"Install a noise cancellation system on the aircraft..."
Des'nay work! Qinetic (UK equivalent of DARPA) wasted lots of money to find out what most engineers already know, with the pointless NXT system (albeit their objective was internal noise). If you could design a system than radiated a phased array of acoustic sources, the power requirement, or system mass, is rediculous. It would at any rate only work on the lower frequencies
The best you can ever do is to minimise the noise sources, then absorb as much of it as you can. Maybe some research into compliant rotor tips, with viscous damping, is required. Rotor blade damping makes sense anyway, to my mind, to reduce aeroflex vibration sources...
Mart
Last edited by Graviman; 17th October 2005 at 18:15.