Ken,
Try to find an old OS 762 muffler, like came with the FP40s back in the day. Cut the stinger off and voila, a lot lighter and LAs run great on these. A little louder but not too bad. I could never convince myself to hang the stock muffler, they're just so big and heavy. Doug said he and Steve used to drill some extra holes as well, he could explain that.
 See you at the field...

Chris

Try it both ways?  I leave the baffle in, and am having pretty good luck.

If you can find it, the muffler from a Tower 40 fits and is maybe half the weight.  I haven't looked at the innards of those to see if they have baffles or not.

Ken,
I MIGHT be out tomorrow morning and will bring the 762 I have on my LA46, the one in the Cardinal, that you are welcome to try as well. Not sure if I will make it though but if I do I'll see you bright and early!

Sorry...just got the reference to the weight needed...you mean ballast, not the weight in grams of the 3030...my bad.
I hope I can get out there tomorrow morning...want to get some more flights on the new K77 in the Bear!!

Chris:

Thanks, I have a baffle for the 3030 in my cart.   I plan to fly once without then put it in and see what happens.  When I named my design the Sandpiper I never envisioned having to fly with Bears! Poor thing is scared.

Ken

The "modern" OS mufflers are said to be 1/4 wave pipes, and taking out the baffle (or "Cone of Silence") is said to spoil that wonderfullness. I would rather experiment with opening the muffler outlet and the hole in the center of the cone. Somebody has probably already done these tests.

I can tell you that the stock OS .46LA muffler works splendidly on a Magnum XLS .36. That and watching several stock .46LA's flying Pathfinder ARFs running lean in the OH8s, I'm inclined to think some muffler work could be interesting. However, if you read Randy's pinned articles, the simpler method would be to plug in a bigger venturi/restrictor.  Steve

I have sold a lot of  TT 36  39 mufflers for  use on the LA 40 and 46, they work great and are lighter than the  OS ones
and  you will be pleasantly surprised at how well the  Cyclone 11 x 4.5  works on an LA 46, run cool cycles faster than the AOC and gives a broader envelope to run in, Many run a HIGH RPM  4/2 with it, other use a small venturi and run a  wet 2 stroke

Randy

I'm scared of the Bear too! First 60 sized ship I've ever flown! I'm used to 40 sized. Sure did pull hard when I had a lean run the other day....two hander for sure!

Chris:

Missed you on the way out.  About the roll in the Cardinal.  Put a 2sq" tab on the outboard flap.  Mine is 1/2" x 4" and cured the roll completely.  It needs the tip weight and the tab stops the roll it creates.

Ken

Ken

Based on what Steve?
Reflective wave pipes rely on reflective surfaces along their entire length and a modern OS muffler has as off set right angle bend from the manifold to the expansion chamber specifically design NOT to reflect any wave back into the combustion chamber, 1/4 or not.

Sure the insert cone looks quite capable to bounce any wave up and down the length of the expansion chamber but then what?
How does it enact further?

I have proposed this before, the system is not reflective or length based but Helmholtz volume based and removal of the cone effects the volume between chambers much more than the length.

   You need to study wave propagation in closed systems a little more. For instance, why it doesn't matter very much if you have a 90 degree angle in system. You know the acoustic waves get as far as the exhaust outlet, to cause the bang-bang-bang sound instead of a "whoosh".

    You are making the same sort of mistake that others make when describing "true" venturis - assuming that real systems have to look like simplified illustrations from elementary textbooks to work the same way.


    Brett

Just to cover this off, any system that claims to be based on wavelength is dependant on "lengths"  and the length or distance demonstrated in any of the reflective walls to the source in a tube muffler such as here are simply not long enough to resonate at rpm frequencies found in model two stroke engines. At a guess you would have to spin at 80 000rpm if you claim that the first reflective (but unfocused) wall works here.
Sure an acoustic pulse can be witnessed at the venturi but do you honestly think that its reflective based considering the labyrinth it has travel through in order to be realised?

Externally it normally is a reflective system working from the combustion chamber centre to the first plane of reflection and internally  it is acoustic or pressure based.

For those midly interested in this I suggest researching the Magic Muffler of pylon racer fame, that genius system combines both reflective and acoustic modes (side branch resonator in this case) in one pipe.

I labour on this because people can make a better informed choice if they understand the 'why' of any decision.
I believe the claim that it is better to leave the baffle in, why?
Because an acoustic system tends to be of no detriment outside of its range, the engine carries on as normal and simply benefits when the frequency of the engine rpm matches the volume of the chamber.

Very different to a reflective system that is much more critical to setup.

Cheers.