ukmike

Pe Reivers.
Sorry if you think my approach is "Stupid". but it does offer a very low cost alternative which is what the writer asked for originally.
Also, as I stated in my reply, I have used it many times to quiet existing installations which has made an unflyably noisey plane, flyable.
If the results are not liked then just remove the restrictor, refit the self tappers and fly away, Noisely.
Mike

dogshome

I don't think adding baffles to a very noisy and unrestricted muffler is in any way 'stupid'. What he's done is to recreate the sort of baffling found in trimmers and saws. A poor choice of wording in 'stupid' ! [:'(]

There are obviously more efficient ways of doing it - but for a pipe and header you are looking at 2/3 the cost of the engine. Pitts type approx 1/2 the cost.



Un-flyable plane made flyable [sm=regular_smile.gif]


In fact to (mis) quote Victor Kiam "I was so impressed..."

dogshome

I just ran my SPE26 with the baffle in - it is a lot quieter. Normally I have to wear ear defenders in my back yard. It's still loud, but now I can hear induction roar where it was completely drowned by exhaust before.

Unfortunately I don't have a tacho so can't tell about absolute performance. I did have to richen both needles ever so slightly.

I think a DIY intake bend is stage II for my SPE. Having the DL intake via a long stack into the fuz certainly loses noise. It might just make the UK noise limit then

pe reivers

No,
In my .15 diesels, 8x6 graupner 3-blades, in my gassers I use Mejzlik.

Today I test flew my "new" 1/4 scale piper cub (@25lbs) with 58ccMVVS, side muffler and much reduced stinger outlet. Test prop was a 3W 22x12, and the engine was quite silent. Still enough power vor nearly vertical climb.
I had planned to put on a 22x10x3 Mejzlik, but the plane is a floater and needs a prop that puts the brakes on so I can land on the strip instead of the ditch at the strips end. So I will choose a 24x8x2 for the next tests. This goes to show, that there is not always freedom of choice. The plane has a voice in this as well.

Super08

My Feedback: (2)

Cambo
I got to hear mine run today with a Bisson wrap around pitts and my friends DL with the stock muffler. Mine is noticeably quieter than the stock muffler. It doesn't have that load "bark" to it when it is idling. We have no meter to test it with but it is less irritating to the ears.

rmh

No one will like this -as you actually have to construct it - but it is incowl
the problem is getting enough volume and no exhaust port restriction and NONE of th commercial Pitts do this as well as needed - the large Supersonic works well but noise is still high.
You can't have your Kate and Edith too-

pe reivers

Tony clark also uses that kind of muffler for the zenoah engines he uses. This must be the most quiet, and least restrictive system.
Fitting the Clark muffler for his 62 on a 58cc MVVS yielded 78 dB(A) at 7 meters. Prop was 22x10x3 at only 5900 rpm though. In a Yak, still enough for very convincing 3D.
I used a similar device, constructed as integrated engine mount, for my ST2300. It had 22 times stroke volume, single chamber and long thin stinger pipe. It was very quiet, and hardly restrictive. Will post picture. The T-line in the pressure pulse line for the fuel pump (modified Walbro) is to prime the engine. The regulating membrane pressure is connected with the muffler in standard glow fashion.

buck1856

My Feedback: (49)

See if you can use one of these mufflers from here.And or parts or get an idea,maybe somthing.
http://www.airpowertechnologies.net/APT_Home_Page.html

Cambo

My Feedback: (2)

Hi everyone
So a drove over to the field on saturday to get it tested. It is 102 decibles currently. However, just about every gasser was failing the test and now everyone is freaking out. I was told to wait a bit before i do anything.
Anyway I am going to take a trip to the hardware store today and see if i can get something to fittle with my exhaust. Thanks for the tips.

Oh, btw. This engine will hover the plane at a scary low rpm. It started burbling as if it is going to idle. It has unlimited verticle at less than 1/2. I am not going to worry about a few 100 rpms.


Thanks
Cameron

Cambo

My Feedback: (2)

Just got done. I am not sure if it is below 94db or not but it is noticably more quiet. Lost 300rpm i think. I would prefer to just not use this but we will see.

buck1856

My Feedback: (49)

If just about every gas engine at your field failed then all you guys that failed just need to go find a place to fly by yourselves.We have an old abanded air strip that we found a hole in the fence,no one cares yet.

