United States of America (1945)
Observation Scout Floatplane – 10 Built
XOSE-1 taking off. Notice it is painted in the wartime colors. [axis-and-allies-paintworks.com]The XOSE-1 was an observation float plane built by the Edo float company during World War II and was intended to be a possible replacement for the OS2U Kingfisher. Before being built, the type seemed promising and ten prototypes were ordered. Although development was slow, the aircraft would finally fly after the war had ended. Testing showed the design was riddled with flaws and, with the end of the war making the observation floatplane obsolete and unnecessary, the XOSE-1 program was cancelled.
History
Photo of the mockup XOSE-1.
Before America had entered the Second World War, it was realized that many assets in the United States arsenal were outdated to some degree. Many aircraft were unable to compete with their contemporaries around the world. One such piece of equipment would be the ship launched floatplane. A concept that originated in the 1920s and 1930s, it involved the use of small floatplanes that were carried aboard large warships and could be deployed via catapults for a number of tasks to assist their mothership. These missions included long range scouting, spotting for the warships’ main guns and also providing anti-submarine protection using depth charges or torpedoes. Most of America’s larger warships were equipped with catapults at the time for this purpose. The dedicated ship-based floatplanes the United States Navy (USN) operated at their entrance to the war was the aging Curtiss SOC biplane and the Vought OS2U Kingfisher. The latter would soon replace the former and would enter widespread service after the Attack on Pearl Harbor. Although the Kingfisher was just entering service, the search for a modern seaplane that would eventually replace the aircraft began. The new type was expected to carry out the same duties as its predecessor but also be able to effectively protect itself if needed. The OS2U only had one .50 caliber machine gun for offense, which wasn’t very helpful when against newer fighters. The first and most prominent aircraft that would rise to meet this role would be the Curtiss SC Seahawk, but it would not be the only type that would be built. In fact, a competitor would come from a little known company called Edo.
The Edo Aircraft Company is not a company often mentioned in history regarding the Second World War. The company was founded in 1925 by Earl Dodge Osborne, with the name being an acronym of his own name. Despite being rarely discussed among historians, Edo was immensely crucial to the war effort for the USN. Edo was a primary producer for aluminum floats before the war and would be the main producer for the floats on Navy floatplanes, like the OS2U. It was estimated that up to 95% of floats used on USN aircraft were built by Edo. Not only was Edo responsible for the production of the floats, they were also known for adapting said floats for use on the aircraft that would use them. Edo had become known for their work on floats, but they worked on a handful of their own floatplane designs in the years before WWII had started. However, this was around the time the company was created in 1925, and aircraft design had changed drastically since then. Given their background and knowledge with designing and fitting floats, the USN requested that the Edo company should attempt to design their own modern floatplane for the ship-based observation role. Eager to attempt building a modern aircraft, Edo eagerly accepted the request. On January 11th, 1944, they would begin work on their floatplane, which would be called the XS2E-1.
Frontal view of an XOSE-2 or XTE-1. The two were visually identical from the outside. [axis-and-allies-paintworks.com]The preliminary design of the XS2E-1 was deemed acceptable by the Navy and an order for ten prototypes was made. The XS2E-1 would be a two seat design with a Ranger V-770-8 engine. The engine mount and cowling would also both be designed by Ranger (this company would become Fairchild after the war.) Additionally, a Westinghouse 19 turbojet was to be installed in the rear of the aircraft to offer increased thrust for evasion or to give chase to an enemy aircraft. This would make the aircraft a mixed powerplant type. Another order for eight more units was made some time after the first order, but an exact date is unknown. On March 16th, 1944, the USN opted to change the floatplane’s design. The Westinghouse 19 turbojet that was planned for the project was experiencing its own difficulties in development.
