Throughout the war the Germans had a vigorous development program for rockets and rocket
powered/assisted aircraft. The emphasis on this technology was not lost on their American counterparts.
In September 1942, a design feasibility study was produced by Northrop for a rocket-powered
interceptor. This led to a contract for a series of vehicles which consisted of three gliders, two of which
were designated MX-334, and a powered version, the MX-324. The MX-324 was to be powered by an
Aerojet liquid-fuel rocket engine. All three planes were to be test vehicles for a later craft, the XP-75.

The gliders were constructed of a metal tubing center section, with plywood elsewhere. In an unusual step,
the pilot position was to be prone, thus allowing this to be a true all-wing aircraft, with no protruding cockpit. This also had the advantage of allowing the pilot to withstand high g-forces during maneuvering.

Although the craft was designed as a pure flying wing with no vertical surfaces, it was later shown that a
vertical fin would be needed at higher speeds. Consequently, a plywood fin braced with wires was added.

The first flight of the MX-334 occurred on October 2, 1943. The first powered flight of the MX- 324
took place the following July. The flight tests revealed that the handling characteristics of the design were
as good or better than those of the other flying wings.

Several of the test flights nearly killed the pilots. During one, the pilot accidentally pulled the upper and
lower escape hatch cover release instead of the tow line release. With the smooth shape of the mid-wing
no longer a streamline, severe buffeting resulted. The pilot was able to land the plane successfully.

Another fortunate near-tragedy happened when the glider got caught in the propwash of the P-38 tow
plane. The plane pitched up, stalled, and went into a spin. When it recovered, it was upside down, and the
pilot was lying on the roof, unable to reach the controls. He managed to open the escape hatch and
parachuted. The plane continued gliding in circles at the same rate of descent as the parachute. When the
glider finally landed, it was damaged beyond repair.

The rocket motor used in the MX-324 used monoethylaniline and red fuming nitric acid, both of which
would kill the pilot. Three years after the first flight of the Me 163, Harry Crosby flew the first American
rocket powered aircraft. The flight began on the morning of July 4, 1944. After a tow to 8,000 feet from a
P-38, the Aerojet motor was ignited and it began to produce 200 lb. of thrust. The flight lasted over four
minutes and ended with a safe landing.

The fate of the MX-324 is unknown.