but the engines requested were experiencing difficulties during testing, and wouldn’t be operational until after the war. Aside from testing, the War Council didn’t find the Giant important enough to warrant these new engines, and instead four Canton-Unne Salmson Z9 engines were given to the project instead. These engines would power two pusher and two puller propellers. With the engines finally in place, the completed Kennedy Giant was ready for its first flight.
The Kennedy Giant being constructed outside. (Jane’s All The Worlds Aircraft 1919)
The Giant’s first flight was in the later months of 1917. The aircraft would be set in the position for takeoff on the runway, with veteran test pilot Frank Courtney at the controls of the massive machine. The engines were set to full throttle, and as the aircraft gained speed, it only managed to make a short hop off the ground, being airborne for only a moment. It was found that the engines given to Kennedy were not able to take the Giant airborne. With the craft being so ungainly to move, and no desire to give the aircraft better engines, Kennedy’s giant aircraft was abandoned in the fields of the Hendon Aerodrome to rot, with a second attempt at a flight never materializing. Kennedy himself wasn’t discouraged by the failure of his aircraft and he began working on a smaller version that he hoped would achieve flight. Information on this version is sparse, but it was still in development after the war, and despite starting construction, the program was canceled in 1920. No photos or details on this smaller version are known. By 1920 the Giant project was going nowhere. With the war over, the War Council decided such a large aircraft was no longer a worthwhile investment.
A side view of the completed Kennedy Giant. (Jane’s All The Worlds Aircraft 1919)
In 1923, Kennedy would sue the War Council, now the Air Ministry, over a patent he had filed regarding the aircraft. During the war while he was working on the Giant, Kennedy would design a unique system for the tail gunner of the aircraft. The Air Ministry allegedly gave the design plans regarding the Giant to Handley Page in 1917, with the company applying for a patent on the tail gunner position on March 15th, 1918. Kennedy would file for the same patent for his Giant only a day later on the 16th. His case would be dismissed. The last time the Kennedy Giant would be mentioned regarding this case was in an aircraft magazine in 1923, which refers to the Giant still parked at the airfield at Hendon, most likely in poor condition from neglect. An some later date, the Giant was scrapped.
Design
Size comparison shot of the Giant next to a Bristol F.2 fighter. (Jane’s All The Worlds Aircraft 1919)
The Kennedy Giant was a large four engine heavy bomber built using experience gained from the development of the Russian Russky Vityaz and Ilya Muromets. The fuselage of the Giant was of wood construction and was entirely rectangular. All along the sides of the fuselage were celluloid covered windows. The cockpit had several large rectangular windows with good visibility for the pilot. Controls consisted of two large wheels connected to yokes that directed its control surfaces. Located in the upward slope of the nose, there was a window that assisted with bomb aiming. The wings of the aircraft were two bay, meaning a forward and aft row of struts between the upper and lower wings which were covered in fabric, with a wingspan of 142 feet (42.3m). The wings all had the same chord, but the upper wings were longer than the lower. Only the upper wings had ailerons. At the rear of the aircraft were the tail and elevators. Both of these were covered in fabric. The tailfin itself was rather small for the size of the aircraft and most likely would have negatively affected performance had the aircraft achieved sustained flight. The aircraft was powered by four 200 hp ( 149.1 kW ) Canton-Unne Salmson Z9 nine-cylinder water-cooled radial engines powering four wooden propellers. Two of these engines were to be used in a pusher configuration, while the other two were positioned in a tractor configuration.
Despite never being armed, plans for armament of the Giant exist. The aircraft would be armed defensively with 4 machine guns of unknown type. One of these would be located in the nose, one would be located behind the wings on top of the fuselage, and the last two would be in the tail. The tail gunner would have a unique seat option for the gunner, where it could act as either a seat or a kneepad depending on how the gun was being fired. This seat design would be the cause of the lawsuit in 1923. An unknown number and type of bomb would have been used. The bombs would have been held nose down by two arms. A selector gear would control which bombs were dropped while indicating how many were left.
Conclusion
The Kennedy Giant was an earnest attempt to create a heavy bomber using experience gained by Kennedy in Russia, but due to inadequate engines would never be truly realized to its fullest potential. What is interesting to note is the specifications listed for the Giant would actually make it larger than the Zeppelin Staaken R.VI, which is considered the largest production airplane of the World War I. Had it even flown, the Giant would likely have experienced maneuverability issues as its vertical stabilizer height was rather inadequate for the size of the aircraft. After the failure of the Giant, Kennedy would file for bankruptcy, as the program had personally cost him quite a lot of money. He would eventually move to America in the 1930s.
Variants
Kennedy Giant – Large, four engine heavy bomber prototype. One built but did not achieve sustained flight.
Postwar Kennedy Giant – Very little is known of this variant aside from it being a smaller version of the Kennedy Giant. It was under construction when the program ended.
Operators
United Kingdom – The Kennedy Giant was built for the British War Council as a prototype heavy bomber.
The first version of the completed Kennedy Giant – by Ed JacksonCloseup view of the cockpit of the Kennedy Giant. (The Imperial War Musuem Footage)View of the tail of the Giant. (The Imperial War Musuem Footage)The mid-section of the Giant. (The Imperial War Musuem Footage)Kennedy demonstrating the controls of the Giant while in the cockpit. (The Imperial War Musuem Footage)Kennedy walking down the interior of the Giant. (The Imperial War Musuem Footage)
Grey, C. G. Jane’s all the world’s aircraft, 1919 : a reprint of the 1919 edition of All the world’s aircraft. Newton Abbot: David & Charles, 1969. Print.
Mason, Francis K. The British bomber since 1914. London: Putnam, 1994. Print.
USSR (1938-1940)
Experimental Long-Range Bomber – 1 Prototype Built
The Belyayev DB-LK [airwar.ru]In the late thirties and early forties, the Soviet aviation industry had developed and tested a variety of aircraft design concepts, some quite peculiar. While generally unknown around the world, a number of these strange aircraft would represent a serious departure from anything resembling their contemporaries. Such is the case with Victor Nikolayevich Belyayev’s DB-LK experimental long-range bomber.
History
Victor Nikolayevich Belyayev, March 1896 – July 1953, began working for the Department of the Marine Experimental Aircraft Construction, OMOS, in 1925, where he gained his first experience in aircraft design. In the following years, he worked for the Central Aerohydrodynamic Institute, TsAGl, and Tupolev. During this time, he became an advocate for tailless aircraft designs. He also argued that the so-called “batwing” or “butterfly”, offered better performance, due to their reduced drag and better stability, than regular wing designs.
The “batwing” design possessed a slightly forward-swept wing with back curved tips. Belyayev managed to construct a glider, designated BP-2, which was equipped with this kind of wing design in 1933, on which he tested this concept. During its test flight, it was successfully towed in the air from Crimea to Moscow, where it proved to have good stability and control during flight.
The BP-2 glider in flight. [airwar.ru]The next year, Belyayev participated in the competition for a new Soviet military transport plane design. His design was unusual, as it consisted of a large wing and two nacelles, powered by Tumanskii M-87B 950 hp (708 kW) engines. His design was not approved nor did he build a working prototype. However, four years later, he would reuse this project and adapt it for the role of a long-range bomber. In 1938, he designed the DB-LK long-range flying wing bomber, which the TsAGl approved and ordered the construction of a fully operational prototype. The prototype was built the following year by factory No.156 and by November 1939 it was ready for testing.
Technical Characteristics
The DB-LK had an unusual overall design with no classical fuselage. Instead, the crew, armament, and other equipment were located in the two extended engine nacelles that ended in glazed tail cones (gondolas), somewhat similar to the later German Fw 189. The two extended engine nacelles were, technically speaking, the plane’s fuselage. The semi-monocoque fuselages were constructed by using a combination of metal frames and longerons covered with a duralumin sheet. The DB-LK was designed in this unusual configuration in the hope of reducing the overall drag and weight and thus increasing its speed and range.
The DB-LK’s wings had a unique design, where beside the “batwings” there was an additional center wing section between the two fuselages. Also, the wings were slightly swept to the front with back curved tips. The wings consisted of an airframe covered with light metal stressed-skin. The outer wings had a Gottingen 387 profile, while the center section had a CAHI (TsAGI) MV-6bis profile. The wing edges were curved at an angle of -5° 42′.
A side view of the DB-LK. The strange wing design can be seen. [elpoderdelasgalaxias.wordpress.com]The rear tail was located on the middle section wing between the two fuselages. The tail consists of one fin and a large 20 ft2 (1.9 m2) rudder. Above the rudder, a smaller tailplane with two, one on each side, large elevators was placed.
A rear view where the large tail and the left glazed rear cone can be seen. [airwar.ru]One Tumansky M-87B 950 hp (708 kW) 14-cylinder radial engine was installed at the front of both nacelles. For these engines, three-bladed propellers with variable pitch were used. It was planned to upgrade these two with much stronger 1,100 hp (820 kW) M-88 engines, or even the 1.700 hp M-71, but this was never implemented. The fuel was stored in the wing and fuselage tanks, with a total fuel load of 3.444 l.
The landing gear retracted rearwards, with one wheel (900 x 300 mm) in each fuselage. During later testing, the landing gear design was changed with a forward retractable one. This whole landing gear system was operated hydraulically. There was a small fixed rear wheel (450 x 150 mm) located at the bottom of the tail unit.
The DB-LK was to be operated by a crew of four: the pilot, navigator, and the two rear gunners. The pilot position was in the left cockpit and the navigator in the right. The gunners were positioned in both rear glazed cones. One of the two gunners was also the radio operator. The crews entered their positions through roof hatch doors. The two glazed cones could be mechanically rotated 360° by using a small electric engine located at the fuselage top, but the sources do not specify why this was done.
Inside the pilot cockpit [авиару.рф]The interior of one of the two fuselages. In the picture on the right, the rear machine gun mount can be seen. On the left, the radio and the mechanism that rotated the whole glazed cone can be seen. [авиару.рф]Both rear glazed tail cones had a recess where a twin 7.62 mm (.30 caliber) ShKAS machine gun mount was installed. These machine guns had a -10 to +10 field of fire in all directions. Besides these four machine guns, there were two additional ones forward mounted in the leading edge of the center section. These two machine guns were operated by the pilot. In total, around 4,500 rounds of ammunition were provided for these machine guns. The bomb bays were located behind the landing gear doors in each of the two nacelles.
