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  #1  
Old 04-25-2018, 11:57 PM
Av8rRob's Avatar
Av8rRob Av8rRob is offline
 
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Default How to build and fly a Rv-14 to be quiet?

Ok guys heres the question, what choice would you make while building and how would you takeoff to be as neighbor friendly and quiet as possible (within reason). Im thinking a vetterman exhaust with a muffler, maybe a 3 blade mt prop? Any other ideas and how would you climb out?

Thanks, just brainstorming some ideas
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  #2  
Old 04-26-2018, 01:55 AM
control control is offline
 
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A muffler and then 3-blade to get the diameter down.

If you have plenty of runway and feel comfortable with trading safety with neighbor relations: mark where you get 2500rpm and do take offs with 25/2500....
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  #3  
Old 04-26-2018, 11:48 AM
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flyboy1963 flyboy1963 is offline
 
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Default speed, pressure, direction etc....

if we look for good examples, ( not necessarily practical) you seem to see a trend; more prop blades, lower tip speed, more cylinders, so each has less 'bark' ( 6-cyl?), minimum rpm of the engine and prop, mufflers, and pointing the exhaust up or sideways at the very least.

airframe noise would be pretty minimal, perhaps not worth going after those few decibels! I saw the Lockheed skytamer at Arlington many years ago, it was almost imperceptible flying over at 100'!!!

https://acesflyinghigh.files.wordpre...x900-yo-3a.jpg

http://fantastic-plastic.com/LockheedYO-3ABoxArt.jpg
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  #4  
Old 04-26-2018, 08:02 PM
vetterman vetterman is offline
 
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Default YO3A

I don't know where you came up with the name sky tamer, but the picture you posted is the YO-3A, it's official name. I flew that in Vietnam 2 of them actually, 005 and 007. My call sigh was Nightrider 0 2. I was based at Bien Tuey and we flew at night only over triple canopy jungle, the Mekong River, and Ho Chi Ming trail. Now don't get all excited about noise reduction with regards to this aircraft. It was totally experimental-that's what the Y stood for, and I'm extremely lucky to have survived the whole episode. A long time ago ,but seems like yesterday. Larry v.
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  #5  
Old 04-26-2018, 08:40 PM
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I believe there are three still around. The Museum of Flight in Seattle has one on display which is reported to be flyable, the Army Aviation Museum at Fort Rucker just finished restoring one and the Vietnam Helicopters Museum in Concord, CA has a flyable one. I do not know which serial numbers, but I believe there were eleven built.

Sorry for the thread drift.

http://www.dothaneagle.com/army_flie...61d17f88b.html

http://www.vietnamhelicopters.org/yo-3a-quiet-star/
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  #6  
Old 04-26-2018, 08:52 PM
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Bob Martin Bob Martin is offline
 
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Default 6 bladed prop for noise control

https://acesflyinghigh.files.wordpre...x900-yo-3a.jpg

More thread drift.....
Is that 6 blade prop the new Hartzel composite......on a mccauley hub??
or the WW 74HRT-6...painted black?
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  #7  
Old 04-26-2018, 08:58 PM
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I cannot recall exactly which defence book I saw it, perhaps one of the Bingelis ones, but there was a drawing and an explanation of a muffler built to keep the noise down that was bolted along the fuselage centreline.

Basically it consisted of a tube of perforated steel or mesh wrapped in Fiberglass(??) wrap, and then contained in another steel tube. The commentary was it was remarkably quiet.

My Google-Fu is working today, HERE is a link to the concept.
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  #8  
Old 04-26-2018, 09:08 PM
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My experience with props, unofficial no testing involved, just what I “hear”.

Cessna 182 - change McCauley 2 blade to MT 2 blade; MT 2 blade noticeably quieter. (More engine and exhaust sound than wind/prop sound.). Performance negligible but MT smoothness unsurpassed.

RV-9A - Change Catto 2 blade to Whirlwind 2 blade; whirlwind 2 blade noticeably quieter. Change 2 blade whirlwind to 3 blade Catto. 3 blade Catto noticeable louder than 2 blade whirlwind. 3 blade Catto performance better than the other two. P factor seems higher as well. YMMV
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  #9  
Old 04-27-2018, 07:25 AM
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kentlik kentlik is offline
 
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Quote:
Originally Posted by KRviator View Post
I cannot recall exactly which defence book I saw it, perhaps one of the Bingelis ones, but there was a drawing and an explanation of a muffler built to keep the noise down that was bolted along the fuselage centreline.

Basically it consisted of a tube of perforated steel or mesh wrapped in Fiberglass(??) wrap, and then contained in another steel tube. The commentary was it was remarkably quiet.

My Google-Fu is working today, HERE is a link to the concept.
R, in the 80's we called those "glass pac's" or cherry bomb's lol

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  #10  
Old 04-27-2018, 07:35 AM
Tomcat RV4 Tomcat RV4 is offline
 
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I am giving away my age ,but that’s what we called in 60s also Tom
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