The McDonnell Douglas X-36 Tailless Fighter Agility Research Aircraft, now known as Boeing X-36, was an American prototype jet built without a conventional tail assembly. It successfully completed its first flight in May 1997 and went on to achieve its project goals in approximately 30 subsequent flights. While it is now retired, it left a legacy of setting records and inspiring further innovations that continue to patrol the skies today.

The Lockheed XFV, also known as the “Salmon,” was an American experimental tailsitter prototype aircraft developed by Lockheed in the early 1950s. Its primary purpose was to showcase the concept of a vertical takeoff and landing (VTOL) fighter for convoy protection. Initially, both Convair and Lockheed vied for the contract, but in 1950, the requirement changed, calling for a research aircraft that could potentially evolve into a VTOL ship-based convoy escort fighter.

MIT’s D8 Series design aims to set a new standard for passenger liners and transports in the coming years. Its distinctive “double bubble” frame, based on a modified tube and wing structure, enables a considerably wider fuselage compared to conventional aircraft. The incorporation of ultra-low sweep wings not only reduces drag and weight but also provides additional lift. Furthermore, the fully embedded engines placed aft of the fuselage significantly enhance the aircraft’s maneuverability.

The Vought V-173 “Flying Pancake,” an experimental aircraft designed for the U.S. Navy, made its debut in the mid-1940s. It featured two piston engines concealed within the body, powering propellers situated on the wingtips’ leading edge. However, the timing of its introduction coincided with the end of World War II, rendering this flying-saucer-like fighter aircraft largely impractical and of little use to the American military.

The H-4 Hercules 2, a massive 200-ton aircraft, earned the nickname “Spruce Goose” due to its wooden frame, primarily constructed from birch. Designed by filmmaker and business magnate Howard Hughes, this heavy transport aircraft holds the distinction of being the largest fixed-winged seaplane ever built. Though just one was ever constructed, it now resides in an Oregon museum.

Designed for low-speed observation tasks, the British-made Edgley EA-7 Optica serves as a cost-effective alternative to helicopters. It completed its inaugural flight in December 1979, and within the subsequent three years, the company achieved full manufacturing capacity, obtained UK certification, and delivered its first customer aircraft. Despite these accomplishments, the required additional investment for the final phase of full production did not materialize.

Wind-tunnel experiments and computer models can only provide limited insights into the complexities of an object moving swiftly through the atmosphere. For a comprehensive understanding, sometimes the best approach is to take the plunge and experience it firsthand. NASA’s AD-1 steps in here. This ingenious aircraft features a wing that can be fully readjusted horizontally by 360 degrees, revolutionizing flight testing. The robust wing can even pivot up to 60 degrees during flight without experiencing significant instability, an impressive feat for a plane constructed in 1979.

The Convair F2Y Sea Dart, an American seaplane fighter aircraft, utilized hydro-skis for takeoff and landing. It made its inaugural flight in 1953 and was retired in 1957. Remarkably, this plane remains the only seaplane to have surpassed the speed of sound. Unfortunately, the program faced setbacks and was eventually canceled due to unsatisfactory results and a tragic accident on November 4, 1954. During that incident, test pilot Charles E. Richbourg lost his life when the Sea Dart he was piloting disintegrated midair.

The Korabl Maket, also known as the Caspian Sea Monster in English, was a Soviet experimental aircraft crafted by the Central Hydrofoil Design Bureau during the 1960s. Its inaugural flight occurred in October 1966, but sadly, it was destroyed in 1980. Before its demise, this extraordinary creation was captured and revealed to the world, sparking intrigue and curiosity. Its unexpected discovery by the United States led to intense espionage efforts during the Cold War to decipher its purpose, making it a distinctive event in that era.

The Caproni Ca.60 Transaereo, also known as the Noviplano or Capronissimo, was a prototype of a massive 9-wing flying boat designed as a transatlantic airliner for 100 passengers. Equipped with 8 engines and 3 sets of triple wings, it took its first flight in 1921 but was unfortunately destroyed during its second flight. Despite intentions to rebuild, the project was ultimately abandoned due to its prohibitively high cost.