Depending on the sources, the load capacity of the bomb carried is different. The authors Yefim G. and Dimitri K. note that the bomb load was 1000 kg (2,200 lb) with another 1000 kg that could be carried on external racks. According to Bill G., the capacity of each bomb bay (in each fuselage) was one 1000 kg (2.200 lb), two 500 kg (1.100 lb), or smaller bombs with a total of 1000 kg (2.200 lb) weight.
Both front and rear views of the DB-LK’s unusual design. [авиару.рф]
Flight Tests
While being completed in November 1939, the first extensive flight test would only begin the following year. This was due to the unwillingness of the test pilot to fly this plane. He did not believe that it was safe to fly due to its unorthodox design. During this time, the plane received the nickname “Kурица” (chicken).
In order to move the entire project testing through this roadblock, the Soviet Direction of the Air Force Scientific test institute, GK Nil WS, appointed M. Nyuikhtikov as the main test pilot, supported by aircraft engineer and test pilot T. T. Samarin and N. I. Shaurov. Under the new leadership, the tests were carried out in the spring of 1940. During the new leadership, the DB-LK was extensively tested in over 100 flights.
During these flights, the pilots managed to reach speeds of 245 mph (395 km/h) at sea level and 300 mph (490 km/h) at an altitude of 16,400 ft (5,000 m). The DB-LK needed a 2,030 ft (620 m) long airfield for landing and taking off. However, the DB-LK was never truly trialed with a fully loaded payload. The numbers presented above would have likely been different with a full payload of equipment.
The test pilot Nyuikhtikov, after flying on the DB-LK, pointed out some issues with the plane’s design. The main problems were the inadequate overall flight-control system, poor visibility for the pilot and the navigator, especially on the ground. He also noted the poor construction of the landing gear. These reports were examined by the Nil WS Commission led by A. I. Filin. They agreed that the control system should be improved, but Filin had a positive opinion on the landing gear construction. Ironically, during a test flight, where Filin was the pilot, there was a landing gear malfunction during the landing when one of the front wheels broke free, after a possible collision with a treetop. The aircraft was only lightly damaged and the testing continued, but this led to a change in the landing gear design.
There were also other problems mentioned during the tests, like uncomfortable cockpits, low-level of fire protection, structural problems, a limited firing arc of the rear-mounted defense machineguns, and the tendency for the crew compartments to be filled with exhaust fumes from the engines. To solve these issues, there were plans for the DB-LK improvements, with stronger engines, wings, and various other modifications, to be completed by late 1940 but they were probably never implemented.
Rearview of the accident. [авиару.рф]
Conclusion
Despite plans for more testing and improvements, unfortunately for the DB-LK design team, they never got a chance to do so. In late 1940, the Nil WS Commission gave orders for the cancellation of the DB-LK program. The main reason for this was the decision for the production of the Il-4 as the main Soviet long-range bomber.
Nazi Germany (1943) Rocket Powered Fighter – 10 Built
The first operational Me 163 prototype. [luftwaffephotos.com]During the Second World War, the Luftwaffe experimented with a number of unorthodox designs. This included a handful of rocket-powered aircraft, like the Me 163. This particular aircraft was created thanks to the somewhat unexpected combination of two different projects. One was the airframe designed by Alexander Martin Lippisch, and the second was the rocket engine developed by Helmuth Walter. Following the testing of the first prototypes, a small series of some 10 aircraft were built that were mainly used for testing and training.
Alexander Martin Lippisch and Helmuth Walter
The history of Me 163 was closely related to the work and design of aircraft engineer Alexander Martin Lippisch and rocket development pioneer Helmuth Walter. Lippisch was somewhat unorthodox in his aircraft design work, to say the least. He was quite interested in the development of gliders and later aircraft that were either completely lacking a tail unit or of an all-wing configuration.
In 1921, Lippisch, together with a colleague, participated in the formation of the so-called Weltensegler GmbH (World Glider Ltd.) company. At that time, the Germans were prohibited from developing and building military aircraft. The Germans worked around this prohibition by instead focusing on gliders and civilian aircraft which if needed would be quickly converted for military use, and conducted secret experiments. While glider development may seem like a waste of effort, it actually provided the Germans with an excellent foundation on which they managed to develop the Luftwaffe during the 1930s, becoming a formidable force at the start of the war. In 1925, Lippisch joined Rhön Rossitten Gesellschaft RRG, where he soon began working on his first glider. It was named Storch I, and incorporated his unusual all-wing design.
Over the years, Lippisch also became interested in rocket technology. With assistance from Fritz von Opel, Lippisch managed to build a rocket-assisted glider. This contraption was flight tested in June 1928. This was actually the first-ever rocket-assisted flight in the world. While initially successful, the glider crash-landed, and caught fire. The plane would be lost in the accident.
This accident did not prevent Lippisch from experimenting with rocket-powered all-wing gliders. He focused his work on a powered version of his Storch V glider. For this project, he used an 8 hp DKW engine. His work was successful and he managed to find investors who were willing to provide funds for the project. This led to the development of the Delta I all-wing aircraft during the late 1920s, and it was followed by Delta II, III, and IV.
Lippisch Delta I prototype. [aviastar.org]Following this, Lippisch joined the Deutsche Forschungsinstitut DFS, where he worked as an engineer. There, he developed a series of new glider designs, like the DFS 40. In 1938, the work of Helmuth Walter came to his attention. Walter was a young scientist who was highly interested in rocket propulsion. He managed to gain military funding, which greatly helped in his work. In 1937, he even managed to gain attention from the Reichsluftfahrtministerium RLM (German Air Ministry). The RLM formed a Sondertriebwerke (Special Propulsion System Department) with the aim of experimenting with rocket engines in the aircraft industry. While this department was mainly focused on developing rocket engines for short take-off assistance, Walter desired a more prominent role in rocket propulsion. He intended to develop a rocket engine that could replace standard piston engines. Walter managed to develop such an engine, named Walter TP-1, which was fueled by the so-called ‘T-Stoff’ (hydrogen peroxide) and ‘Z-Stoff’ (water solution of either calcium or sodium permanganate). His engine design would be tested in 1939 on the He 176. However, the final results were disappointing and the engine did not go into production.
The DFS 194 predecessor
Lippisch and his design team began working on a new project incorporating the Walter rocket engine. Initially, the project was designated simply as Entwurf X (Design X), before being changed to 8-194 and finally DFS 194. Work on the prototype came to a temporary halt as the DFS lacked proper production capabilities to finish the aircraft. To keep the project going, the RLM instructed Messerschmitt to provide the necessary manpower and production support.
Given the small chance of progression in the DFS and in order to increase the speed of the project, Lippisch and his team moved to Messerschmitt’s base at Augsburg at the start of 1939. He also tried to negotiate with Heinkel for the production and development of the DFS 194 project, but nothing came of this. At Augsburg, Lippisch and his team worked in Messerschmitt’s newly formed Department L (which stands for Lippisch).
The DFS 194 prototype served as the base for the future Me 163. [nevingtonwarmuseum.com]The first calculations were promising, as the plane would be able to reach a speed of 550 km/h (342 mph). Once completed the DFS 194, was transported to the secret German rocket test center at Peenemunde-West Airfield during the summer of 1939. During ground tests, it was noted that the engine installation was poorly designed and too dangerous to be actually flight tested. Instead, it was decided to use the design as a glider. Surprisingly, despite this huge setback, production orders for three prototypes were given. Initially, these were designated simply as Lippisch V1, V2, and V3, but would be renamed to Me 163A V1 to V3. This was mainly done to mask the true purpose of this aircraft, as this was the name given to an older, rejected Bf 163 Messerschmitt reconnaissance aircraft project.
The Me 163A Prototype Series
The RLM was not satisfied with the general design of the engine compartment initially tested on the DFS 194. They requested that for further Me 163 development, it would need to be substantially changed. In addition, the engine was to be replaced with the Walter R II-203 engine. This engine was to have a manually regulated thrust ranging from 150-750 kg of thrust (330-1,650 lbs). The engine compartment was also to be completely redesigned in order to have easy access to the main components for maintenance.
Following the start of the Second World War in September 1939, the work on the Me 163 slowed down but still went on. The first unpowered flight by the Me 163 V1 prototype, in some sources marked as V4, (KE + SW) was carried out during early 1941. This prototype was towed by a Bf 110 heavy fighter. Once at a sufficient altitude, the V1 was released. During the test flight, the pilot, Heini Dittmar, managed to reach a speed of some 850 km/h (528 mph) during a dive. While this was a great starting point for the project, Hitler, following military victories in Poland and in the West, ordered that funds for such projects be reduced. In the case of the Me 163, this meant that only two more additional prototypes were to be built.
Side view of the Me 163 V1 (V4).[luftwaffephotos.com]In May 1941, a wooden mock-up of a Me 163 was completed, which was then transported to the Walter Werke. Once there, it was to be equipped with the R II-203 engine. Once the first prototype was fully completed and equipped with this engine, the first tests were carried out at Peenemunde-West in August 1941. The test pilot was once again Heini Dittmar. After a series of test flights that lasted from August to September 1941, the Me 163 prototype showed promising results. The pilot managed to reach top speeds of 800 km/h (500 mph). At this time, the second V2 prototype was also equipped with a rocket engine and used in various test flights. Ernst Udet, Director-General of the Luftwaffe, was highly impressed with its performance. He even gave orders that an additional 8 prototypes were to be built, bringing the total to 13 at this time.
Once the prototype was equipped with the R II-203 engine, the first tests were carried out in August 1941. These proved to be highly successful, which led to an increase in interest for the Me 163 project. [Spate & Bateson]At the start of October, Heini Dittmar said that, in order to fully test the Me 163’s flying performance, the fuel load had to be increased. On his personal insistence, the V3 (CD + IM) prototype, was fully fueled. This is according to W. Spate and R. P. Bateson (Messerschmitt Me 163 Komet). Other sources like M. Griehl (X-Planes German Luftwaffe Prototypes 1930-1945) this aircraft was described as being the V8 prototype instead. On the 2nd of October 1941, he took to the sky, initially towed by a Bf 110. At an altitude of 3,960 meters (13,000 ft), Dittmar activated the engine. After reaching a speed of 965 km/h (600 mph), he lost control of the aircraft as the result of compressibility effects. The prototype began a rapid descent toward the ground. He then switched off the engine, which enabled him to regain control, after which he landed safely on the ground. Later analysis of the flight indicated that Dittmar managed to reach a speed of 1002 km/h (623 mph). As the whole project was undertaken under great secrecy, this success was not published at the time.
