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GeneWeber
04-03-2004, 05:43 PM
Hi Folks,

Rotax sells a 90 degree exhaust outlet elbow that can be welded onto the 447 and 503 (and perhaps a few other) mufflers. It’s a bit pricey for a little piece of steel.

Has anyone found a suitable alternative? A 1.5” ID tube will fit.

Thanks & Regards,

Gene
RayPierce
04-04-2004, 06:51 AM
Me too! :confused:
Doug Riley
04-05-2004, 08:45 AM
The one that goes on the muffler outlet? Why bother? Save a few ounces, money, time and eliminate one more thing to rust or fall off...

I never use 'em.
GeneWeber
04-05-2004, 05:50 PM
Hi Doug,

But doesn’t it keep water out of the muffler if the gyro is ever caught out in the rain (snow in VT ;) ), and keep the inside of the muffler from rusting? That is the only reason I’m interested in it. That elbow is pricey, but the cost of a new muffler is obscene.

Regards,

Gene
Doug Riley
04-06-2004, 08:14 AM
Gene: I don't use those elbows. I don't park my gyro outside, but it gets wet now and then. I have never had a muffler rust problem, other than cosmetic surface rust on the outside of the canister. Mufflers typically rust inside from the moisture and corrosives contained in the exhaust itself, not from stray moisture from the outside. At least 2-stroke exhaust contains some oil!
GeneWeber
04-06-2004, 08:22 AM
OK, Thanks Doug.
gyropilot
04-06-2004, 08:40 AM
Gene,

I did weld on one of those $$$ Rotax elbows to the muffler used with my 503. I did this so I could direct the exhaust outlet back and upward (away from the ground) and into the rotor system. I've had many people remark how quiet and unobtrusive my gyro is when flying overhead at low altitude... even at full power.

Having said that, I think the 90 degree exhaust elbow is only worth the cost/weight if used to direct the sound... forget about the water-in-the-muffler issue. No water will get in when the engine is running, and when not running, you should be putting covers on the intake and exhaust anyway to keep crap and bugs out!

Of course exhaust noise is only part of an aircraft's noise signature (intake and prop noise being contributors), but every bit helps.

Regards,

John L.