Ambience: EC120 Helicopter 360 Turn, clapping hands in a wind tunnel and an office
Computer simulations can only take you so far in testing new aircraft. One of the best ways to try out a new design is with a full-scale model in a wind tunnel. Iâ€™m Jim Metzner and this is the Pulse of the Planet. William Warmbrodt is Chief of the Aeromechanics Branch at Ames Research Center, home of the worldâ€™s largest wind tunnel.
â€œThis facility has a test section, or a channel where we introduce our model for testing, that is forty feet high and eighty feet wide. That’s larger than a two-lane highway with trucks traveling in both directions on all four lanes. The facility is very large and we can blow the winds past the model being tested above three hundred miles per hour. Typical helicopters only fly perhaps two hundred miles an hour maximum speed, and so we can test the technology that we are pursuing up to its maximum and beyond the speed it would see in flight.â€
The wind tunnel where these tests take place has been soundproofed. For comparison hereâ€™s the sound of a hand clap in a room without soundproofing.
Ambience: Hand clap in standard room
And hereâ€™s the sound of a hand clap in a soundproofed area of the wind tunnel.
Ambience: Hand clap in wind tunnel
And why is soundproofing important to these tests?
â€œThe test section walls do not reflect acoustic sounds. They’re called anechoic. This allows us to be able to make measurements in the wind tunnel of the noise that is generated by the model, without the contamination due to reflections or reverberations of noise coming off other surfaces that has been reflected by the walls themselves. This facility is unique in the world in its ability to test helicopter rotors in an anechoic environment.â€
Pulse of the Planet is made possible by the National Science Foundation, with additional support from NASA. Iâ€™m Jim Metzner.