---------------------------------------------------------- RV10-List Digest Archive --- Total Messages Posted Tue 10/27/15: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:41 AM - Re: Re: Soundproofing the QB fuselage (Jim Combs) 2. 06:42 AM - Re: Re: Soundproofing the QB fuselage (Linn Walters) 3. 07:37 AM - Re: Re: Soundproofing the QB fuselage (Jim Combs) 4. 09:20 AM - Re: Re: Soundproofing the QB fuselage (Werner Schneider) 5. 10:47 AM - Re: Re: Soundproofing the QB fuselage (Jim Combs) 6. 01:17 PM - Re: Re: Soundproofing the QB fuselage (Werner Schneider) ________________________________ Message 1 _____________________________________ Time: 05:41:59 AM PST US Subject: Re: RV10-List: Re: Soundproofing the QB fuselage From: Jim Combs Speaking of sound. Has anyone considered doing anything to muffle the exhaust noise? That would appear to be the source of quite a lot of noise. The -10 has a quite loud engine noise at any power setting other than idle. Just a thought. Do Not Archive Jim C On Mon, Oct 26, 2015 at 10:20 PM, John Cox wrote: > Kelly thanks for bringing it back from transgressing to Thermal from > Acoustic infiltration. You remind me of Dan Newland's posts and his > lecture at OSH on material, cost, effort and resulting gains. Sound and > Thermal are two separate pursuits. Beginning with the source helps the > remediation. > > Dan used to work at ORCO down in Emeryville, CA before moving to the NW > and tackling insulation on high end boats with Pegasus. > > John Cox > > > On Sun, Oct 25, 2015 at 7:18 PM, Kelly McMullen wrote: > >> The general rules of thumb are that it takes 3 dBA change for most >> humans to detect. 10 dBA is an order of magnitude change, roughly 50% less >> sound energy in the decreasing direction. >> All noise scales are logarithmic. >> If you can get your cabin from 100 dBA to 90 you will think it is a major >> change. >> There are a lot of factors involved. Frequency, vs pulsation. Exhaust vs >> prop noise. Noise through windshield vs noise through firewall vs noise >> through belly or fuselage sides. Noise also decreases fairly rapidly with >> distance. Back seat should be less than front seat. Does your insulation >> tend to reduce vibration of the exterior skins or not. >> >> On Sun, Oct 25, 2015 at 6:27 PM, Bob Turner >> wrote: >> >>> >>> I think Bill's comments are right on. Even a minimal effort seems to >>> improve the thermal insulation. But it takes a major effort (and added >>> weight) to make any real difference in noise. One issue is the way most >>> humans judge sound levels. It takes about a 30% decrease in sound intensity >>> before the average person can detect any change at all! >>> >>> -------- >>> Bob Turner >>> RV-10 QB >>> >>> >>> >>> >>> Read this topic online here: >>> >>> http://forums.matronics.com/viewtopic.php?p=448281#448281 >>> >>> >>> >>> >>> >>> >>> >>> ========== >>> -List" rel="noreferrer" target="_blank"> >>> http://www.matronics.com/Navigator?RV10-List >>> ========== >>> FORUMS - >>> eferrer" target="_blank">http://forums.matronics.com >>> ========== >>> b Site - >>> -Matt Dralle, List Admin. >>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution >>> ========== >>> >>> >>> >>> >> * >> >> get="_blank">http://www.matronics.com/Navigator?RV10-List >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> >> * >> >> > * > > > * > > ________________________________ Message 2 _____________________________________ Time: 06:42:05 AM PST US Subject: Re: RV10-List: Re: Soundproofing the QB fuselage From: Linn Walters I'm going out on a limb here so keep the saws away! I believe most of the 'engine noise' is due to the prop, not the engine itself. That comment comes from experience with my Pitts. With the -10 having mufflers, I have a hard time believing you can hear the exhaust itself. Having said that, with the exhaust exiting fairly close to the fuselage, there may be impulse waves hitting the fuselage creating 'noise'. Since I'm not flying yet, and I haven't heard many -10s ..... I throw this out for discussion. Linn On 10/27/2015 8:06 AM, Jim Combs wrote: > Speaking of sound. Has anyone considered doing anything to muffle the > exhaust noise? That would appear to be the source of quite a lot of > noise. The -10 has a quite loud engine noise at any power setting > other than idle. > > Just a thought. > > Do Not Archive > > Jim C > ________________________________ Message 3 _____________________________________ Time: 07:37:30 AM PST US Subject: Re: RV10-List: Re: Soundproofing the QB fuselage From: Jim Combs Sounds like some data gathering may be in order. On Tue, Oct 27, 2015 at 9:06 AM, Linn Walters wrote: > > I'm going out on a limb here so keep the saws away! > I believe most of the 'engine noise' is due to the prop, not the engine > itself. That comment comes from experience with my Pitts. With the -10 > having mufflers, I have a hard time believing you can hear the exhaust > itself. > Having said that, with the exhaust exiting fairly close to the fuselage, > there may be impulse waves hitting the fuselage creating 'noise'. > Since I'm not flying yet, and I haven't heard many -10s ..... I throw this > out for discussion. > Linn > > On 10/27/2015 8:06 AM, Jim Combs wrote: > >> Speaking of sound. Has anyone considered doing anything to muffle the >> exhaust noise? That would appear to be the source of quite a lot of >> noise. The -10 has a quite loud engine noise at any power setting other >> than idle. >> >> Just a thought. >> >> Do Not Archive >> >> Jim C >> >> > > ________________________________ Message 4 _____________________________________ Time: 09:20:34 AM PST US Subject: Re: RV10-List: Re: Soundproofing