Category Archives: Community Creations

Republic F-74 Thundercloud (Fictional)

usa flag USA (1946)
Fictional Prototype Fighter Bomber – 11 Built

Inspired by the Kyushu J7W and Curtiss-Wright XP-55, the P-later-F-74’s radical wing designs lifted its position in aviation history to the jet age’s dawn. With a canard layout and its inverted, swept-back gull wings, this little-known fighter-bomber was a broad new attempt at close air support by Republic Aviation. Meet the unnamed member of the “Thunder family” – F-74 Thundercloud.


After Japan’s surrender in 1945, the U.S. Naval Technical Mission to Japan immediately commenced. Found at an abandoned hangar of the Itazuke Air Base, an aircraft with a radical design caught everybody’s eyes. This is the Kyushu J7W Shinden, an interceptor with a canard layout and a pusher engine at the back, similar to the U.S. Army’s XP-55 Ascender. Along with other interesting Japanese designs, the J7W was dismantled, crated, and shipped to the U.S.

Immediately after the Second World War, USAAF launched their next generation multirole strike fighter program. The winning project of the contract would be awarded the codename P-74. However, most major companies such as North American and Lockheed were busy creating their first jets, leaving Republic Aviation the only participant. Impressed by the J7W’s perfect integration of nose-mounted weapons and the large but streamlined fuselage that houses powerful engines, Republic decided to give it a shot, as a then-intermediate candidate of the P-84 Thunderjet.


The F-74 was an all-metal, monocoque, low-wing cantilever monoplane. Its unique canard layout consisted of a pair of compound delta wings that integrated an inverted “gull wing” design with a pair of dihedral wing tips that houses the ailerons, and a pair of smaller, less swept back trapezoidal canards at the front of the aircraft, immediately behind and above the modular weapon bay. Two vertical stabilizers are positioned at the joint between the main wing and the wingtips, with anti-skid wheels on the bottom. A pair of long and narrow side intakes drew upcoming air into the rear-mounted, air-cooled radial engine (R-3350 or 4360) that drove a set of four wide paddle blade style constant speed propellers [1].

The nose-mounted weapon bay could be easily swapped at any frontline airfield to suit different combat scenarios, ranging from the basic “six-pack” .50 machine guns to a pair of powerful 37mm cannons. The powerful R-4360 engine also allowed an assortment of weapons to be carried under its wing pylons, ranging from unguided rockets, general purpose and napalm bombs, to machinegun pods that further enhance the aircraft’s firepower.

Not Your Average Cumulonimbus

Only one year after Republic “won” the contract by being the sole participant, on 17th August 1946, the XP-74-A-0-RE prototype flew for the first time. With a R-3350 engine and simulated counterweights instead of guns, the aircraft displayed favorable control characteristics. Its low-speed handling was surprisingly well for an aircraft this size, thanks to its large wing area and powerful pitching leverage provided by the front-placing canards. The only two complaints of the test pilot were its large torque on the takeoff roll and the fragile rear propeller he broke on landing. The first problem was addressed by applying more trim, with the second one solved by adding a pair of anti-skid wheels under the vertical stabilizers.

However, the Army paused the XP-74 project in favor of the jets. The project was also overshadowed inside Republic themselves, because their jet replacement of the P-47 Thunderbolt – the XP-84 Thunderjet – already took to the skies six months before XP-74 did. All testings were halted and the project group was dissolved, despite the emergence of another high-altitude interceptor variant, the XP-74B.

Luckily, the newly-formed USAF changed the fate of this plane one year later. Facing threats of probable “Communist-containing” wars (Korean War and subsequently Vietnam War), the Air Force needs a reliable attacker with a large payload as a suitable backup to the new and unreliable jets. The Thundercloud was revived under the name of F-74. Republic offered the USAF an improved version, dubbed as the F-74D. With a powerful R-4360 radial engine and four 20mm AN/M3 cannons, this machine could rain down deadly ordnances at an incredible efficiency [2]. Five D-variants fought during the Korean War, with one of them later modified for the Project GunVal, carrying four T-160 cannons as an experimental configuration. After the retirement of all F-74s, some were acquired by NACA and later NASA as X-74s for experimental airfoil research.


