All posts by Gunther Arnold

Grumman AF-2W Guardian (Airmodel, Vacu, Parts scratch built)

TYPE: Anti-submarine search aircraft

ACCOMMODATION: Crew of four

POWER PLANT: Pratt & Whitney R.2800-48W Double Wasp, rated at 2,400 h.p.

PERFORMANCE:  317 m.p.h. at 16,000 ft

COMMENT: Originally designed as a replacement of the highly successful Grumman TBF Avenger anti-submarine search aircraft. In place of defensive armament the new torpedo-bomber had a Westinghouse 19XB turbojet in the tail to give it a high escape speed. Later the the design was revised and a large ventral radar set was built in. In that configuration the aircraft was used as a hunter in cooperation with the Grumman AF-2S as a killer. A total of 153 AF-2W were built.

Republic XP-69 (Anigrand, Resin)

TYPE: High Altitude Fighter

ACCOMMODATION: Pilot only

POWER PLANT: Wright R-2160-6 Tornado, rated at 2,500 h.p.

PERFORMANCE: 453 m.p.h.

COMMENT: This project was designed as a fast high altitude fighter capable of intercepting and destroying high altitude enemy bombers. The design incorporated new innovations such as a pressurized cabin, laminar flow wing, and contra-rotating propellers. A mock-up was built, but the project was cancelled because the Wright R-2160 42-cylinder engine was never produced. In 1944 Republic modified a two P-47D’s for testing Chrysler XI-2220 inverted-Vee liquid-cooled engines (Republic XP-47H). This made an extremely finely-streamlined cowling of low frontal area necessary similar that project shown here.

 

Junkers Schlachtflugzeug (Unicraft, Resin)

TYPE: Close Support Fighter Bomber.  Project

ACCOMMODATION: Pilot only

POWER PLANT: Daimler-Benz DB-ZTL 109-007 Bypass turbojet, rated at 1.150 kp each

PERFORMANCE: Not available

COMMENT: Project of a heavily armed jet aircraft from 1941. Pilot’s cockpit, engines and ammunition compartments were heavily armoured from underside. Due to lack of experience with nose landing gear on earth fields a nose skid was planned. Thrust deflecting flaps behind the exhausts allowed short take-off runs

 

Convair XP-81 (Anigrand, Resin)

TYPE: Long-Range Escort Fighter

ACCOMMODATION: Pilot only

POWER PLANT: One General Electric T31-GE-1 turboprop engine, rated at 2,300 h.p. and one Allison J 33-GE-5 turbojet engine, rated at 703 kp

PERFORMANCE: 507 m.p.h. at 30,000 ft

COMMENT: The Consolidated Vultee XP-81was a development of the Consolidated Vultee Aircraft to build a single seat, long range escort fighter that combined use of both turbojet and turboprop engines. Although promising, the lack of suitable engines combined with the end of World War II doomed the project.
Two prototype aircraft were ordered on February 1944 that were designated XP-81. The engine selection was an attempt to couple the high-speed capability of the turbojet engine with the endurance offered by the propeller engine. The XP-81 was designed to use the General Electic TG-100 turboprop engine in the nose driving a four-bladed propeller and a General Electric J33 turbojet in the rear fuselage. The turboprop would be used for normal flight and cruising and the turbojet added for high-speed flight.
The first XP-81 was completed in January 1945 but because of developmental problems the turboprop engine was not ready for installation. A decision was then made to mount a complete Packard V-1650-7 Merlin engine package from a North American P-51D Mustang aircraft in place of the turboprop for initial flight tests. This was done in a week and the Merlin-powered XP-81 was sent to the Muroc airbase where it flew for the first time on 11 February 1945. During 10 flight test hours, the XP-81 displayed good handling characteristics except for inadequate directional stability due to the longer forward portion of the fuselage. This was rectified by enlarging the vertical tail.
While 13 Convair YP-81 pre-production aircraft had been ordered, the capture of Guam and Saipan eliminated the need for long-range, high-speed escort fighters and then, just before VJDay the contract was cancelled, after 85% of the engineering was completed. The YP-81 was to be essentially the same as the prototype but with a lighter and more powerful General Electric TG-110 (XT41) turboprop engine, the wing moved aft 0.25 m, and armament of either six 12.7 mm machine guns or six 20 mm cannon.
After the XP-81 was returned to Vultee Field, the TG-100 turboprop was installed and flight testing resumed, including the first flight by an American turboprop-powered aircraft on 21 December 1945. However, the turboprop engine was not able to produce its designed power; producing only the same output as the Packard Merlin (1,490 hp) with the resultant performance limited to that of the Merlin-engined version.
With the termination of hostilities, the two prototypes continued to be tested until 1947 when they were both consigned to a bombing range as photography targets (Ref.: 24).

