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Several of our projects merited further investigation when variable pitch rotors and propellers were coupled with high torque electric motors and revealed interesting noise attributes. To that end, we built an anechoic chamber, a space designed to absorb the reflections of sound, to test the noise levels of the new rotors and propellers. Through it we discovered that at constant thrust, RPM could be changed to yield a “sweet spot” where propulsive efficiency is maximized and noise is minimized. This key discovery is of great value for the noise-sensitive UAM market and is part our conceptual design tools. Read more about this area of research on page 24.
Electrification is Key to UAM Industry After an exhaustive exploration of the underlying technologies that may enable greener aviation and UAM, two critical scaling laws appeared to be acting as major barriers. First, the weight of the current batteries would not allow battery-only aircraft to go at the speeds of commercial aircraft. The second is that simple hobby- style fixed rotors could not be scaled up when used for both propulsion and control. There are workarounds for these two barriers but neither is simple. The answer for the heavy weight of batteries is hybrid- electric. This can be a gas engine tied to
Anechoic Chamber Developed in-house, the fully instrumented anechoic chamber is used for validation and verification of computational fluid dynamics- based acoustic studies. In an effort to minimize UAM noise, tests are conducted on the university’s novel prop-rotors.
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