  • XP-74A-0-RE – Initial prototype for the USAAF. First flight on 15th Aug. 1946. No armament, R-3350 engine.
  • YP-74A-1-RE – Small pre-production series starting from Dec. 1946. Armed with 6 Browning M3 12.7mm MGs. 5 built.
  • P-74B – High-altitude heavy interceptor variant. 2x 37mm M10 cannons and 2x M3 12.7mm MGs. R-4360 engine with supercharger. None built.
  • F-74D-1-RE – Ground attack variant for the USAF. 4x 20mm AN/M3 cannons, R-4360 engine without supercharger. 5 built, 3 converted from A-1 variant in 1949.
  • F-74D-2-RE – Testbed for T-160 autocannons during Project GunVal in 1953. 4x 20mm T-160 cannons. 1 converted from F-74D-1.
  • X-74A – Two aircraft served for NACA and later NASA for experimental airfoil research. R-4360 engines with supercharger. 2 converted from YP-74A pre-production models.


  • [USA] – Evaluated by the U.S. Army and later Air Force. 8 deployed in the Korean War. Retired 1953[3]. 2 used by NACA/NASA. Fate unknown.


Republic XP-74/YP-74/F-74 Specifications

Wingspan 41 ft 2 in / 12.54 m
Length 44 ft 2 in / 13.46 m
Height 15 ft 1 in / 4.59 m with landing gears
Wing Area 322.05 ft² / 29.92 m²
Engine 1x R-3350-23 (2,200 hp) (A model only)

1x R-4360-31 (3,000 hp) (other variants)

Empty Weight 11,000 lb / 4763 kg
Maximum Takeoff Weight 19,000 lb / 8618 kg
Fuel Capacity 1514 L internal, up to 3x 416L drop tanks
Climb Rate 15m/s at sea level (D-1 model)
Maximum Speed 430 mph / 692 kmh at 10,000 ft / 3,048 m
Cruising Speed 400 mph / 644 kmh
Range 750 mi / 1207 km on internal fuel, D model
Maximum Service Ceiling 36,900 ft / 11,200 m for A-1

26,000 ft / 7,925 m for D-1

Crew 1x Pilot
Armament A-1:

6x 12.7mm Browning M3 (400 rpg)


2x 12.7mm Browning M3 (400 rpg)

2x 37mm Browning M10 (60 rpg)


4x 20mm AN/M3 (250 rpg)


4x Ford T-160 (150 rpg)




“Literally Fake News”, The Fake News Department of the United States of America, September 1946., “The Republic F-74D” official promotion booklet, Republic Aviation, 1949., “A Brief History of the Rice Field Attackers in Korea and Vietnam”, Tingwong Sum, 1983., Images: Side Profile Views by Ed Jackson –


Project 337

Soviet Union (1941)
Biological Weapon – 1 Built

With recent study trips to Russia, the Plane Encyclopedia team has been working closely with the Russian Archives to record and scan aircraft performance data and various other aviation related documents. While doing this, the team has accidentally rediscovered a series of then-classified documents regarding a secret biological weapon designed in 1941 intended to be used on Berlin in an attempt to stop or at least delay the German advance on Moscow. Classified “Project 337” by the Soviets, the weapon would have been able to bring havoc on any city it was deployed on. Come read the story of the newly discovered Project 337!


In the early stage of Operation Barbarossa during the shift of fall to winter, the Soviet high command became increasingly worried and desperate for a way to halt or at least delay the seemingly unstoppable German advance. On September 29th of 1941, a top secret meeting was held at the Kremlin to discuss the current losses of the Soviet Union, and how to replace the lost equipment. With mostly desperate ideas such as using outdated equipment such as 19th century rifles and cannons taken from stockpiles. Finally, a serious and feasible idea was brought up, which was to bomb Berlin with biological weapons, causing the city to plunge into chaos, and to warrant the retreat of the Germans. With Stalin liking the idea, he immediately agreed and ordered the project to be finished no later than November 29th.