The Me 163 in the middle was the aircraft that Heini Dittmar flew when he reached a speed of 1002 km/h (623 mph). [Spate & Bateson]Following these events, the Me 163 project got a temporary boost in prominence, with Herman Goring himself placing great interest in it. Ernst Udet additionally placed an order for 70 new Me 163 airframes together with engines for the B version in October 1941. A month later, things changed dramatically for Me 163 after Udet committed suicide. His replacement, Erhard Milch, was less interested in unconventional aircraft designs, like the Me 163. Work on the project nevertheless continued.
A breakup with Messerschmitt
While the Me 163 project was underway, relations soured between Willy Messerschmitt and Lippisch. Messerschmitt personally disliked the Me 163, partly due to its unique overall design, but also given that he was not involved in its development. By 1943, Lippisch left Augsburg and moved to Vienna. While not physically present in the design bureau, he tried to maintain contact with the Me 163 development team at a distance.
In the meantime, Messerschmitt was unwilling to be involved in the Me 163 project, under the excuse that his company was already overburdened with the production of other aircraft. For this reason, the production of further Me 163 aircraft was instead given to Klemm Leichtflugzeugbau, a relatively small aircraft company owned by Hans Klemm.
Production of the A-0 series
While the V1 prototype was mainly used for initial testing, the V2 would serve as a base for the A-0 series. An initial order for ten A-0 aircraft was previously given to Messerschmitt, but only seven were completed. The remaining three aircraft were actually completed by the Klemm factory. These were all completed from 1941 to 1942. The number of prototypes built is not clear in the sources. The numbers range from 1 to 8 prototype aircraft. According to S. Ransom and H.H. Cammann (Jagdgeschwader 400), while three prototypes were meant to be built initially, not all met the requested specifications, except one, which received the V4 designation. Author M. Griehl (Jet Planes of the Third Reich) on the other hand noted that the V4 was the first prototype. He explained that the previous three prototypes were actually related to the initial Bf 163 reconnaissance project that was rejected.
In-Service
Of the 10 built Me 163 A-0 planes, not all were equipped with fully operational engines. A number of them were instead operated as unpowered gliders. This version was not intended for combat operations and was mainly used for crew training and further experimentation.
At the end of November 1943, the V6 aircraft was lost in an accident with the loss of the pilot. In another accident at the end of 1943, another pilot died when the engine stopped working during a takeoff. While the pilot tried to turn back for a landing, having limited control, the aircraft hit a ground station radio antenna before hitting the ground and exploding. It was discovered in an investigation that the undercarriage dolly bounced off the ground much higher than usual, and struck the aircraft, damaging the rocket engine. Some prominent pilots, like Hanna Reitsch, actually had the chance to flight-test the Me 163 aircraft. At least one aircraft was still operational by February 1945 and was used for testing the 55 mm R4M rockets by Erprobungkommando 16.
Me 163A at Peenemunde, 1943. [Ransom & Cammann]At least one Me 163A survived up to February 1945. It was used by Erprobungkommando 16 (Eng. testing or evaluation-coomand) in Silesia to test the 55 mm R4M rockets. This unit had the primary function of testing and examining the newly built Me 163 and helping in the development and improvement of its overall design. Besides these, no other armament was installed on the Me 163 A series. Source Source: W. Spate and R. P. Bateson Messerschmitt Me 163 Komet
Technical Characteristics
The Me 163A was a high-speed, rocket-powered, swept-wing, short fuselage, mixed-construction tailless aircraft. The Me 163A fuselage was built using metal, divided into three sections, the front cockpit, central fuel tank, and the aft engine compartment.
The wooden wings had a very simple design consisting of two spars covered in thick fabric. If needed, the wings could be detached from the fuselage for transport. At the wings’ trailing edges ailerons were placed, which the pilot during flight used for pitch and roll. The wing area was 17.5 m² (57.4 ft²). The tail did not have the standard horizontal stabilizers, instead of having a single large vertical stabilizer. Despite this, no major problems during flights were ever noted on the Me 163A.
For the pilot to enter the cockpit he was provided with a ladder placed on the left side of the aircraft. The cockpit canopy opened upwards. Overall visibility was poor, and later versions would have an improved canopy. While it did offer some improvements for the pilot’s line of sight, it would not resolve the overall poor visibility of the aircraft. Given that the Me 163A was based on a DFS 194 glider, it was equipped with minimal instrumentation needed for the aircraft to be flown.
View of the Me 163A’s cockpit interior. [Spate & Bateson]The Me 163A was powered by a single HWK R II 203 rocket engine, which gave 750 kg (1,650 lb) of thrust. The main fuel consisted of a mix of T and Z Stoff. These two chemicals were highly reactive, volatile, and prone to explosion. To avoid this, extensive preparation and security measures were necessary. The maximum speed this engine achieved was some 850 km/h (530 mph). This high speed was achieved to some extent thanks to the aircraft’s low weight. The empty weight was 1,140 kg (2,513 lbs) while the maximum takeoff weight was 2,200 kg (4,850 lbs).
Interestingly, in order to save weight, the Me 163 did not have a conventional landing gear unit. Instead, during take-off, it was provided with a specially designed two-wheel dolly. It would be jettisoned upon take-off. When landing on the airfield, the Me 163 used a retractable skid located beneath the fuselage.
Despite the A series having not been designed to have any weapon systems, at least one Me 163A was tested with the installation of the 5.5 cm (2.16 in) R4M air-to-air rockets.
Production Versions
DSF 194 – Prototype whose further development led to the creation of the Me 163
Me 163 Prototype Series– Prototype aircraft
Me 163A-0 – 10 Pre-production aircraft built
Conclusion
The Me 163A series, despite its unusual appearance and overall design, proved to be a rather successful aircraft. It had some shortcomings, mostly regarding its dangerous fuel load. Upon completion of successful testing, order for the Me 163B version was given.
Me 163A Specifications
Wingspans
8.85 m / 29 ft 3 in
Length
5.25 m / 17 ft 2 in
Height
2.16 m / 7 ft 8 in
Wing Area
17.5 m² / 57.4 ft²
Engine
One HWK R II 203 rocket engine with 750 kg (1,650 lbs) of thrust
Empty Weight
1,140 kg / 2,513 lbs
Maximum Takeoff Weight
2,200 kg / 4,850 lbs
Maximum Speed
850 km/h / 530 mph
Crew
1 pilot
Gallery
Me 163A – Illustrated by Carpaticus
Credits
Written by Marko P.
Edited by by Ed Jackson & Henry H.
Illustrations by Carpaticus
Sources
D. Nešić (2008) Naoružanje Drugog Svetsko Rata-Nemcaka. Beograd.
W. Spate and R. P. Bateson (1971) Messerschmitt Me 163 Komet , Profile Publications
M. Ziegler (1990) Messerschmitt Me 163 Komet, Schiffer Publishing
M. Emmerling and J. Dressel (1992) Messerschmitt Me 163 “Komet” Vol.II, Schiffer Military History
E. T. Maloney and U. Feist (1968) Messerschmitt Me 163, Fallbrook
S. Ransom and H.H. Cammann (2010) Jagdgeschwader 400, Osprey publishing.
D. Donald (1990) German aircraft of the WWII, Brown Packaging books ltd
D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
M. Griehl (1998) Jet Planes of the Third Reich, Monogram Aviation Publication
M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book
German Empire (1917)
Heavy Bomber Prototype- 4 Built
Linke-Hoffman R.I 40/16 side view. [The German Giants]The Linke-Hofmann R.I was an experimental heavy bomber developed by the German Empire in 1917. The R.I would be unique, as one of the first prototypes to be constructed mostly out of a translucent material known as cellon, with the idea that it aircraft would be harder to spot. Unfortunately for the designers, cellon is highly reflective and ended up making the craft a much more noticeable target. After the failure with cellon, more work continued on the prototypes, now of normal fabric skinned construction. Due to poor performance caused by several design choices, the type was not mass produced and was subsequently cancelled.
History
A drawing of the R.I done by Linke-Hoffman. Notice the 3 gun positions. [German Aircraft of Minor Manufacturers Volume II]During times of war, it is not too uncommon for companies, factories and other industrial firms to be drawn into the war effort and end up producing materials that are as far away from their specialty as possible. Sometimes, this can end in a surprise success or a total blunder. This was no exception in the first World War for the German Empire. The concept of the military airplane had seen its first successes early in the war,and the need for aircraft was on the rise, but a major problem came in the fact that there were few dedicated airplane companies in Germany at the time. Thus, the Empire would call upon many of its industrial manufacturers to begin designing and producing aircraft, even if they were not familiar with working in that field. Linke-Hofmannn would be one such company.
3-Way drawing of both versions of the R.I [The German Giants]Linke-Hofmann, sometimes misspelled Linke-Hoffman, was founded in 1912 and was a manufacturer of railroad components, mainly locomotives and rolling stock. In early 1916, the company would enter the field of aviation by using their factories for aircraft repairs and for license built construction of aircraft. Some aircraft types they built under license were the Roland C.IIa, Albatros C.III, Albatros C.X and the Albatros B.IIa. At the same time, Linke-Hofmann was also awarded a contract to produce their own aircraft. The first of their home built aircraft would be an R-Plane type or Riesenflugzeug (giant aircraft), which was the designation given to the largest multi-engine bomber aircraft of the Empire. Linke-Hofmann’s R.I design would be a strange looking machine. Its fuselage was short and tear-drop shaped to streamline the design . Each pair of wings would be mounted extremely high and low on the fuselage in an attempt to increase lift. Four internal engines would be connected to four propellers, two in pusher configuration and two in puller configuration. Most interestingly, a majority of the tail of the aircraft would be made out of a material called Cellon. Cellon (Cellulose Acetate) is a translucent, plant-based material similar to film that was tested on several German aircraft in WWI, swapping out the normal fabric. The idea behind having the airframe covered in such material was that it was thought to make the aircraft harder to see. In addition to the Cellon, the R.I also had a very large cockpit with a number of windows to give much better visibility. Many of these design choices were made as it was thought they would make the design perform better in the long run, but they would ultimately lead to its downfall.
