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PZL.23A and B ‘Karaś’

Poland, Uncategorized, , , , ,

Polish Flag Poland (1934-1939)
Type: Light Bomber/Reconnaissance, Number built: 240

In the early 1930s, the Polish Air Force began modernizing its fleet as tensions rose in central Europe. Among its top priorities was acquiring a specialized class of aircraft capable of performing both reconnaissance and bombing missions. The goal was to develop a modern, all-metal aircraft that could fulfill both vital combat roles. This ambition materialized in the form of the PZL.23, produced in two main variants: the PZL.23A, and the improved PZL.23B. A total of 250 aircraft were built, and the design even achieved modest export success. These aircraft went on to serve in the early stages of the Second World War II, seeing combat against both Germany and the Soviet Union, with some measure of success.

The Polish Bomber/reconnaissance plane PZL.23 Source: https://en.wikipedia.org/wiki/PZL.23_Kara%C5%9B

History

At the start of the 1930s, the Polish Air Force was primarily equipped with outdated aircraft. This was the case with its bomber formations, which mostly relied on French canvas-skinned, biplane bombers, such as the Breguet 19. These aircraft were fragile, had a relatively small bomb-carrying capacity, and were intended more to harass the enemy than to inflict significant damage.

The role of the light bomber/reconnaissance aircraft was mostly taken by the French Breguet 19 biplane in the post war years. Source: https://commons.wikimedia.org/wiki/File:Samolot_Breguet_19_B2_NAC_1-W-1555-2.jpg

In 1931, the Polish Air Force initiated the development of a new bomber designed to provide close support to ground forces. In addition, it was also to perform the role of reconnaissance operations, this request being primarily based on the experience gained during the Russo-Polish War of 1919–1920. During that conflict, both sides employed a limited number of aircraft, mainly for reconnaissance and bombing operations. As a result, the Polish Air Force sought to replace its aging fleet with new aircraft capable of effectively performing both roles.

In 1931, the Polish Air Force issued a requirement for a new single-engine, monoplane aircraft. It was to accommodate three crew members and be capable of carrying several hundred kilograms of bombs, serving the dual roles of bomber and reconnaissance platform. Few proposals were submitted, including the high-wing PSW.19 and the Lublin R.XVII biplane. Of the two, only the PWS.19 was built and tested, but it was ultimately not accepted for service.

The PSW.19 was a proposal from Podlaska Wytwórnia Samolotów (Eng. Podlachian Aircraft Factory) for a new bomber/reconnaissance plane. However, the design was not accepted for service. Source: https://www.armedconflicts.com/PWS-19-t185849#valka_group-2

The winning design came from a young engineer named Stanisław Prauss, working at Państwowe Zakłady Lotnicze (PZL, or State Aviation Works). Prior to this project, Prauss had worked on the PZL.13, a single-engine passenger aircraft, which was a modern design for its time, featuring an all-metal structure. Despite its innovative features, the project was ultimately canceled in 1931.

Following that setback, Prauss and his team dedicated much of late 1931 to drafting design plans, and performing critical calculations for the new military aircraft. In order to accelerate development, Prauss chose to incorporate several elements from his earlier PZL.13 project into the new design.

To expedite development, Prauss decided to incorporate several elements from his earlier PZL.13 project. The overall shape of his earlier design was clearly reflected in the later production aircraft, including the fixed landing gear, engine configuration, and fuselage design. Source: http://www.samolotypolskie.pl/samoloty/2296/84/PZL-13

By early 1932, a full-scale wooden mock-up of the fuselage was completed. Both the drawings and the mock-up were presented to the Polish Aviation Department in the spring of that year. After analyzing the wooden construction and technical documentation, the department approved the project and ordered the construction of three prototypes for testing.The first prototype was completed by 1934, powered by a 593 hp Bristol Pegasus II M2 radial engine. Although not of Polish origin, the engine was produced under license in Poland, with the original rights obtained from the United Kingdom. The overall design was simple: a conventional linear crew arrangement with a weapons bay between them. The rear gunner was also expected to serve as the bombardier, for which a small under-fuselage compartment was provided. For defense, the rear gunner operated two machine guns, one mounted dorsally and the other ventrally. Lastly, another crew member was tasked with aiming and releasing the bombs. A forward-firing machine gun was also planned for the pilot’s use, though it remains unclear whether this was ever actually fitted to the prototype.

The prototype, designated PZL.23/I, was flight-tested in early April 1934. Interestingly, it received the nickname Karaś, meaning Crucian-carp, a species of fish.  Its performance in the was rather poor, and several design flaws became apparent, such as a cramped interior, limited crew visibility, and vibrations in the rear section. Bombing trials were also problematic: when released, the bombs would shift from a vertical to a horizontal position, then back to vertical, as they fell from the aircraft. This erratic behavior significantly reduced bombing accuracy.

Further tests were carried out to refine the overall design throughout 1934 and into 1935. Eventually, the prototype was handed over to the Polish engineering college, where it was used for training new engineers. It remained there until the fall of Warsaw in September 1939.

The first prototype, although successfully flight-tested, was found to have several design flaws. As a result, after 1934, it was eventually repurposed as an instructional airframe.Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/

In late 1934, work began on a second prototype, designated PZL.23/II. The most notable change was the removal of the centrally located bomb bay. Instead, bombs were mounted under the wings, and the former bomb bay space was expanded to provide more space and improve visibility for the crew. Additionally, the engine was lowered by 10 cm to improve the pilot’s forward view. Other improvements included the addition of new leading-edge slats and flaps.

Testing revealed that many of the previously identified issues had been resolved; however, forward visibility was still considered unsatisfactory. Unfortunately, testing of the PZL.23/II came to a sudden and tragic end. At the end of July 1935, all three crew members were killed in a crash landing. The investigation concluded that the pilot had made a serious error, with some speculating it may have been a deliberate act of suicide.

Following the loss of the previous aircraft, another prototype (designated PZL.23/III) was constructed in 1935. This version incorporated several improvements over its predecessor, including an enlarged canopy and a raised pilot’s seat. These modifications significantly enhanced the pilot’s forward visibility, addressing a major flaw in earlier designs.

An especially interesting feature of the PZL.23/III was the addition of a hydraulically operated rear machine gun mount. This system allowed the rear gunner, if necessary, to engage targets approaching from the front by raising the machine gun above the forward fuselage. However, while seemingly innovative, this setup was likely difficult to use effectively in combat.

Production and Service Problems 

Following the successful testing of the third prototype, the Polish Air Force placed an order at the end of 1935 for the production of 200 aircraft. These were to be manufactured at the PZL factory in Warsaw-Okęcie, with the first batch of 40 aircraft scheduled to begin production at the start of 1936. However, after only a few units were built, production was abruptly halted due to a critical issue: the unreliability of the Bristol Pegasus engines.

These engines, produced under license in Poland, were plagued by numerous mechanical problems that required extensive troubleshooting and rework. To make matters worse, the engines were not manufactured in the UK, which meant acquiring replacements or parts from abroad was not an option, given differences in manufacturing tolerances. It wasn’t until September 1936 that these issues were finally resolved, allowing production to resume. The aircraft entered service under the designation PZL.23A, and the initial order of 40 aircraft was finally completed in November 1937.

Unfortunately, matters only worsened once the aircraft entered operational service. The planes delivered to the Polish Air Force proved deeply disappointing, bordering on unusable. The engines were underpowered, limiting the aircraft to a maximum altitude of just 3,000 m. Additionally, the automatic leading edge slats frequently malfunctioned, often deploying mid-flight without warning and causing severe stability problems. As a result, the aircraft was ultimately deemed unsuitable for combat roles and relegated primarily to reconnaissance duties.

Need For Improvements 

Abandoning the PZL.23 at that point would have seemed a waste of both resources and time, two things the Polish military could ill afford. Starting from scratch would have required significant time, with no guarantee that a new design would be any more successful. In the face of rising threats from both Germany and the Soviet Union, officials in the Polish Air Force sought ways to salvage the PZL.23 project.

One of the first PZL.23A production aircraft. Source: https://tvd.im/aviation/1666-pzl-p-23-karas.html

The first option considered was installing a stronger engine. PZL engineers decided to equip the aircraft with the newly produced Bristol Pegasus VIII engine, which had just entered production in Poland. This engine offered the advantages of its greater performance and a reliable local supply of parts, making it a logical choice. A prototype designated PZL.23/III was fitted with this engine and tested.

The third prototype was equipped with the new engine. Source: T. J. Kopanski PZL.23 Karaś

Although the speed increased only slightly (from 263 km/h to 274 km/h), the upgraded aircraft could now reach an altitude of 7.3 km, a significant improvement over the previous 3 km ceiling. In addition to the new engine, several other modifications were introduced: the leading-edge slats were removed, the  elevator was redesigned, and an extended antenna mount was added to the observer’s gondola for in-flight radio use.

Lastly, the new variant received two machine gun mounts in the forward engine compartment, compared to only one in the earlier model. However, due to a shortage of available machine guns, only one was actually installed in most aircraft. With these improvements, production of the updated model continued under the designation PZL.23B (sometimes referred to as Karaś II). With the introduction of the B variant, the remaining A variant aircraft were mainly employed as trainers. Some of them were thus equipped with dual controls.

The most common variant was the PZL.23B, which resolved many issues with the previous model. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en
Nearly all PZL.23A aircraft were converted into trainers by rebuilding them with dual controls, as was likely the case with this example, which probably belonged to the training school at Krosno. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en

Production

After the production of 40 PZL.23A aircraft, the remaining 160 units were built exclusively in the upgraded PZL.23B variant, and the initial order for 200 aircraft was completed by September 1937. Due to high demand, the Polish Air Force secured additional funding and requested the construction of 50 more aircraft. This follow-up order was fulfilled by February 1939.

In total, 240 aircraft of the Variant A and B (in addition to three prototypes) would be built.Source: https://panssarivaunut.blogspot.com/2016/02/pzl23-karas.html

Experimental Project 

Dive Bomber

While the PZL.23 shared some visual similarities with the German Ju 87 dive bomber, the Polish Air Force initially did not consider employing it in this role. However, by 1936, the idea of using the aircraft as a dive bomber began circulating among Air Force officials. To test the feasibility of this concept, one  PZL.23A was modified to serve as a prototype, designated PZL.23/IV. This prototype could be easily identified by the removal of the bombardier’s gondola.