When the XS2E-1 was drafted, the turbojet, due to its development, had become much heavier than what Edo was expecting. Due to this weight increase and a high demand for the jet engine on other aircraft projects, it was removed from the XS2E-1. This caused a weight problem in the aircraft’s design, as it no longer had the additional thrust needed to operate with its then-current weight. Edo changed the aircraft’s design drastically to make the XS2E-1 lighter. A significant revision done was the removal of the second seat, making the aircraft a smaller, single-seater aircraft. This, however, meant all the work the 2nd crewmen was intended to do was now transferred to the pilot, which would include operating the radar system in addition to flying and observing.
A frontal shot of an XOSE-1 demonstrating its folding wings. [axis-and-allies-paintworks.com]After the loss of the turbojet and the switch to a single seater design, it was decided to change the aircraft’s role to an Observation Scout floatplane. Another reason for the change was that, developing parallel to the XS2E-1, was the Curtiss SC-1 Seahawk mentioned earlier, an aircraft that was meant to fill the Scout role for the USN. Finding that developing two aircraft with the same role was redundant, the USN authorized the role change on the XS2E-1. With the new role, the XS2E-1 was redesignated as the XOSE-1. Not long after the role and design change, a full-scale wooden mockup of the new XOSE-1 was built and an inspection was held on November 24th, 1944. An early criticism of the design was linked to the removal of the second seat, as would-be operators complained the intense workload was too much to put onto the pilot. A variant was soon conceived, the XOSE-2, which would address this workload issue by reintroducing the second seat for another crewman. This second crewmen would be tasked with operating the onboard radar system and performing observation duties. An order for two XOSE-2s to be built, as well as for a derivative of the XOSE-2 that would be a dual-control training version, soon followed after conception of the two-seat variant. The trainer would be named the XTE-1. Progress on the program overall was slow up to this point, but Edo had added many innovative features to the design to improve its performance.
Side view of an XOSE-1 taking off. [axis-and-allies-paintworks.com]The war came to an end before the XOSE-1 could take flight. The end of the war saw most of the projects the USN was working on be terminated immediately, as there was no purpose in developing them anymore. The XOSE-1, however, was saved from this fate, as the USN allowed the floatplane to continue development after the end of the war. The XOSE-1’s first flight took place on December 28th of 1945, only a few months after the war had ended. Since there was no urgency to press this new type of aircraft to the frontlines anymore, funding to the program was cut and work slowed down in accordance. The XOSE-2 version finally flew on September 24th, 1947, two years after the war was over. Two XOSE-2s were built. It is unknown exactly when the first XTE-1 was completed and flew, but two of this type were built as well. Originally, during its debut, the XOSE-1 was painted in the standard blue-on-the-top-white-on-the-bottom that mid war USN aircraft used, but would later be colored in the dark blue that late/post-war Navy aircraft were painted in.
Rear view of an XOSE-1 with the floats detached and the wheels attached instead. [axis-and-allies-paintworks.com]Despite being a company that had only built a handful of planes two decades prior, the XOSE-1 was very promising from the outset, but problems soon began to arise during testing. The XOSE-1 experienced trouble with the Ranger built engines. The two seater XOSE-2 experienced many more problems and major changes had to be implemented in the design. Some remedies to the problems included increasing the height of the tailfin and the addition of a ventral strake below the tail to help with stability. Stability issues were found to be caused by the two seater’s larger canopy installed on the largely unmodified fuselage. By the time the stability issues were resolved, it was almost for naught, as the aircraft program was going nowhere.The shipborne floatplane type itself was beginning to show its obsolescence compared to newer technology. Exactly when the program ended or the whereabouts of the ten XOSE built are unknown, as details about the program during this time are sparse. It is unknown if the XOSE-1 was ever even tested from a ship, as many warships postwar would have their catapults removed. Most of the testing was done via land or sea takeoff, with wheels attached to the floats or a landplane conversion where the floats were replaced with a conventional landing gear. The type would be slowly replaced by ship-based helicopters, an idea that had begun during the Second World War and expanded upon thereafter. The era of the scout floatplane, especially shipboard ones, was over. It is most likely all of the XOSE-1s and its derivatives were scrapped before 1950, as all shipboard seaplane squadrons had been disbanded in 1949.