The R.I 8/15 under construction. The Cellon is clearly visible [German Aircraft of Minor Manufacturers Volume II]The Cellon tail of 8/15 [German Aircraft of Minor Manufacturers Volume II]
The completed R.I 8/15
Work began on the first R.I in the later months of 1916 under Chief Engineer Paul Stumpf, who previously worked for the AEG aircraft works. The first R.I was completed in early January of 1917 and was named the R.I 8/15. Testing of the aircraft began, but its first flight was delayed due to the unconventional steel tires coming apart during taxiing attempts. Improved versions of the tires were built that were much more stable than the first. Shortly after, the R.I 8/15 would fly for the first time from the Hundsfeld Airfield near Breslau, but the exact date is unknown. Early test flights showed the design was flawed and as time went on, performance began to suffer, although the exact reason was not known. Noticeably, the wings seemed to be the root cause of the lag in performance. The aircraft’s controls would occasionally become heavy and unresponsive, resulting in a partial loss of control. To amend this to some degree, several additional struts were added to the main wings, but this would not save the aircraft from disaster. On May 10th 1917, during its 6th test flight, two of the wings on the R.I 8/15 would collapse mid-flight and the aircraft would slam into the ground at full speed. Remarkably, all of the crew of the aircraft would survive, but the airframe itself would be destroyed in a blaze of fire caused by the crash. Unfortunately, 1-2 ground crew would die from the flames while trying to put them out.
The destruction of the 8/15 would force Linke-Hofmann to look into designing an improved model. At this time, many of the design choices Linke-Hofmann made with the aircraft would show how ineffective and even detrimental they were. The wings themselves were the root cause of the crash, as they were not stable nor very well supported. The Cellon material, which was thought to make the aircraft invisible, actually ended up doing the exact opposite, as the material was highly reflective, especially while the aircraft was airborne. Cellon itself also was not the most stable material to make most of the tail section of the aircraft out of, as the material itself could easily bend and warp during rough weather. Even when the material worked as needed, it aged to a yellow color that would remove the translucency. Even before the aircraft took flight, Linke-Hofmann would be criticized for making an aircraft mostly out of the little tested material. In order to amend these issues, the Idflieg ,,the Imperial organization that handled aircraft development, ordered several improved models to continue the development of the type, as the 8/15 had crashed before most of the evaluation had completed. Linke-Hofmann would then begin construction on the improved models, serial numbers 40/16 through 42/16. These improved variants on the R.I attempted to fix many of the issues that plagued the 8/15. The wing structure was redesigned to be significantly more stable, with additional struts forming an overall better design. Most of the Cellon in the aircraft had been replaced with standard fabric, with only a few small patches of the tail containing it, likely to serve as observation windows. The landing gear was also heavily improved, something the Linke-Hofmann Engineers were quite proud of. Lastly, the new airframe was also built to accommodate three positions for machine gunners. These small improvements mended these few issues, but the aircraft’s design was still riddled with flaws.
40/16 in flight. [German Aircraft of Minor Manufacturers Volume II]Details regarding the history of the improved variants are, unfortunately, not well known. It is unknown exactly when the R.I 40/16 first flew or when it was even built, but the handling of the aircraft had been significantly improved upon over the 8/15. Maneuverability was especially stated to be superb compared to the older model, but its general performance was still considered to be unsatisfactory. Landing the aircraft was stated to be terrible due to the high location of the pilot and the slow landing speed.
The crashed 40/16 after a taxiing accident. [German Aircraft of Minor Manufacturers Volume II]During one landing attempt while testing the 40/16, the test pilot misjudged how close he was from the landing strip due to the height of the aircraft and damaged the landing gear. Due to the teardrop shape of the aircraft, the entire thing went nose down into the ground, crushing the entire cockpit section. It is unknown if anyone was killed or injured during the crash, but no attempt was made to repair the aircraft afterwards and it was likely scrapped. Details on the 41/16 and 42/16 are even more lacking. Some sources claim they were never completed, while other sources state they were complete and ready for inspection before the program concluded. 41/16, in particular, has virtually no information or photos of the aircraft, but two photos exist of a finished 42/16 sitting outside the Linke-Hofmann factory in Breslau.
Design
A direct frontal view of 40/16. The unique engine-propeller arrangement can be seen clearly, as well as the tall profile of the aircraft. [German Aircraft of Minor Manufacturers Volume II]Pilot’s position of the R.I [German Aircraft of Minor Manufacturers Volume II]The Linke-Hofmann R.I was a four engined R-Type aircraft with a large teardrop-shaped fuselage covered in fabric. The fuselage was designed in such a “whale” configuration to contain its engines and reduce drag, but this was only ever tested on smaller aircraft and likely detrimentally affected the R.I. The front of the aircraft was divided into three different floors. The first floor contained the pilot’s position and the wireless station for communication. This floor had extensive glasswork to provide a good view around the front of the aircraft. The large amount of glass used in the cockpit only helped during clear weather as, during rain or if illuminated by a searchlight, it would cause visibility to suffer from light reflection and condensation.
Engine Room containing the four Mercedes D.IVa engines
The second floor contained the four Mercedes D.IVa engines. The third and lowest level contained the bombardier’s station and four internal fuel tanks. The tail of the R.I differed between the two variants. On the earlier 8/15, the tail was composed mostly of Cellon, while on the later 40/16, it was covered in fabric. The tail of the aircraft had a biplane horizontal stabilizer and three vertical fins for vertical stabilizers. The two additional fins vertically and the upper wing of the horizontal stabilizers were used as control surfaces on top of the conventional placement of said control surfaces. The wings of the aircraft were placed high and low on the aircraft, with the fuselage height directly separating each wing. Only the upper wings had ailerons fitted. The wings on the 8/15 were actually the lightest of any R-Plane built, which was a likely factor in its crash. The 40/16 had improved and more stabilized wings compared to its predecessor. The aircraft originally was planned to have four propellers, two in tractor and two in puller configuration but this design aspect doesn’t appear to have ever left the drawing board. Instead, only two were used in tractor layout. The engines powered the propellers in a very unique way. Each side of the aircraft had one propeller, which was connected to a pair of engines via outrigger frames and powered through a drive shaft connected to a bevel gear. Each pair of engines powered one side. This was done so that, in the event one of the engines was disabled through either malfunction or combat, the propellers would still have power going to them. A disabled propeller would begin windmilling, or rotating without power, and cause significant drag. On larger aircraft, this would seriously alter performance and cause the aircraft to lose speed and airflow due to drag. This complex system was put into place to prevent this from happening.
R.I 40/16 outside of the Linke-Hofmann factory. [The German Giants]No armament was carried aboard the R.I, but several proposals were made. Three machine-guns of unknown type and caliber were to be located at three positions around the aircraft. Two were located on the tallest point of the body, with one facing forward and one facing backward to cover all angles. The third gun position was located in the middle of the aircraft, with two open windows on each side to provide maximum firing range to each side. Given it was an R-Plane, the R.I would have used bombs had it entered mass production, but it’s loadout was never addressed, since the type was considered a failure.
Conclusion
The only two images of the Linke-Hoffman R.I 42/16 near the Linke-Hoffman factory [The German Giants]With the destruction of two aircraft and the type severely underperforming to expectations, the Idflieg lost their faith in Linke-Hofmann’s R.I program and it was promptly cancelled before January 1918. The 41/16 and 42/16 were most likely scrapped before the end of the war. The type was riddled with flaws from the beginning due to the strange decisions made by Linke-Hofmann in designing their first aircraft. Despite their failure at the start of their aircraft manufacturing career, Linke-Hofmann would use the experience learned from the R.I to create an improved and much more traditional looking R-Plane aircraft, the R.II.
Variants
Linke Hofmann R.I 8/15 – First version of the R.I. This version’s tail and rear fuselage were constructed of the transparent material Cellon.
Linke Hofmann R.I 40/16 – Improved version of the R.I 8/15. This type had many slight modifications, such as a better wing structure, a more stable landing gear, and was no longer constructed of Cellon. 3 of this type were built.
Operators
German Empire – The Linke-Hofmann R.I was an R-type aircraft meant to be used in the heavy bomber role for the German Empire. However, due to poor performance, the type was never mass produced or sent into service.
The Linke Hofmann R.8/15 – Note the extensive use of transparent cellon for the aft portion of the fuselage.The Linke Hofmann R.40/163-Way drawing of both versions of the R.I [The German Giants]
Credits
Written by: Medicman11
Edited by: Stan L. & Henry H.
Illustrations by Ed Jackson
Sources
Kosin, Rüdiger. The German fighter since 1915. Baltimore, Md: Nautical & Aviation Pub. Co. of America, 1988. Print.
Herris, Jack. German Aircraft of Minor Manufacturers In WWI Volume 2: Krieger To Union, Columbia, SC: Aeronaut Books, 2020. Print.
Haddow, G. W., and Peter M. Grosz. The German giants : the German R-planes, 1914-1918. London: Putnam, 1988. Print.
Empire of Japan (1945) Kamikaze Aircraft – 105 Built
The Ki-115 suicide aircraft [Combat Workshop via Pinterest]
Throughout 1945, it was becoming clear to Japanese Army Officials that an Allied invasion of the Japanese mainland was growing ever more likely. Seeing as their navy and airforce had been mostly destroyed, they needed new weapons to fight off a probable Allied attack on Japan. Among these new weapons were Kamikaze aircraft, with many older designs having already been used in this role. However, some Kamikaze aircraft were to be specially designed for such a role, being cheap and able to be built quickly and in great numbers. One such aircraft was the Ki-115 Tsurugi (Sabre) which was built in small numbers, and never used operationally.
History
Rear view of Ki-115 suicide aircraft [ijaafphotos.com]Following the extensive loss of men, materiel, and territory during the fighting in the Pacific, the Japanese Army and Navy were in a precarious situation, especially as there was a great possibility of an Allied invasion of their homeland. Unfortunately for them, the Japanese fighting forces on the ground, in the air, and on the sea were mostly mere shadows of their former selves, unable to prevent the rapid Allied advance across the Pacific. This was especially noticeable after the costly Japanese naval defeat during the Battle of Leyte Gulf in October 1944 and later Battle of Okinawa which ended in July 1945.. The desperation, or better said fanatical refusal to accept that the war was lost, led to the development and use of Kamikaze (divine wind) tactics. This name was taken from Japanese history, the term arose from the two typhoons that completely destroyed the Mongol invasion fleets.
Essentially, the Kamikaze were Japanese pilots that used their own explosive-laden aircraft as weapons, and sought to crash into important targets, such as Allied warships. This term also entered widespread use to designate all Japanese suicide craft used in this way. During the war, these tactics managed to sink over 30 Allied ships and damage many more.
