Some were simply before their time while others were of no time in particular (or perhaps shouldn’t have been).
Others still look like they were designed for a science fiction movie. Take a look at ten US military aircraft that never quite made it.
It did indeed make a vertical take-off, transitioned to horizontal flight and back again in 1957. It was then demonstrated in Washington DC where it crossed the Potomac River, coming to rest at the Pentagon. Unfortunately the Air Force chose not to develop the Ryan X-13 Vertijet any further because there was a lack of operational requirement.
It was seen as a potential motorcycle of the air and, certainly, the early tests showed quite a lot of promise.
However, once further studies had been conducted it was discovered that the HZ-1 was too difficult to control in untrained hands.
This was further evidence when on test flights the contraption crashed twice. The project was cancelled. (Image Credit)
F2Y Sea Dart
In November 1954 the Sea Dart disintegrated in mid-air during a demonstration for the Navy and the media, killing its test pilot. That was the end of that, but the Navy had been losing interest anyway as problems with supersonic fighters on aircraft carriers had been solved and the Sea Dart had outlived its potential and use.
The first prototype suffered massive engine failure and the second came down in 1948, killing its pilot (Captain Glen Edwards, after whom Edwards Air Force Base is named). The aircraft suffered structural failure and the outer wing sections became detached from the center section, effectively putting paid to the program.
The aircraft was tested extensively and made appearances at a number of air shows in the 1950s. However it was eventually scrapped for more traditional cargo carrying models.
All in all a really cool idea, however, the project was soon scrapped. The reason for its cancellation is almost mundanely obvious. The US Air Force decided that aerial refuelling was a much safer way to extend the range of its fighters.
Republic XF-103 Thunderwarrior
A-12 Avenger II
The project was however, way too expensive and it was cancelled in 1991.
The flying wing concept was back in vogue by the nineties and the Avenger was in the shape of an isosceles triangle with the cockpit at its apex. The internal weapons bay would carry smart bomns and other air-to-ground ordnance. Perhaps not unsurprisingly the A-12 gained the nickname the Flying Dorito. (image Credit)
Convair XFY Pogo
Technical problems such as this aside, had they persisted it would have meant that only the most experienced pilots could have flown the Pogo and so putting one on every small warship would not have been feasible. However, with only half the speed of contemporary jet engine fighters which were at the time approaching Mach 2, the project was put on hiatus in 1954.
We will finish with one that was successful – well, almost. The Lockheed YF-12 was a prototype interceptor which spawned the SR-71 Blackbird. However, despite breaking all sorts of records during testing, including a speed record of 2,070.101 mph (3,331.505 km/h) and altitude record of 80,257.86 ft (24,462.6 m), both on 1 May 1965, the program ended in 1968. One word says it all – Vietnam. At the time defense of continental USA was less of a priority and so the project was shelved.
However, there is a happy ending for the Lockheed YF-12. They continued flying for many years with the USAF and with NASA in the role of research aircraft.