Design
An Edo XOSE-1 in flight [axis-and-allies-paintworks.com]The Edo XOSE-1 was a single-seat floatplane design of all metal construction. It’s floatation was provided by one large aluminum float under the hull, and two smaller aluminum floats on the wingtips. This layout was used on almost every USN floatplane. In addition to floats, the aircraft was also able to be launched via catapult aboard a ship. An optional wheeled undercarriage was also available for ground based takeoffs.
The body of the aircraft would be constructed of metal and would contain 135 lbs (61 kg) of armor. The overall weight of the aircraft would be 5,316 Ib (2411.3 kg) standard and 3,973 Ib (1802 kg) empty. The fuselage would have a length of 31 ft 1 in (9.5 m) and a height of 14 ft 11 in (4.5 m). The XOSE and its variants had a unique construction that allowed many parts of the aircraft to be easily accessible for maintenance.
A rear view of an XOSE-1 with its wings folded back. [shu-aero.com]The Edo XOSE-1 and all of its variants were equipped with the Ranger V-770-8 inline engine that gave it a top speed of 188 mph (302 km/h), a cruising speed of 111 mph (178.6 km/h) and a stall speed of 61 mph (98.2 km/h). The aircraft would have a climb rate of 1,350 ft/min (411.5 m/min) and a maximum service ceiling of 22,300 ft (6797 m). The XOSE-1 would also have a range of 600 mi (965.6 km).
The cockpit would allow protection for the pilot, as the canopy was bulletproof. The canopy was one piece and would slide down and behind the cockpit for easy movement in. On the XOSE-2/XTE-1, the cockpit would be lengthened to accommodate the additional crewman, who would do observation and radar tasks. The canopy on the two seater versions would be two parts and the forward segment would slide back over the rear section.
Fuel would be stored in the fuselage in self-sealing fuel tanks. The tail section of the aircraft would be of metal construction as well. The only differences between the two versions were on the two seaters, in which the tail of the aircraft had to be extended height-wise and a vertical strake beneath the tail was added. Both of these changes helped in the stabilization of the two seaters. The wings of the aircraft were also constructed of metal and would have a wingspan of 37 ft 11 in (11.6 m). The wings would utilize a unique feature for some of its control surfaces. The flaps, that extended outwards from the folding line, would retract automatically if enough water impacted them. This was put in place to prevent damage to these flaps. Additionally, there were retractable slats on the leading edge of the wings to increase drag. The wings themselves could be folded inward for easy storage aboard ships or hangars. Interesting to note, the wings had a manual folding system instead of a hydraulic system most aircraft at the time had.
For armament, the XOSE-1 was equipped with two M2 .50 caliber machine guns as standard. Two hardpoints were equipped on the wings that could allow the XOSE-1 to carry two 350 Ib depth charges or two 50 gallon drop tanks. Additionally, two emergency rescue racks could also be carried on the underside for air to sea rescue missions. A single hardpoint could also be used to carry a radar pod. There is also mention of the XOSE-1 having smoke projectors as well. The two-seat XOSE-2 would lose one of the M2 machine guns and only carry a single gun. The XTE-1 variant would be completely unarmed, given it was only a trainer.
Conclusion
With the Edo XOSE-1 program being terminated, this would be the last time Edo would build an aircraft all on their own. However, Edo would propose a very interesting concept to the US Navy in the 1950s for an amphibious fighter similar to the Convair F2Y Sea Dart. However, this type would never be built.
Variants
XS2E-1 – Initial design of the XOSE-1. The XS2E-1 was a two seater and mounted a larger engine as well as a Westinghouse J19 jet engine. This design was changed and became the XOSE-1.