The British Aerospace Nimrod MRA4 was designed as a maritime patrol and attack aircraft with the purpose of succeeding the Hawker Siddeley Nimrod MR2. The aim was to prolong the lifespan of the Nimrod fleet for several decades by incorporating upgraded features, such as advanced Rolls-Royce BR700 turbofan jet engines that nearly doubled the flight range. When viewed from different perspectives, the aircraft may not appear particularly surprising, but from this vantage point, it undeniably presents a rather peculiar sight!

Built by Stratolaunch and designated as the “Scaled Composites Model 351 Stratolaunch”, this aircraft features an unconventoinal twin-fuselage design. 6 whole PW4056 engines power this behemoth of a plane. The impressive part is that it actually flies. It’s been on several flights between 2021 and 2022.

The Mil V-12 holds the title of the largest helicopter ever constructed. It underwent an unsuccessful first flight in June 1967, followed by a successful flight in July 1968, but was ultimately canceled. Due to design limitations, Mil considered various rotor systems, including a tandem layout like the Boeing CH-47 Chinook, but encountered significant issues. After studying single rotor layouts that proved unfeasible, they settled on the transverse layout for the final version.

During the Cold War, North American Aviation developed an experimental nuclear warhead delivery system resembling flying saucers. Wright-Patterson Air Force Base in Ohio managed the project. In the 1950s and 1960s, the U.S. military and NASA experimented with such designs. One of these LRV projects was declassified in 1999. If you spotted a flying disc near these bases back then, it could have been one of these unique aircraft.

The PZL M-15, a jet-powered biplane, was crafted by WSK PZL-Mielec, a Polish aircraft company, specifically for agricultural aviation. Due to its unconventional appearance and the loud jet engine, the aircraft earned the nickname “Belphegor,” after a noisy demon. The development of the M-15 can be traced back to a Soviet need for a modern agricultural aircraft to replace the Antonov An-2. It was at the insistence of Soviet officials that jet propulsion was chosen to drive this aircraft.

Designed by B.J. Schramm in the early 1960s, this single-seat light helicopter, also known as the RotorWay or Schramm helicopter, was marketed even before its construction, starting in 1958. Schramm’s aim was to create a simple and easy-to-maintain helicopter with minimal components. While it wasn’t initially ready for mass production, the Scorpion, RotorWay’s first production helicopter, proved to be successful upon its introduction in 1967. As of 2022, RotorWay continues to manufacture helicopters.

In 1931, construction of the aircraft known as the Kalinin K-7 was initiated by the Soviet Union. This colossal aircraft, conceived by World War I aviator and aircraft designer Konstantin Kalinin, was among the largest of its time, boasting impressive dimensions of 91 ft 10 in (28m) in length and a wingspan of 173 ft 11 in (53 m). The K-7 featured a unique design with a pusher engine configuration, six tractor engines positioned on the wing leading edge, and underwing pods, twin booms, and machine-gun turrets.

During its operational period, the K-7 undertook seven successful flights before encountering a catastrophic structural failure that led to a devastating crash. Regrettably, this unfortunate event led the Soviets to terminate the project in 1935.

The Northrop XP-79, designed by John K. Northrop in 1942, featured a pilot lying down and was powered by two Westinghouse 19B turbojets. Initially considering a rocket motor, Northrop abandoned the idea due to poor outcomes. The aircraft used a monocoque skin instead of aluminum. However, in 1945, a tragic test event of the modified XP-79B led the company to cancel the project, ultimately destroying the aircraft.

Designed by Reimar and Walter Horten, the Horten Ho 229 was a World War II prototype flight/bomber created for Germany. Their objective was to fulfill Reichsmarschall Göring’s request for an aircraft capable of carrying 1,000 kilograms (2,200 lbs) of bombs at a speed of 1,000 kilometers per hour (620 mph). To meet this demand, jet engines were chosen, but the Junkers Jumo 004 engine consumed a significant amount of fuel. Despite this, research continued until the war’s end.

In 1945, the U.S. military acquired the V3 prototype, transporting it to the U.S., where it remains today as the sole surviving Horten Ho 229. It is on display at the Smithsonian National Air and Space Museum.