jetstream muffler for Webra 120 (Full Version)

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FredRasener -> jetstream muffler for Webra 120 (2/24/2005 3:20:24 AM)

I have a Quest 90 that I am planning to use a webra 120 on. I was thinking of using a pitts muffler but it really does not fit well in the narrow cowl. The plane is one I got used and it is already setup to mount the engine with the cylinder pointing to the 7 to 9 o'clock position. I am wondering if the jetstream mufler would work well in this application.

I am looking more for quietness and fit to the engine airplane combo. As`the 120 should pull this plane well.

Any info you can give would be appreciated.

If you are not familiar with the Quest 90 it is a 90 size pattern plane that was sold by Creek Hobbies and is now being sold by Ultra RC




bob27s -> RE: jetstream muffler for Webra 120 (2/24/2005 4:57:44 PM)

Hi Fred,

Thanks for writing...

I am familar with the Quest. I was actually considering one myself, and maybe using the bse-120 and turbo-jett combination :) However I have not had an opportunity to measure the cowl to be 100% sure of the installation for either the turbojett or jettstream. I 'think' the cowl is wide and deep enough for the turbo - if i side mount the engine.

From what I can see, the jett-stream installation should be ok. Looks like they have it set up so an OS91 stock muffler can install in the belly pan with the engine clocked off as you noted. In that case, the jett-stream should fit. Dimenions for the jett-stream are on the jett web site in the TECH section. Look up the SJ-120 muffler as a reference. This will give you a better idea.

The Webra 120 runs very well on the jett-stream. The muffler is tuned to the 9.5K-12K rpm band. Prop within this range, and you will have a very nice combination. Somewhere at or just over 10K peak rpm is perfect.

Noise wise....... that is always a tough call. Depends so much on the airframe and installation. With the RPMs down in the 10K range, it is pretty quiet. Prop noise in minimal. Quieter than a full length muffled pipe? Probably not. For reference, last summer I measure my BSE-100 and 120 size turbojett below 87db at 3 meters, grass, 15" prop (10000 rpm) on my AW Edge. The jett-stream should be just a little bit above that.

You may email Dub directly at jettengr@sbcglobal.net for specifics on the muffler and current pricing.

I hope this has been helpful!
Bob




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