XOSE-1 – Single seat reconnaissance floatplane. The XOSE-1 had two .50 Cal M2 machine guns mounted in the wings and two hardpoints for depth charges. 6 were built.
XOSE-2 – Two seat version of the XOSE-1. The E-2 version would have a radar operator, a lengthened canopy, and only a single .50 cal for defense. Two were built.
XTE-1– Tandem control version of the XOSE-1. This version would be unarmed and would be used for training purposes. Two were built.
Operators
United States of America – The XOSE-1 and its variants were only tested by the United States Navy.
Edo XOSE-1 Floatplane Specifications
Wingspan
37 ft 11 in / 11.6 m
Length
31 ft 1 in / 9.5 m
Height
14 ft 11 in / 4.5 m
Wing Area
237 ft² / 22 m²
Engine
520 hp (387.7 kW) Ranger V-770-8 Inline Engine
Propeller
2-blade Hamilton Standard constant-speed propeller (9ft / 2.7m diameter)
Powerplant Ratings
Horsepower output
Altitude
Take Off
550 hp
Sea Level
Normal
(Approx. 84% Throttle)
500 hp
800 ft / 244 m
Fuel Capacity
120+58 US Gal / 454+219 L
Weights
Empty
3973 lb / 1802 kg
Gross
5316 lb / 2411.3 kg
Maximum
6064 lb / 2750.6 kg
Climb Rate (at sea level)
1,350 ft / 411.5 m per minute
Maximum Speed
188 mph / 302.6 kmh
Cruising Speed
111 mph / 178.6 kmh
Stalling Speed
61 mph / 98.2 kmh
Range
600 mi / 965.6 km
Maximum Service Ceiling
22,300 ft / 6797 m
Crew
1 pilot
Armament
2x 12.7x99mm / .50 cal Browning AN/M2 machine guns
Edo XOSE-1 in Standard Wartime ColorsEdo XOSE-1 with the additional ventral stabilizers addedA view showcasing the retractable flaps on the engine.
Two Edo XOSE-1s in flight together [shu-aero.com]A side view of the XOSE-1 in flight A side view of the XOSE-1 in flight. [axis-and-allies-paintworks.com]Rear view of an XOSE-2 or XTE-1. [axis-and-allies-paintworks.com]
Credits
Article written by Medicman11
Edited by Stan L. and Ed J.
Illustrated by Ed Jackson
Jane’s All the World’s Aircraft 1947
Norton, Bill. American aircraft development of WWII : special types, 1939-1945. Manchester: Crécy Publishing Ltd, 2016. Print.
Wagner, Ray. American combat planes of the 20th Century : a comprehensive reference. Reno, NV: Jack Bacon & Co, 2004. Print.
The Douglas XTB2D-1 “Skypirate” was a large, single-engine torpedo bomber built for use on the Midway class carriers during World War 2. At the time, it was the largest aircraft to be used aboard a carrier, dwarfing even two-engine designs. Unfortunately for the Skypirate, engine troubles, little support from the US Navy (USN), and numerous setbacks with the construction of Midway-class carriers nearly doomed it from the start. By the time it was airworthy, it was trying to fill an obsolete role which other aircraft, such as the TBF/TBM Avenger, already filled adequately. Work continued after the war, with several attempts to revive the program but it proved to be too costly and the Skypirate program was finally cancelled in 1947, with the two prototypes being scrapped in 1948.
History
With engagements such as the Battle of the Coral Sea and the hunt for the Bismarck, the effectiveness of torpedo bombers, such as the TBF/TBM Avenger and Fairey Swordfish, was clear. With the announcement of the large Midway-class carriers, the possibility of a new torpedo-bomber/scout bomber came about. In February 1942, a competition was put forward by the Navy for this role. The Douglas Aircraft Company, based in Southern California, proposed the Skypirate. The single-engine Skypirate was picked from eight different designs, most of which were two-engined. The Bureau of Aeronautics (BuAer) wasn’t expecting a single engine design to be submitted, assuming the specified massive carrying capacity would require a two-engine design. The program was being headed by Ed Heinemann as lead designer and Bob Donovan as the chief engineer, who would be on the project until the end.
