# Supersonic speeds?

by Schalchlin05
Tags: speeds, supersonic
 P: 2 I really have no idea what category this type of question goes in. I'm actually a senior in high school but I think this may be a college level question because I'm in the highest level physics class my school offers and the teacher doesn't know how to do it. I saw it on a UIL test for science. It said that this bird could somehow fly at mach 3.8..what angle does the supersonic wave (i think thats what it called it) come off at? If anyone knows how to explain the solution to this problem please do. Thank you.
 Sci Advisor PF Gold P: 2,793 The sine of the Mach angle is equal to the reciprocal of the Mach number... Was the 'bird' made by Lockheed perchance?
 P: 2 thanx a lot...and i'm not sure if it was or not
 Admin P: 21,915 Supersonic speeds? For notes on Oblique shock waves, see - http://www.grc.nasa.gov/WWW/K-12/airplane/oblique.html for more details, see NACA 1135. http://www.grc.nasa.gov/WWW/K-12/air...s/naca1135.pdf Mach 3.8 maybe too high for the SR-71 Blackbird, which reportedly had a maximum speed of 3.3+ under the right conditions.
 P: 699 Thats a quick freaking bird.
The angle to what Nenad has referred as $$sin\theta=M^{-1}$$ is what you are looking for. To add something, that angle is the angle formed by a weak shock wave far away from the body (at the order of ten times the characteristic lenght of the body). This wave is the so-called Mach Wave. It is named as a Weak Wave because behind it the flow remains supersonic. At very short distances of the body nose, the proper form of the surface enhances a Bow Shock, which has a variable $$\theta$$ because the Mach Number varies behind it from subsonic to supersonic at larger distances.