WHAT DOES SILVER COIN OF SUPERSONIC PLANE MEAN?

I had no apprehension about it due to the fact we had no rocket fuel on board. And so when we acquired to altitude and went throughout the standard method of countdown and here I used to be in an incredibly tiny cockpit and it was pretty dim, and Hastily when the X-1 was unveiled through the B-29 I had been in bright daylight and I could listen to