Focke-Wulf Ta 154A-0 (Pioneer) with Fw 190F-8 (Revell) “Mistel 7”, Mistletoe 7)

TYPE: Bomber Formation Destroyer (” Pulkzerstörer”) as as pickaback (“Mistel”) combination of a Ta 154 and a Fw 190

ACCOMMODATION: Pilot only in the Fw 190

POWER PLANT: Two Junkers Jumo 213E, rated at 1,750 h.p. (Ta 154) and BMW 801D-2, rated at 1,700 h.p. (Fw 190)

PERFORMANCE: Not available

COMMENT: Six  Ta 154 pre-production aircraft should be adapted for the “Huckepack” composite role. The Ta 154 had an explosive charge in the forward fuselage and was piloted by a Focke Wulf Fw 190 . It was proposed that the Mistel combination – reportedly designated “Mistel 7” (“Mistletoe 7”) – should be aimed at the bomber formation, the pilot detached his aircraft from the superstructure and then detonated the charge by radio signal. None combination was realized.

North American XB-28 Dragon (Anigrand, Resin)

TYPE:  Medium Bomber

ACCOMMODATION: Crew of five

POWER PLANT: Two Pratt & Whitney R-2800-27 air-cooled radial turbocharged engines, rated at 2,000 hp each

PERFORMANCE: 372 m.p.h. at 25,000 ft

COMMENT: The North American XB-28 (NA-63) Dragon was an aircraft proposed by North American Aviation to fill a strong need in the United States Army Air Corps for a high-altitude medium bomber. It never entered production, with only two prototypes being built.
The order for a high-altitude medium bomber was put out on 13 February 1940; the XB-28 first flew on 26 April 1942. The XB-28 was based on North American Aviation‘s’s highly successful B-25 Mitchell, but as it evolved it became a completely new design, much more reminiscent of the Martin B-26 Marauder. The overall configuration of the B-25 and XB-28 were fairly similar; the most important distinction was that the twin tail of the B-25 was changed to a single tail on the XB-28. It was among the first combat aircraft with a pressurized cabin.
The XB-28 proved an excellent design, with significantly better performance than that of the B-25, but it was never put into production. High-altitude bombing was hampered significantly by factors such as clouds and wind, which were frequent occurrences in the Pacific. At the same time, medium bombers were becoming much more effective at lower altitudes. The gains in aircraft performance that came with high-altitude flight were not considered sufficient to justify switching from low-altitude bombing.
Even though the Army Air Forces rejected the XB-28 as a bomber, they ordered another prototype. Designated XB-28A, it was meant to explore the possibility of use as a reconnaissance aircraft. The XB-28A crashed into the Pacific Ocean off Southern California after the crew bailed out on 4 August 1943 (Ref.: 24).

Focke-Wulf Ta 154A1-R1 (Hasegawa)

TYPE: Fighter-bomber, close support aircraft

ACCOMMODATION: Pilot and observer/radio operator

POWER PLANT: Junkers Jumo 213E, rated at 1,750 h.p. each

PERFORMANCE:  332 m.p.h. at sea level

COMMENT: Projected close support fighter bomber on the basis of the Ta 154A-1. None built

Chance Vought Jet Skimmer (Unicraft)

TYPE: Carrier-borne STOL-fighter

ACCOMMODATION: Pilot only

POWER PLANT: Two Westinghouse J 34-WE-30 turbojet, rated at 760 kp each

PERFORMANCE: Not available

COMMENT: Projected  jet version of the piston engine powered XF5U-1. No further details available

Focke-Wulf Ta 154A-0 “Moskito” (Hasegawa)

TYPE: Night and Bad-weather fighter

ACCOMMODATION: Pilot and Radar observer

POWER PLANT: Two Junkers Jumo 213E, rated at 1,750 h.p. each

PERFORMANCE: 404 m.p.h. at 23,250 ft.

