HI-ALT TESTS OF F-8 CRUSADER ROCKETS

     Flame-outs Above 60,000 ft. Firing Sidewinders

I was a Test Pilot in the Service Test Department at NTC Patuxant River back in the early 60s.  A lot of new and different airplanes were there during those days.  I envied the guys in Flight Test and Carrier Qualification Departments doing some exotic test flying in the new aircraft.   However, I did have some great experiences flying over 25 different aircraft at Pax River.  My favorite project was trying to determine why the F-8 Crusader flamed out when firing a sidewinder missile above 60,000 ft.  You might ask "Why did we care?"   The Department of Defense wanted a shoot down capability against the Soviet Foxbat MIG that was known to operate at altitudes up to 70,000 ft.  Find the problem and fix it was the order at the time.

I first worked on simulated dead stick landings on the Mojave Desert lakebed and became fairly proficient at that.  Next step was to ensure I could reach the lakebed after firing the missile from above 60K in the target range.  This worked out ok.  I also had a battery backup to help with an engine restart.  The fun part was climbing to 40K then heading for the range in AB, gradually descending to 35K to accelerate to the Vmax of 1.9 mach, then zooming up at a 45 degree angle climb, reaching about 70K, firing the sidewinder and then floating over the top at g.  The engine did flameout from lack of oxygen from the large rocket plume at that altitude. The engine did relight every time after descending below 35K.   I experimented with hitting the engine igniter switch, located inside the throttle quadrant, prior to firing the missile.  This did not work at first, but after hitting the switch more than 5 seconds prior to firing the missile, it worked.  This discovery resulted in development of a fix that provided continuous ignition every time the weapons switch was turned on.

              

Most of these flights were relatively uneventful except for two that did raise my pucker factor.  One was a problem with the space suit that was caused by my own negligence.  When the engine flamed out at 70K I lost cabin pressurization that would cause the space suit to expand.  One time I forgot to tighten one of the belts. When the engine flamed out at 70K, the pressurization was lost, my space suit started to expand and my head was pushed up to the canopy and the control stick was almost out of reach.  My comment was "Oh s***!"  Fortunately, I could barely reach it with my finger tips and was able to recover.

The other occurrence was the loss of Unit Horizontal Tail (UHT=elevator) control upon return to base.   Again my comment was "Oh s***!"  So far I had one successful landing for every takeoff with the F8, but this looked like ejection time.  Luckily, I could control the attitude with trim tab.  How many of you have attempted to land the F8 using only the trim tab?  Another fun project was penetrating thunderstorms with the F8 and F4, but that is another story.

Semper Fi

Ray Stewart, Lieutenant Colonel U.S. Marine Corps (Ret.)

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