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Anybody familiar with how the military creates stealth choppers that aren't as noisy? I'm assuming it has to do with blade design, but would these changes be ap
by hanniabu 7y ago
Anybody familiar with how the military creates stealth choppers that aren't as noisy? I'm assuming it has to do with blade design, but would these changes be applicable at smaller scale and would it be enough of a sound reduction?
- Anechoic 7y agoFrom what I heard 3rd/4th hand/speculation, the "stealth" helicopters are quieter than normal helos but at the cost of efficiency and maneuverability. There are always tradeoffs. edit: what nradov said.
- nradov 7y agoThere's no such thing as "stealth" really, but they can optimize blade shape for noise reduction and put mufflers on engines. Those measures reduce aircraft performance (no free lunch in aviation).
- yummypaint 7y agoSome first order guesses: -Have lots of blades on the same rotor so the assembly can turn slower -Put the tail rotor inside a shroud -Having a smaller rotor might help, since the spread in air speed across the length will have less variation (less sure if this would help) -Turbine engines can be pretty loud, I'm guessing the same is true of other powertrain components. Maybe put the loudest stuff on the roof.
- starpilot 7y agoThe most promising theory is that the "stealth hawk" used actuated micro flaps on its blades' trailing edges to reduce noise and vibrations. I would put money on this being true. Flapped blades have been studied in academia for over a decade, it's definitely an engineering problem now and has clear benefits. http://www.helijapan.org/pdf/general/general05/Friedmann/Japan-05VF-notanimated_PART-1.pdf http://www.helijapan.org/pdf/general/general05/Friedmann/Jap...