Thermal Protection System -Why So Hot?

ambience: Arc Jet, F-15 Jet

You want to know why a high-speed aircraft heats up as it flies through the atmosphere? Think bicycle pump! I’m Jim Metzner and this is the Pulse of the Planet. Ames Research Center engineer John Balboni works on thermal protections systems, the materials that protect an aircraft from high temperatures.

“Well, there are two effects that will heat aircraft when it travels at very high speed. One isyou think of friction, such as when you’re rubbing your hands together. You can warm your hands by the action of friction. There is some friction between the air and the aircraft that produces some heat. There’s another effect, and that’s the compression. There’s a shockwave in front of a body that travels faster than the speed of sound, and at the speeds that I’m talking about for thermal protection are really 5 times the speed of sound, even 10 to 20 times the speed of sound. And there’s a compression wave in front of the vehicle, and that compression wave will literally compress the gas.”

John’s referring to the atmospheric gas that the aircraft is flying through.

“It raises the pressure of the gas very quickly, and what that does is it raises the temperature of the gas. And so, now, the airplane is actually flying through its own compression-heated gas. You can also think of something around your garage, such as a bicycle pump. When you use a bicycle pump, and you pump up a tire very quickly, the pump itself will get hot, and that is the compression creating heat. When we’re talking about spacecraft entering from orbit at 25,000 feet per second. The surface of the vehicle will reach temperatures in excess of 3,000 or 4,000 degrees Fahrenheit.”

In order to test the materials that protect high-speed aircraft, researchers have to replicate these extreme temperatures. We’ll find out how they do that in future programs. Pulse of the Planet is made possible by the National Science Foundation, with additional support from NASA. I’m Jim Metzner.

Thermal Protection System -Why So Hot?

How is a bicycle pump like a space shuttle? Think compression!
Air Date:06/19/2007
Scientist:
Transcript:

ambience: Arc Jet, F-15 Jet

You want to know why a high-speed aircraft heats up as it flies through the atmosphere? Think bicycle pump! I’m Jim Metzner and this is the Pulse of the Planet. Ames Research Center engineer John Balboni works on thermal protections systems, the materials that protect an aircraft from high temperatures.

“Well, there are two effects that will heat aircraft when it travels at very high speed. One isyou think of friction, such as when you’re rubbing your hands together. You can warm your hands by the action of friction. There is some friction between the air and the aircraft that produces some heat. There’s another effect, and that’s the compression. There’s a shockwave in front of a body that travels faster than the speed of sound, and at the speeds that I’m talking about for thermal protection are really 5 times the speed of sound, even 10 to 20 times the speed of sound. And there’s a compression wave in front of the vehicle, and that compression wave will literally compress the gas.”

John’s referring to the atmospheric gas that the aircraft is flying through.

“It raises the pressure of the gas very quickly, and what that does is it raises the temperature of the gas. And so, now, the airplane is actually flying through its own compression-heated gas. You can also think of something around your garage, such as a bicycle pump. When you use a bicycle pump, and you pump up a tire very quickly, the pump itself will get hot, and that is the compression creating heat. When we’re talking about spacecraft entering from orbit at 25,000 feet per second. The surface of the vehicle will reach temperatures in excess of 3,000 or 4,000 degrees Fahrenheit.”

In order to test the materials that protect high-speed aircraft, researchers have to replicate these extreme temperatures. We’ll find out how they do that in future programs. Pulse of the Planet is made possible by the National Science Foundation, with additional support from NASA. I’m Jim Metzner.