The plane makes a t=2-second loop (Let’s assume circular) at v= 500mph, or 223.5 m/s. The centripetal force a = (v^2)/r. Let c be the circumference of the circle
r = c/2pi = vt/2pi
a=(v^2)/r = (v^2)/(vt/2pi) = 2pi.v/t = 702m/s/s
G force = a/g = (702m/s/s)/(9.8m/s/s) = about 71 Gs.
I had a hard time getting to the end. That was the most annoying video! Ugh!
Yeah welcome to the future where unmanned vehicles perform maneuvers which would kill a human pilot. That’ll be our pizza delivery in ten years.
Yep. It took me a bit to see through the jerking back and forth, but I eventually could see the glider. It’s the silvery white flash whipping through. I was impressed.
Yep. Nice concept, nothing to see here.
“Motor-less RC plane” i.e. glider. Anyway, how do they measure the speed? If it’s just gps, it’s (A) inaccurate, and (B) the speed over the ground. If they are flying with a 65 mph tailwind, it’s a bit of a cheat. (I think they said the speed record was a peak speed, not average over a circuit.)
Radar.
You could hear someone calling out the speed with each loop, and the person presumably running the radar is given credit at the end of the video.
Undoubtedly there were fighter planes that broke the sound barrier. The hard part was to survive the experience.
Problems start when the tips of the propellers start to go supersonic and the roots of the propellers don’t. This sets up vibration in the airframe. Then if the wings do manage to go supersonic, the centre of lift (which is always slightly aft of the centre of gravity) takes a leap even further aft, which tends to pitch the nose (which was already pitched down) even further down, making it almost impossible to recover from the dive.
This usually preceded catastrophic failure of the airframe.
There were two vital pieces of technology that led to the conquering of the sound barrier. The critical one was the all-flying tailplane (as opposed to having a fixed horizontal stabiliser and a moving elevator). This technology was developed by the British at the end of WWII and was crucial to allowing the pilot to counteract the fatal downward pitching tendency.
The other technology was the swept wing, developed by the Nazis which helped to smooth the transition to supersonic flight.
Watching that video puts me in mind of autogyros and I wonder if the dynamic soaring thing is self limiting the way autogyro blades are? Gyro blades reach a speed at which they are happy and don’t deviate very much from that.
Could also add jet /rocket engines to your list as being necessary for a safe transition to supersonic flight.
This reminds me of a part of Neal Stephensonʻs Seveneves, in the first chapter of Part Three. Kath Two flies a one-person glider fast enough and high enough on the existing winds and thermals to reach a point below low earth orbit to land in a hangar slung from a bolo.
It must be time to re-read that book.
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