Unfortunately, the dimensions, location, team and materials used to develop Project 337 is unknown as the documents that specifies these are still classified and withheld by the Russian government. What is known however, is that the disease which would be used in Project 337 was tularemia.

This rather unclear photo shows what appears to be the finished Project 337 prototype, resembling a huge metallic peanut with the black canopy.

With extensive research in the Russian archives, two photos of Project 337 were able to be obtained. The first photo shows the roof of the weapon, which consisted of a bowl shaped canopy with more than a dozen holes. This would have been how the tularemia bacteria would be released. The second photo shows what seems to be the finished Project 337 prototype, which looked like a huge metallic peanut with the black canopy.

The upper section of the weapon, which consisted of a bowl shaped canopy with more than a dozen openings. This would have been how the tularemia bacteria would have been released.

On December 1st of 1941, Project 337 was completed and was now ready to be tested on Berlin. To carry such a weapon, the Soviet Air Force began looking for a capable heavy bomber which would be able to fly at tall heights. Although scarce, the bomber chosen was the Petlyakov Pe-8 bomber. A single Pe-8 was transferred from the Far East Regiments and modified to carry Project 337. As for personnel, experienced pilots Lieutenant Igor N. Timoshenko, Junior Lieutenant Dima I. Pokryshkin and Lieutenant Mikhail Gorkin were chosen to complete the task of dropping the prototype biological weapon on Berlin. These pilots were not told of the contents they were carrying, and was only instructed to fly to Berlin, drop the payload and return to base as the Soviets still wished to maintain the secrecy of the project.

On December 5th, Lieutenant Igor N. Timoshenko, Junior Lieutenant Dima I. Pokryshkin and Lieutenant Mikhail G. Gorkin took off in the Pe-8 carrying Project 337 at 8:31 PM from an undisclosed secret airfield. With the intent of maintaining stealth, the Pe-8 crew would have maintained radio silence in order to not get detected. Approximately 1 hour and 14 minutes into the flight, the Soviet ground crew were surprised to receive an emergency radio call from the aircrew. According to the recently declassified Soviet documents, the ground crew reported that Lieutenant Gorkin shout in the radio in panic that the Pe-8’s inner starboard engine caught fire, and that the plane was rapidly losing altitude. Lieutenant Gorkin decided the best thing to do was to perform an emergency landing, and he made this decision known to the ground crew. Unfortunately, the documents stated that contact was lost with the crew during the botched emergency landing. One of the documents dated April 1st of 1944 stated that efforts to locate the Pe-8 has failed, and that the plane likely crashed into a body of water. Due to the loss of the sole bomb, tests were unable to be completed and the project was set back. This led to the eventual abandonment of the project as the Soviets couldn’t afford to spend more time development such a weapon.

The final document which referenced Project 337 dated April 20th of 1948 mentioned that the incident which caused the destruction of the Pe-8 was improper maintenance. It is said that the mechanics responsible for the maintenance were executed, while the radio crew were sent to the gulag. Timoshenko, Pokryshkin and Gorkin’s families were all sent a letter stating that they died in combat as heroes. In conclusion, Project 337 can be considered a failure. With the current evidence that the Plane Encyclopedia team has, it is reasonable to assume that the Pe-8 carrying Project 337 is perhaps still out there buried beneath layers of mud, sand, or water, never to be seen by mankind again.


Rep. No. Поддельный источник, используемый для апрельских дураков (04.01.1944) (1944).

Rep. No. Полностью реальный источник, а не подделка (04.20.1948) (1948).

Doc. No. Я люблю Энциклопедию (01.14.1943).