Thermal Protection System -Testing

Music
Ambience: Arc Jet

How do researchers replicate the rigors of high-speed flight? With a very large blowtorch. I’m Jim Metzner and this is the Pulse of the Planet. Thermal protection, defense against extreme heat, is necessary to safeguard high-speed aircraft. Engineer John Balboni tests heat-shield materials at Ames Research Center.

“One way of testing it is with a wind tunnel called an arc-jet. An arc-jet is a very high-temperature wind tunnel. In fact, what it is, is more like a very large blowtorch using an electric arc to heat gas to very high temperatures to the same temperatures as reentry 10,000 degrees or higher. Arc in arc-jet stands for an electric arc, very much like a lightning bolt that you see in a storm, except a lightning bolt is a flash that only lasts for a microsecond, and what I’m talking about in an arc-jet is a standing arc that is continuous, but very large as large as a room. Now, it requires a tremendous amount of power to heat the gas to this high temperature, and so, an arc-jet flow stream is only going to be small of the order of a few feet in diameter. A piece of the heat shield material can then be inserted into this very high-temperature stream, and its response will be measured by how hot it gets or, perhaps, by how much it ablates. An ablation, then, means that it burns away and melts at a controlled rate, and that rate must be known very accurately in order to design a spacecraft to survive the reentry. And so, now you can test a piece of the heat shield that’s only about as big as a dinner plate. And then, from that, you have to extrapolate if that material could then survive on the spacecraft or aircraft, which could be 100 feet long or more.”

We’ll hear more about heat shield materials in future programs. Pulse of the Planet is made possible by the National Science Foundation, with additional support from NASA.

Thermal Protection System -Testing

How do aerospace researchers replicate the rigors of reentry? With a giant blowtorch!
Air Date:06/25/2007
Scientist:
Transcript:

Music
Ambience: Arc Jet

How do researchers replicate the rigors of high-speed flight? With a very large blowtorch. I’m Jim Metzner and this is the Pulse of the Planet. Thermal protection, defense against extreme heat, is necessary to safeguard high-speed aircraft. Engineer John Balboni tests heat-shield materials at Ames Research Center.

“One way of testing it is with a wind tunnel called an arc-jet. An arc-jet is a very high-temperature wind tunnel. In fact, what it is, is more like a very large blowtorch using an electric arc to heat gas to very high temperatures to the same temperatures as reentry 10,000 degrees or higher. Arc in arc-jet stands for an electric arc, very much like a lightning bolt that you see in a storm, except a lightning bolt is a flash that only lasts for a microsecond, and what I’m talking about in an arc-jet is a standing arc that is continuous, but very large as large as a room. Now, it requires a tremendous amount of power to heat the gas to this high temperature, and so, an arc-jet flow stream is only going to be small of the order of a few feet in diameter. A piece of the heat shield material can then be inserted into this very high-temperature stream, and its response will be measured by how hot it gets or, perhaps, by how much it ablates. An ablation, then, means that it burns away and melts at a controlled rate, and that rate must be known very accurately in order to design a spacecraft to survive the reentry. And so, now you can test a piece of the heat shield that’s only about as big as a dinner plate. And then, from that, you have to extrapolate if that material could then survive on the spacecraft or aircraft, which could be 100 feet long or more.”

We’ll hear more about heat shield materials in future programs. Pulse of the Planet is made possible by the National Science Foundation, with additional support from NASA.