We saw The Guess Who in Cadott Wisconsin at the summer rock festival several years back. They played quite a few BTO songs, which would be led in by saying, "A little something from another band I'm familiar with". Fabulous show on a hillside in rural Wisconsin.
Great frame of mind. This one really rings true as well.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwj3iubD0NT-AhXAkokEHYcyCYAQwqsBegQICBAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D5JAHAFvcr2o&usg=AOvVaw1Og1IWKq24UvFcEZzIBHCM
Gene,
I have a DH220 in great shape if you are interested. It's just sitting on the shelf currently. Was planning on recapping it at some time, but you know how time is.
PM if you would like more info or pictures.
I seem to remember reading that the water also absorbed the sound energy as well, which was enough to shatter concrete alone.
EDIT: Acoustical damage to the launch vehicle not the concrete. Definitely protects the concrete from the heat though.
Here is a white paper on your topic. A lot of engineering jargon but it boils down to the space vector (SV) control scheme reduces acoustical noise compared to constant voltage (CV) or variable voltage (VV) schemes. PWM frequency also play a large part in it as well.
Much of the "noise" from a BLDC type motor is caused by the driver system. The high frequency oscillations to create the rotating field resonated in the stator coils and in the rotor, of which most would make a great bell prior to adding the magnets. Many controllers/drivers even use that...
1,1-difluoroethane (DFE; HFC-152a, Freon® 152a) is used as a propellant in gas dusters, and it is sometimes misused as a recreational “drug” to induce an altered mental state.
Yes, I also prefer the doobie and/or Jamesons whiskey.