Allied anti-aircraft fire was often concentrated in order to prevent Kamikaze attacks. But, despite this, Japanese aircraft would often get through. [Wiki]The suicide attacks were mostly carried out using any existing aircraft that was operational, including older trainers and obsolete aircraft. Kamikaze are a subject with a great deal of nuance and can be difficult to understand through a conventional lens. However, supplies of these aircraft would inevitably become limited and their previous usage meant fewer would be serviceable compared to newer, more expensive models. Thus, the Japanese Army wanted a specially designed Kamikaze aircraft that could be produced in great numbers. These aircraft needed to have a simple construction and use as little of dwindling material stockpiles as possible.
On 20th January 1945, the Japanese Army contacted the Nakajima aircraft manufacturer with instructions to design and build such an aircraft. The basic requirements included a bomb load up to 800 kg (1,760 lbs). It had to be able to be powered by any available radial engine in the range of 800 hp to 1,300 hp. The maximum speed desired was 515 km/h (320 mph). Construction and design had to be as simple as possible. They also wished to speed up the whole development and production process and also to reduce the need for skilled labor. It was especially emphasized that the undercarriage had to be jettisonable, not retractable. It was not expected for the aircraft to fly back, so a retractable landing gear was not needed and this would make the production and design process somewhat quicker.
First Prototype
The job of designing this aircraft was given to Engineer Aori Kunihiro. He was supported by engineers from Ota Manufacturing and the Mitaka Research Institute. While Nakajima received the contract in January 1945, it only took two months to complete the first prototype. In March 1945, this prototype was presented to the Japanese Army and then put through a series of tests. Almost immediately, a series of faults with the design were noted. This was not surprising given that the whole design process lasted only two months. During running on the ground, the fixed and crude undercarriage was difficult to control. The pilot’s poor frontal visibility further complicated matters. This was unacceptable even for skilled pilots, while less experienced pilots would have had great difficulty in successfully operating it on the ground. The Army rejected the prototype and requested a number of modifications to be done.
The Ki-115 first prototype. [ijaafphotos.com]The Ki-115 cockpit was positioned in the middle of the fuselage and offered the pilot limited forward vision when on the ground. [Wiki]
Technical Specifications
The Ki-115 was designed as a low-wing mixed construction suicide attack aicraft. The front fuselage, containing the engine compartment, and the central part were built using steel panels. The engine compartment was held in place by four bolts and was specially designed to house several different potential engines. Eventually, the Japanese chose the 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine. It had a fixed-pitch three blade propeller. In order to help reach its target quicker, two small auxiliary rocket engines were placed under each wing.
The wings were built using all-metal construction with stressed skin. The rear tail unit was built using wood and was covered by fabric. The cockpit was placed in the upper centre of the fuselage. It was semi-open, with a front windshield.
As requested, the Ki-115 prototype had a fixed and jettisonable undercarriage. It had a very simple design, using simple metal tubes with no shock absorbers. While two wheels were used in the front, a tailskid was used at the rear. The fixed undercarriage tested on the prototype proved to be highly ineffective. All later produced aircraft were instead equipped with a simple and easy to build shock absorber.
Ki-115 side view [ijaafphotos.com]The armament consisted of a bomb load of up to 800 kg (1,760 lbs). This included using either a single 250 kg (550 lb), 500 kg (1.100 lb) or 800 kg (1.760) bomb. The bomb was not to be dropped on the enemy, but instead be detonated once the aircraft hit its target. Beside the bomb, no other armament was to be provided on the Ki-115.
The Ki-115 was initially meant to be supplied with a fixed undercarriage, which proved to be problematic. Production aircraft were instead provided with simple shock absorbers. [ijaafphotos.com]
The Fate of the Project
Once the prototype was back in Mitaka Kenkyujo (where the prototype was built), the engineers began working on improving its performance. The redesigned undercarriage, which incorporated a simple shock absorber, was completed by June 1945, by which time a series of test flights were done. By August 1945, some 104 Ki-115 aircraft were ready. Two Ki-115s were given to Hikoki K.K., where the Japanese Navy Air Force was developing its own suicide attack aircraft. By the war’s end, none of the Ki-115s built would be used in combat.
Surviving Aircraft
The Ki-115 planes were later captured by the Allies, and nearly all were scrapped. Surprisingly, two Ki-115s have survived to this day. One can be seen at the Pima Air & Space Museum. This aircraft is actually on loan from the National Air and Space Museum. The second aircraft is currently located in Japan. Not wanting to potentially damaged tis aircrafts on the side of caution no restoration attempts are planned for the near future.
The surviving Ki-115 at the Pima Air & Space Museum. [Wiki]A picture of the second surviving aircraft taken during the 1980’s in Japan. [hikokikumo.net]
The Ki-115b Proposal
In order to further improve the aircraft’s performance and reduce cost, the Ki-115b version was proposed. This included replacing the all-metal wings with ones built of wood. These new wings were larger and had to be equipped with flaps. To provide the pilot with a better view, his cockpit was moved to the front. Due to the end of the war, nothing came from this proposal.
Production and Modifications
The Ki-125 was built in small numbers only, with some 104 production planes plus the prototype. These were built by the two Nakajima production centres at Iwate (22 aircraft) and Ota (82 aircrafts). The production lasted from March to August 1945.
Ki-115 prototype – Tested during early 1945.
Ki-115 – In total, 104 aircraft were built, but none were used operationally.
Ki-115b – Proposed version with larger wooden wings, none built.
Only 105 Ki-115 aircraft, including the prototype, were ever built. [ijaafphotos.com]
Conclusion
Luckily for the Japanese pilots, the Ki-115 was never used operationally. It was a simple and crude design which was born out of desperation. If the Ki-115 was ever used in combat, it would have likely presented an easy target for enemy fighters and suffered from poor reliability due to its cheap construction.
Ki-115 Specifications
Wingspan
28 ft 2 in / 8.6 m
Length
28 ft 1 in / 8.5 m
Height
10 ft 10 in / 3.3 m
Wing Area
133.5 ft² / 12.4 m²
Engine
One 1,130 hp Nakijama Ha-35 14 cylinder radial piston engine
Another Ki-115 Tsurugi in Natural Metal with 500kg Type 92 BombKi-115 Tsurugi in Green with 500kg Type 92 BombKi-115 Tsurugi in Natural Metal with 500kg Type 92 Bomb
Credits
Written by: Marko P.
Edited by: Stan L. & Henry H.
Illustrations by Ed Jackson
Sources
R. J. Francillon (1970) Japanese aircraft of the Pacific war, Putham and Company
D. Nešić (2007) Naoružanje Drugog Svetskog Rata Japan, Tampoprint
D.Mondey (2006) Guide To Axis Aircraft Of World War II, Aerospace Publishing
Nazi Germany (1940)
Jet Powered Bomber & Reconnaissance Aircraft – 8 Prototypes Built
The Ar 234 A V6 (GK+IW) prototype. [Warbirdphotographs]
Following a request from the German Ministry of Aviation (Reichsluftfahrtministerium – RLM), in 1940, German aircraft manufacturer Arado began working on a new multi-purpose jet powered plane. Arado’s work would lead to the development of the advanced and sophisticated Ar 234 aircraft. During 1943, a small series of eight prototypes would be built and used mainly for testing, but some saw operational service.
History
During the spring of 1940, Arado was contacted by RLM officials with a request to design a completely new multi-purpose jet aircraft to be used for bombers and for reconnaissance duties. This aircraft was to be powered by new jet engines which were under development by Junkers and BMW. Interestingly, besides the request that it should be able to reach the British naval base at Scapa Flow in Northern Scotland, no other performance requirements were specified. The sources do not specify the precise base of operation for these reconnaissance missions. Geographically, the closest territories under German control were south Norway and Denmark, although it is possible that these aircraft would have had to operate from air bases in the occupied territories in Western Europe, either from France, the Netherlands or Belgium. This would require an estimated range of over 900 km. In essence, the RLM gave Arado free reign in terms of the overall design and its performance. If the prototypes built were satisfactory, an initial order for 50 aircraft was to be given.
Work on this new design was given to engineer Rüdiger Kosin, as Arado’s Technical Director, Walter Blume, was uninterested in this project. When work started, it received the Arado Erprobungs (experimental) 370 designation. During the initial phases, there were several different proposals about the number of crewmen, wing size, weapon configuration and the number of engines. After nearly a year, in October 1941, the first proper project, designated the E 370/IVa, was completed. This proposal was mainly intended to be used as a reconnaissance aircraft and was to be equipped with camera equipment. It was to be powered by two BMW P 3302 turbo jet engines. The armament was quite modest and consisted of only one 13 mm MG 131 machine gun. As this aircraft was to operate from short-length airfields, the designers came up with the idea to use a wooden retractable skid for landing, which was to be mounted beneath the fuselage.
E 370/IVa drawings. [Smith & Creek, Arado 234 A]
The project was presented to RLM officials in late October of 1941. They were satisfied and gave permission for the production of 50 aircraft. During the evaluation, it received the 8-234 designation. Unfortunately for Arado, the head of the RLM Technical Department, Ernst Udet, committed suicide just a few weeks later. He was replaced by Erhard Milch, who was more interested in aircraft that were already being produced rather than the proposed Arado project. This without a doubt affected the earlier mentioned initial production order, as the initial order for 50 seems to disappear from record. Despite this setback, work on the E 370 continued. During early 1942, some modifications to the fuselage were made with the aim of increasing its size and strength. The unusual skid undercarriage was replaced by a retractable wheeled bogie system.
In February 1942, Erhard Milch visited the Arado company. He was presented with the drawings and calculations for the improved E 370 model. He was generally impressed with what he saw, and gave his permission for the construction of a wooden mockup. The order would be increased to six prototypes in the following month. The aircraft was to take off using a small three wheel dolly. After the aircraft was in the sky, the dolly was jettisoned and landed with the help of a parachute, meaning it could be used again. In addition, the idea of using a retractable skid undercarriage was reintroduced. If needed, jettisonable Walter HWK auxiliary rocket take-off engines could be attached under the wings. Throughout 1942, many additional modifications and changes were made to the design. Great attention was given to the testing of different engine types and configurations.
By the end of 1942, the number of prototypes to be built was once again increased to 20. The first seven aircraft were to be powered by Jumo 004 engines, with prototype V8 powered by four BMW 003 engines, and V9 through V14 with two BMW 003 engines. The remaining aircraft were to be powered by four BMW 003 engines. The first prototype was meant to be built by November 1943, with the last in October 1944. Surprisingly, these 1942 plans actually started to be completed early, with the first 3 prototypes ready by August 1943. Thanks to this, it was possible to run the first test trials even earlier than anticipated.
