Actually, I wouldnt be surprised if the Active Noise Control was an automotive analogue... something consisting of aimed speakers in the aircraft cabin or headrests that provided several zones of silence.. each situated where an occupant's head would be. Move too far out of that area of silence and it gets noisy..  But that solution doesnt do anything for the guys outside the aircraft.
 
Dave

Ed Anderson wrote:

Seems to me that the acoustical wave generated by the canceling device would have to be of a magnitude similar to the amplitude of the nose wave you are trying to cancel - that's like 125+ db!!!.  Plus its speaker would probably need to be able to withstand a great deal of heat surely in the 100s of degrees F.  The theory has been around for years, but the practically of the idea - at least for engine exhaust for aircraft has eluded me for certain. But who knows? if its possible then its just technology that is needed to meet the conditions of the environment (very harsh and hostile).

 

Ed A

----- Original Message -----

From: David Staten

To: Rotary motors in aircraft

Sent: Monday, May 09, 2005 6:04 PM

Subject: [FlyRotary] Re: center rotor OFF

Ok... so whats the solution for all the people who are nearby when you fire the engine up? Your neighbors, etc?
 
Dave

Mark R Steitle wrote:

Here is the answer to the muffler problem.  Active Noise Control.  No big, heavy, draggy muffler needed.   

<snip from “Canadian Driver” article>

…Active Noise Control is unique to this vehicle. Active Noise Control (ANC) uses sound waves generated from the audio speakers to cancel out any booming noise from the powertrain. The ANC controller uses a microphone to detect any noise and then generates a signal 180 degrees out of phase to cancel out the original noise.

<snip>

Mark S.

---

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Russell Duffy
Sent: Monday, May 09, 2005 2:24 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: center rotor OFF

I'm thinking this would not be a good plan.  For the piston engines you referred to, I bet they have a way to control the valves with solenoids so the deactivated pistons aren't producing compression. 

Actually they do have compression. No fuel or fire.

Bill Jepson 

OK, make me look it up :-)  Apparently, they stop the valves from opening, rather than leaving them open.  I couldn't find anything that gave details of exactly what point in the sequence they stop the valves, so the cylinder could either be full of air (silly and wasteful of power), empty of air (would cause vacuum that would be as bad as the compression force), or perhaps somewhere in between.  

Here's the best article I found, though with annoying ads.  Don't forget about those active controlled engine mounts to smooth out the 3 cylinder operation in economy mode.  Just boggles the mind what they'll do to make improvements in economy. 

http://www.canadiandriver.com/articles/jk/041014.htm

Cheers,

Rusty (Great Plains VW 2180 running, and for sale)

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