Thread: Can anyone answer this question for me?

At 80,000 feet, how fast do you have to be traveling to produce enough friction to melt titanium?

If anyone can answer that or tell me how to figure it out, it would be very helpful.

Thank you.

I presume that the 80,000 feet bit is to with the pressure of the surrounding air (if there is much of it at that altitude!) Under vacuum, I think that titanium sublimes rather than melts.

The reason I ask is my buddy and I were talking about the SR-71 Blackbird and we were trying to figure out the top speed of the plane. Him and I both knew that when the BB landed the titanium skin was warped slightly. This is where the question derived from. I don't have the scientific know how to calculate this nor do I have any idea what sort of equation to use for this.

Any help anyone can offer would be fantastic.

http://www.sr-71.org/blackbird/records.php

Metals can warp well below their melting temperature as well.

Originally Posted by Jshep08

The reason I ask is my buddy and I were talking about the SR-71 Blackbird and we were trying to figure out the top speed of the plane. Him and I both knew that when the BB landed the titanium skin was warped slightly. This is where the question derived from. I don't have the scientific know how to calculate this nor do I have any idea what sort of equation to use for this.

Any help anyone can offer would be fantastic.

The temperature due to aeroheating is very sensitive to the geometry of the body, so altitude and speed are completely insufficient to determine temperature.

If the skin of the SR-71 were anywhere near the melting point of the titanium skin (over 3000 F), the pilot would be a crispy critter from the radiant heat.