COMMENT: The Ta 154V 15, the eighth pre-production  Ta 154A-0, was equipped with the FuG 220 Lichtenstein SN-2 radar, fitted with a “Hirschgeweih” (Stag’s Antlers) antennae array

Vought XF5U-1 Flying Flapjack (Hasegawa)

TYPE: Carrier-based fighter

ACCOMMODATION: Pilot only

POWER PLANT: Pratt & Whitney R-2000-2  radial engine, rated at 1,350 h.p. each

PERFORMANCE: 452 m.p.h. at 28,000 ft (estimated)

COMMENT: The Vought XF5U “Flying Flapjack” was an experimental US Navy fighter aircraft designed by Carles H. Zimmerman for Vought during World War II. This unorthodox design consisted of a flat, somewhat disc-shaped body (hence its name) serving as the lifting surface. Two piston engines buried in the body drove propellers located on the leading edge at the wingtips
A developed version of the original Vought V-173 prototype, the XF5U-1 was a larger aircraft. Of all-metal construction, it was almost five times heavier, with two 1,400 hp Pratt & Whitney R-2000 radial engines. The configuration was designed to create a low aswpect ratio aircraft with low takeoff and landing speeds but high top speed. The aircraft was designed to keep the low stall speed and high angle of attack from the V-173 prototype while providing for better pilot visibility, cockpit comfort, less vibration, and provisions to install armament. This included a cockpit redesign moving the cockpit from the leading edge of the wing to a nose nacelle that extended further in front of the leading edge. The arrestor hook was changed to a dorsal hook that would diminish the drag from the apparatus.
Normally, a wing with such a low aspectratio will suffer from very poor performance due to the degree of induced drag created at the wingtips, as the higher pressure air below spills around the wingtip to the lower-pressure region above. In a conventional aircraft, these wingtip vortices carry a lot of energy with them and hence create drag. The usual approach to reducing these vortices is to build a wing with a high aspect ratio, i.e. one that is long and narrow. However, such wings compromise the maneuverability and roll rate of the aircraft, or present a structural challenge in building them stiff enough. The XF5U attempted to overcome the tip vortex problem using the propellers to actively cancel the drag-causing tip vortices.The propellers are arranged to rotate in the opposite direction to the tip vortices, with the aim of retaining the higher-pressure air below the wing. With this source of drag eliminated, the aircraft would fly with a much smaller wing area, and the small wing would yield high maneuverability with greater structural strength.
The propellers envisioned for the completed fighter — unlike the torque-reducing counter-rotating propellers of the V-173 design — were to have a built-in cyclic movement like a helicopter’s main rotor, with a very limited ability to shift their center of lift up and down to aid the aircraft in maneuvering. Initially, the aircraft used propellers originally designed for the V-173 prototype.These propellers would be replaced with propellers taken from the Vought F4U-4 Corsair. An ejection seat was fitted to allow the pilot to clear the massive propellers in the event of an in-flight emergency. Although the prototype was unarmed, a combination of six M2 Browning 50-caliber machine guns or four M3 20mm cannopns would be mounted in the wing roots in service.
The XF5U design was promising: specifications given at the time promised great maneuverability and speeds up to 452 mph. However, it came at the time when the United States Navy was switching from propeller driven to jet propelled aircraft. By 1946, the XF5U-1 project was already long over its expected development time, and well over budget. With jet aircraft coming into service, the Navy finally canceled the project on 17 March 1947, and the prototype aircraft (V-173) was transferred to the Smithsonian Museum for display. Although two aircraft were constructed, a lone XF5U-1 underwent ground runs but never overcame vibration problems. Taxi trials at Vought’s Connecticut factory culminated in short “hops” that were not true flights. The only completed XF5U-1 proved to be so structurally solid that it had to be destroyed with a wrecking ball (Ref.: 24).