jptonks

Hello all,

I am installing an OS 1.60 in a Great Planes Giant Big Stik, following the instruction manual. The engine will be mounted sideways so that the muffler will be at the bottom of the airplane,

Since there is no cowl to be concerned about, what is the quitest muffler that I can use on this engine? I am not concerned about maximum power, if some rpms are lost due to the muffler's design it will not affect my sport flying at all.

I wear two hearing aids and I am sensitive to rc engine sounds. THe quietest muffler I can find would be much appreciated.


John T.

maukaonyx

John T,

My son and I both run the 160 with a slimline pitts style muffler. It is not quiet, and I'm not sure what would make that big 2-stroker "quiet". My son is sensitive to keeping his hearing so he wears ear plugs when we fly. I guess I am wondering if you can turn down your hearing aid to a comfortable level when you fly? Or wear a headset ear protection thing when you fly? Just some ideas since wearing those would protect you from not just your own plane's noise, but from all others too. Jon

anuthabubba

My Feedback: (102)

There are 'after mufflers' out there that attach at the tailpipe of a stock (or any) muffler to quiet them. A multi chambered tuned pipe would be quieter than a lot of other types of mufflers. Have read of long tubes attached to tail pipes for routing exhaust residues are effective at reducing noise levels too. A moussecan type exhaust would likely be quieter than a stock muffler. Operating the engine at lower rpm, w/ large prop, will also make it quieter. Least expensive of these suggestions would be some heater hose from the auto parts store attached to the tailpipe of the stock muffler. Might work. Might not.

Terry in LP

wildnloose

a tuned pipe will be the quietest setup. but its not cheap and it requires some design considerations(ie-which prop, rpm, and header length). Here is some good info:

Pipes - The Aeroslave CF pipe, without a doubt, is the BEST I have run!! LIGHT, at 3.2oz, it has a quiet, mellow tone, and tunes identical to the Mac's. I highly recommend it!! I like the Mac's (and the clones I found) also, run these at 23 1/2 to 24" FOLLOWING the header/curve, measured FROM the glow plug. This will give you around 8200-8400, 17 x 12 prop or equivalent load. Not real critical, just don't get it too short.
The ES Composites pipe(s) from Ed Skorepa are ALSO very good, have the long, fragile stinger integral on the exit. Very high quality manufacture, tune very similarly to the Aeroslave. VERY nice pipes. 2C140S8, or M8 (his best seller, I'm told), and the 2C160L8 works too, although it is a HUGELY LONG tuner setup. Go with the M8 if there's a problem with tunnel length at all.

Also search in the pattern forum for more info...

combatpigg

My Feedback: (3)

I wear 2 hearing aides also. It's simple enough to remove the hearing aides before flying and put on a protective headset when working around a screaming engine. Once launched, I rip off the headset and enjoy [what I can] of the music that is performing at a distance.
Tuned pipes do a nice job of tuning out the harsh barking sound, they sound beautiful.

CustomPC

A tuned pipe would be the quietest solution and if you rotate the engine mount to the a suitable angle the pipe will run right along the side or centered along the underside of the plane.

Here is a video of my Webra 1.45 with a tuned pipe: http://www.youtube.com/watch?v=0Cx-NtJe_bk

If it sounds quiet in the video, that because it is quiet. I think the prop makes more noise at some points.

If you compare my other video with a .91 and Jett muffler you can hear how much louder the .91 is, and both videos were taken on the same day with the same camera location, within 30 minutes of each other.

David Bathe

Not wishing to create a problem here but: A "tuned pipe" is the last thing you want. A Tuned Muffler pipe is what you're after.
Many people believe those big, so called tuned pipes you see on F3A planes are to increase performance. They certainly where years ago but today, they're not. They're mufflers, designed to reduced engine noise to comply with the super-strict FAI noise requirement... whilst not robbing performance.
The OS 1.60 has been used by many pilots flying in the middle/upper classes for years, and has a great following. What this means is that there are quite a few muffler pipe combos out there.
The problems are that 1, they tend to be big (I have a German Greve muffler... it's set at 87cm from the plug!) And 2. They tend to be expensive. But boy, with the correct prop they're quiet.
To keep things simple, You should check out what Macs have to offer before going for the exotic import stuff.
Remember prop choice plays a major roll in sound reduction. In F3A they're swinging FAR bigger props than the average John and at much lower RPMs. They certainly don't suffer from lack of performance... quite the contary. They've got it worked out!
If you go for an F3A solution you'll just mount the engine inverted with a wrap-around header, coupled to the muffler running down the underside of the aircraft. Add a little stinger pipe on the end and you'll have the cleanest model you've ever... the oil flying out pasted the tail.
BTW. Slimline/Bisson are just dreadful... noisy as hell. They're only useful purpose is to divert oil out of the cowl; Just.