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How to build and fly a Rv-14 to be quiet?

Av8rRob

Well Known Member
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
 
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.wordpress.com/2016/08/img_0026-2-700x900-yo-3a.jpg

http://fantastic-plastic.com/LockheedYO-3ABoxArt.jpg
 
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.
 
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_flier/news/yo--a-builds-on-silent-flight-began-by-qt/article_68f353f0-260e-11e8-b23d-33261d17f88b.html

http://www.vietnamhelicopters.org/yo-3a-quiet-star/
 
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, :D HERE is a link to the concept.
 
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
 
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, :D HERE is a link to the concept.

R, in the 80's we called those "glass pac's" or cherry bomb's lol

40837288725_8378598c09_m.jpg
 
European members?

Mufflers are required in a lot of areas in Europe. Someone ( Sport Aviation, flying, etc.) did a story a few years back about flying quiet in Europe. Had a lot of photos of GA aircraft and they were equipped with a long muffler ( at least 3?)
which was attached along the centerline of the belly. I was interested at the time but everyone I talked with over here said why rush it till they were ever required.
Probably be a lot nicer flight as long as the performance of the aircraft wasn?t effected too much. Maybe some of our members from over the pond can chime in.
 
From a European member...

NACA deduced that the propeller noise dominates and that exhaust noise is next in light propeller driven airplanes. Here is a snippet from the summary of this NACA paper:

"Results of this study show that propeller noise dominates engine exhaust noise even though the exhaust noise has a relatively high intensity. It is concluded, therefore, that in order to reduce the outside sound level of an airplane materially, It will be necessary to modify the propeller to operate at low tip speeds and to have a large number of blades. The practical use of this conclusion is a matter of considerable technical complexity involving many compromises. An effective engine exhaust muffler will also be required."

Many European countries charge higher landing fees for noisy aircraft, which drives people to fit smaller diameter propellers (which usually means more blades), propellers that are better damped (wood core or whatever), reduce the maximum propeller RPM (often to 2,500) and fit exhaust mufflers. One supplier of exhaust mufflers is Gomolzig but they are $$$. Another is Liese (also $$$).

EDIT: Forgot to add this "make your own muffler" link.

Also checkout this VAF post - it's about getting a noise certificate on an RV-10 in Switzerland.
 
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Black knob/blue knob?

Rob, you will almost certainly have to take the plane to Lincoln or some other airport to do your phase one------I would be extremely surprised if you get the approval to use your home strip.

Lincoln is great place for first flight/phase I, and after you get comfortable with the plane, mark off the length of your strip and practice takeoff in that distance with the power pulled back, and/or with lower takeoff RPM---- and see what that does for the noise------need someone on the ground for sure to observe/listen.

All you might need may be the black or blue knob------
 
Rob, you will almost certainly have to take the plane to Lincoln or some other airport to do your phase one------I would be extremely surprised if you get the approval to use your home strip.

Lincoln is great place for first flight/phase I, and after you get comfortable with the plane, mark off the length of your strip and practice takeoff in that distance with the power pulled back, and/or with lower takeoff RPM---- and see what that does for the noise------need someone on the ground for sure to observe/listen.

All you might need may be the black or blue knob------

Mike,
Do you know if the restriction still is removed for Placerville? UP to a few years ago, they would not allow first flight out of KPVF but I believe it was removed.
 
I think Dick W. did his phase 1 with the Moose at PVF------might talk to him.

He is across the taxiway and a few hangars east, now flying a C182 or somesuch.

EAA folks might know also?
 
Yes, and in the late fifties, if you really wanted to PO all your neighbor you would put on steel packs, which were nothing more then a slight interruption to a straight exhaust system. Guaranteed to get you a ticket in twenty four hours.

Today, any self respecting dump truck with a Jake Break is a good ten decibels higher without the traffic violation :) Interesting how societies' expectations and tolerances change over time.
 
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