An impressive look at the massive Skypirate from the front.
In November of 1942, Douglas was given permission to begin production of two prototypes and a mockup of the XTB2D-1 (then called the Devastator II, before being changed to Skypirate). Delays in the development of the Midway class would continue to hamper the Skypirate throughout its life. The finished product was a formidable aircraft, capable of carrying four torpedoes from land or two torpedoes from a carrier, the former being four times the carrying capacity of the TBM Avenger. In March and May of 1943, the mockup was inspected and an order for 23 production aircraft was put in. This was enough for a single squadron to operate from a Midway carrier. Problems began about this time, with the delivery of engines and propellers being delayed. By 1944, the Skypirate was still not airborne and it was obvious it wouldn’t be operational anytime soon. With earlier torpedo bombers performing adequately, a lack of support from the Navy, most of the Japanese fleet in shambles and continued delays with the Midway class (which would eventually sail after the war), the 23 production planes were cancelled. On February 18th, 1945, the first Skypirate was rolled out of the production facility, being completed on March 13th and finally going airborne on May 8th. Neither of the prototypes had any defensive armaments, but they were tested with torpedoes and drop tanks. Although no production was to ever start, the Skypirates would continue flying until the end of the war. During one such flight in June of 1945, a Skypirate was damaged mid-flight, but the craft was brought down safely. Engine problems were a frequent issue with the Skypirate and propeller problems would ground it in August of 1945, not flying again until after the war.
Perhaps the most well known photo of the aircraft, the Skypirate prepares to land.
Postwar, the aircraft industry changed with the introduction of jet aircraft, thus eliminating the need for many prototypes being developed during the war. The Skypirate was no exception. With the torpedo bomber role now fading, the Douglas firm looked at other options to revive their Skypirate. Some ideas included using the Skypirate for an electronic warfare role or even as an anti-submarine aircraft (a role overtaken by another piston engine aircraft, the Grumman AF Guardian), but none of these propositions ever managed to become reality. As the Cold War was just beginning, the Skypirate program ended in 1947 and the 2 prototypes were scrapped in 1948.
Design
The Skypirate is most likely the largest single-engine aircraft to ever be designed for carrier operations. In comparison, the twin-engined B-25 Mitchell medium bomber measured around the same in length and width.
The 2nd prototype in flight, notice how the tail is shorter in comparison to the first prototype.
The initial Skypirate design had an internal bomb bay, which the prototypes dropped in favor of four external Mark 51 Mod 7 bomb hardpoints. These hardpoints could carry a range of weapons including 500Ib-2000Ib bombs, torpedoes, depth charges, mines or even incendiary bombs. The use of up to 4 Mk.13 Torpedoes (from land) were planned had it entered production. The Skypirate could alternatively carry up to 8,400Ibs of bombs. For offensive armament, the Skypirate had 4 M2 Browning machine guns in the wings. For defense, it had a Firestone model 250CH-3 remote turret behind the cockpit which carried 2 M2 Brownings and a turret in the back of the lower fuselage which carried a single M2 Browning. The lower turret was remotely fired through electronic control and powered hydraulically. Drawings indicate that Mark 2 Gun Containers could be added for extra forward firepower but none were ever attached during testing. 300 gallon drop tanks were also fitted during testing and could have been used had the craft been operational.
The sole mockup made alongside the 2 prototypes.
