Muffler for DLE 55 in 1/4 Pitts Python
 

OK, here's the situation.

I have an Aeroworks Checkmate that is as far as I can take it until I get a muffler on it. Once I have that I can balance it then mount the batteries wherever they need to go and then the switches so they're convenient and reach the batteries, receiver and optical ignition switch.

The problem is that the Jtec muffler designed for the Checkmate is no longer being made because it had a design defect and it was breaking. So people were sending them in and production was stopped.

Right now there isn't a muffler that fits as far as I can tell. Aeroworks is trying to get something working but they don't have anything yet.

The engine is the side exhaust, by the way.

I bought a standard Pitts muffler that I was told would fit but I'd have to put holes in the bottom of the cowl for the outlets. It doesn't fit that way though. The can portion of the muffler interferes with the cowl so that I'd have to cut away about half the bottom of the cowl to get the cowl on and off.

I can use the stock muffler if I cut off most of the outlet and cut an exit hole in the cowl. It won't be pretty but it won't be as ugly as what I'd have to do to get a Pitts muffler to fit. The reason I don't do that is I'm told the stock muffler is pretty much worthless and doesn't meet noise requirements at a lot of fields.

So does anyone have any genius ideas for me? I can fly the maiden in a matter of days once I have a muffler that fits.

Personally I would go with the stock muffler. It is the lightest option, makes the most power and is most easily replaced. I had a set of Jtec mufflers once........just once. Yes it is also the loudest option however not by much. The solution to the noise is prop selection. On the 55 the PT 23x8 or the Falcon 23x9 will be fairly quiet. The goal is to keep the engine below 6,000 rpm. I currently run a 150 with canisters, very quiet at idle but very loud in the air, the culprit is the Bolly prop I am running, soon I will be trying a Mejzlik. I expect it to quiet down greatly.

Caffeen, no rocket science here. Try these guys. Dan.
http://www.bissonmufflers.com/en/index.html

You could have Jtec make a muffler similar to what they use to make for the Checkmate. The custom muffler could retain the can design they originally had on their original muffler (straight back from exhaust port) but leave off the exhaust stacks that exited way aft of the muffler (these are what broke off). In their place, just have them install the normal (2) stacks just like any other Pitts style muffler. This way you would have a muffler can that would fit inside your cowl (good) but you would still have to cut two exit holes for the stacks. Not sure if the above helps but Jtec will custom build most anything you want if you can send them a drawing. They've done (2) custom mufflers for me this past winter and the prices are quite acceptable.

Thanks for the help guys. It's been raining crazy here for different parts of the day every day for the last several days but if it's clear tomorrow morning I'm going to run up the engine for the first time with the stock muffler for a couple things. One just to run it and get it roughly set. I also want to see how loud it is before I make any decisions about cutting up the cowl to use the stock muffler.

I did check the bisson site a couple weeks ago and didn't see anything that looked like a winner. It's hard to tell when you can't hold the actual product.

I was supposed to called Aeroworks yesterday but never got around to it. I'll call them today and see if they worked anything out with Jtec.

Truckracer - how do you know about the Checkmate muffler? Did you have one or know somebody with one?

OK, I just talked to Aeroworks and they have some Checkmate mufflers coming in from Jtec. Apparently there has been a design change to strengthen them. When I talked to Kim at Aerotech last week he mentioned that they had put some webs on the muffler and seemed to be holding up. I don't know what they did to the muffler I'm getting (I forgot to ask) but I suspect it's something like that. They said they'd have them in three weeks so I'm not going to cut up my cowl and just wait but I'll still go ahead an run up the engine a little bit.

I read about it on various forums, no personal experience. There's quite a bit of info out there if you do some searching. One problem they had, other than breakage, was the amount of weight hung well back of the exhaust port. Some guys had a very hard time keeping the mufflers tight. Thats why I suggested a hybrid muffler that is a combination of the original Checkmate muffler and a typical wrap around Pitts.

My searches for Checkmate info didn't produce much at all. I found a build thread at the Canadian site and maybe three videos on youtube. I've been doing regular searches since before I ever bought the plane but not for the muffler specifically. Actually I did but the first result was the Aeroworks site and I went there. Hopefully this muffler will work properly. I don't see why there's an issue. Battleships are welded together and don't break.

So it sounds like someone doesn't know how to weld or doesn't know how to select metal. I can't see any reason for something that light with so little force on it failing. It's not like tons of aircraft are landing on it. It has to endure a few G's in aerobatic flight and hard landings.

Probably a vibration thing like most gasser exhaust problems. Add to that an unusual design and you can get problems. With Jtec, you won't have a workmanship or materials problem.