Tuesday, February 14, 2012

America's First Rocketplane

Acme Telephoto wirephoto with an embedded caption. This is the only known
photo of the MX-324 during powered flight, although there are a number of images
extant that were taken during the initial glide testing. Back "in  the day", it was
fairly common for photos to be retouched (yes, even long before Photoshop became
a verb!), and this one is quite heavily retouched, so much so that the caption writer
had to note that "this is an actual photograph". The actual flight took place on July
5, 1944, so presumably this dateline is February 13, 1946.
In 1942, Jack Northrop began to pursue one of his most persistent dreams: to perfect the flying wing. This version, the XP-79, was to be a rocket-powered flying-wing fighter aircraft. To test some of the concepts, he first built three MX-324 test aircraft. One of these was later powered by a rocket motor built by Aerojet Corp. In order for the pilot of both the XP-79 and the MX-324 to withstand the anticipated high-G loads, he would fly lying prone.

The first flight of a MX-324 glider took place on October 2, 1943, at the remote Harper Dry Lake, not far from today's Edwards AFB and Mojave Air and Space Port, where modern rocket plane development is underway. The small aircraft were towed aloft behind a P-38 Lightning. There were several incidents that seriously jeopardized the program. During one of the glide test flights, the pilot pulled the wrong handle when it came time to jettison the tow rope...he had grabbed the escape hatch release by mistake! The aerodynamic changes that this caused led to severe buffeting, but he was able to land safely. On another test flight, one of the MX-324s was lost when the tiny glider got caught in the P-38's prop wash, and entered a spin. When the pilot recovered, he was inverted and lying on the ceiling, unable to reach the flight controls. Instead, he bailed out and parachuted to safety. The -324 continued its gliding descent inverted and was damaged beyond repair on hitting the lakebed.

The engine used on the MX-324 was a 200-pound-thrust Aerojet XCAL-200 liquid-fuel compound rotary rocket, which actually was comprised of several smaller rockets that rotated about an common axis. The fuel was monoethylaniline and red fuming nitric acid.

The first powered flight of the MX-324 took place on July 5, 1944 (some accounts state that it was on July 4, other say it was July 22; date confusion is not surprising, since even the photo of the then-top-secret aircraft wasn't release for two years!) with Northrop test pilot Harry Crosby at the controls. The plane was towed to 8,000 feet, and Crosby then release the tow rope and ignited the engine. The flight lasted only four minutes, 3:30 under rocket power, but was considered a success.

Just over a year later, on September 12, 1945, Harry Crosby was at the controls of the XP-79 prototype when it went out of control during its maiden flight. He was killed while trying to bail out.

Historian's note: there's a lot of confusion about this plane, as would be expected from a secret project conducted during this time period. Besides the variation of first flight dates, even the model designation is in dispute. Northrop historian Ira Chart states that the MX-324 was the unpowered glider and the MX-334 was the powered version. Author Andreas Parsch states the opposite. It is clear, though, that in the official news release accompanying our photo, two years after the flight the powered version was being referred to as the MX-324.

Update: After this posted this morning, I received the following note from one of my Mojave rocket plane friends: "Well... America's third rocketplane, but arguably America's first military rocket plane, as the caption claims. In 1931, William G. Swan flew a rocket glider at Bader Field in Atlantic City. In 1941, Lt. Homer Boushey took off in a JATO-equipped Army Air Corps Ercoupe from which the propeller had been removed. The MX-324 was probably the first airplane designed from the outset for rocket power." Thanks, Randall!


  1. I've heard of this plane before and I think that flying it in the prone position would have been the closest thing to being Superman. Imagine flying head first through a canyon in this thing. My memory could be flawed but it seems like I remember a plane like this that was designed to slice through enemy aircraft mid-flight. (could be a false memory) Fantastic post Alan!

  2. It is odd looking "Photo"... looks more like a drawing. I wonder where or if any real photos of it still exist. Reminds me of the Horton IV glider. It does look like a very cool plane I didn't know about. Thanks.