Along with such an impressive weapons payload, the Skypirate was full of advancements which would have improved its performance. To get such a large aircraft off the ground, the Skypirate was powered by a single Pratt & Whitney XR-4360-8, the largest radial engine ever built up to that time. The engine had a unique exhaust style that combined the exhausts in alternating rows to lower the effects of backpressure. Being a carrier-based aircraft, the Skypirate had folding wings as well as a catapult hook. The inclusion of a tricycle landing gear was also interesting, as it helped with bomb loading and carrier space. Most single engine aircraft of the time preferred using a tailwheel. The Skypirate had large flaps that extended the length of wingspan. The outer flaps served as ailerons while the midsection flaps were used as dive flaps. The dive flaps could also be lowered to help the aircraft cruise or assist in turning to help ease the stress off the aircraft when fully loaded. To assist with bombing or flight in general, a Type 3 Sperry vacuum-controlled, hydraulic autopilot was also to be added. A de-icing system was also added that pumped hot air over the wings and tail section.
The planned modifications of the prototypes are interesting to note. The 2nd prototype (Bu.36934) differed from the first, having a shorter tail of 8.6 ft, compared to the regular 10.5 ft tail of the original design. This was done most likely to conserve valuable space when inside a carrier. Along with these differences, plans to fit a jet engine in the fuselage of the 2nd prototype were made, but nothing ever came to fruition. The first prototype (Bu.36933) had a larger tail and was planned to be converted for the scout bomber role. These plans included adding cameras onboard. As with the jet engine designs, these also never came to be.
Variants
XTB2D-1 Bu.36933 – Prototype version, lacked any armament
XTB2D-1 Bu.36934 – The 2nd prototype. The tail was shortened to 8.6 ft. Also lacked any armament.
TB2D-1 – Proposed production version, 23 were ordered and planned production was to be 100 built every month. These versions were to be fitted with four .50 caliber machine guns in the wings, two in a Firestone power turret and one remotely controlled in the ventral hull. Eventually, the production versions were cancelled in favor of higher priority projects.
Operators
United States of America – Slated to be used aboard the Navy’s Midway-class carriers, with the end of the war and other setbacks, the XTB2D-1 was never used operationally.
The design team poses with the first Skypirate on rollout day.
TB2D-1 Specifications
Wingspan
70 ft / 21.3 m
Length
46 ft / 14 m
Height
22 ft 6 in / 6.9 m
Wing Area
605 ft² / 184.4 m²
Engine
1x 3,000 hp ( 2240 kW ) XR-4360-8
Propeller
1x 8 bladed Hamilton Standard contra-rotating propeller
Fuel Capacity
501 US gal / 1896 L
Oil Capacity
28 US gal / 106 L
Empty Weight
18,405 lbs / 8350 kg
Gross Weight
28,545 lbs / 12950 kg
Maximum Weight
34,760 lbs / 15765 kg
Rate of Climb at Sea Level
1,390 ft / 425 m per minute
Time to 10,000 ft / 3048 m
8.2 minutes (Normal) 10.2 minutes (Military)
Time to 20,000 ft / 6096 m
22.3 minutes (Normal) 26.5 minutes (Military)
Maximum Speed
340 mph / 550 km/h at 15,600 ft / 4755 m
Cruising Speed
168 mph / 270 km/h
312 mph / 500 km/h (with torpedoes)
Range
1,250 mi / 2010 km (Torpedoes)
2,880 mi / 4635 km (Maximum)
Maximum Service Ceiling
24,500 ft / 7470 m
Crew
1 pilot
2 gunners
Armament
4 Browning M2 machine guns mounted in the wings (1600rds)
Douglas XTB2D Skypirate Side ViewDouglas TB2D Skypirate Side View – With the Defensive Gun Pod
The last known photos of the Skypirates before being scrapped.One of the prototypes with mounted Mk-13 torpedoes.A back view of one of the prototypesFirst prototype of the Skypirate on the runway.An impressive look at the massive Skypirate from the front.Perhaps the most well known photo of the aircraft, the Skypirate prepares to land.The 2nd prototype in flight, notice how the tail is shorter in comparison to the first prototype.The sole mockup made alongside the 2 prototypes.The design team poses with the first Skypirate on rollout day.
United States of America (1945)
USA (1945)