Work on the First Prototypes
Work on the construction of the first prototype began in late 1942. During this time, the name was changed to Ar 234. Progress was slow due to problems with the delivery of the Jumo 004 engines, which only arrived in February 1943. These engines were tested and immediately proved to be problematic, as they failed to achieve the promised 850 kg (1879 lbs) thrust. Once fitted with these engines, the first prototype, Ar 234 V1, was used for static ground testing and taxiing trials. No flight was initially accepted due to the short runway at Brandenburg, where the prototype was built. For this reason, the prototype was moved to a Luftwaffe airfield at Munster. During July 1943, this aircraft was mainly used for ground tests. In late July, there was an accident when one of the Jumo engines caught fire. The damage was minor and was quickly repaired. On 30th July, Ar 234 V1 made its first test flight piloted by Horst Selle. The flight was successful, with no problems with the aircraft. The dolly, on the other hand, was lost when the parachute failed to properly open. In early August, there were again problems with the same engine. To avoid any potential threat to the aircraft, it was simply replaced by an engine taken from Ar 234 V3, which was under construction. On 9th August, another test flight was undertaken. During this flight, Selle reached a speed of 650 km/h (400 mph) without any problems. The dolly was once again lost, similarly to the first one. Additional changes were made to the position of the parachute on the dolly, which proved to be the solution to this problem. The V1 prototype would be lost in an accident where the pilot overshot the landing field and crash landed on 29th August. While the aircraft was not repaired, parts of it were reused for testing other equipment.
The Arado 234 V1 first prototype. This particular aircraft would be lost in an accident where the pilot overshot the landing field and crash landed on 29th August 1943. [Warbirdphotographs] V1 during the third test flight, during which the dolly parachute release system was successfully tested. [Luftwaffephotos]
The V2 prototype was completed in late August 1943. There were some issues with the engine, which had to be replaced. The aircraft was otherwise trouble-free. It was moved to Alt Lonnewitz, where it was mainly used for engine testing. In late September 1943, V3 made its first flight. While, initially, it was to be equipped with a pressurized cabin and an ejector seat, this was never implemented.
In early October 1943, the V2 prototype, with its pilot, Selle, were lost in a fire. This accident prompted the Germans to introduce automatic fire extinguishing systems on all of the Ar 234 prototypes, including later ones. Another change was introducing ejection seats to avoid any further pilot casualties. Due to this accident, there were some delays in the Ar 234 project. Testing continued in November, when V3 was piloted by Walter Kroger. On the 21st of November, the V3 aircraft was transferred to Insterburg to be presented to Adolf Hitler, together with other experimental jet aircraft, like the Me 262 and Me 163. Hitler was highly impressed and even gave orders that some 200 aircraft be built during 1944. During this time, V4 was also flight tested. Both V3 and V4 were used until June 1944 for various roles, including crew training, after which they were removed and replaced with later Ar 234 B versions. By the end of 1943, V5, fitted with Jumo 004 B-0 engines. was introduced.
During early 1944, two Arado 234 aircraft would be tested with a four engine configuration. The idea was that the use of four smaller engines would provide similar performance to the larger ones. V8 was powered by two pairs of BMW P.3302 engines. V6 (which was built later than V8) was tested with four BMW 003 engines placed in four separate wing-mounted nacelles. During a routine flight of V6 at the start of June 1944, all four engines stopped working only 17 minutes after take-off. The pilot was forced to conduct an emergency landing of the plane, after which it caught fire and was heavily damaged, rendering it a complete loss. After this accident, and due to many other engine problems with both versions, all further work on the multi-engined Ar 234 A was discontinued. These would later serve as the basis for the Ar 234 C version instead.
V6 powered by four BMW 003 engines placed in four separated wing cowlings. [Luftwaffephotos] V6 after a forced landing in June 1944, shortly before the engines began to burn. This accident and problems with the engines put an end to the development of the multi-engined Ar 234 A version. [Warbirdphotographs] V8 was powered by four BMW P.3302 engines placed in pairs. [Warbirdphotographs]
Technical Characteristics
The Arado Ar 234A (as they were designated later on) prototypes were designed as all metal, high-wing turbojet-powered experimental reconnaissance planes. Their fuselages had a semi-monocoque design with a flat top. The wings consisted of two main spars, each with 29 ribs. They were covered with metal stressed skin. Each wing was connected to the fuselage by four bolts. If needed, these could easily be taken off and removed. At the rear, there was a more or less conventional tail unit.
The Ar 234 was used to test a number of different engines. The first 4 prototypes were powered by two Jumo 004 A-0 engines, which had 840 kg (1,850 lbs) of thrust. V5 and V7 used Jumo 004 B-0 engines which provided 900 kg (1,980 lbs) of thrust. The 3.8 m (12 ft) long engines (both types had the same size) were attached to the wings using three bolts. V6 and V8 were powered by four engines which were able to achieve 800 kg (1,760 lbs) of thrust. As the Ar 234 was intended to be used for reconnaissance operations, a large fuel capacity was important. One 1,800 liter fuel tank was placed behind the cockpit, with a second 2,000 liter tank in the rear of the fuselage. With this fuel load the Ar 234 had an operational range of 1,500 km (930 miles). To assist with take-off, the Ar 234 could be equipped with small Walter 109-500 type rocket engines. These had a run time of 30 seconds and could generate 500 kg (1,100 lbs) of thrust. After the Ar 234 was in the air, the rocket motors would be jettisoned and would land on the ground using small parachutes.
The Ar 234 did not have conventional landing gear, but instead used a three wheel 640 kg (1,410 lbs) jettisonable take-off assist dolly. The Ar 234 pilot could control this dolly by using the rudder, which was connected to hydraulic brakes on the dolly. Once in flight, the dolly would detach and then fall back to Earth using a parachute, and could thereafter be reused. Initially, it was discarded during flight, but this proved to be problematic. After some redesign work, the moment of release was changed to just after take-off. There was no risk of the dolly impacting the fuselage in midair, as the parachute pulled it away from the aircraft. When the Ar 234 had to land, it would use the retractable hydraulically operated skid under the fuselage. The engine nacelles were also provided with smaller skids to avoid any damage to them and to provide better stability during landing. The V3 prototype tested in early 1944 used a drag parachute during landing. This proved to be successful and was later implemented as standard from the B series on.
The smaller front wheel on the jettisonable dolly was fully steerable to help during airfield taxiing and take-offs [Warbirdphotographs] Close up view of the large sliding skid. [worldwarphotos.info] Ar 234 during landing. A fuselage skid along with smaller skids placed under the engine nacelles were used instead of wheels. Later versions of the Ar 234 incorporated a conventional wheeled landing gear. [Warbirdphotographs]
The pilot’s cockpit was fully glazed, which provided excellent all around visibility. To enter the cockpit, the pilot used a small hatch placed atop the cockpit. This was not a great design feature as, in an emergency, the pilot could not easily escape the plane. In order to protect the pilot from enemy fire from the rear, a 15 mm thick armor plate was installed behind his seat. Behind this protective armor plate, three oxygen tanks were placed. The instruments were placed on two smaller panels to the left and right of the pilot.
A few Ar 234s were equipped with two Rb 50/30 cameras. These were placed behind the rear fuel tank. These could cover a wide area of 10 km (6 mile) at an altitude of 10 km (33,000 ft).
There were initial plans to arm the Ar 234 with a 13 mm machine gun for self defence. Due to the experimental nature of the Ar 234 A version, no actual armament would actually be installed.
Operational Service
In May 1944, Conny Noell of the Luftwaffe experimental Versuchsverband unit requested that at least two Ar 234 airframes be used for experimental reconnaissance operations after examining the prototypes. The request was accepted and the V5 and V7 aircraft were allocated for this task. Besides the camera equipment, virtually nothing else was changed on these two aircraft.
For the testing of these aircraft, two pilots were chosen, Horst Götz and Erich Sommer. At the start of June 1944, the V5 prototype was tested by Götz during a short 30 minute long flight. He later wrote, after the war “The take-off procedure was not very complicated. First, I engaged the starter, then fed petrol into the combustion chamber until, at approximately 6,000 rpm, I made the gradual change to J2 kerosene. The engines were then reved up to their maximum 9,000 revolutions. After take-off, I throttled the engine back to cruising speed. It was a completely new flying experience. Only a slight whistling noise in the cockpit could be heard. The take-off dolly had functioned quite normally. It was really wonderful”.
Four days later, Sommer also tested this aircraft and gave a similar positive assessment of its overall performance. More flights were undertaken in the following days without major problems. While piloting the V5 prototype during a routine take-off, Götz’ wheeled takeoff dolly release mechanism failed, with the assembly remaining stuck to the aircraft’s landing skids. He immediately tried to land back at the airfield. Despite the dangerous maneuver, he managed to land in a nearby potato field, with minimal damage to the plane.
Around this time, the two test pilots were informed that no prolonged or high-altitude flights had ever been attempted by the Ar 234 prototypes, mostly due to a lack of pressurized cockpit. For this reason, Sommer decided to personally test the Ar 234’s performance at altitude. In late June 1944, he made the first high altitude flight, which lasted over an hour and fifteen minutes at an altitude of 11 kilometers (36,000 ft). During a dive, he managed to reach a speed of 590 km/h (367 mph). A few days later, he made another similar flight that lasted over two hours, during which he managed to cover a distance of 1,435 km (890 miles). When the test flights were completed, both pilots gave positive feedback and evaluations about the performance of the planes and recommended their immediate production.
Following the Allied invasion of German occupied France in 1944, the experimental unit was ordered to move its two aircraft and equipment by train to Juvincourt, in France, by the end of July. Due to delays with the delivery of necessary parts, mostly due to Allied air raids, V7 was finally ready to take to the sky on the 2nd of August. V7’s first operational mission was to take photographs of the Allied landing beaches and the 10 km (6 mile) wide inland strip . The flight was a success, without any problems. The Ar 234’s cameras managed to take nearly 400 photographs of the Allied invasion force, which provided the Germans with vital information about the strength and numbers of the enemy. With this single flight, Sommer managed to achieve what the remaining Luftwaffe reconnaissance units failed to do in two months. During August, some 7 reconnaissance flights were undertaken by the two Ar 234 aircraft. Following the rapid Allied advance, they had to be relocated to Belgium. While V7, piloted by Sommer, arrived without any problems, Götz was less fortunate. During the flight, he was hit by friendly anti-aircraft fire. While damaged, Götz managed to fly up to Oranienburg. But his bad luck for that day was not yet over. His landed Ar 234 aircraft was struck from behind in a ground collision by a Focke Wulf Fw 190 which was attempting a take-off, completely destroying V5. Ironically, the first German operational jet powered aircraft, and the first in the world, was shot down by the Germans and then destroyed by a German fighter plane!