The proposed armament included two forward-firing and two rear-mounted machine guns. The estimated bomb load was 300 kg, though it was hoped that this could be increased to 800 kg for potential export customers. Testing was carried out by the Air Force Technical Institute (ITL) in August 1936. Despite the modifications, it’s overall performance did not improve significantly, and the aircraft proved unsatisfactory in dive-bombing operations.

PZL.42

In April 1937, the prototype was further modified by replacing the single vertical stabilizer with twin vertical tails. This change aimed to improve the gunner’s field of fire. Bombing trials conducted with this version were somewhat more promising. However, for unclear reasons, the aircraft remained at the prototype stage, with only one example ever built. It was later used as a training aircraft until it was destroyed in a bombing raid in September 1939.

The PZL.42 prototype was tested with the new tail design. Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/
An aircraft lost in one of many German bombing runs during September 1939. Source: T. J. Kopanski PZL.23 Karaś

In Service

As the first PZL.23A aircraft became available, they were issued to units for familiarization. The first units to be equipped, in September 1936, included the 11th and 12th Flights of the 1st Air Regiment. The 21st Flight of the 2nd Regiment also received some of these aircraft. However, due to the poor performance of the PZL.23A, they were soon relegated to training duties.

With the introduction of the improved PZL.23B variant in early 1937, more than a dozen units received the updated aircraft. The Polish pilots experienced some difficulty adapting to the new type. This was not due to any inherent flaw in the aircraft or deficiencies in training, but rather because most pilots had been accustomed to flying older biplanes. This issue was not unique to Polish pilots—air forces across Europe faced similar challenges during this period of transition to more modern monoplanes.

Nonetheless, the aircraft was involved in numerous accidents. Between early 1937 and August 1939, a total of 23 aircraft were involved in various incidents, resulting in the tragic loss of 55 lives.

The PZL.23 would be dispatched in small groups of up to 10 aircraft to various units of the Polish Air Force. Source: https://en.wikipedia.org/wiki/PZL.23_Kara%C5%9B

In Action 

Border Actions 

The PZL.23 saw its first operational use against Poland’s neighbors in the year 1938, a particularly turbulent moment in this part of Europe. Nearly all the nations in central Europe  had once formed much of the  German and Austro-Hungarian Empires (including Poland), were embroiled in long-standing border disputes. These tensions escalated rapidly following 1938 as political pressure continued to mount across the continent.

Poland, eager to assert control over territories it considered historically its own, sought to occupy several neighboring provinces. In March 1938, a border clash between Poland and Lithuania triggered considerable alarm, prompting the partial mobilization of the Polish Air Force. However, the operation was poorly organized, hastily executed, and ultimately too late to have any significant impact.

To make matters worse, the relocation of several PZL.23 aircraft to an unprepared airfield near Wilno led to the crash-landing of three planes. By the 20th March, the brief conflict had subsided. Nonetheless, in an effort to intimidate Lithuania, the Polish military carried out a large-scale demonstration flight of over 100 PZL.23 bombers near the Lithuanian border.

The PZL.23 was deployed again in September 1938, this time against Czechoslovakia. At that point, part of Czechoslovakia had already been occupied by Germany with the approval of the Western Allies. Seeing an opportunity, Poland moved to occupy the Zaolzie region. Once again, the PZL.23 aircraft were used primarily as a show of force and did not engage in actual combat.

However, this show of force came at a significant cost. The frequent deployments accelerated the wear and tear on the PZL.23 fleet. Limited availability of spare parts meant that many planes had to be withdrawn from service due to being worn out beyond repair. As a result, some units were disbanded, while others had only a handful of operational aircraft of this type remaining.

Downfall of Poland 

By July 1939, tensions between Germany and Poland had reached a boiling point, and the possibility of war between the two nations was becoming increasingly likely. In response, the Polish Air Force conducted several reconnaissance flights along the German border, primarily using PZL.23 aircraft.

On the 23rd of August, the Polish Air Force began mobilizing. According to Poland’s war contingency plan, in the event of conflict with Germany, the air force was to be divided into two main groups. One group would be placed under the direct control of the Polish High Command, while the other would be attached to various ground formations. By the end of August, nearly all PZL.23-equipped units had been mobilized and prepared for potential combat operations.

On the 31st of August, the Polish Air Force issued orders to implement the pre-war organizational distribution plan. The group under the High Command’s direct control consisted of five fighter flights and the Bomber Brigade. The Bomber Brigade included five flights of PZL.23 aircraft, which were at that point renamed Light Bomber Flights. These were supported by seven reconnaissance flights, each equipped with an average of eight PZL.23 aircraft.

The aircraft allocated to direct ground support roles for the army were dispersed in small groups across various units. Although in theory, they were meant to cover vast territories and participate in reconnaissance or bombing raids, in practice, this deployment strategy significantly reduced their effectiveness. Their numbers were too few in each location to have any real impact in combat.

As of 1st September 1939, the Polish Air Force could field only 114 PZL.23 aircraft. Of these, 50 were allocated to the Bomber Brigade and 64 were assigned to various ground forces. An additional 10 were held in reserve. At least 55 more aircraft were in storage awaiting repairs, and another 45 PZL.23s were being used as training aircraft. Some of these would be pressed into combat as a replacement when nothing else was available. The small number of available aircraft meant that the PZL.23 was a generally rare sight during the war in Poland.

Despite many misconceptions about the war, the belief that the Polish Air Force was destroyed on the first day, is simply not true. While many aircraft were indeed destroyed on the ground, many survived and saw continued use through the conflict. The PZL.23, in particular, saw considerable action in both reconnaissance and bombing roles.

The PZL.23s of the 21st Bomber Flight first entered combat on  2nd September. A single aircraft was tasked with locating a German column near Lubliniec. It successfully identified a German motorized unit and carried out an attack against it. Another aircraft was shot down while on a similar reconnaissance mission, having been engaged by four Bf 109 fighters. On September 3rd, the unit suffered further losses, with several planes downed by superior German fighters and anti-aircraft fire. By 11th September, the unit handed over its remaining four aircraft to the VI Bomber Squadron, and the surviving pilots and crew were evacuated to Romania. Between September 1st and 11th, the 21st Bomber Flight dropped approximately 10 tonnes of bombs and lost six aircraft.

The 22nd Bomber Flight saw its first action on September 3rd, attacking a German column. The bombers were engaged by enemy fighters and anti-aircraft fire, resulting in the loss of three aircraft. Two more were lost in a follow-up attack later that same day. Over the following days, the unit continued to carry out bombing raids against German forces. By 10th September, the 22nd had transferred its remaining aircraft to the VI Bomber Squadron and evacuated its personnel to Romania. By that time, the unit had dropped around 12 tonnes of bombs and lost a total of five aircraft.

 

A PZL.23B from the 22nd Bomber Flight, easily identified by the painted emblem of a flying dragon holding a bomb on the fuselage sides. Source: https://tvd.im/aviation/1666-pzl-p-23-karas.html

The 55th Independent Bomber Flight was another unit that saw heavy action in both bombing and reconnaissance missions. It was almost completely wiped out on 11th September, losing nine of its aircraft. Despite the losses, the unit managed to drop 14 tonnes of bombs in 40 combat sorties. The 64th Light Bomber Flight also suffered significant losses during the war, losing 21 aircraft to German fighters and anti-aircraft fire.

The 24th Reconnaissance Flight was engaged from the very beginning of the conflict, tasked with spotting enemy formations and tracking their movements. On the 3rd September, six of its aircraft took part in a bombing run against a German armored column near Rabka. Polish pilots reported scoring several hits on enemy targets, although one aircraft was lost to anti-aircraft fire.

Despite sustaining losses, the unit still had operational aircraft by the 14th September. The following day, one aircraft was assigned the dangerous task of delivering a message to the Polish High Command in besieged Warsaw. The pilot had to fly 360 km over enemy-held territory and land in a city under siege, with no guarantee that the airfield was still secure. Against the odds, the mission was successful. The aircraft even managed to take off again and return, despite German attempts to shoot it down. The unit remained active until 17th September, when it was forced to evacuate to Romania due to the Soviet invasion from the east.

The 41st Reconnaissance Flight operated a small number of improved PZL.43A aircraft (an export version of the PZL.43 that had been sold to Bulgaria). While most of these aircraft were delivered to Bulgaria before the outbreak of war, a few remained in Poland awaiting final delivery. Initially, they could not be used due to missing components.

Interestingly, on the 6th September, an element of this unit engaged a German reconnaissance balloon near Przasnysz. Despite being protected by anti-aircraft guns, the Polish aircraft managed to shoot it down. By the 10th September, the unit had only two PZL.43As remaining. On that day, during a reconnaissance mission, one of the aircraft was hit by anti-aircraft fire and crashed, killing its crew. The following day, the last remaining aircraft was damaged by an enemy fighter and subsequently lost in a crash landing.

 

A PZL.23B from the 41st Reconnaissance Flight. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en

By the time of Poland’s surrender on the 6th October, 1939, the PZL.23 aircraft of the Bomber Brigade had conducted over 186 sorties, during which they dropped approximately 64 tonnes of bombs. Meanwhile, the independent flight units assigned to the Army saw even more combat activity, flying around 260 sorties. However, these units dropped only about 20 tonnes of bombs, as their missions were primarily focused on reconnaissance rather than bombing enemy positions and forces on the move. Of the 140 aircraft deployed, over 100 were eventually lost in combat during the war.  Far from the myth that the Polish Air Force was destroyed on the first day of the war, they fought with every tool at their disposal until the end.

By the end of the war in Poland, some 120 PZL 23 would be lost in combat. Source: https://www.reddit.com/r/WWIIplanes/comments/12bnmuw/german_personnel_examine_the_remains_of_a_polish/

In the Foreign Service

As soon as the first PZL.23 aircraft left production facilities, the Polish authorities were eager to generate foreign interest. In the spring of 1936, the PZL.23/III was presented at the air fair in Stockholm. Later that year, in November, another aircraft was exhibited at the Paris Air Show. Despite these efforts, Poland failed to attract any significant foreign interest in the design.