Kweasel

My Feedback: (29)

Were they freaking out because they didnt know how to make their planes quiet. Or were they just angry because they could no longer be obnoxious? Giant scale flyers need to spend some time in F3A so they learn some manners.

captinjohn

Has anyone tried steel wool inside the muffler. It should help!!! Capt,n

buck1856

My Feedback: (49)

Thats why i posted that link to airpower.They sell an insert thats suppose to be better than steel wool and its designed to be put in the muffler.This is what they use to put in there round mufflers that are incorperated into the mount system.

captinjohn

The link to Air Power did not seem to work on my puter?????? any ideas why? Capt,n

pe reivers

Capt'n
The days of steel wool are long gone. A good design muffler will be just as good or better, without the steel wool's drawbacks like parts loosening, oil residue saturation etc.
If you need the power without the noise, a tuned pipe with added one- two- or three chamber muffler is the way to go. Only source to consider then will be prop noise, which will happen if prop noise surpasses exhaust noise by 3dB(A).
A good tuned pipe will not be restricted in power by an added muffler, as long as the muffler does not restrict the flow that the tuned pipe needs. (which may be surprisingly little)

dogshome

Buck, I totally disagree with that viewpoint. It won't do you any favours finding another site if someone DOES care and kicks you off because of the noise. I hope you were kidding [] ? Kweasel has put it bluntly but correctly - learn how to silence your aircraft [sm=49_49.gif].


PE Reivers:- You've not commented on the muffler insert? Granted it will lose some power but as a cheap solution to fly an unflyably noisy plane in a noise limited area, it works. Cambo, the original poster is going to try it, if it still gives the power he needs and gets the noise down then great! I need a newer car with a more efficient engine; but I can't afford to buy one just yet.

rmh

For some reason - the physics of two stroke engines are forgotten when it comes to the exhaust system - these are not four cycle engines
power reduction or increase is directly tied to exhaust flow -as it controls intake flow.
No exceptions.
resut ? you can throttle a two stroke with an exhaust control instead of an adjustable carbureter It does not work very well but it does work.

dogshome

Yes. That's fine, no arguments there

What about losing a lot of noise at the expense of losing a couple hundred RPM (say) for zero cost [sm=confused.gif] That's what I'm getting at. Making a noisily unflyable plane flyable has got to be worth it

pe reivers

cost saving is the cheap way of loosing a lot of redundant power. Just pinch that tailpipe! (stinger pipe), overload the engine with too much prop and hey presto, a silent combo.
In the real world, all of us need the best of everything
best power
at lowest noise
best prop pull
best speed
cheapest engine

This of course does not agree with the first sentence

rmh

The problem is that on a given prop -200rpm is a LOT of power - -on larger engines

the best muffler is still the largest one- no way around it -
I fly quiet setups
I detest prop rip and blatty exhaust noise .

pe reivers

200 rpm on a 22x10 prop in the 6300 rpm range is about 10% power loss! Quite substantial, considering many tune their gas engines 200 rpm off peak, whilst in gas engines, peak power already is a rich mixture of about 10% fuel surplus. Add another 10% power loss for extra muffling, and you are down to 20% loss.
This deal of restricted muffling leads to nowhere as you already mentioned.
Indeed the Imac crowd has it figured out how to get the best in power, noise reduction and engine response. At least they should have, because it means stepping over the thin line between winning or loosing a few points.

dogshome

Apologies for seeming pedantic and for posting far too many time in this thread


I didn't buy the 'best' engine and I didn't buy the 'best' muffler (seen that 'best' word many times in the last couple posts):- I bought the cheapest (near-enough) not the best. Probably not alone in that. I also hate loud engines (can't you tell! ) so my DL has a Zimmerman pipe and intake into the fuz. Quiet, powerful and expensive.

The SPE26 is a similar case and I don't want to spend the same again on a decent silencer or pipe. So, I fit a zero cost baffle, it quietens it and makes the thing flyable.

I think it's unfair to dismiss ideas like this as being of no value; of course it is a compromise. BUT it keeps planes flying on sites that they might not otherwise be able to. Have you heard a DL on it's stock muffler? It's virtually the same as open exhaust. Even the kids in my town have some sort of silencer on their scooters (they have to) and they are annoyingly loud. Listen to one soon, it is awful.


So I'm in the field, looking up the ivory tower and all I can see is cloud. Perhaps the climb leads somewhere, who knows. I'm happy flying my quiet, cheap and inneficient model and not disturbing anyone

JoeAirPort

My Feedback: (41)

PE, I wish people like you could get points for rudeness and banned from the site after 100 points. You would have been gone a long time ago. I don't like seeing people being rude to other people who come on this site to enjoy themselves. You ruin it !!!

Cambo

My Feedback: (2)

I was thinking of doing such a thing myself. I asked before but seemed to get no reply. Why can't one just make a "canister like" large chamber can and run it back behind the engine. What if you placed a canister sideways parallel to the engine. Oh, and were do you get headers that make a full u turn.

Cameron