From the heady days of 1947 through to the present day you could be forgiven for thinking the Air Force/NACA X-1 was the lone aircraft probing the sound barrier, but it wasn’t. The Navy had contracted the Douglas Aircraft Corporation to build an aircraft with a similar objective to the X-1. Perhaps if it’s Navy competitor had been blessed with a snappier name, it might have been the one people remembered. I mean, who’s going to mention the “Douglas D-558 Phase I” in casual conversation? Douglas’s PR people obviously recognized the disadvantage when they gave the aircraft the “Skystreak” moniker, but it never caught on.
In fairness the D-558 Phase I was intended to explore the high subsonic range and only capable of going supersonic in a dive (Mach 1.01, and it only did that once). In level flight the best it could achieve was Mach 0.99, a tantalizingly close number that must have frustrated Douglas, the Navy and the plane’s pilots.
The D-558 Phase I was a very small aircraft to minimize drag. This meant the cockpit was minuscule, so small in fact that when Bob Champine noticed streaks on the canopy he realized they were paint from his helmet rubbing against it’s plexiglass surface. So, in typical fashion he didn’t make a big deal of the issue, he just covered his helmet with chamois to prevent the marks. There’s an interesting write up of the aircraft and its size on a site dedicated to pilot Gene May.
The D-558 Phase I came to a sad end on May 3rd, 1948. Shortly after take off the engine compressor disintegrated, throwing turbine blades like machetes and severing the control cables. The resulting crash killed pilot Howard Lilly (on the right below).
The Phase I replacement, inventively named Phase II, was had swept wings and new air intakes for the engine. But the D-558 Phase II (Skyrocket) had a bad start. When delivered to Muroc Field it was woefully underpowered with a Westinghouse J-34 jet engine. Unlike the X-1, the D-558 Phase II was designed to take off from a runway. Most people would therefore expect it to be able to this under it’s own power, but not the D-558 Phase II. At Muroc they discovered the flaps and landing gear created so much drag it wasn’t capable of getting airborne without some form of assistance. The assistance came in the hasty form of attaching JATO rockets to the side of the aircraft. Four rockets were really required for good performance, but in the cash strapped years after WW2, they could only use two per flight. Even with the additional thrust of the rockets, take off wasn’t easy. Pilot Bob Champine outlined the procedure as
1) get up to the maximum speed possible with the jet engine (this would take about mile over the dry lake of Muroc Field)
2) fire the JATO rockets to bring the aircraft up to take off speed.
3) take off
4) immediately retract the landing gear to reduce drag and help the speed gradually rise.
5) with increased airspeed, the flaps could be retracted just before the JATO rockets ran out.
6) dump the rockets at the end of the runway and finally fly.
It’s not quite the take off you’d imagine for an aircraft designed to go supersonic, but in a way it brings it closer to the spirit of the headline grabbing X-planes. They were so highly optimized to explore one or another aspect of flight, they had severe limitations, being launched from a mothership for instance, that could never be tolerated on an aircraft in service. In time the D-558 Phase II was augmented with a version of the same rocket used on the X-1 and eventually reached Mach 2.
In the next post well talk about something that might have been a more serious challenge to the X-1’s historical position. In the meantime, what do you think? Was the Navy cheated of the fame it deserved alongside the NACA/Air Force X-1? Or were its goals too low to propel it into the same historical orbit as the little orange rocket ship?
And would you fly in something so small your head was wedged against the canopy?!
(Images courtesy of NASA and Aerospaceweb.org)