New Delhi: The first form of man-made flying objects were kites.Later the invention of hydrogen led to the invention of hydrogen balloons in the 18th century. In the 19th century experiments with gliders provided the groundwork for heavier-than-air craft. Later, continuous human efforts and advances in engine technology made controlled, powered flight possible by the early 20th-century.With this advancement in technology humans have made some pretty strange aircraft over the years. Have a look at some of the aircraft which looks bit weird in terms of there designs, here is the list:1. The Vought V173 Flying Pancake It was an American experimental test aircraft built as part of the Vought XF5U “Flying Flapjack” World War II United States Navy fighter aircraft program.It was designed by Charles Zimmerman . It managed to fly 190 test flights over Connecticut.Despite being designed in the 1940's, this plane was able to accomplish a near vertical take-off and landing, was remarkably easy to maneuver and found to be almost indestructible. 2. The Hiller X-18This plane was the testing ground for tilt-wing and vertical takeoff and landing planes.It was conceived in 1955 and had its first flight in 1959. The plane had 20 successful flights. 3. Ryan X-13 Vertijet The Ryan X-13 Vertijet was an experimental Vertical Take-Off and Landing aircraft flown in the United States in the 1950s. The main objective of the project was to demonstrate the ability of a pure jet to vertically takeoff, hover, transition to horizontal forward flight, and vertically land. 4. NASA M2-F1 The NASA M2-F1 was a lightweight, unpowered prototype aircraft, developed to flight test the wingless lifting body concept. It looked like a “flying bathtub,” and was designated the M2-F1, the “M” referring to “manned” and “F” referring to “flight” version. 5. AD-1 Oblique Wing Aircraft It's the weirdest plane ever created by NASA. The wing of this plane is oblique, turned 60-degrees across its fuselage.The AD-1 Oblique Wing Research Aircraft was designed and made at NASA's Dryden Flight Research Center—located in Edwards, California, in the western Mojave Desert—in the mid-1970s. Engineers were curious about the aerodynamic characteristics of such a plane, as well as the control laws required to govern it. 6. Aero Spacelines Pregnant Guppy It was a large, wide-bodied cargo aircraft built in the United States and used for ferrying outsized cargo items. Only 1 unit if this aircraft was ever built and it served a good 15 years, starting in 1962. 7. Hughes H-4 Hercules It is a prototype heavy transport aircraft designed and built by the Hughes Aircraft company. It flew only once in 1947 and was designed to carry over 700 people. It was actually a wooden heavy transport aircraft . This heavy transport flying boat is the largest flying boat ever built, and has the largest wingspan of any aircraft in history with span exceeding the length of a football field. 8. Vertol VZ-2 It was a research aircraft built in the United States in 1957 to investigate the tiltwing approach to vertical take-off and landing. Ground tests began in April 1957 and on 13 August, the VZ-2 took off for the first time in hover mode only. On 23 July 1958, the aircraft made its first full transition from vertical flight to horizontal flight.It has been preserved by the National Air and Space Museum in storage at the Paul E. Garber Facility. 9. Airbus BelugaBeluga or the Airbus A300-600ST, is a transport aircraft resembling the Beluga whale. Manufactured by EADS (Airbus S.A.S.) as an Outsize cargo freight aircraft, the Beluga is actually is a version of the standard A300-600 wide-body airliner modified to carry aircraft parts and over-sized or awkward cargo. 10. Northrop Tacit Blue This aircraft was a pioneer in stealth technology. There was only one produced, by the U.S. Air Force, in 1982, which was meant to demonstrate that a stealth low observable surveillance aircraft with a low probability of intercept radar and other sensors could operate close to the forward line of battle with a high degree of survivability. The pioneer plane is currently housed at the National Museum of the US Air Force.