One PZL.23B was modified with a more powerful 925 hp Pegasus engine and equipped with a three-bladed, variable-pitch propeller. This variant was intended for export, but it failed to generate any interest, and was eventually reverted to the standard PZL.23B configuration.

The PZL.23B was modified with a 925 hp Pegasus engine, equipped with a three-bladed, variable-pitch propeller. Source; T. J. Kopanski PZL.23 Karaś

Bulgaria 

The PZL.23 would see some export success. In March 1936, a delegation was sent to Poland by Bulgaria to evaluate and potentially acquire aircraft for their own use. Following a series of negotiations, Poland agreed to sell them 12 PZL.23 bombers.

However, the Bulgarians requested that the aircraft be powered by Gnome-Rhône engines, which presented a design challenge. The positioning of the Gnome-Rhône radial engines and their cylinders prevented the installation of the forward-firing machine gun originally housed within the engine compartment. Polish engineers had to overcome this by finding a new, suitable position for the machine gun within the fuselage, an issue that took some time to resolve.

By the end of summer 1936, the modified variant was ready. Due to changes in both the engine and fuselage design, the new aircraft was given a different designation: PZL.43. Although the contract between Poland and Bulgaria was signed on the 9th April 1936, actual production faced delays. The main issue was the engine: the requested Gnome-Rhône 14N had to be imported from France.

 

Bulgaria was the only country that showed interest in this aircraft, acquiring around 50 of a modified variant designated as PZL.43. Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/

It was not until May 1937 that the last of the ordered aircraft arrived in Bulgaria. The Bulgarians were satisfied with its performance and placed a new order for 42 additional aircraft. These were to be powered by the Gnome-Rhône 14N engine and received the new designation PZL.43A. Most of these aircraft were delivered by late August 1939.

Following the German occupation of Poland, the few PZL.43A units that had not yet been delivered were briefly tested by the Germans before being sent on to Bulgaria. In total, Bulgaria acquired 50 aircraft, comprising both the original PZL.43 and the updated PZL.43A variant.

During the war, these aircraft were primarily used for training purposes, though they were occasionally employed in operations against Yugoslav partisans. By September 1944, due to a lack of spare parts, most had been withdrawn from service. A few remained operational until 1946, when they too were finally scrapped.

Romania 

Besides Bulgaria, Romania also operated some of these aircraft. They came into Romanian possession following the defeat of Poland in September 1939, when a group of 21 aircraft managed to escape German forces by fleeing to Romania. Of these, the Romanians were able to restore 19 to operational status, using the remaining two for spare parts. The aircraft saw extensive action against the Soviets, serving both in bombing, and reconnaissance roles, until 1943, after which they were reassigned to secondary duties. The last of these aircraft remained in service until 1946, when it was finally scrapped.

 

Romania operated at least 19 fully operational aircraft until 1943 when they were relocated for second line duties. Source: https://ww2aircraft.net/forum/media/a-crashed-pzl-23-karas-no-12-romanian-af.25926/

Germany 

After their victory in Poland, the Germans managed to capture several PZL.23 aircraft, most of which were either in poor condition or heavily damaged. They repaired a few PZL.43s and used them for testing purposes. Beyond that, however, they showed little interest in these aircraft.

 

Germans tested some captured aircraft but showed little interest in them. Source: T. J. Kopanski PZL.23 Karaś

Soviet Union 

The Soviets also managed to capture several PZL.23 aircraft, some of which were actually in working condition. These appear to have been put to some use by the Soviets; however, beyond that, nothing else is known about their ultimate fate.

Technical characteristics

The PZL.23 was a single-engine, low-wing aircraft intended for both bombing and reconnaissance missions. The fuselage featured an oval-shaped fuselage cross-section built using a framework of stringers and struts. The tail section employed a semi-monocoque construction for added strength and reduced weight. The entire fuselage was then skinned with duralumin sheeting.

An excellent illustration of the PZL.23 internal component and crew’s positions. Source: https://panssarivaunut.blogspot.com/2016/02/pzl23-karas.html

The wings were constructed in three main sections. The first section consisted of two spars that formed an integral part of the structure. In addition to serving as the attachment point for the rest of the wing structure to the fuselage, this central section also housed the mounting points for the two landing gear units. It was further reinforced to support a bomb rack installed beneath the aircraft fuselage.

Following this were the two outer wing sections, which were built using an innovative method. These outer parts featured a torsion box design, constructed with corrugated heavy-gauge duralumin sheets. These were connected spanwise by additional corrugated, stress-bearing duralumin plates with a smooth finish. Finally, the wing tipsand trailing edge slats were attached to complete the wing. The tail assembly was built using spars and ribs, all of which were covered in duralumin for structural strength and aerodynamic efficiency.

The wing was made up of three sections. The first section was directly attached to the fuselage and housed the landing gear and fuel tanks. This central section was flanked by the two remaining outer wing panels. Source: https://www-airwar-ru.translate.goog/enc/bww2/pzl23.html?_x_tr_sch=http&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en

The cockpit was positioned at the front of the aircraft. In its early development phase, the PZL.23 suffered from poor forward visibility. This issue was eventually addressed in the B variant by lowering the engine and raising the pilot’s seat. Directly behind the pilot sat the observer and bombardier, who was provided with a glazed canopy offering fairly good all-around visibility. Beneath the fuselage was the bombardier’s gondola. Finally, at the rear of the aircraft was the gunner’s position

Close-up view of the aircraft glazed crew compartment. Source: https://panssarivaunut.blogspot.com/2016/02/pzl23-karas.html
The instrument panel. Source: https://jmodels.net/de-hombres-y-maquinas/aire-air/pzl-23-karas/
At the bottom of the fuselage, a small bombardier’s gondola was installed. Source: J. B.Cynk The P.Z.L.23 Karaś

The first variant was powered by a 670 hp Bristol Pegasus II M2 engine. Later production aircraft were equipped with the more powerful 710 hp Bristol Pegasus VIII. In both versions, a two-bladed fixed-pitch propeller was used.

The fuel load consisted of 740 liters stored in six fuel tanks located within the central section of the wings.

The landing gear comprised two front-mounted fixed wheels (775×240 mm), each enclosed in aerodynamic spats. On many training aircraft, these spats were removed. To absorb shock during landings, shock absorbers were mounted on the landing gear legs. At the rear, a small tail skid with a shock absorber was installed.

The defensive armament included one forward-mounted 7.92 mm Wz.33 (Karabin lotniczy wz. 37) machine gun. The rear was protected by two 7.92 mm Wz.36 machine guns. Each machine gun was supplied with 600 rounds of ammunition. The B variant was designed to accommodate two forward-firing guns, but due to a lack of mounts, only one was typically installed. A ventrally mounted machine gun was also present, with an elevation and traverse range of 60 degrees.

For self-defense from rearward attacks, two machine guns were installed. Source: T. J. Kopanski PZL.23 Karaś

Initially, the aircraft’s bomb bay was located just behind the cockpit. However, during early testing, this design proved to be inefficient and was soon eliminated. Instead, bombs were mounted on an external rack positioned under the central fuselage.

This bomb rack could carry a payload ranging from 300 to 700 kilograms, typically using one of the following configurations: six 100 kg bombs, eight 50 kg bombs, or twenty-four small 12.5 kg bombs. In practice, however, loads exceeding 400 kg were rarely employed.

Production and Proposed Versions

    • PZL.23 I-III Prototypes – A small series of three prototypes
    • PZL.23A – An experimental version created by combining the Re.2002’s fuselage with the Re.2005’s wings. One built but never used operationally.
    • PZL.23B  – possibly one modified for this role.
    • PZL.43 – Variant developed for Bulgaria
      • PZL.43A – Further improvement over the previous variant
    • PZL.23/IV – Proposed dive-bomber variant remained at prototype stage
  • PZL.42 – Future modification with new tail assembly, used as training aircraft until destroyed in September 1939,.

Operators

  • Poland – Operated fewer than 50 aircraft.
  • Bulgaria – Purchased 50 PZL.43 and PZL.43A aircraft, with a few remaining in service until 1946.
  • Romania – Acquired 21 aircraft from Polish pilots who escaped to Romania. Of these, 19 were put into service and used against the Soviet Union until 1943.
  • Germany – Captured numerous PZL.23 aircraft, though most were in poor condition. The Luftwaffe showed little interest in utilizing them.
  • Soviet Union – Also captured several PZL.23s, but there is no known record of their operational use.

Conclusion

The PZL.23 has developed something of an unfair reputation as a poorly designed aircraft. While it was far from perfect, it was not as ineffective as it is often portrayed. The aircraft did manage to inflict some losses on German forces, conduct many reconnaissance missions, and remained in service with Poland until almost the end of the campaign. However, like many of its contemporaries, it was too slow to effectively evade or counter enemy fighters. While capable in its designed role, it was adapted for various missions, some of which it was neither designed for nor particularly suited to, such as dive bombing, and it often flew missions without fighter escort. This left the aircraft highly vulnerable and with little chance of survival. Ultimately, nearly all PZL.23s were lost by the time the war in Poland came to an end.

