1. The Thunder screech
An experimental turboprop aircraft, the XF-84H was powered by a a turbine engine that was mated to a supersonic propeller. But due to the noise that the aircraft created using its engines which could be heard 25 miles away while starting up and caused severe nausea and blew out eardrums of the ground crew, led to its cancellation.
2. Intruder from the Future
Imagine a bomber, designed to carry atomic bombs that can fly at an altitude of 15 miles and three times the speed of sound. The B-70 Valkyrie was supposed to be the aviation dream from the future, but while it was developed, the improvements of high-altitude surface-to-air missiles, the change to low-level penetration bombing, the program’s high development costs, and the introduction of intercontinental ballistic missile (ICBMs) led to the cancellation of the B-70 program in 1961. Two prototypes were eventually used; one of them crashed following a midair collision in 1966.
3. The Un-landable Plane
The US government wanted fighters on all their ships instead of having an aircraft take off only from carriers. The XFV Salmon plane was made with landing gear on its tail. But since the pilots couldn’t land backwards on the ship and that the jet was much slower than other contemporary fighters and was far too complicated to fly, the idea of having fighter jets on every ship was dropped.
Former high-ranking members of the Soviet military and the Central Committee of the Communist Party in a series of interviews to the American defense contractor BDM, admitted the existence of the Dead Hand in the early 1990s. Although there were contradictory statements concerning its deployment but for all we know, it is possibly still a fully operational nuclear- control system that can automatically trigger the launch of the Russian Intercontinental ballistic missiles (ICBMs) if a nuclear strike is detected by seismic, light, radioactivity and overpressure sensors, creating a fail-deadly deterrence.
5. The Flying Dorito
The Flying Dorito, also known as A-12 Avenger II was an all-weather, carrier-based stealth bomber replacement for the Grumman A-6 Intruder in the United States Navy and Marine Corps. However, due to the extra cost for the over-runs, the project was dropped in 1991 after wasting more than 5 billion dollars.
6. Iceberg Aircraft Carrier
In the World War II the British developed a plan, Project Habakkuk, to build an aircraft out of a mixture of wood pulp and ice (pykrete). The idea was dropped as they realized that it was a huge waste of time and resources.
7. Lunar Nuclear Bomb
Unites states decided to test a nuclear weapon on moon in order to enhance the public morale after the Soviet Union’s early lead in the space race. The project was called 119-A, however it was never carried out as they realized that having a man on the moon is far better than to try and annihilate it.(wonderfulengineering)