5 ms·
> [When] at Mach 2.2, the air feels like Jello. I know that's a metaphor, but it got me thinking. Can someone more learned help me out: does air behave in a n
by venning 9y ago
> [When] at Mach 2.2, the air feels like Jello.
I know that's a metaphor, but it got me thinking. Can someone more learned help me out: does air behave in a non-Newtonian manner at supersonic speed?
- idlewords 9y agoYou can think of it this way: at subsonic speeds, air ahead of the aircraft "knows" that the plane is coming, and can flow around it. At supersonic speeds, this information doesn't propagate forwards, and the plane smashes into the air ahead of it, creating a shock wave. I'm anthropomorphizing and oversimplifying (airflow over a wing can be locally supersonic even in subsonic flight) but I don't care because I enjoy thinking of this in terms of information flow.
- Avshalom 9y agoI am delighted by the idea of a little anthropomorphic chunk of air shouting "Move, there's a plane coming!" and then face palming upon realizing too late that it is using sound to warn other bits of air about something moving at supersonic speeds.
- 6stringmerc 9y agoNot an engineer, but from my understanding air is a fluid that can be compressed. At extreme rates of speed in general atmospheric conditions, that results in a compression that the object is punching through. Often I learn about this stuff from high speed auto experiments (Bugatti, Toyota Land Speed Cruiser).
- rkangel 9y agoThe speed of sound through air is effectively the speed of shockwaves through air. The way that the air responds to being pushed around at speeds faster than its shockwaves can respond results in something that behaves more like a liquid than a gas.
- CalChris 9y agoBy non-Newtonian I think you mean relativistic. Boom is going Mach 2.2 or about 1500 mph. Light is going 186,000 mile per second. Not even close.