Muffler for .35 FP

The stock muffler on my .35 FP exhausts straight back, non adjustable. On my 20 FP, TT .25 GP, and LA .25 the exhaust is at an angle and can be rotated to minimize oil on the plane. I have tried one of those bent rubber tube things but using the supplied wire ties is not working. Either the tallish grass I fly off of gets it, or just basic maneuvers work it loose. Two options I see: Some type of available hardware store tube and a way to attach it better, or a replacement OS/Tower/TT/Etc. muffler that will fit and has the angled/adjustable exhaust (part number unknown to me) that I might snag off SSW Classifieds or *bay. Suggestions please.

Best regards,

Clay,

Anything you attach to the muffler will almost certainly increase back pressure and power. Nothing you suggested is going to reduce the about of oil on the plane unless you install a tuned-pipe that exits the rear of the plane. The OS mufflers that you can rotate the exit pipe in my opinion do nothing, once the oil gets in the air it's going everywhere.

The stock mufflers are quite restrictive. The RC muffler does rotate like that on the 20/25 FP, but it is heavier and still restrictive. So that is available, but...

I can get a "Big Art" muffler made for you that would have the stinger aimed down (or up or sideways--whatever) that would be lighter and less restrictive than either stock muffler, but you are still going to get oil on the plane.

Now, ironically, what I have seen leaves the least amount of exhaust residue on the plane is a tongue muffler. Instead of all of the exhaust coming out of the muffler in a steady stream which then whirls around and hits the plane because that's the way the air currents are flowing through the prop, the tongue muffler makes for a finer mist as it separates the exhaust into tiny droplets. For whatever reason, this then seems to leave less residue on the plane. This is also the lightest muffler (and the cheapest of the after market types). But don't put a "rubber ducky" on. It only adds weight and more back pressure which you don't need.

I should have mentioned that I’m flying my ARF Nobler with the .35 FP and power was not an issue with the tube thing I had been using. It did help keep the oil from blasting directly at the wing LE and I would have continued to use it if I could have kept it attached. It is now somewhere in the grass awaiting it’s lawnmower fate.

I understand that I’ll always get oil on the plane with any set up. I was just surprised that with this particular muffler it ended up aligned with the LE and pretty close to it. It doesn’t seem like some of the oil is getting on the plane, it seems like all of the oil is getting on the plane. What’s worse? An ounce of oil or the weight of a rubber ducky. Also should mention that the way I fly (just getting into inverted the lazy eight way) I will probably not notice subtle differences in power, etc.

My experience with the other mufflers has been on profiles (including a Ukey John sold me some time ago, thank you very much) which puts the exhaust stream away from the plane better to begin with. Thanks for the suggestions on tubes and tounges. I may take you up on that.

Actually, the older bullet shaped muffler from the FP35 is a better muffler than the newr high restriction units.

THey need to be opened up a bit though. Cut off the outlet spout, and open the remaining hole so a piece of 3/8 aluminum tubing fits in the hole. Clean it all up and JB weld (Metal filled repair epoxy) a short piece of tubing in the hole. If you want, put it in at an angle to get a bit better deflection.

FWIW

I like it!

LAST EDITED ON May-20-04 AT 11:52 AM (CDT)
 
One of the most important reasons that castor mixes and oil percentages greater than 15% are avoided by many RC fliers is their dislike for cleanup with the oilier mixes. They will literally burn up their engines using poor fuel mixes just to have less residue to clean off.

That said, you could try testing some different fuels. Any time I run any mix with a lot of castor, my planes seem terribly slimy. I like my PowerMaster 10/22 fuels pretty well - using those as a base, I tend to use Klotz instead of castor to raise the oil percentage when I already have 11% castor, though.

I buy some Byrons fuel when I can't get the PowerMaster, and for that one I do add only castor to bring the oil percentage up where I want it, because there is only a small amount already in that blend.

P.S. Appro Pro of not much, when the 4-2-4 run was still pretty much limited to Fox 29's and 35's, and not yet as popular as it eventually became, the Fox made more mess inverted than the Torps of that era did. Quite a few of us were indifferent to both Foxes and to the four cycle run in the mid-1950's. With an inverted Torp, the bottom of the plane wasn't covered in slime the way it was with a Fox.

.

Kiwi

do some experimenting with exhaust positions to determine what works best on your plane. The obvious position may not be right. I flew the Interceptor a bunch of times with the exhaust tube pointing straight down(profile mount engine). Most of the oil ended up on the bottom of the wing with some blowby finding its way to the top. Kind of by accident I repositioned the exhaust tube pointing straight out towards the outboard tip. Now 90% of the crud stays in the air and only a little bit ends up on the plane. Looks like the different angle lets the swirling exhaust stream roll the smoke away from the plane. With the exhaust straight down it seems to roll around and back onto the wing.

With chip mufflers, try it both ways. Sometimes reversing it will also cause the exhaust to roll away from the plane better.

If you put a 2/56 sheet metal screw into the side of the exhaust tube, near the end, it will act as a stop and hold the exhaust extension on. Use a tie-wrap around the extension, ahead of the screw.

Phil,

I’ve made this same observation on my pukey profiles with “adjustable exhaust exit”. You are correct that “the obvious position may not be right” (also true in many other endeavors, but I won’t go into that:o ). Thanks for the idea of using the screw as a stop. Wish I had thought of that before I DQ’d myself, or at least had to take an attempt, by ejecting my Rubber Ducky. Oh, the shame.

Scott,

Thanks for the offer. I just saw your name mentioned in SN yesterday. May take you up on the offer after I determine what the best exit angle is, probably using another Rubber Ducky = shame to the second power.

Best,

>If you put a 2/56 sheet metal screw into the side of the exhaust tube, near the end, it will act as a stop and hold the exhaust extension on. Use a tie-wrap around the extension, ahead of the screw.

>Phil C

snipped...

Phil,

Aha! I've been waiting months and months to catch you in a major error, to ridicule you without mercy.

There is such a thing as 2-56 sheet metal screws? All of my 2-56 numbers appear to be machine screws, but there could be some sort of mistake here.

Hug...

DAN THERE are both kinds....

THere are SELF-TAPPING, 2-56 machine screws, but Sheet metal screws are more like wood screw threads without the taper. numbered by diameter only, no thread pitch.

LAST EDITED ON May-22-04 AT 00:04 AM (CDT)
 
Clay I will build you a muffler the right size for your engine with the exit tube pointing anywere you want it. I like to do things the right way. please Email [email protected] Scott Dinger