Sommer was stationed with his aircraft at Volkel in Holland until the 5th of September, when it was relocated to Rheine base. On the 10th, Sommer performed a reconnaissance flight over the Thames Estuary but, without direct orders, continued up to London. The next morning, he was informed that, due to this action, he was to be arrested and court martialed. Sommer immediately contacted Götz and explained the situation to him. Götz immediately took action and, after persuasions and threats, managed to get the charges against Sommer dropped. After the war, they both found out who demanded Sommer’s arrest. It was the chief of the V-2 program, Hans Kammler, who had feared that the pictures of London would prove the failure of his rocket program.
Part of the damage suffered by V5 during the forced landing and after being hit by ground anti-aircraft fire, shortly before being hit by an Fw 190 taking off. [Smith & Creek, Arado 234 A]
Sommer made at least four more reconnaissance flights with Ar 234 V7 before it was finally replaced with a B version, which was essentially just a copy of the previous version but with a wider fuselage and a more conventional completely retractable wheeled landing gear. After this, V7 was mainly used for crew training before being damaged during a take-off accident on 19th October 1944. After it was repaired, Götz made a flight to Oranienburg, where the plane was removed from service.
Production
Of the Arado 234 A series, only 8 aircraft were ever produced, as they were used for experimentation of various equipment and engine units.
V1 (TG+KB) – Badly damaged during a harsh landing.
V2 (DP+AW) – Was lost in a flight accident.
V3 (DP+AX) – Was presented to Hitler, who authorized the Ar 234 production. Used for various testing until July 1944.
V4 (DP+AY) – Similar to the V3 prototype, used up to June 1944 mainly for crew training, when it was removed from service.
V5 (GK+IV) – The first aircraft to be used operationally, but was lost when damaged by friendly ground-based anti-aircraft fire.
V6 (GK+IW) – Heavily damaged during a landing accident and caught fire soon after.
V7 (GK+IX/ T9+MH) – Used operationally until October 1944, when it was damaged in a take-off accident. Written off as a complete loss.
V8 (GK+IY) – Tested with a four engine configuration, but proved to be highly problematic.
Conclusion
While only a small number of Ar 234A planes were built, they proved to be successful designs. During the initial development phase and in their experimental use in service, no major issues were noted. The major drawback was the insufficient quality of the engines and the use of a jettisonable takeoff dolly. Following the success of the Ar 234 A, the development and production of the B and C versions was approved.
V1, the first prototype, made its first test flight piloted by Horst Selle at the end of July 1943. It would eventually be lost in an accident when the pilot overshot the landing field and crash landed on 29th August 1943. Ar 234 V5 was the first aircraft of the small production series to be used operationally during the Allied Liberation of France in 1944. It would be lost after a series of unfortunate circumstances culminated with a ground collision with a Focke Wulf 190 which was attempting a take-off. Ironically, the first German operational jet powered aircraft, and the first in the world, was shot down by the Germans and then destroyed by a German fighter plane! V5 was fitted with Jumo 004 B-0 engines. V6 was tested with four BMW 003 engines placed in four separate wing-mounted nacelles. During a routine flight at the start of June 1944, all four engines stopped working, forcing the pilot to conduct an emergency landing of the plane. After this, the plane caught fire and was heavily damaged, rendering it a complete loss.
Nazi Germany (1944)
Jet Fighter – 1 Incomplete Prototype Built
The P.1101 prototype after the war [Wiki]
During the war, German scientists and engineers managed to develop and build a number of jet powered aircraft, several of which went on to see combat. What is generally less known are the large number of experimental jets that were proposed and prototyped. These designs utilized a great variety of engines, airframes, and weapons. One of these unfinished projects was the Messerschmitt P.1101 jet fighter.
Need for a New Jet Fighter
Line drawing of the P.1101 [Luftarchiv]During the war, the Germans introduced the Me 262, which had the honor of being the first operational jet fighter in the world. While it provided better performance than ordinary piston powered aircraft, it was far from perfect. The greatest issues were that it was expensive to build, required two jet engines, and could not be built in sufficient numbers. The German Air Ministry (Reichsluftfahrtministerium; RLM) wanted a much simpler and cheaper design powered by a single engine. They issued a competition for a new jet fighter ,code named 1-TL-Jäger, during July 1944 for all available aircraft manufacturers. Some of the requirements listed were that it would be a single seater, have a maximum speed of 1000 km/h (620 mph), an endurance of at least one hour, armor protection for the pilot, make use of the Heinkel HeS 011 engine, and had an armament that had at least two 30 mm (1.18 in) MK 108 cannons. During a meeting with the leading German aircraft manufacturers held in September 1944, Messerschmitt presented the P.1101designed by Waldemar Voight.
The Messerschmitt P.1101 Development History
Drawing of the P.1101 before a number of design changes were introduced. [Luft46.com]Messerschmitt’s engineers and designers began working on designing a single engined jet aircraft at the start of 1943. Two projects, P.1092 and P.1095, were both powered by a single Jumo 004 jet engine, but, as the Me 262 was entering full production, their development was largely suspended. These projects were shelved until the RLM competition in 1944. Seeing a new opportunity, Messerschmitt presented drawings of a new project named P.1011, which was influenced by the previous projects. It had an all-metal fuselage construction and was powered by one HeS 011 engine with the air intakes placed on the wing’s roots. It also had a V-tail.
Following the meeting with the RLM officials in September, some changes were made to the P.1101’s overall design. Instead of two air intakes, a single one in the nose was to be used. This also necessitated the redesigning of the cockpit, which was moved back. In addition, the rear V-tail was replaced with a standard fin design. At this early stage, the possibilities of using this aircraft for other purposes were still being explored. Beside the standard fighter, other roles which were considered were night fighter and interceptor. On 10th November, the owner of the company, Willy Messerschmitt, issued orders to begin working on the first experimental prototype. To speed up the developing time, it was proposed to reuse the already produced components of the Me 262. The Me 262 fuselage, wings design and construction were to be copied.
End of the Project
The P.1101 prototype was only partially completed in early 1945. It appears that, despite Messerschmitt’s attempts to complete this project, the RLM simply lost interest. Messerschmitt’s other projects, like the P.1110 and P.1111, showed greater potential than the P.1101. This, together with the fact that the promised engine never arrived, meant that the single incomplete prototype was put into storage at the Messerschmitt Oberammergau research center. It remained there until the war’s end, when it was captured by American forces.
Technical Characteristics
Side view of the P.1101. This picture was taken at the Messerschmitt Oberammergau base. [Luftarchiv]The P.1101 was a single seater, jet engine-powered mixed construction fighter. The lower parts of the all-metal fuselage were designed to house the jet engine. In the front of the fuselage, a round shaped intake was placed. To the rear, the fuselage was additionally reinforced to avoid any damage due to the heat of the jet exhaust. The underside of the fuselage was to have a skid to help better land during an emergency.
While it was originally intended to be powered by the HeS 011 engine, the power plant was never supplied and the Jumo 004B was to be used as a replacement. The main fuel tank, with a capacity of 1,100 liters (290 gallons), was placed just behind the cockpit. Only a mock-up engine was ever installed in this aircraft, so it was never tested properly, even on the ground. Due to this, it is unknown what the P.1101’s overall flight performance would have been. Some sources give rough estimates, such as that it could have reached 890 km/h (550 mph) at sea level and up to 980 km/h (610 mph) at higher altitudes. Of course, these are only estimations contingent on the fact that the plane had no other problems during operational flight. In addition the general ability to test flight characteristics in the transonic-supersonic range were extremely crude at this point.
Close up view of the P.1101’s large front air intake for the jet engine. The markings painted on it were probably added by the Americans after the war. [Luftarchiv]The wing’s were made of wood materials. The prototype would have a completely innovative feature, namely the sweep angle of the wings could be adjusted at different angles ranging between 35° and 45°. The rear vertical and horizontal tail assembly was also made of wood.
The P.1101 had a retracting tricycle-type landing gear. It consisted of one forward mounted and two mid-fuselage wheels. All three retracted rearwards into the fuselage. The cockpit had a round shaped canopy with good all around vision.
The basic armament configuration consisted of two MK 108 cannons with 100 rounds each. These were placed in the front lower part of the fuselage. There were proposals to increase the firepower by adding two more MK 108 cannons, and the use of experimental air-to-air missiles was also considered. As the prototype aircraft was built to test overall flight performance, no armament was ever installed.
Rear view of the tail assembly. [Luftarchiv]
In American Hands
The restored P.1101 in America. [Pinterest]Advancing American soldiers reached the Messerschmitt Oberammergau base during April (or May) 1945. The single P.1101 was found there and, for some time, left open to the elements. The Bell Aircraft Chief Designer Robert Woods came to know of the existence of this aircraft. Once he had a chance to examine it, he organized for it to be shipped back to America for further study. It would be restored and used as testing mock up aircraft. The Bell aircraft design bureau paid great interest to the variable wing design. Working from the P.1101, they would eventually develop the Bell X-5, one of the first operational aircraft that could change the position of its wings during flight.
The Bell X-5 aircraft, which was heavily influenced by the German P.1101 design [WIki]
Conclusion
While incorporating the innovative feature of variable swept wings, the P.1101 was another victim of the chaotic state Germany was in at the end of war. Whether this aircraft could have performed its role is unknown, and while it never flew for the Germans, it helped the Americans develop the Bell X-5 after the war which incorporated the same variable wing design.
P. 1101 Specifications
Wingspans
27 ft / 8.24 m
Length
30 ft 1 in / 9.13 m
Height
9 ft 18 in / 2.8 m
Wing Area
170 ft² / 15.8 m²
Engine
One Jumo 004B or one HeS 011
Empty Weight
5,725 lbs/ 2,600 kg
Maximum Takeoff Weight
8,950 lbs / 4,060 kg
Fuel Capacity
1,100 l / 290 Gallons
Estimated Maximum Speed
610 mph / 980 km/h
Estimated Cruising speed
550 mph / 890 km/h
Crew
1 pilot
Armament
Two 108 MK cannons
Messerschmitt P.1101 PrototypeInitial P.1101 Design prior to changes
Credits
Article by Marko P.
Edited by Stan L. and Henry H.