PZL.23A  Specifications
Wingspans 13.95 m / 45 ft 9 in
Length 9.82 m / 31 ft  9 in
Height 3.3  m / 10 ft 10 in
Wing Area 26.8 m² /  288  ft²
Engine 670 hp Bristol Pegasus II M2 engine
Empty Weight 1,928 kg / 4,250 lbs
Maximum Takeoff Weight 2,813 kg / 6,201 lbs
Maximum Speed 304. km/h / 189 mph
Cruising speed 240 km/h / 150 mph
Range 1.300 km / 807 miles
Maximum Service Ceiling 3.000 m / 9.842 ft
Crew 1 pilot, observer, rear gunner
Armament
  • One forward-mounted machine gun
  • Two more at the rear
  • 600 kg bombs

 

PZL.23B  Specifications
Wingspans 13.95 m /  45 ft 9 in
Length 9.82 m / 31 ft  9 in
Height 3.3  m /  10 ft 10 in
Wing Area 26.8 m² /  288 ft²
Engine 710 hp Bristol Pegasus VIII
Empty Weight 1,980 kg / 4.251 lbs
Maximum Takeoff Weight 2,893 kg / 6,378 lbs
Maximum Speed 319. km/h /200 mph
Cruising speed 270 km/h / 168 mph
Range 1.260 km/ 782 miles
Maximum Service Ceiling 7.300 m / 23.949 ft
Crew 1 pilot, observer, rear gunner
Armament
  • One forward-mounted machine gun
  • Two more at the rear
  • 700 kg bombs

Illustration

Credits

Source:

  • T. J.  Kopanski (2004) PZL.23 Karaś, Stratus
  • J. B. Cynk (1966) The P.Z.L.23 Karaś, Profile Publication
  • J. B. Cynk (1971) Polish Aircraft 1893-1939, Putham
  • B. Belcarz and R. Peczkowski (2001) White Eagle:s The Aircraft, Men and Operation of the Polish Air Force 1938-1939, Hikoki

 

 

 

Hafner Rotabuggy

UK, , , , , , , ,

UK Union Jack United Kingdom (1943-1944)
Rotor Kite Transport – One prototype

During the Second World War, airborne troops became an essential component of modern military strategy. They allowed armies to wreak havoc on unprotected rear areas by destroying critical targets, such as the enemy’s vital command structures, and the infrastructure supporting their army. However, one major drawback was that once on the ground, these troops were lightly equipped and moved at a walking pace. However, an engineer named Raoul Hafner proposed an innovative solution: airlifting light vehicles using unpowered rotary wings, similar to those later used in helicopters. His concept involved towing the vehicle, behind a truck or light aircraft until lift off. Once airborne, it would be released, and the pilot would use autorotation to fly the vehicle to the landing zone. A prototype was built and tested, but with the advent of larger gliders, the project was ultimately abandoned.

The experimental Hafner Rotabuggy. Source: www.macsmotorcitygarage.com

An Airborne Dilemma

With the abundance of US-supplied military vehicles, the British sought ways to incorporate them into various roles, and experiments. Among those interested was Raoul Hafner, a rotor kite enthusiast. Rotor kites were essentially unpowered rotary-wing aircraft that shared many design features with later helicopters. While helicopters can take off under their own power, rotor kites cannott, instead, they need to be towed by a larger aircraft, or a suitable ground vehicle. Once airborne, they rely on airflow over their rotary wings to generate lift and remain airborne. This can be achieved by descending to generate speed and lift, having a strong wind to keep the rotor wing turning, or remaining tethered to another vehicle for the entirety of the flight. Although this technology was inexpensive to build, it was never implemented on a larger scale.

Hafner was born in Austria in 1905. In his early twenties, he developed an early interest in rotorcraft design, and in 1928, he collaborated with Bruno Nagler on an early helicopter prototype. In the early 1930s, Hafner emigrated to the United Kingdom, where he began working on gyroplanes there, he designed and built a functional prototype known as the Hafner A.R.III Gyroplane. Hafner continued refining his designs, but with the outbreak of World War Two, he was briefly held in state custody due to his Austrian origin.

Raoul Hafner would go on to play a vital role in the history of helicopter development. However, his early work was primarily focused on an unpowered variant known as the rotor kite. Source: en.wikipedia.org

Upon his release, Hafner began working on a solution to Britain’s shortage of materials needed for parachute construction. His goal was to develop an inexpensive, one-man rotor kite to carry an infantryman deep behind enemy lines. The core principle behind his concept was that, given the scarcity of materials required for parachute production, a small, easy-to-build, and simple-to-control rotor kite could serve as a cost-effective alternative. These kites were designed to be towed into the air by another aircraft and then released near the designated target. Once released, the pilot/paratrooper would glide down slowly before proceeding to their objective. Hafner followed with a small prototype series of these aircraft, designated the Hafner Rotachute. While his work showed promise, it ultimately resulted in only a limited number of experimental prototypes, with no further large-scale implementation.

The so-called Hafner Rotachute was an experimental attempt to develop an alternative to parachutes. While the concept was intriguing, it never progressed beyond a small prototype production run. Source: en.wikipedia.org

He soon expanded on that idea, if he could devise a way to land soldiers, why not include light vehicles as well? Paratroopers, who were often dropped behind enemy lines to wreak havoc among key targets, were frequently left vulnerable as they were lightly armed and had limited mobility. The challenge, however, was that airdropping even light vehicles was no simple task. Hafner theorized that his rotor kite design could be expanded and enlarged to allow for the airlifting and deployment of light vehicles. If successful, this would provide paratroopers with a means of transportation, increasing their effectiveness in combat.

The overall design was intended to be as simple as possible. A standard light vehicle, left mostly unmodified, would be partially enclosed within an aerodynamic fuselage, likely made of plywood, to provide lift and protect the crew from the tow aircraft’s propeller wash, and the wind. A rotary assembly would be mounted on top, while a large tail section at the rear would ensure lateral stability. Upon landing ,assuming a safe descent, the crew would discard the fuselage, leaving the vehicle fully operational and ready for use without issue.

In 1942, with this idea in mind, he approached the Central Landing Establishment, later renamed the Airborne Forces Experimental Establishment, to present his proposal. While, at first, the concept of attaching a makeshift rotary wing to a lightweight wheeled vehicle may seem dangerous and wasteful, it would be phenomenally valuable should it succeed. Developing an effective method for transporting such vehicles over long distances would have provided significant combat advantages. This was especially crucial at a time when the Allies were considering various plans and strategies for invading occupied France, plans where airborne units played a star role. Thus the Central Landing Establishment saw potential in this idea, and Hafner received approval to move forward with its development. Now, Hafner needed to find a suitable light chassis for the job. Fortunately for him, he didn’t have to search for long, the answer was already in the hands of the UK’s ally across the Atlantic.

A Well-Known Icon

In the 1930s, the leadership of the US Army closely observed the rapid military developments unfolding in Europe and the Pacific. In response, the Army sought to modernize its forces, starting with an increase in mobility for its reconnaissance units and couriers, which at the time primarily relied on horses.

Initially, as in Germany, motorcycles were introduced for this role. While they were an improvement over horses, they had significant limitations, primarily their limited carrying capacity, as they could only transport the driver, one additional passenger, and a very small amount of cargo. It became clear that a larger, more capable vehicle was needed.

This led to the  development of small, relatively inexpensive, all-wheel-drive light vehicles. Throughout the 1930s, the Army conducted extensive testing and evaluation of several different designs. After these trials, a final decision was made to adopt Willys-Overland Motors’ design, known as the Willys MB, but generally, it was simply referred to as the  Jeep, as the Army’s standard lightweight reconnaissance vehicle. Unbeknownst to them at the time, they had just created one of the most iconic military vehicles in history.

The Willys MB would become one of the most iconic military vehicles in history. Source: en.wikipedia.org

While Willys was set to produce these new vehicles, the immense demand and the need to utilize the vast production capacity of its competitor, Ford, led to the company also receiving orders to manufacture the vehicle. Although Ford was allowed to make some modifications, the overall design had to remain to ensure all mechanical components for the vehicles were interchangeable. Between 1941, when production began, and 1945, over 600,000 of these vehicles were produced. They saw widespread service across the globe during and after the war, with a significant number still in use today.

Initially designed for reconnaissance operations, their sheer numbers and popularity led to their adaptation for various roles. These included medical evacuation, combat, self-propelled rocket launchers, and long-range raiders for missions against enemy rear positions. They were also used as command vehicles, among many other roles.

The vehicle was widely exported to Allied nations, including the UK, which received tens of thousands. Even the Soviet Union acquired them and eventually developed its own variant. Given the vast stockpile of these vehicles, it is unsurprising that Hafner chose to test his idea using one of them.

The Jeep saw extensive use by British special forces in North Africa, where it played a crucial role in raids targeting enemy rear positions. Source: wikipedia.org

Name

The unusual vehicle was known by many nicknames. It received the Air Ministry designation ML 10/42 Special Rotating Wing Glider. It was also called the Malcolm Rotaplane, Flying Jeep, and Blitz Buggy. Eventually, it became best known simply as the Hafner Rotabuggy. For the sake of simplicity, this article will refer to it as the Rotabuggy.

Building and Testing the Vehicle

After receiving approval, the next task was to find a suitable chassis, and someone capable of building the vehicle or aircraft. Given the abundance of options, Hafner decided to utilize the US-supplied Jeep light reconnaissance vehicle. For the construction of the working prototype, he approached R. Malcolm Ltd., a small company that had been building aircraft components during the war.

Once the base components were selected, the construction of the working prototype began. It was likely completed by mid-1943. The first flight trials of the Rotabuggy were scheduled for November 1943. These trials were planned to be conducted using a Diamond T 4-ton 6×6 truck as a tug vehicle. This was seen as a simple, cost-effective, and safe option, given the prototype’s early development stage, far too early for tests with aircraft. The flight tests were carried out on the 16th November, 1943. Despite numerous attempts, the crew was unable to get the Hafner Rotabuggy off the ground, as they could not achieve the necessary speed to generate lift.

The Rotabuggy’s shape in its early experimental phase was still evolving. Experimenting with the design led to many changes, such as the introduction of much larger tail fins. Source: www.nevingtonwarmuseum.com

Further tests were carried out on 27th November. This time, a stronger, albeit unspecified, tug vehicle was used. The initial test was successful, as they managed to lift the Rotabuggy into the air. The first flight test using a tug aircraft, specifically a Whitley Bomber, was conducted in December 1943. However, the first design problems were identified during this test flight. At a speed of 80 km/h (50 mph), the vehicle experienced strong vibrations, forcing an early end to the flight.

Subsequent tests with a similar tug vehicle showed that the vibrations persisted at speeds of 70 km/h (45 mph) and higher. Additionally, during one test flight, one of the rotors struck the tail fin, damaging it in the process. Following these tests, the Rotabuggy was temporarily grounded for various repairs and modifications.

By February 1944, the Rotabuggy achieved a speed of 112 km/h (70 mph), and many more tests were carried out throughout 1944. On September 11th, 1944, the first major test flight was undertaken. At a height of 120 m (400 feet), after being towed by a Whitley bomber, the small buggy was released. After some brief difficulty controlling the aircraft, the pilot managed to land the vehicle, though with some effort.

In later stages, it would look visually much different, having a fully enclosed cockpit. Source: www.macsmotorcitygarage.com

Fate

Given the extensive testing, it was clear that there was significant interest in this project. However, despite more than a year of development, the project was ultimately canceled. The primary reason for this was not the new concept itself but rather the fact that the British had begun mass-producing gliders, such as the Waco CG-4, which could carry a Jeep within its fuselage. As a result, the Rotabuggy was no longer needed.

