Author Topic: Aircraft cockpit noise reduction  (Read 7130 times)

Ross Carlisle

  • Guest
Aircraft cockpit noise reduction
« on: September 18, 2003, 08:10:16 PM »
I have a two seat airplane, pusher design, with a fabric covered fuselage.  The engine and propeller are only 6 feet from the pilot /passenger.  I wear an aviation headset that reduces the noise level to the ears but the engine/prop noise is so loud that I can not use a radio or intercom.  My thought was to build a V shaped wall of .015 aluminum and fasten this to the airplanes interior structure.  This would form a sort of shield, not a complete sound proof enclosure, which is not possible, but a shield between the noise and the pilot.  My question is....What should I use in addition to this aluminum wall?  Should I use foam on both sides or just the "noise" side?  Keep in mind, this solution needs to be very light.  As we say in the airplane business, if you throw it in the air and it comes back down, it's too heavy :).

Thanks very much for any input.   Ross

Boborther

  • Guest
Re: Aircraft cockpit noise reduction
« Reply #1 on: September 19, 2003, 10:16:39 PM »
Ross,

Sure, I would definitely line the shield with the closed cell foam mat. Both side would be good. There is no such thing as "overkill" when it comes to soundproofing. The 1/2" foam mat should do the trick.
Now keep in mind that an aircraft, just like a car, transmits engine noise and vibration directly through the engine cowling into the windshield valance, then through the windscreen (which is usually invisible to sound) and ultimately into the cockpit.
Now it is against FAA regulations to glue the foam to the engine side of the cowling, however, if you can get some of the foam adhered to the inside part of the winshild valance, you will stop the vibration and much of the sound from reaching the windscreen and thus keep it from entering the cockpit.
 A half a roll of the 1/2" foam mat (100 sq ft) is $262.50 plus a little shipping, and that is generally enough to do a Cessna 182 or similar aircraft. The weight would be around 35lbs. Hope this answers your questions Ross.

Sincerely,

Bob Orther
Super Soundproofing Sales /Technical Associate
www.soundproofing.org
boborther@soundproofing.org
Phone (760) 752-3030
Orders only!  (888) 942-7723
When Peace of Mind is all that Matters!

Ross Carlisle

  • Guest
Re: Aircraft cockpit noise reduction
« Reply #2 on: September 22, 2003, 02:35:32 AM »
Thanks Bob....That helps, but 35bs is a bit on the heavy side.  This airplane is an ultralight trainer.  The only thing between you and the engine/prop 6 feet behind you is some 1.7oz dacron.  The aluminum shield would go overhead and in the rear of the passenger compartment.  This would put the shield directly between the engine and pilot/pax.  The overhead panel would be about 2x4 and the rear panel would be about 2x5.  Can the mat be bought by the foot?  I think a half roll might be way too much.  Also....Given the shield panel dimensions, what would the weight of the required mat be?  I'd like to keep it under 10lbs.

Thanks....Ross

Boborther

  • Guest
Re: Aircraft cockpit noise reduction
« Reply #3 on: September 22, 2003, 10:34:08 PM »
Ross,

 I was giving you the weight for an entire 1/2 roll of the 1/2" foam mat. Now just to cover the aluminum shield would probably be less than 2 lbs. depending on the size of your shield. I didn't know if you were going to soundproof the entire aircraft, aside from just doinges doing the shield.  My 'bad'  on that one, but I still feel that this closed cell foam would be the ticket to line the shield with. I would actually consider doing both sides of the shield for some extra soundproofing. I think if the shield is properly constructed and properly situated, you will be amazed at the results. I can't see your needing much more than 3 lineal  feet of the 1/2" closed cell foam mat. Ross, I sure hope this clears things up for you as far as the closed cell foam mat. Thanks for the re-post.

Bob Orther
Super Soundproofing Sales /Technical Associate
www.soundproofing.org
boborther@soundproofing.org
Phone (760) 752-3030
Orders only!  (888) 942-7723
When Peace of Mind is all that Matters!

wolfman

  • Guest
Re: Aircraft cockpit noise reduction
« Reply #4 on: November 02, 2012, 07:46:52 AM »
We have designed and are building a composite aircraft in the pusher configuration ( engine behind the cockpit ) and are intending for it to be headset free. The windshield will be in clean undisturbed air, the propeller is above the fuselage, and we are concerned about the drum effect on the fuselage. To this end we have reduced the propeller speed by 700 rpm, installed a five bladed propeller and are using a catalytic converter. All this is supposed to reduce our noise level by 11dB.
Is it advisable to cover the entire cockpit in sound proofing material ( our guess is 3/8" for this and 3/4" for the fire wall ) on the cockpit side? Will it be beneficial to apply sound proofing on the inside of the fuselage under the propeller?

Looking forward to your response. :)
 
Wolf

supersoundproofing

  • Administrator
  • ****
  • Posts: 262
  • I love Super Soundproofing!
    • Super Soundproofing Co
Re: Aircraft cockpit noise reduction
« Reply #5 on: November 02, 2012, 09:58:01 PM »
We have designed and are building a composite aircraft in the pusher configuration ( engine behind the cockpit ) and are intending for it to be headset free. The windshield will be in clean undisturbed air, the propeller is above the fuselage, and we are concerned about the drum effect on the fuselage. To this end we have reduced the propeller speed by 700 rpm, installed a five bladed propeller and are using a catalytic converter. All this is supposed to reduce our noise level by 11dB.
Is it advisable to cover the entire cockpit in sound proofing material ( our guess is 3/8" for this and 3/4" for the fire wall ) on the cockpit side? Will it be beneficial to apply sound proofing on the inside of the fuselage under the propeller?

Looking forward to your response. :)
 
Wolf


You don't mention the useful load of the aircraft, so it's hard to suggest material that's very effective but weighs 1 Lb per sq ft. like MLV.

So to keep it simple, use 1/2" SSP foam where it will do the most good;  That is into the direct sound path from the engine noise and the prop noise.  If needed after testing, you can double it up or add it to other places, bearing in mind the 1/2" mat weighs 1/4 Lb per sq ft.

Keep in mind the engine and prop create their own radiation pattern of sound and it is hard to block  such a large "cloud" from the cockpit.

Best to call us to discuss if I haven't clarified sufficiently.

BJ
Super Soundproofing Co
www.soundproofing.org