Illustrated by Carpaticus
D. Nešić, (2008). Naoružanje Drugog Svetsko Rata-Nemačka. Beograd.
D. Monday. (2006). The Hamlyn Concise Guide To Axis Aircraft Of World War II, Bounty Books.
D. Sharp (2015) Luftwaffe Secret Jets of the Third Reich, Mortons Media Group
M. Griehl (2012) X-Planes, Frontline Books
R. Ford (2000) German Secret Weapons of World War Two, MBI Publishing
Jean-Denis G.G. Lepage (2009) Aircraft of the Luftwaffe 1935-1945, McFarland and Company
J. R. Smith and A. L. Kay (1972) German Aircraft of the Second World War, Putnam
The Modli-8 in use with the Yugoslav Aviation after the war. www.paluba.info
The Modli J.M. 8 was designed in the Kingdom of Yugoslavia, built by the Independent State of Croatia (NDH), and after World War II, operated by the Federal People’s Republic of Yugoslavia (FPRY). It was an inexpensive training aircraft that would be used in this role up to 1950.
The Beginning
The story of the Modli J.M. 8 began in 1938, when an aircraft engineer from the 1st Air Force Regiment (stationed at Novi Sad), Josip Modli, finished work on a new light training aircraft design. He originally intended to design and build a single seat trainer that was cheap and simple to manufacture by using mostly wood. He also intended to gain the interest of amateur aviators and aeroclubs with a low price. The J.M. 8 designation comes from the initials of the designer’s name. Due to its small size and low price, it earned the nickname Komarac/komaрац (Mosquito).
The following year, Modli actually began building this aircraft. He reused the small 18 hp engine taken from a damaged French HM.14 Pou du Ciel (Nebeska Vaš/Небеска Ваш in Serbian). Four had been bought from France in 1935 but, due to construction problems, their use was limited and all were damaged during test flights. One was tested at Novi Sad, where the 1st Air Force Regiment was stationed.
Modli reused the engine from a damaged HM.14 Pou du Ciel for his first prototype. Four of these small aircraft were bought from France. www.vazduhoplovnetradicijesrbije.rs
At that time, word of his design and work reached the Yugoslavian Air Force Headquarters. Headquarters then instructed (or ordered, depending on the sources) aircraft engineer Tišma, who was co-owner of the Albatros aircraft manufacturer from the cit of Sremska Mitrovica, to contact Modli. After short negotiations, Tišma and Modli reached an agreement that Albatros should finish the construction of the J.M. 8. If the design received any mass production orders, Modli agreed to provide Albatros with a license for its production.
The J.M. 8 was completed in early 1941, with testing scheduled to begin in March. Due to bad weather, Albatros’ main airport at Ruma was flooded during March and early April, so no tests flights were conducted. During the outbreak of the April War (Axis invasion of Yugoslavia), all finished and partially constructed planes from Albatros were loaded on a train on the 10th of April. Because of the great confusion due to the outbreak of war and the lack of documentation, the fate of this train and its cargo is unknown to this day.
After the end of the April War, the Serbian Air Force Commission made estimates of all unpaid pre-war designs, including the Modli J.M. 8, in order to arrange for future payments for military contracts. The commission, after analysis of the Modli J.M. 8 documentation, concluded that the aircraft did not meet any military requirements and was suitable for civilian use only.
Technical Characteristics
The Modli J.M. 8 was designed as a single engined, high wing, mixed construction (but mostly wood) training aircraft. Its fuselage had a simple design made of plywood. The high wings and the rear tail were made of a wooden structure covered with fabric. For better flight controls, Modli used two modified Gottingen 426 longerons. The wings were connected to the fuselage with three “N” shaped metal bars on both sides and with two additional ones in the centre. The tail had a large rudder and elevators made of wood.
It was powered by the two cylinder Aubier & Dunne 18 hp engine. The engine compartment was covered with duralumin. The two-bladed propeller was made of walnut. A fuel tank with a capacity of 16 liters was placed in the center of the wing.
The landing gear was fixed, but was equipped with rubber shock absorbers for greater comfort and control during landing. There was no rear wheel, being instead equipped with a small skid and shock absorber.
The pilot’s cockpit was fully open with a small windshield at the front. The cockpit had a simple design and was equipped with basic controls and instrumentation. These flight instruments included an airspeed indicator, fuel level, tachometer, and altimeter. As the first prototype was never adequately tested, details about its flying performance are not known.
During World War II
After the Yugoslavian capitulation, its territories were divided between the Axis forces. The Germans created the Independent State of Croatia (Nezavisna Država Hrvatska) puppet state. Despite promises of sending military equipment, weapons and aircraft, the NDH was mostly supplied with older or captured equipment. The NDH aviation industry was heavily dependent on supplies from Germany and Italy, as it lacked any major production capacity or industrial development, meaning domestic production was not possible. The only attempt at domestic production was with the Modli aircraft.
In 1941, Modli joined the new NDH Air Force with the rank of Flight Captain as a flight school instructor. He immediately began working on his second prototype, now simply called Modli-8. Unlike his first prototype, the second one was powered by a stronger four-cylinder Praga-B giving 40 hp. As this engine was too strong for the prototype, its power was reduced to just 20 hp. For the landing gear, two smaller rear wheels from a German Me-109 were reused. The Modli-8 was also shorter in comparison to the first prototype by 0.94 ft (15 cm).
In 1943 Modli was transferred to the technical workshop of the 1st Air Base in Zagreb, where he continued to develop his plane. In 1944, the Modli-8 was completed and introduced to NDH operational service according to authors T. Lisko and D. Čanak. Unfortunately, they do not give more information on its service history. According to authors B. Nadoveza and N. Đokić on the other hand, noted that Modli deliberately delayed the production of the Modli-8 and it was never fully completed for use by the NDH.
On 26th October 1944, Josip Modli fled to Slovenia at the helm of a Bücker Bü 131 “Jungmann” in hopes of joining the Yugoslav Communist Partisans. Meanwhile, his assistants and friends in Zagreb hid the Modli-8 prototype in the attic of an old shed. Due to the chaos and confusion caused by the war, it was easy to hide the small and lightweight prototype. The Modli-8 would survive the war intact.
The Modli-8 was the only NDH domestically-built aircraft during the War. These two pictures may be the only ones of the Modli-8. Source: www.paluba.infok
In NDH service, the Modli-8’s lower fuselage, wings, and tail were painted in silver. The upper part of the fuselage and vertical stabilizer was blue. The wings struts were painted in red, while the middle of the fuselage wore a red stripe on both sides with a white outline. There were NDH markings with a large “JM8” painted on the tail. The color scheme would remain the same after the war but the NDH marking would be replaced with the Communist Star.
After the War
After the collapse of the NDH and the German forces in Yugoslavia, Modli, now Captain in the Yugoslav People’s Army, moved his prototype from Zagreb to Skopje, where it was completed in an army workshop. Modli himself flew the prototype during the summer of 1945. Surprisingly , he did not report this flight to his superiors and an alarm was raised, with several fighters launched to intercept him. Modli was lucky, as this incident did not affect his military career. The Modli-8 was, by order of Air Force Command, moved to Belgrade for further tests. The aircraft proved to be a good design, as it was easy and pleasant to fly according to test pilot Vasilije Vračević. There were some issues with the sensitivity of the large rudders and elevators during flight. For take off, it only needed a very short 170 m (558 ft) runway, and could land on a 125 m (410 ft) airfield. The maximum speed was around 100 km/h 223 mph at an altitude of 1 km.
The Modli-8 was then given to Aircraft Center Vršac, where it was used for training and propaganda flights. It was used operationally up to 1950, when it was removed from Army service. During its operational service, the Modli-8 was also used as a glider trainer. Under the right conditions it could be used as a glider with the engine shut off, which was useful for glider training.
Josip Modli later (date unknown) designed a two-seater version named Modli-9, but it was never fully completed. Both the Modli-8 and the unfinished 9 were given to the Croatian Technical Museum (Zagreb) after the death of Josip Modli in 1974.
Production and Modifications
Despite being cheap, easy to build, and pleasant to fly, the Modli-8 was never adopted for military or civilian service. The first prototype was never fully tested due to the outbreak of the war and was lost (precise fate unknown). The second prototype was built during the war and was in use up to 1950. Despite the good feedback for its flight performance from the military, the Modli-8 was rejected for production, mostly due to the recent adoption of the BC-3 Trojka.
Modli J.M.8 – First prototype powered with Aubier & Dunne engine, lost in WW2.
Modli-8 – Second prototype powered by Praga-B engine and with other minor improvements, in service until 1950.
Modli-9 – Two-seater version, never fully completed.
Conclusion
Despite the few number of built aircraft, the Modli J.M. 8 had a small but interesting development history, changing owners several times. It had the honor of being the only aircraft built in Croatia during World War II. Despite its simplistic nature, it saw extensive use as a trainer after the war.
Operators
Kingdom of Yugoslavia – One built prototype
Independent State of Croatia (NDH) – Constructed one prototype but never tested
Federal People’s Republic of Yugoslavia (FPRY) – Operated the Modli-8 up to 1950.
Modli-8 (second prototype) Specifications
Wingspans
31 ft 2 in / 9.5 m
Length
19 ft 7 in / 6 m
Height
6 ft / 1.85 m
Wing Area
36.25 ft² / 11.05 m²
Engine
One four cylinder Praga-B 40 hp engine
Empty Weight
474 lbs / 215 kg
Maximum Takeoff Weight
705 lbs / 320 kg
Fuel Capacity
16 l
Climb Rate to 1 km
In 10 minutes
Maximum Speed at 1 km
223 mph / 100 km/h
Take of run
558 ft / 170 m
Landing run
410 ft / 125 m
Range
124 mi / 200 km
Maximum Service Ceiling
5578 ft / 1,700 m
Crew
1 pilot
Armament
None
Gallery
Illustrations by Carpaticus
Modli CroatiaModli Yugoslavia
Sources:
T. Lisko and D. Čanak (1998), The Croatian Air Force In The WWII, Nacionalna i sveučilišna knjižnica, Zagreb
Vojislav V. Mikić, (2000) Zrakoplovstvo Nezavisne države Hrvatske 1941-1945, Vojno istorijski institut Vojske Jugoslavije
B. Nadoveza and N. Đokić (2014), Odbrambena Privreda Kraljevine Jugoslavije, Metafizika Beograd.
Nebojša Đ.and Nenad M. (2002), IPMS Yugoslavia and Yugoslavian Aviation Special Interest Group Bulletin No 1-4,
Germany (1943)
United Kingdom (1917)
USSR (1938-1940)
German Empire (1917)
Empire of Japan (1945)
Yugoslavia (1939-1950)