While his Rotabuggy project reached an unsuccessful dead end, this was not the end of Hafner’s story. Given his expertise in rotor aircraft development, he was appointed Chief Designer and head of the newly established Helicopter Division at Bristol. Hafner’s work at Bristol was highly successful, and he played a pivotal role in advancing early British helicopter design. His contributions were instrumental in the development of aircraft such as the Type 171 Sycamore, and the large tandem-rotor Bristol Belvedere.

He was also among the first aircraft engineers to receive the Dr. Alexander Klemin Award, a prestigious honor in the field of vertical flight aeronautics. Tragically, in 1980, Hafner disappeared at sea when his boat went missing and was never found.

Technical characteristics

The Rotabuggy fuselage was an extension added to the U.S. Jeep, designed to enable controlled flight. During testing, it was concluded that the Jeep could be dropped from a height of up to 2.35 m (7.7 ft) without suffering any major mechanical breakdowns. It could thus theoretically survive rough landings on unprepared ground.

Essentially, it consisted of a standard Jeep with four metal bars arranged in a pyramidal shape at its base. To enhance structural integrity, two additional metal bars connected the front and rear pairs. Atop this framework, a rotor unit was intended to be installed.

Another metal frame was attached to the rear section, consisting of at least four long stringers reinforced with smaller crossbars. Surrounding this structure, a series of almost circular frames, decreasing in size toward the tail section, were added to shape the fuselage.

A clear view of the Rotabuggy’s internal framework, which consists of at least four long stringers reinforced with smaller crossbars and enclosed in a plywood skin. Source: www.macsmotorcitygarage.com

The structure forming the base of the fuselage was then covered with plywood for aerodynamics. The sides and top were essentially flat, without any noticeable features. Large windshields were added at the front and on the crew’s side doors, providing excellent, almost all-around visibility. This gave the crews a clear view, more than sufficient for landing the aircraft. While little data for its flight characteristics survive, its estimated rate of sink at a speed of 77 km/.h (48 mph) was 4.9 m/s (960 ft/min)

Large windshields were added at the front and on the crew’s side doors, providing excellent, almost all-around visibility. This gave the crews a clear view of their surroundings. Source: rafbeaulieu.co.uk
The rear part of the fuselage was essentially flat, featuring only a slight curve. Source: /www.nevingtonwarmuseum.com

To help provide lateral stability, a large tail assembly was added to the vehicle’s rear. It consisted of two fairly large vertical stabilizers. Interestingly, there were no rudders on these fins. Lastly, a small landing skid was located at the end of the vehicle’s tail.

 

The tail assembly features two large fins that provide much-needed lateral stability. Source: www.nevingtonwarmuseum.com

The crew consisted of two members: a driver and a pilot. The driver was seated on the left side, as in the original Jeep configuration. The pilot sat in the opposite seat and was responsible for controlling the rotor blades, which were used to lift the vehicle off the ground. To control the vehicle, the pilot was provided with a control column, a rotor tachometer, and a set of basic and glider navigational instruments. Once on solid ground, the vehicle would be driven like a regular Jeep.

The Rotabuggy used rather long rotor blades, with a diameter of 14.22 meters (47 feet). There were some issues with this length, as on at least one occasion, they damaged the rear tail assembly, luckily without injuring its crew.

The control column for the aircraft. Source: aviadejavu.ru
The Rotabuggy used rather long rotor blades. There were some issues with this length, as on at least one occasion, they damaged the rear tail assembly. Source: aviadejavu.ru

Surviving Aircraft

Since it never progressed beyond the prototype stage, it is not surprising that the vehicle did not survive to the present day. The prototype was eventually refurbished back to a standard Jeep . However, being such an intriguing design concept, a replica was built by the Wessex Aviation Society. can now be seen at the British Museum of Army Flying in Middle Wallop, Hampshire.

While the prototype did not survive, the Wessex Aviation Society managed to modify a Jeep and create a modern replica of the Hafner Rotabuggy. Source: www.reddit.com

Conclusion 

The Hafner Rotabuggy was surely an interesting and unique attempt at utilizing the relatively new rotorcraft design. In theory, this concept would allow for an alternative method of airdropping men and materials, including vehicles.

While the Rotabuggy had some issues, such as severe vibration during flight, it was generally considered a mechanically sound design. However, its main drawback was that, despite its novelty, it did not offer significant improvements over the gliders already in use. As stronger and more capable gliders were developed, which could transport both personnel and lightweight vehicles, the Rotabuggy became obsolete.

Although its service life was short, the project played a vital role in shaping Hafner’s future work in rotary-wing aircraft, ultimately contributing to the development of various helicopter designs.

Hafner Rotabuggy  Specifications
Length 2.9 m / 9  ft 6 in
Height 2.06 m / 6  ft 9 in
Main rotor Area 15.9 m² /  173 ft²
Engine None / ( 60 hp in Jeep)
Empty Weight (for Jeep only) 964 kg / 2,125lbs
Maximum Takeoff Weight 1,411 kg / 3,110 lbs
Maximum estimated speed 241 km/h / 150 mph
Cruising estimated speed 130 km/h / 80 mph
Crew Two – The pilot and the driver
Armament
  • none

Illustration

 

Credits

 Source:

   

Modli J.M. 8

WW2, Yugoslavia, , , ,

Yugoslavia flag Yugoslavia (1939-1950)
Trainer – 2 Prototypes

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 Aubier & Dunne 18 hp engine was reused for the first prototype. Source: www.vazduhoplovnetradicijesrbije.rs

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 Croatia
Modli 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, 

 

 

Fizir Prelazni FP-2

WW2, Yugoslavia, , , , ,

Yugoslavia flag Yugoslavia (1933-1947)
Training aircraft – 81 Built

Front view of the FP-2. [vazduhoplovnetradicijesrbije.rs]
The FP-2 was designed as an advanced two seater biplane trainer for the Yugoslav Royal Air Force in late 30s. It would be used to equip pilot training schools for some years before WW2. During World War II, it would be used by the Axis powers, which managed to capture a number of them, for limited ground attack operations. The FP-2 would survive the war in smaller numbers and remain in use up to 1947.

History

As the Yugoslav Royal Air Force began to develop and acquire more modern types of aircraft, the need for advanced training aircraft became apparent. Due to the obsolescence of older trainers, the Yugoslav Royal Air Force Command issued orders to begin developing a new series of advanced trainers in 1933. One of the designs submitted was the Fizir FP-1 biplane made by Zmaj. Despite its disappointing overall performance, a new design was desperately needed. At the same time, a design team composed of Rudolf Fizir and Dušan Stankov began working on a new model named FP-2. In a later address to Zmaj management in May of 1940, Dušan Stankov wrote that he was responsible for the design of the FP-2, with little to no input from Rudolf Fizir. While the Royal Air Force command was more in favor of a monoplane design, the FP-2 nevertheless received a green light.

Name

The capital letters in the name FP-2 are an abbreviation for “Fizir Prelazni 2” (Физир Прелазни ФП-2). Depending on the source, it is also sometimes identified as F.P.2. During its operational service in the Yugoslav Royal Air Force, it was also known as F.P.2-K7 after its engine name, or Fizir-Stankov F.P.2 after its designers. This article will use the FP-2 designation, as it is best known today.

What is interesting is that the FP-2 name may suggest that it was an improved version of the earlier FP-1. In reality, these two projects had nothing in common. This name was done mainly for administrative reasons, in order to obtain the funds allocated for FP-1.

Work on the Prototype

Work on the first prototype began in early 1933. At this time, the Yugoslav Royal Air Force officials were negotiating with the French for licenced production of several Gnome-Rhone engine designs, including the K-7, K-9 and K-14. For this reason, it was decided to test the performance of these engines by installing them into several prototype aircraft. This decision included the FP-2 ,which was to be powered by a French Gnome-Rhone K-7, making 420 hp.

The first prototype was officially completed by the end of 1933. It was flight tested by Zmaj test pilot Pavle Bauer. The pilot performed a series of test flights without any problems. As the first flights were successful, the FP-2 was given to the Yugoslav Royal Air Force for further testing in early 1934. For the testing of the FP-2, a commission of seven members was tasked with determining its exact flight performance. The test flight series began on the 19th of February, and after only four days a preliminary report was submitted to the Yugoslav Royal Air Force Command. The report gave mostly positive remarks on the FP-2 performance, with a few changes requested, such as increasing of the fuel load, a better position for the instruments inside the cockpit, modifications of the seats etc. The K-7 engine performance was deemed sufficient, and it was also noted that the testing of the FP-2 with any other engines at the moment was not required. This commission also urged for the FP-2 to be put into production as soon as possible. 

The FP-2 design team expected that a production order was to be given shortly by the Yugoslav Royal Air Force Command. But this was not the case for several reasons. The main problem was the inability of the Rakovica factory to locally produce the K-7 engine by 1936.  Due to high prices, the Yugoslav Royal Air Force could not buy these engines directly from France. Another issue was the adoption of the new Rogožarski ‘PVT’ high-wing training aircraft which used the same engine and offered better performance than the FP-2.

In order to solve this problem, the Zmaj engineers decided to replace the K-7 with the nine-cylinder Valter Pollux II (320 hp) engine. The ensuing flight tests carried out showed that the new engine only worsened the flight performance of the FP-2, due to lower power output. Thus, Zmaj was forced to replace it with the original K-7.

From the end of October to the first half of November 1934, more tests were carried out on the FP-2 with the K-7 by a second commission. This new commission had six members and was tasked with FP-2’s overall performance more thoroughly. These tests also included the testing of a few different types of propellers. The results showed that the metal type propellers gave better performance. In addition, the operational radius was evaluated and the results showed that, at the speed of 100 mph (161 km/h), the FP-2 could stay operational for three hours. Several pilots flight tested the FP-2 and, in general, positive remarks were given about its performance. The changes in the cockpit instrument arrangement was also rated as an improvement. After the tests were completed, this commission gave positive reviews for the FP-2 and suggested that it should be adopted for production as a basic trainer, but not as a fighter trainer due to the lack of performance for this role.

