X-1 was made to investigate that Place — and finally fly over and above it, turning into a supersonic craft. once they listened to a boom on the ground, Yeager signaled to Ridley, “This machmeter is all screwy!” https://mohamadgfbg431613.get-blogging.com/30371201/get-supersonic-silver-coin-plane-things-to-know-before-you-buy