Modify Sparrowhawk xhaust?

[enewbold]

Folks, I'm getting SERIOUS noise complaints from many residents around the Newark-Heath, OH, airport every time I take students up in the Sparrowhawk. I've tried to modify flight paths to accommodate these people, but that's not helping much. The Sparrowhawk is just plain LOUD.

Has anyone thought about removing those stub exhaust plates, adding some longer extensions and/or a couple of motorcycle-type mufflers to the machine?

Any suggestions along these lines?

Thanks very much,
Ed

[GyroRon]

It isn't just engine noise, it is also noise from the prop. Look into getting a Prince two blade P tip prop and maybe somekind of spinner to cut down on alot of that noise.

[BigBen]

Ed,
Ron is correct that most of the "disturbing" noise for the Sparrowhawk and RAF types (read that as high powered Subaru engined) comes from the prop and that would be a good place to start.
A way to address the exhaust noise could be the tuned "stub" exhaust tubes addressed by Don Parham in Homebuilt Rotorcraft, March 1992 issue. I plan to use them on my planned modified RAF (EJ22). The only exposure I have to this system was at Oshkosh in the late 80's and used on a 2 cylinder VW ultralight built by Christine Aero (from South Carolina). It was very quite and had no negative effect on the already minimal power output. One neat positive is the exhaust system only weighs about 5 pounds total for a 4 cylinder engine.
I would like to hear from Don or anybody else who has tried these pipes.

[mgoroff]

Ed,

I had no noise complaints with the stock exhaust and prop as long as I was 1000agl and 4500 rpm or less over populated areas. I was told it sounded "different", but not any worse than a noisy cessna at the same altitude.

I now have a variable pitch IVOprop on my SH and the noise levels are way down as I cruise around at 4200rpm and can easily go to 4000rpm over populated areas. Folks on the ground tell me it is definately quieter now when I fly over and quieter than many prop planes .

Marc

[JRB549]

I know we want to all get along, however I feel that there is going to be aircraft noise an a AIRPORT. People bulid houses next to sewage plants and complain about the smell. I just dont get it.

[enewbold]

I know we want to all get along, however I feel that there is going to be aircraft noise an a AIRPORT. People bulid houses next to sewage plants and complain about the smell. I just dont get it.Hell, I've been wondering about that for as long as I've been flying, and still don't understand it! But, sooner or later, homeowner associations form up and start making life difficult for us.

Most of my flying involves TOL work with students; so, as you can imagine, I'm at low altitudes and running at high power levels. It's mostly those people directly under the departure end of the runway who complain the most.

I do try to vary the lessons with flying right-hand patterns for a couple of laps, and then switching to left-hand pattern for the next few laps. I'm afraid that all I'm accomplishing, however, is to irritate all of the people under BOTH patterns! :ohwell:

I was hoping to find a relatively quick and easy way to quiet the machine down. As I'm leasing it from a company, the owner doesn't want to sink in any more money for a new prop, so that's ceased being an option for me.

( ...sigh... )

Ed

[bones]

I tried not to put this post up but i just had too in the end, a simple fix is a rotax, they are so quiet, :) i had a house right at the end of my runway, a race horse trainer lived next door, with his training track not more than 100 yards away, all i did was wait until they finished training one and head off, before the next one came out. :first: We got on great.
I know your gonna say they dont have the power, but some one obviously never told the WASA about it cause it flys great with a 914. :rapture: :noidea:

[Greg Lockhart]

Does anyone know if the newer stainless steel aircraft mufflers used on the SparrowHawk II are quieter than the older Supertrap mufflers used on the earlier SparrowHawks?
Thanks
Greg

[Chuck Roberg]

Does anyone know if the newer stainless steel aircraft mufflers used on the SparrowHawk II are quieter than the older Supertrap mufflers used on the earlier SparrowHawks?
Thanks
Greg

The Sparrow Hawk II that I flew which is the later model. I was told it's the noisiest gyro around. Being inside I really could not tell. But Tom Milton and other club members told me it was really noisy.

[Heather Poe]

Randy Coplen's Sparrowhawk had the original Supertrapp exhaust system, and we received noise complaints. The newer design Aircraft Exhaust system was swapped in, and it still received complaints. Finally, the exhaust system from I'm Flyin (http://www.imflyn.com/exhaust.htm) were put in, and the noise levels were changed to the loudest to middle of a pack of aircraft as measured by a Radio Shack sound level meter.

[lanichol]

Ron Menzie had the same complaints with the new Sparrowhawk muffler. He went back to the old RAF style muffler.

Tech Welding builds an old RAF style muffler

http://www.techwelding.com/

Other discussions on mufflers.

http://www.rotaryforum.com/forum/showthread.php?t=16613&highlight=exhaust

http://www.rotaryforum.com/forum/showthread.php?t=16960&highlight=exhaust

[CLS447]

Ed from Tech welding told me he doesn't build exhausts anymore.

Go figure?

[GyroRon]

GyroJake here on the forum can make the absolute most quiet exhaust for a Subbie as possible. On his old two place gyro, at idle the engine was so quiet you could not hear the exhaust at all, just the prop spinning and the valves opening and closing in the heads. It was amazing. Not sure if he would build exhausts for others, but I suspect he would.....

[automan1223]

For starters the stock super trap short pipe setup on the SPH is a quick and dirty exhaust as you have found out it stinks with the decibels department as well.

As posted before the Im flying exhaust is more in line with making more power and less noise. You need a muffler and a long tailpipe that exits away from the prop not into it. Preferably the tail pipe should exit somewhat horizontally not straight down.

Prop issues, the warp drive prop with square tips is one noisy bugger. A prince prop or in flight adjustable ivo is the way to go. If you can slow down the prop you reduce the noise. You might not be able to mitigate the noise on a power takeoff but cruising in for landing should be a much quieter operation.

Keep us posted.

J