Here is an example of how difficult it is to get a plane off the ground, so to speak. This doesn’t only refer to mechanics, but also to money. The Adam A700 was a victim of financial issues, even though it was produced during the early 2000s aviation start-up boom. Things looked positive, as many plane start-ups were succeeding, but sadly the Adam was not one of the fruitful ones.
The six-seat A700 had two Williams FJ33s mounted on the fuselage and twin wing-mounted booms supporting aft twin rudders, linked by a high horizontal stabilizer. The same went for its A500 piston-powered sister. By 2008, the Adam went bankrupt and was never seen again.
Army standards are high, as they should be. Equipment, tools, and especially aircraft need to be of an impeccably high standard. This is for combat after all and things need to run as smooth as possible. When the Curtiss-Wright VZ-7 burst onto the scene, it looked like it was born for the army.
It even got the nickname "the flying jeep," and all signs pointed to "yes." No doubt that this thing was dangerous and unique, there weren't any shrouds around the propellors. Nevertheless, the military did just not approve of it and it never really saw its potential. Farewell flying jeep, you tried.
The Hiller X-18 was sort of the guinea pig for tilt-wing and VSTOL technology and for some time things looked hopeful. One might even call this particular flying machine a prototype for the Osprey. Sadly things took a turn and the X 18 engineers discovered that it couldn't even withstand a gust of wind.
The engines were not cross-linked, resulting in engine failure and ultimate crashing. Less ideal for planes. To much crashing deterred production, the Hiller X-18 came to a halt and all production was ceased. It did however inspire later models and laid the groundwork for more developed technologies.
Aviation Traders Carvair
The Carvair had its first take-off in the year 1961, but of the 21 built planes that were built, as many as eight of them were involved in crashes. That does not say much for reliability. This probably had something to do with the fact that the Aviation Traders company founded by entrepreneur Freddie Laker attempted to convert the surplus of Douglas DC-4 engines into car transporters, fit for 25 passengers.
Knowing the reputation of Douglas, this did not sound like a good idea. Of course, there is a lot of money in transporting cars and the details were overlooked. The result was many many accidents. Needless to say, it was discontinued.
Opinions vary on whether or not the Wichita-built Starship was ever a creation of beauty or a total absurdity. Commercially, it was unquestionably, an utter failure. 53 (too many) of these ridiculous planes were produced between the 1980s and early 1990s.
Over a decade later, in 2003, to be precise, Raytheon Aircraft and the Federal Aviation Administration announced they intended to recall all of the Starships ever made and additionally scrap the ones that had been made because the airframer could no longer support them. A monumental loss indeed. It's safe to say that this was quite the failure and example of overly lavish designs that are completely unnecessary.