Technical Characteristics

The FP-2 was designed as a single-engine, two-seater basic trainer biplane. The FP-2 was made using wood as its main construction material and then covered with canvas. Its wooden elements were connected using metal pleats and rivets. The fuselage consisted of 16 oval shaped frames that were all connected with four long wooden spars. The wing’s construction was made of wood and then covered with fabric. Rear tail unit was made using a combination of metal and wood, which was then covered in  fabric. The landing gear was a fixed design with two wheels equipped with shock absorbers. There was no rear tail wheel and instead used a small skid which also was provided with a shock absorber. In winter, the front wheels could be replaced with skis.

It was powered by the French K-7 Gnome-Rhone 313 kW (420 hp) engine. The engine itself was placed on a ring shaped housing made of metal and duralumin construction. The maximum speed achieved with this engine was 148 mph (238 km/h). Being designed as a trainer aircraft, its crew consisted of a pilot/instructor and the student.

In Service Before War

For its service in the Yugoslav Royal Air Force, the first prototype was purchased for 577,000 Dinars in 1934. Next year, the contract for the construction of the first batch of 20 aircraft was signed. These were to be produced and given to basic training schools by 1936. All 20 aircraft were completed on time and were given to the First and Second basic training Schools. A few were temporarily given to the Fighter plane school until the more advanced PVT could be built. Once the PVT was adopted for service, the fighter school FP-2s were given to the basic training schools.

The FP-2 was mainly used to replace older training aircraft models that were in service. In its intended role, the FP-2 proved to have satisfactory performance and generally fulfilled the role of a basic trainer successfully. Only one accident was reported in 1938, when, due to a pilot error, control of the plane was lost and it crashed to the ground. The pilot managed to jump out of the plane and safely landed.

The FP-2 was considered a successful basic trainer by the Royal Air Force before the war. [airwar.ru]
During the production run, there were only minor modifications between the different planes. The FP-2 which were built in 1939 were modified with improved control panels with more updated instrumentation. Zmaj also proposed a modified FP-2H powered by the K-9 engine for use by the navy, but it was not adopted. 

By March 1941, around 9 FP-2 aircraft were reportedly awaiting repairs at the Zmaj factory. The fifth batch of 15 FP-2 were to be built by mid-1941. The materials and engine were assembled but, due to the outbreak of the war, none were delivered to the Yugoslav Air Force. Production of the FP-2 was carried out until the Axis invasion of Yugoslavia in April 1941. 

During the April War

At the time of the Axis attack on Yugoslavia in April 1941, all FP-2 were still assigned to the two basic training schools. The First pilot school was transferred near Sarajevo shortly before the outbreak of the war, along with 10 FP-2. The school was operational until the German capture of Sarajevo. The commander of this school, Colonel Adalbert Rogulja, ordered the entire unit to surrender to the Germans without attempting to sabotage its aircraft. 

The Second pilot school, located at the Kapino polje near Nikšić, had 15 FP-2. As the area was not  attacked by Axis forces, this school was operational until the end of war. The remaining FP-2s were stationed in smaller numbers across Yugoslavia. One was destroyed by the Germans in Novi Sad, and a few more in Niš and Pančevo. By the war’s end, both the Germans and Italians managed to capture an unknown number of FP-2s.

In German Service

The Germans managed to capture the Zmaj factory and an unknown number (possibly more than 15) of FP-2 across Yugoslavia. But they were more interested in the factory itself than the FP-2, and for this reason did not use the aircraft that were captured.

In Italian Service

The Italians managed to capture around 13 fully operational FP-2. One was transported to Italy to be flight tested with other captured Yugoslav aircraft (Do-17K and Hurricane) in early June 1941. The remaining 12 FP-2s were stationed at Tirana, but then repositioned in May 1941 to Shkodër to join the 5° Gruppo, which was part of the 39ª Squadriglia. This unit was equipped with older IMAM Ro-37 aircraft. As these were prone to malfunction, the Italians simply reused the FP-2 and pressed them into service. They were mainly used for liaison missions between Tirana and Shkodër. But Partisan activity began to increase in the area and faced with a lack of any other aircraft, the Italians began to arm the FP-2s. The FP-2s were armed with machine guns taken from the Ro-37 aircraft.

The 39ª Squadriglia would be operational until June 1943 in the Shkodër region. It was then returned to Italy and, while it is not clear, there is a chance that at least three FP-2 were still operational with this unit. The final fate of the FP-2s in Italian service is unfortunately not known.

In NDH Service 

After the April War ended, the Germans captured all surviving aircraft production factories, including Zmaj, in Yugoslavia. They restarted production for their own needs. The newly formed NDH (Independent State of Croatia) puppet state asked the Germans for a number of aircraft for their newly formed air force. This included any available Yugoslavian aircraft that survived the war. The Germans supplied the NDH with FP-2s captured in Sarajevo during the war.

In the case of the FP-2s at the Zmaj factory, there were engines and parts for the incomplete fifth production series that could potentially be built. The Germans delayed any decision whether to allow the NDH to take these aircraft. In 1943, an arrangement was reached between the NDH Aviation Force officials and the representatives of Zmaj for the delivery of the 15 FP-2 aircraft. The production process was slow due to the lack of a qualified workforce and constant sabotage by resistance movements. By 1944, only eight FP-2s were completed for the NDH. The remaining seven would remain in Zmaj factory hangars until they were captured by the victorious Communist Partisan forces in October 1944. 

During the war, the NDH Air Force used the FP-2 in its original role of a training aircraft. As the Partisan activity began to rise, some FP-2s were modified by adding bomb racks for six 12 kg (27 lb) bombs. These were then used to fight the Partisans, but as neither the pilot nor the observer were supplied with parachutes, these operations were dangerous.

FP-2 in Croatian service during the Second World War. [histaviation.com]
By 1944, it was obvious that the Axis were on the losing side and, for this reason, many NDH pilots tried to escape to the Partisan side whenever it was possible. One of them was Mitar Оbućanin. While flying an FP-2 (6822) in late August 1944, he escaped to the Partisan held island of Vis. This plane would be used by the Partisans for reconnaissance and liaison. Another attempt was made in October by pilot Drago Markotić and assistant Milan Aćimović. The escape failed and the plane was shot down by German AA ground fire. The pilot was captured and executed but his assistant managed to escape.

This FP-2 (6822) is the plane in which Croatian pilot Mitar Оbućanin defected to the Partisan side. It was then put into service by the Partisans from the isle of Vis. The FP-2 received a large Red Star painted on its side.[vazduhoplovnetradicijesrbije.rs]
The NDH had around 23 FP-2s in their Air Force. The aircraft supplied by the Germans received serial numbers 6801 to 6815 and the ones acquired from Zmaj were 6816 to 6823.

After War Service

With the liberation of Zemun, where the Zmaj factory was located, seven incomplete FP-2s were found abandoned. By late April 1945, two FP-2s were completed and put to use by the new Communist Yugoslav Air Force. The last five were completed by mid 1945. In total, around 13 were operated by the Yugoslav Air Force after the war. They would not remain long in service due to a lack of spare parts. They were mostly used as a target tug to haul flying targets for ground AA crew training.

The parts of one FP-2 can now be seen at the Belgrade Aviation Museum near the Nikola Tesla Airport.

Side view of the FP-2. [airwar.ru]
One of the 13 FP-2s operated by the new Communist Yugoslav Air Force after the war. [vazduhoplovnetradicijesrbije.rs]
 

Production

The FP-2 was produced in several batches from 1934 to 1940. The first batch consisted of 20 aircraft, followed by a second one with 15 planes in 1937, another 15 planes in 1939, and the final batch of 15 in 1940. An additional 15 planes were to be built in 1941, but due to the outbreak of the war, this was never completed. 

Before the war, the total production number of FP-2s made by Zmaj was 65 aircraft, plus the prototype. During the war and, in small numbers, after the war, an additional 15 were built. In total, 81 FP-2 were built.

Modifications

  • FP-2 – Main production version
  • FP-2H – A proposed naval version powered by the K-9 engine, but not adopted for service.

Operators

  • Kingdom of Yugoslavia – Used some 66 planes for pilot training.
  • SFR Yugoslavia – After the war used seven aircraft of this type. They were all captured at the Zmaj factory. These planes were designed for the NDH but never delivered on time.
  • NDH – A dozen aircraft of this type were delivered to the Air Force of the NDH in 1941 by the Germans. In 1944, another eight aircraft were delivered from the Zmaj factory in Zemun.
  • Italy – Used 13 captured planes from May 1941 to June 1943 against the rebels in Montenegro and Albania.
  • Germany – Captured smaller numbers of FP-2s but did not use them.
FP-2 Specifications
Wingspan 35 ft 5 in / 10.8 m
Length 25 ft  11 in /  7.9 m
Height 9 ft 6 in / 2.9 m
Wing Area 310 sq ft / 28.8 m²
Engine One Gnome-Rhone 7K, 7-cylinder radial, 313kW (420 hp) engine
Empty Weight 1.630  lbs / 740 kg
Maximum Takeoff Weight 3.170 lbs / 1,450 kg
Maximum Speed 148 mph / 238 km/h 
Cruise speed:  124 mph / 200 km/h
Effective range 360 mi / 580 km
Maximum Service Ceiling 22,300 ft / 6,800 m 
Crew Two (Instructor and student)
Armament None

Gallery

Illustrations by Carpaticus

FP-2 in Croatian service during the Second World War
FP-2 in Italian Service – 39ª Squadriglia

Credits

  • Article by Marko P.
  • Edited by Stan L. and Ed J.
  • Illustrations by Carpaticus
  • Č. Janić i O. petrović (2011) Kratka Istorija Vazduhoplovstva U Srbiji, AEROKOMUNIKACIJE Beograd.
  • D.Babac (2008), Elitni Vidovi Jugoslovenske Vojske U Aprilskom Ratu, Publish.
  • Vojislav V. Mikić (2000) Zrakoplovstvo Nezavisne Države Hrvatske 1941-1945, Vojno  istorijski institut Vojske Jugoslavije
  • Vojislav V. Mikić (1998) Italijanska Avijacija u Jugoslaviji 1941-1943, Vojno  istorijski institut Vojske Jugoslavije
  • B. Nadoveza and N. Đokić (2014), Odbrambena Privreda Kraljevine Jugoslavije, Metafizika Beograd.
  • T. Lisko and D. Čanak (1998), The Croatian Air Force In The WWII, Nacionalna i sveučilišna knjižnica, Zagreb
  • F. Vrtulek (2004) Ludbrežanin Inženjer Rudolf Fizir, Podravski Zbornik.  
  • http://www.vazduhoplovnetradicijesrbije.rs/index.php/istorija/229-fizir-fp-2

Messerschmitt Me 163S Habicht

Weimar and Nazi Germany, WW2, , ,

Nazi flag Nazi Germany (1945)
Rocket Interceptor Trainer – 1 Built

A rear 3/4 view of the Soviet captured “White 94” Me 163S. Colorization by Michael Jucan [Yefim Gordon]
The Messerschmitt Me 163S (Schulflugzeug / Training Aircraft) Habicht (Hawk) was an unarmed two-seat training glider based off of the famous Messerschmitt Me 163 Komet. Originally designed for the purpose of training novice pilots for landing, the Habicht ultimately never saw active service with the Germans and only a single example was produced through the conversion of a serial Me 163B-1. With the sole example captured by the Russians after the war, the Habicht underwent extensive testing by the Soviet Air Force which helped them understand the flying characteristics of the Komet and prepared Soviet pilots for flying the powered Komets. The Habicht undoubtedly played a part in helping Soviet engineers understand the Komet and thus played a part in the future development of Soviet rocket aircraft.

