WARNING! WAR STORY FOLLOWS!
I saw my first SR-71 in 1968 when one came in for an emergency landing at Utapao AFB Thailand. It was still a "secret" aircraft based out of Okinawa and normally only departed and returned at night. So no time was wasted once the crash trucks had checked it out. It was towed posthaste into one of the large B-52 hangars where the hangar doors were shut tight and an security perimeter quickly established around it.
Then maybe a week later, unannounced of course, it was towed out of the hangar with it's engines running. We watched it taxi to the end of the flightline (hammerhead) where it immediately hit afterburner and took off down the flightline. When wheels went in the well that aircraft went straight up into the clouds at a 90 degree angle and disappeared in a flash, blink-of-an-eye (almost), fast... I mean fast.
It was pretty darned amazing to watch the thing (it's a big plane) disappear into the clouds that quick.