The McDonnell XV-1 is an experimental Convertiplane developed by McDonnell Aircraft for a joint research program between the United States Air Force and the United States Army to explore technologies to develop an aircraft that could take off and land like a helicopter but fly at faster airspeeds, similar to a conventional airplane.

The XV-1 would reach a speed of 200 mph (320 km/h; 170 kn), faster than any previous rotorcraft, but the program was terminated due to the tip-jet noise and complexity of the technology which gave only a modest gain in performance.

[3] On 20 June 1951, the Air Force and Army signed a Letter of Intent with McDonnell to award a contract to develop an aircraft based on their design.

[4] McDonnell benefited from previous design work on the Model M-28 and had a complete mockup ready for inspection by the Army and Air Force by November 1951.

[5] McDonnell enlisted Kurt Hohenemser[6] and Friedrich von Doblhoff, the Austrian helicopter designer of the WNF 342, to provide technical direction in developing the tip-jet driven rotor system.

[2] Built mostly from aluminum, the XV-1 fuselage consisted of a streamlined tube mounted on skid landing gear, with a rear-mounted engine and a pusher propeller.

A three-bladed main rotor powered by blade tip pressure jets was mounted on top of the fuselage, above the wing roots.

The tether had lead weights intended to keep the aircraft in ground effect until issues with the rotor's tip-jet propulsion system were solved.

Technological advances in conventional helicopter rotor design and engines in the following years would eventually negate the XV-1's performance margin.