Here is a true story about canopy knives and busting out with them.

When I was a young pup at USAF pilot training (Williams AFB in Phoenix, AZ) in 1972, the T-38 maintenance folks had a canopy that was about to be scrapped.  Before removing it. Air Training Command decided that they would make a training film for us students.  This way we would have a real demonstration of the process of emergency egress via cutting tool vice opening the canopy.  Up to that time, this procedure had only been discussed in the class room and none of our instructors had any knowledge of it actually being used.

Well, they ran the entire student body out to the flight line to watch the blessed event.  Here comes the valiant instructor in full dress with winter flying jacket, Nomex flight suit w/flying gloves, g-suit, helmet, O2 mask, parachute etc.  It is summer and hot enough to melt the asphalt, but the official mantra is that this will be so quick that he will be fine.  Keep in mind he has the helmet on and strapped, O2 connected up, is strapped in completely, visors down and ready to die from the heat in a heart beat.

They roll the film, the instructor closes the canopy, the drums roll and the command to "bust out" is given.  The intrepid warrior removes the breaker from its bracket and commences to chop.  I lost count after about 50 strokes, but he never broke it during the filming.  The best he did was get the blade to protrude through the plex by about 1/4 inch.  By this time we students are practically falling down, in fits of laughter, and the leadership is highly embarrassed.

Because of the heat, the instructor nearly passed out and the test was over.  The officials were still curious what it would really take to break the canopy adequately, so they had him remove all his safety gear, except gloves, and keep going for a while longer.  Eventually he had about a two inch diameter hole all the way through.  He gave up entirely then and was so exhausted he practically needed assistance to get down the ladder.  Then we could see that both his hands were covered with blisters that were now bleeding profusely.

Never did see the film.  Somehow, it failed to enter the training curriculum.

What lessons to learn?  Has anyone seen a canopy from a real pressurized airplane broken in this manner?  Sure would be nice to know it can be done.  One last point, this was not the windscreen, which is presumably thicker. Instead it was only the lowly canopy, which just has to take 5 PSI of pressurization.  The windscreen, BTW, has to take the 4 lb chicken at 200 Knots (or was it a 2 lb chicken at 400 Knots).  Getting too old to remember which, but that's a story for a different time.  Just be real sure it isn't frozen during the test.


Tom Thibault
Class 73-05
Williams AFB