History

A closeup view of the Me 163S showing the right wing. [Yefim Gordon]
The Messerschmitt Me 163 Komet was one of Nazi Germany’s most famous aircraft produced during the Second World War. Although bearing the title of the world’s first mass-produced rocket-powered interceptor, the Komet did have its fair share of flaws, such as the volatile and sometimes dangerous Walter HWK 109-509 rocket engine, which prevented it from becoming an effective weapon against the Allies.

As the Komet was designed to have a limited amount of fuel to engage Allied bombers, pilots were expected to glide the Komet back to friendly airfields once they disengaged from combat. With gliding landings as a potential problem for the less experienced pilots, one of the ideas proposed by Messerschmitt designers in 1944 was to introduce a dedicated trainer variant of the Komet which would have a student pilot accompanied by an instructor pilot. Designated as the Messerschmitt Me 163S (Schulflugzeug / Training Aircraft) Habicht, the trainer glider differed from the production model with the addition of an instructor’s cockpit behind the forward cockpit. This addition was accompanied by the removal of the Walter HWK 109-509 rocket engine and the Habicht would have to be towed by another aircraft in order to get airborne. Another interesting addition to the Habicht was a second liquid tank behind the instructor’s cockpit for counterbalancing. All the liquid tanks would be filled with water for weight simulation and ballast. A total of twelve examples were planned for production, but only one was produced due to wartime production constraints.

The sole example of the Habicht was built by converting an earlier Me 163B-1 production model. Due to the scarcity of information regarding the Me 163S, it is unknown exactly when the Habicht was produced and what sort of testing it may have undergone during German possession. However, it is known that the Soviet Union was able to capture the only example during the final stages of the World War II’s Eastern Front. The sole Habicht was sent to the Soviet Union along with three Me 163B Komets during the Summer of 1945 for thorough inspection and testing. In historian Yefim Gordon’s book “Soviet Rocket Fighters – Red Star Volume 30”, he claims that in addition to the three Komets, seven Habicht trainer models were also captured. This, however, remains quite dubious as there is no evidence that more than one Habicht existed, and all current photographic material, research materials, and books all suggest that only a single example was produced.

The Me 163S in simulated flight configuration aided by struts. [Yefim Gordon]
As the Soviets were particularly interested in rocket propulsion aircraft, the State Defence Committee issued a resolution which called for the thorough examination of the Walter 109-509 jet engine and the Me 163 Komet along with captured German documents on rocket propulsion. The three Me 163B Komets, of which only one was airworthy, and the Me 163S Habicht were sent to the Flight Research Institute (LII), the Valeriy P. Chkalov Soviet Air Force State Research Institute (GK NII VSS), and the Central Aerohydrodynamic Institute (TsAGI). The Habicht and Komets saw extensive testing in Soviet hands, undergoing several structural, static and wind tunnel tests. During the initial flight testing period, the Komet only flew as a glider as Soviet pilots and engineers were unsure of whether or not the Walter rocket engine was ready for use since bench tests were not completed. Securing the T-Stoff and C-Stoff propellants for the rocket engine was also a problem. In order to understand the handling characteristics of the Komet, the Habicht was flown numerous times at different altitudes, as was the unpowered Komet. A Tupolev Tu-2 bomber was responsible for towing the Habicht to these altitudes. Under Soviet ownership, the Habicht was given the nickname of “Карась” (Karas / Crucian Carp) due to the glider’s distinct silhouette. The test pilot responsible for flying the Habicht was Mark Lazarevich Gallaj. In general, the Habicht was considered relatively easy to handle by the Soviet test pilots. It is unknown how many test flights the Habicht underwent, but the aircraft certainly aided Soviet pilots in understanding the handling characteristics of the Komet. The Habicht’s service came to an end once the Soviet state trials of the Komet concluded. The sole example was scrapped sometime in 1946, along with seemingly all the other Komets.

If the Me 163S was able to be mass produced and flown with the Luftwaffe, the aircraft would have been a valuable tool to train German pilots. Landing the Komet was a problem for some pilots and in some cases resulted in fatalities but, with the use of the Habicht, the number of accidents would have certainly decreased.

Design

The Me 163S hung upside down in an unspecified TsAGI workshop for static testing. [Yefim Gordon]
The Messerschmitt Me 163S Habicht was a semi-monocoque aluminum based two-seat training glider developed off the standard tailless Messerschmitt Me 163B-1 Komet. The sole example was converted from a production Komet, which meant dramatic modifications had to be made to the aircraft. The Walther HWK 109-509 rocket engine was removed and in its place was a cockpit for an instructor. The fuel tanks in the airframe were all filled with water to simulate fuel weight while another water tank was added behind the instructor’s cockpit for ballast purposes. There was no armament fitted to the glider. There was a small transparent section between the student pilot’s cockpit and the instructor pilot’s cockpit, presumably for the purpose of communication. As there are no known German documents on the Habicht and Russian documents are scarce, not much is known on the other differences the Habicht may have had. Detailed specifications of the Habicht are unknown, but theoretically it should have been identical to the standard Me 163B-1 Komet except for possibly weight, air drag and center of gravity.

Operators

  • Nazi Germany – The intended operator and producer of the Me 163S Habicht.
  • Soviet Union – The main operator of the Me 163S Habicht. A single Habicht was captured and tested by the Soviets after the war. The Habicht was scrapped in 1946.

*Editor’s note: As noted above, the exact specifications of the Me 163S Habicht are unknown. However they are presumed to be similar to that of the Me 163B-1 Komet.

Gallery

Illustrations by Haryo Panji https://www.deviantart.com/haryopanji

Me 163S Habicht “White 94” in Russian Service [Haryo Panji]
Me 163S Habicht in German Service [Haryo Panji]
 

 

Now known as the “White 94”, the Me 163S sits idly by. [Yefim Gordon]
A closeup view of the Me 163S showing the transparent section between the two cockpits. [Yefim Gordon]
The Me 163S in simulated flight configuration aided by struts. [Yefim Gordon]
A top down view of the “White 94” Me 163S. [Yefim Gordon]
A photo of the “White 94” Me 163S in flight being towed by a presumed Tupolev Tu-2. The pilot in the photo is likely Mark L. Gallaj. [Yefim Gordon]
The Me 163S inside TsAGI’s T-101 wind tunnel for testing. The struts support the Habicht and simulate its flight configuration. [Yefim Gordon]
An alternate closeup view of the Me 163S during static tests. [Yefim Gordon]

Yet another inverted static test, but this time the tail wheel strut and tire were removed from the Me 163S. [Yefim Gordon]

Sources

Fw 44 Taxiing

Focke-Wulf Fw 44 Stieglitz

Uncategorized,

nazi flag Germany (1932)
Trainer & Sport Plane – 3,000 Built

The Focke-Wulf 44 (Fw 44) was the most famous Focke-Wulf design after the famous Fw 190 fighter. The aircraft was a biplane with a fabric-covered welded steel-tube fuselage sporting wooden wings with fabric and plywood coverings, powered by a 140hp (104kW) Simens Sh 14 radial engine. This aircraft was primarily designed as a two-seat aerobatic civilian training aircraft but was later used for military purposes.

History

Fw 44 Taxiing
Fw 44 Taxiing

The origin of the Fw 44 Stieglitz (Goldfinch) started in 1932 when designer Kurt Tank, conceived the two-seater double-decker of mixed construction. In its prototype stage it had a number of unacceptable flight characteristics. The frst prototype was making its first flight in the late summer of that year with pilot Gerd Achgelis at the controls who problems with oscillations.

Kurt Tank had joined The Focke-Wulf Company in November 1931 from BFW, later Messerschmitt, and headed the design and flight test department for Focke-Wulf at the same time, replacing Heinrich Focke who was preoccupied with rotary-wing activities. Tank would remain in the position until the end of the World War II.

After further extensive flight testing, undertaken by Kurt Tank himself, he found the root of the problem. While flying the prototype back from a test flight, he happened to be looking at the shadow of the plane on the ground and he noted that the tail’s shadow blurred which indicated some kind of vibration in that area. Then the whole aircraft shook. Having landed he and his engineers check the tail of the aircraft and they found that the vibrations were being caused by separate cables operating the elevators. By joining these together to make the elevators act as one unit, the vibration problem was eliminated.

With this issue solved the Focke-Wulf 44 “Stieglitz” soon proved to have excellent handling characteristics and powerful aerobatic capabilities that won many prizes in numerous competitions, such as the Artificial Flying World Championship.  The Fw 44 was popular, and known aircraft all over the world as a simple training glider. Following many successful aerobatic displays around Germany, demand for this aircraft was so great that other German manufacturers manufactured the Fw 44 under license. In addition to the export models, production began in several other countries, such as Argentina, Austria, Brazil, Bulgaria and Sweden. It served as a standard training aircraft at the German transport school and the Luftwaffe.

