Madhatter Posted March 1, 2022 Report Share Posted March 1, 2022 Just curious if anyone has done any cowl insulation or heavier firewall insulation to reduce cabin noise. I recently temporarily installed a "swiss muffler " to the existing exhaust system which did not reduce DBa on full power ground runs. I believe the lack of adequate sound insulation is the majority of the noise level. Carbon fiber is a very poor barrier for sound especially very thin walls such as the cowling and firewall. There is nothing you can do about the propeller or 1/8 inch windshield or the close engine placement. Quote Link to comment Share on other sites More sharing options...
Anticept Posted March 1, 2022 Report Share Posted March 1, 2022 There were the "asbestos" firewall covers that were being offered for a while. Had foil and fiberglass insulation. Flight design claimed it reduced cabin noise. Mine came shipped with it but due to firewall damage, I had to remove it. I would say try lining the inside side of the firewall first as an experiment. Noise dampening through barriers requires mass to be effective unfortunately. Foam or blankets are only effective at reducing reflected noise from within a compartment. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted March 1, 2022 Report Share Posted March 1, 2022 I never much cared for ANR headsets until the CT. Running David Clark One-X made a nice comfort improvement and the blue tooth with a bit of background music has been a big change in the long trips. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted March 1, 2022 Author Report Share Posted March 1, 2022 Ceramic 2000 insulation looks like a candidate to apply over the existing firewall upgrade, it's about 0.4 inches thick and a high tech flexible stainless covered dense firewall barrier. Cowling insulation would have to be more adaptable to curvature. Maybe when I do my rubber change is the time to try it. CTSW cabin noise level exceeds 100 DBa which is over twice that of an average certified aircraft. Remember when you used a cabin speaker and a hand mike, can't happen in a CT. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted March 1, 2022 Report Share Posted March 1, 2022 1 hour ago, Madhatter said: Ceramic 2000 insulation looks like a candidate to apply over the existing firewall upgrade, it's about 0.4 inches thick and a high tech flexible stainless covered dense firewall barrier. Cowling insulation would have to be more adaptable to curvature. Maybe when I do my rubber change is the time to try it. CTSW cabin noise level exceeds 100 DBa which is over twice that of an average certified aircraft. Remember when you used a cabin speaker and a hand mike, can't happen in a CT. Cost? Weight? Quote Link to comment Share on other sites More sharing options...
Madhatter Posted March 1, 2022 Author Report Share Posted March 1, 2022 Low cost, low weight. I guess that depends on how cheap someone is Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted March 1, 2022 Report Share Posted March 1, 2022 2 hours ago, Madhatter said: Low cost, low weight. I guess that depends on how cheap someone is Sounds too expensive for me then! Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted March 1, 2022 Report Share Posted March 1, 2022 I have noticed from observation that the CTSW seems louder than the CTLS when running during maintenance without a headset on. At least to the naked ear. The SW also feels rougher while running. I suspect it is due to the different engine mounts. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted March 1, 2022 Report Share Posted March 1, 2022 I flew in a LS last fall and agree it was quieter than my SW Quote Link to comment Share on other sites More sharing options...
Madhatter Posted March 2, 2022 Author Report Share Posted March 2, 2022 I did a mapping of the cabin with a DB meter in flight just now. The exhaust pipe is not the issue as I suspected earlier. The greatest noise level is from the firewall and forward above the glare shield . The firewall carbon fiber is only about 1/16 inch in some areas as is the top cowl. The thin firewall blanket is not going to do much for noise. Most aircraft benefit from a longer tailpipe but not this one. Quote Link to comment Share on other sites More sharing options...
sandpiper Posted March 4, 2022 Report Share Posted March 4, 2022 When I went from Zulu 3’s to Bose X it made a significant difference to me. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted March 5, 2022 Author Report Share Posted March 5, 2022 On 3/1/2022 at 5:44 PM, Tom Baker said: I have noticed from observation that the CTSW seems louder than the CTLS when running during maintenance without a headset on. At least to the naked ear. The SW also feels rougher while running. I suspect it is due to the different engine mounts. The E-Prop made a major improvement in vibration far better than I expected. Quote Link to comment Share on other sites More sharing options...
Scrapman1959 Posted March 5, 2022 Report Share Posted March 5, 2022 Guys, don’t waste your time trying to insulate the cabin of a CT or CTLS. You will make no noticeable difference. Sound deadening is a science, and the vibrations moving the walls of the cabin have a great deal to do with the extreme noise level in either of the FD cabins. Spend your money on the best most comfortable headset you can find. I actually put in foam earplugs for trips over an 1.5 hrs and then put Bose A20 s on. You can NOT replace lost hearing. You can turn up your com to hear the radio fine with this combination of foam plugs and Bose A20s. If you have ever experienced ringing after a 4 hour CT flight, congrats, you have lost some hearing. When I started flying the Tecnam P2008 with the low compression turbo 914 engine, it was startling how quiet the cabin was, compared to the CTs. It is no louder than any other continental, or Lyc powered AC. I believe a lot of the lower decibel level can be attributed to a smoother low compression engine. You feel less vibration throughout the entire AC, including thru the seats etc. The Tecnam has a very refined interior, but that is not making it noticeably quieter in my opinion. We will be able confirm this theory soon, when the CTLS starts getting delivered with the 914T. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted March 5, 2022 Author Report Share Posted March 5, 2022 I have insulated many aircraft with the correct insulation in the correct places with a very high degree of success. The owners of these aircraft did not consider it a wast of time. This includes a number of my own aircraft. If you don't persist in trying to solve some of these issues you will never achieve any success. It has worked for me for 50 years both private and in the corporate aerospace industry. Not all my endeavors are successful but some are significant. Quote Link to comment Share on other sites More sharing options...
Anticept Posted March 5, 2022 Report Share Posted March 5, 2022 I wouldn't be surprised if part of the cabin noise is traveling through the mounting too. That said, this whole topic reminded me that I could swear up and down my own CT has somehow gotten louder when I got back into flying. Now I realize, I had the old firewall insulator beforehand... Quote Link to comment Share on other sites More sharing options...
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