the QB fuselage From: Werner Schneider I can add a few facts here from 2 RV-10s which got through noise measurements in Switzerland: both limited to 2500 RPM for noise reduction!! test flights with close to MTOW. #1 Barret IO 540 Hartzell 2 blade C2YR-1BFP/F8068D 2 2 Liese silencers typ RV-10 behind the standard Vetterman empty 721 kg (1590 pounds (has the pod attach points)) some foam (thin) is sprayed onto the inside of the fuselage but noise level inside is a bit higher (1 dB(A)) and subjective a higher vibration level can be felt On flight testing following parameters were achieved (calculated to SL): Vy 100 KIAS RoC 1360 fpm TO over 15m/45ft 1305 ft/398m Measured with 79.2 dB(A) on overflights referenced to 300m /984 ft over the microphone #2 Mattituck TMX-IO 540 MT 3 blade MTV-12B-193/53 standard Vetterman 6 into 2 no silencer empty 763.5 kg (1683 pounds all over insulated like Tim did with the foam rolls). noise level inside is lower (1 dB(A)) especially on the back seat the plane is very smooth with little vibration. On flight testing following parameters were achieved (calculated to SL): Vy 98 KIAS RoC 1425 fpm TO over 15m/45ft 1243 ft/379m Measured with 77.5 dB(A) on overflights referenced to 323m /1060 ft over the microphone Remarks, the prop being 4" larger on the 2 blade gets closer to the critical mach numbers (louder) the 3 blade better in climb gets the #2 an advantage of being roughly 8% higher over the mic. #2 is with insulation inside more quiet but as the vibration level is less it is the question what is causing it. Interesting, the 3 blade wins without the silencers over the 2 blade with silencer, something I would not have thought before, but could be, that the insulation on the fuselage bottom does stop reflection waves from the exhaust gases. Just data so you need to make up your own mind on that Cheers Werner > On 10/27/2015 8:06 AM, Jim Combs wrote: >> Speaking of sound. Has anyone considered doing anything to muffle the >> exhaust noise? ________________________________ Message 5 _____________________________________ Time: 10:47:02 AM PST US Subject: Re: RV10-List: Re: Soundproofing the QB fuselage From: Jim Combs Do you have any idea of the engine RPM / manifold pressure on those flights? On Tue, Oct 27, 2015 at 12:17 PM, Werner Schneider wrote: > > I can add a few facts here from 2 RV-10s which got through noise > measurements in Switzerland: > > both limited to 2500 RPM for noise reduction!! test flights with close to > MTOW. > > #1 > > Barret IO 540 > Hartzell 2 blade C2YR-1BFP/F8068D 2 > 2 Liese silencers typ RV-10 behind the standard Vetterman > empty 721 kg (1590 pounds (has the pod attach points)) some foam (thin) is > sprayed onto the inside of the fuselage but noise level inside is a bit > higher (1 dB(A)) and subjective a higher vibration level can be felt > On flight testing following parameters were achieved (calculated to SL): > Vy 100 KIAS > RoC 1360 fpm > TO over 15m/45ft 1305 ft/398m > Measured with 79.2 dB(A) on overflights referenced to 300m /984 ft over > the microphone > > #2 > > Mattituck TMX-IO 540 > MT 3 blade MTV-12B-193/53 > standard Vetterman 6 into 2 no silencer > empty 763.5 kg (1683 pounds all over insulated like Tim did with the foam > rolls). noise level inside is lower (1 dB(A)) especially on the back seat > the plane is very smooth with little vibration. > On flight testing following parameters were achieved (calculated to SL): > Vy 98 KIAS > RoC 1425 fpm > TO over 15m/45ft 1243 ft/379m > Measured with 77.5 dB(A) on overflights referenced to 323m /1060 ft over > the microphone > > Remarks, the prop being 4" larger on the 2 blade gets closer to the > critical mach numbers (louder) the 3 blade better in climb gets the #2 > an advantage of being roughly 8% higher over the mic. > > #2 is with insulation inside more quiet but as the vibration level is less > it is the question what is causing it. > > Interesting, the 3 blade wins without the silencers over the 2 blade with > silencer, something I would not have thought before, but could be, that the > insulation on the fuselage bottom does stop reflection waves from the > exhaust gases. > > Just data so you need to make up your own mind on that > > Cheers Werner > > > On 10/27/2015 8:06 AM, Jim Combs wrote: >> >>> Speaking of sound. Has anyone considered doing anything to muffle the >>> exhaust noise? >>> >> > > ________________________________ Message 6 _____________________________________ Time: 01:17:59 PM PST US Subject: Re: RV10-List: Re: Soundproofing the QB fuselage From: Werner Schneider Jim, engine RPM was 2500 RPM as CS and limited to that as otherwise they would not pass the noise measurement in this country. Actually measured levels were #1 77.2-79.5 dB(A) we had 1019 hPA QNH on that day, RPM varied between 2477 and 2575 (the 79.5 dB(A)) #2 (He might have MP logged) 74.0-76.2 dB(A) we had 1018 hPA QNH on that day, RPM varied between 2489 and 2500 But then this is corrected according ICAO to represent noise level on Sea Level in standard atmosphere as well as height, power and RPM are corrected. Cheers Werner On 27.10.2015 18:43, Jim Combs wrote: > Do you have any idea of the engine RPM / manifold pressure on those flights? > > > On Tue, Oct 27, 2015 at 12:17 PM, Werner Schneider > wrote: > > > > > I can add a few facts here from 2 RV-10s which got through noise > measurements in Switzerland: > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv10-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV10-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rv10-list Browse Digests http://www.matronics.com/digest/rv10-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.