1. AD-1 Oblique Wing.

Based on the idea that being able to shift wing positions around would be more fuel efficient, NASA went to work building this one. The theories proved to be correct, but flying the plane presented some unpleasantness.

2- Tacit Blue

In some situations the need for stealth outweighs aerodynamic concerns. Tacit Blue was created in the 1980s for such scenarios. It’s bubbly and boxy body allowed it to fly undetected by radar.

3- X-29 Forward Swept Wing Jet.

Its wings look like they’re on backwards, but that wasn’t what prevented this plane to get very far out of the testing stage. The problem was that it couldn’t be controlled by a human pilot if its computer system malfunctioned, and we all know how fickle computers can be.

 

4- XFY-1 Pogo

The thing with many planes is that you just can’t park them in a tight Spot. Enter the Pogo, which was designed to fly horizontally but land vertically. It came equipped with landing gear on its tail end.

5- The Scaled Composites White Knight Two

Designed to ferry a sub-orbital spacecraft between it's twin fuselages, the Scaled Composites White Knight Two, first flown in 2008, can ascend to a maximum height of 70,000 feet. The pilot steers from the right fuselage. Virgin Galactic plans to use this ship to carry its SpaceShipTwo to 50,000, where it will detach from the White Knight and ascend to suborbital altitudes of nearly 70 miles.

6- Rutan Model 202 Boomerang

The Rutan Model 202 Boomerang is asymmetrical for an entirely different reason. This 1996 aircraft was built to still be controllable in the event of an engine failure for either of its twin engines.

7-Avro Canada VZ-9AV Avrocar

Who wouldn’t love to have their own, personal flying saucer? The problem with this 1950s attempt was that engineers couldn’t get the craft more than 3 feet off the ground without encountering big problems.

8- McDonnell XF-85 Goblin. I

It was supposed to be a plane that could fit inside another plane for bombing purposes, but it just never panned out. Try though they might, getting the little one back onto the mothership proved to be too dangerous a maneuver.

9- The Antonov A-40 Krylya Tanka 

Tanks have become a war machine staple, but their travel range is limited. Hoping to expand upon potential territories, a Russian engineer added wings to one hoping it could be dropped wherever one would like. The plane’s test flight was its only one.

10- The de Lackner HZ-1 Aerocycle

The balance-driven de Lackner HZ-1 Aerocycle was built with the dual hope of flying single-man reconnaissance missions and building the greatest Bond-villain chair of all time. A pair of crashes grounded the idea, but the dream lived on.