One interesting fact about Fw 44 is that the body of one plane, the design retaining both the fuselage and engine, was used as the basis for the world’s first “practical” helicopter known as Focke-Wulf Fw 61.

Stieglitz’s Sporting Success

The Fw 44 was known for participation in numerous flight competitions, especially in the 1930s and always scored high, thanks to pilots Gerd Achgelis and Count Otto von Hagenburg.

  • 1935 Stuttgart Seventh German Art Flying Championship
    Gerd Achgelis achieved second place after Willi Stor who flew in a Messerschmitt M35 plane.
  • 1936 Eighth German Aerobatics Championship at Munich-Oberwiesenfeld
    Count Otto von Hagenburg won  second place. Willi Stor was victorious again with his Me. M35 plane.
  • 1936 Summer Olympic Games in Berlin
    Perhaps the most publicized aviation event in pre-World War II Germany was held in conjunction with the 1936 Olympic Games. Adolf Hitler, who wished to impress the world with the strength of Germany’s aviation industry, arranged the 1936 Berlin Summer Olympics Games to include the first ever aerobatics competition. This flying event took place within the track and field stadium. Graf Otto von Hagenburg as a pilot won the men’s competition, flying the new Fw 44. It’s very likely that the aerobatics competition was staged in a way to enhance Germany’s potential results. Either way, the German built planes and their pilots were well regarded as exceptional.
  • 1934 Paris World Championship
    An enormous event, with some 150,000 spectators crowded into the military parade-ground at Vincennes which had been modified for this occasion.
Fw 44 Stieglitz in Flight - 2008
Fw 44 Stieglitz in Flight – 2008

The initial compulsory competition required a list of manuevers to be performed within a time limit of eight minutes, including a right-hand and a left-hand spin, a bunt, a negative loop forward and upward, and an inverted 360 degree turn. Each contestant was also afforded the opportunity to fly their own routine for ten minutes. The sequence was to be submitted in advance to the judges, and each maneuver was assigned a difficulty coefficient set in the rules. New maneuvers were also awarded appropriate coefficients, but most were found to be already in the catalogue of 87 maneuvers. The judges’ task was to assign each figure a mark between 1 and 5 points for quality of performance, with a zero for figures not executed. These were then multiplied by the difficulty coefficients, the totals of all the judges were then averaged to obtain the final score.

Gerd Achgelis achieved third place with a score of 527.6 points. The winner was the German pilot Gerhard Fieseler, designer of the Fieseler Storch, with a score of 645.5 points.

Production Variants

Thanks to its exceptional flying characteristics, it was ordered by many nations around the world. In addition to export orders from Turkey, Switzerland, Bolivia, Chile, China, Czechoslovakia, Finland and Romania, it was produced under license in Argentina, Austria, Brazil, Bulgaria and Sweden. The Fw 44 was built in substantial numbers for the Luftwaffe, serving as a trainer until the end of the World War II. It was also in use by the Deutsche Luftsportverband and Deutsche Verkehrfliegerschule. Exact production numbers are not known, due to production in Germany by Focke-Wulf and and many other subcontractors such as AGO, Bucker and Siebel, in addition to other license agreements worldwide. It is assumed that the production numbers are between 1900 to more than 3000 planes. Focke-Wulf had to build another factory just to keep up with demand for the plane.

The production variants differed from each other in minor equipment details. The most numerous variants were the Fw 44C, Fw 44D and Fw 44F, with all three models utilizing the same Siemens Sh 14a engine. The final production Fw44J model had a 160 hp Siemens Sh 14a-4 seven-cylinder radial engine.

  • Fw 44A
    The Fw 44A was powered by a 150hp Siemens Sh14a engine, and was used for flight tests. This model was in production until the end of 1932.
  • Fw 44B
    The improved Fw 44B first appeared in 1933, with production commencing in 1934. The Fw 44B, had an Argus As 8 four-cylinder inverted inline air-cooled engine of 90 kW (120 hp). The cowling for this engine gave the plane a more slender, aerodynamic nose. The other change was in the extension of the fuselage from 6.6 to 7.3 meters, which was tested on this model.
  • Fw 44C
    This model was used extensively by the Luftwaffe at advanced training schools throughout the Second World War. The Fw 44C, was powered by the Siemens Sh 14a engine, which offered the best overall performance.
  • Fw 44D
    The D model was same as the Fw as 44 C, but with different exhaust manifold. The plane got a small luggage compartment made of fabric, which was attached to the rear cockpit. From 1934 onwards, improvements were taken into series production. Due to the high demand for this model, it was temporarily produced in other plants (Bücker Flugzeugbau – 85, AGO – 121, and an additional 515 planes under license). The Luftwaffe ordered some 1,600 examples of this model.
  • Fw 44E
    Basically identical with to the D model, it was equipped with an Argus As 8 engine. It was built in limited number, only 20, in 1934.
  • Fw 44F
    An upgrade of the D model. With some luggage compartment modifications, and the replacement of the rear pad with a landing wheel.
  • Fw 44H
    Only one plane of this model was produced in 1936, and was used only for testing. This model was equipped with a six-cylinder engine (118hp).
  • Fw44J
    The J model was mainly intended for export and was equipped with the 160 hp Siemens Sh 14a-4 seven-cylinder radial engine. This model was demonstrated in Sweden in late 1935, and in February 1936. The testing resulted in a license agreement between the Swedish aviation administration and Focke-Wulf on September 29, 1936. Two test aircraft were ordered, receiving the Swedish designation P2.

Operators

  • Germany
    The Luftwaffe used the Fw 44 until the end of the World War II, mainly as a trainer aircraft in the Flugzeugführerschulen. The Germans used more than 1,600 planes. Many famous German aerobatic pilots flew the Fw 44 aircraft, including Gerd Achgelis, Adolf Galland, Emil Kopf, Ernst Udet and perhaps most famously Hanna Reitsch, who flew on almost all aircraft models.
  • China
    China purchased around twenty Fw 44’s which were all used during the Second Sino-Japanese War where all were lost in action. Some of them were modified for combat missions.
  • Bulgaria
    In November 1936, the first six Fw 44 J were delivered and in May 1939 ten more followed. By February 1940 twenty more planes were delivered to Bulgaria, making a total of 46 J models. After the war surviving planes were handed over to Yugoslavia.
  • Sweden
    In late 1936, 14 aircraft were ordered from Focke-Wulf. ASJA, AB Svenska Järnvägsverkstädernas Aeroplanavdelning, and the Swedish Railway Workshops Aircraft Department placed an order for 20 more aircraft in June 1937, while the Central Verkstaden at Västeras (CVV) placed an order for 37 more aircraft in 1939. Another 12 were ordered from Focke-Wulf in 1940, however, these were produced by Flugzeugwerke CKD at Prague, Czechoslovakia.
    These were used for elementary and aerobatic training. Other training units flew this plane, and after withdrawn from basic training in 1946-1947, it was used for liaison, observation, glider-tug, and other ancillary roles. After being withdrawn from use, many came ended up on the civil registries in Sweden and Germany.
  • Turkey
    8 planes were ordered and delivered in 1939.
  • Finland
    As the Fw 44 was suitable for operation in polar regions, Finland required the aircraft for basic pilot training. In April 1940, a contract was signed between Finland and Focke-Wulf, for delivery of 30 Fw 44 J models.
  • Norway
    Norway placed an order for ten Fw 44 Js, which were delivered in April 1940.
  • Austria
    From 1936 onwards Austria’s Federal Army used the Fw 44 as a basic school training aircraft, with some ten aircraft were purchased from Focke-Wulf. The Fw 44 was also produced under license. Some 40 Fw 44J models were produced by Hirtenberger Patronenfabrik, (Wiener Neustadt).
  • Argentina
    Argentina ordered fifteen Fw 44 Js in January 1937, and built another 60 under license.
  • Brazil
    Built a production facility to produce the plane in some numbers.
  • Chile
    In September 1937, Chile signed an agreement to buy 15 Fw 44 J models.
  • Yugoslavia
    Some war trophy aircraft were taken from the Bulgarians as war reparations and used after the war as trainers.

Fw 44 Specifications
Wingspan  29 ft 6 in / 9 m
Length  23 ft 11 in / 7.3 m
Height  8 ft 10 in / 2.7 m
Wing Area  215 ft² / 20 m²
Engine  1x 150hp (112-kW) Simens Sh 14a 7- cylinder radial piston engine
Max Take-Off Weight 1,727 lb / 785 kg
Empty Weight 1,243 lb / 565 kg
Loaded Weight  1,694 lb / 770 kg
Climb Rate  56 ft/s  /  17 m/s
Maximum Speed  115 mph / 185 kmh
Range  419 mi / 675 km
Maximum Service Ceiling  12,795ft / 3,900 m
Crew  2 (student and instructor)

Gallery

Fw 44 Stieglitz in Flight - 2008
Fw 44 Stieglitz in Flight – 2008
Fw 44 Trainer with Swastika
Fw 44 Trainer with Swastika
Fw 44 Taxiing
Fw 44 Taxiing
Fw 44 - 1977 Helsinki
Fw 44 – 1977 Helsinki
Focke Wulf FW-44 J
Focke Wulf FW-44 J

 

Sources

Mondey, D. (2002). The Hamlyn concise guide to Axis aircraft of World War II. Edison, N.J: Chartwell Books., Nešić, D. (2007). Naoružanje drugog svetskog rata, Namacka-ratno vazduhoplovstva knjiga 2. Beograd., Wilson, J. (2007). Propaganda Posters of the Luftwaffe., Wermacht History. (n.d.). Focke-Wulf Fw 44., Avia Deja Vu. (n.d.). Focke-Wulf FW.44 Steiglitz., Valka. (2012). Focke-Wulf Fw 44 Stieglitz., Focke-Wulf Fw 44. (2017, June 5). In Wikipedia, The Free Encyclopedia., Siteunseen Ltd. (2015). Focke-Wulf Fw 44 Military Trainer Aircraft. Images: Fw 44 in Flight 2008 by Markus Kress / CC BY-SA 3.0, Fw 44 Taxiing by bomberpilot / CC BY-SA 2.0, Fw 44 Trainer with Swastika by Siteseen Ltd, Fw 44 Engine by VollwertBIT / CC BY-SA 3.0, Fw 44 – 1977 Helsinki by fsll2 / CC BY-NC 2.0