Yep! I've ripped off a wing or two due to too much power. Wait, is ther such as thing as too much?

Dave

Back in the control line days, they used to say that even a rock would fly with enough power. I think not!

I have a Pawnee 40 with a OS 55 AX with a 13 / 6 prop will do anything I wont !!!!

with DLE 20 on 90 and 120 air frame 1 on a 90 EXTRA 260 and one on a 120 cub

I would not try to put a DLE 20 on it !!!! ( Pawnee )

MyGOD uneless you do a lof of beefing up to the front of it the DLE 20 will rip it off

The H 9 Pawnee is purty light air frameIt does not like or was ment to Fly Fast !!!! My $0.02 R/L

The black break-in goo is still there but at least now  I have it diverted away from the fuselage while I'm breaking it in . As already stated it will be there for awhile and after I run a gallon of dino oil mix through I will switch over to  Klotz oil and should have it in the air by then.
Before I test the 13X6 prop I'm going to take the muffler apart and see what I can do to seal-up all of the seams and bolt holes as it leaks worse than a glow muffler.

Yes we did test it with the BissonBIS04046 PITTS MUFFLER: 40NT,EVO52NX,60NX. The volume of the muffler is slightly smaller than the included muffler but the test results were generally pretty good. We are working on one of our own design with slightly more volume but it will be a wile beofre that is available.

Pete
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Pete,
That Bisson pitts muffler you mentioned appears to be for a horizontal installation. Is there one available for an inverted installation?
I think most scale planes that use this engine would look best with it mounted inverted with a proper inverted pitts muffler that fits inside the cowl.

Steve

Your wanting what is called a wrap around muffler which I'd buy now if one fit to the evo 10 that way you can invert the engine

I have a Pitts that I bought for my JBA 15. Not a wrap around since it was a side mounted engine with the exhaust pointed down. Don't know if this would work or not. If I get the evo 10 I may try it. We'll see.

It has diminished a little but still creates a mess. Iwill be switching to STIHL as well. I don't think that will help though. Ithink the goo is due to the high oil content.

I don't think you''ll see much goo after the engine is broken in.

I would like to see how it responds with the mac's black muffler, one piece unit. We are talking the extra volume version for the 55AX and 60NX. My 55AX's really come alive with this extra volume version muffler since it is larger than the .46 version.

If a certain pipe is tuned for glow, I don't know if that tuning is necessarily optimal for the same engine in gas.

I took the muffler apart and used some high-temp sealant around the rubber seals and on both ends of the bolt. Ran the engine to do some more break-in testing and it seems to have sealed up the leaks.....so far.

<hr size="1" style="color:#7a99d2; background-color:#7a99d2" />Running the ninth tank of fuel and I tried an APC 12.25X3.75 prop to get some RPM readings.


www.youtube.com/watch

[youtube]http://www.youtube.com/watch?v=_rIDBDi90As[/youtube]

Still on the ninth tank. Changed over to an APC 13X6 prop and got some readings. I will run three more tanks using this prop and the 20:1 dino-oil mix. Then I'll switch over to 20:1 using Klotz oil and test fly the plane.


www.youtube.com/watch


[youtube]http://www.youtube.com/watch?v=h2eX7Yke5ak[/youtube]

You read my mind! I was thinking the same thing and will see if my OS 55AX MACs muffler will fit. If so, I might have some stats for you on Sunday (wx permitting).

Dave

I couldn’t wait for the weekend and decided to see what the MACs muffler would do. I switched to an APC 12x6 and got 10900 RPMs out of the stock muffler on the ground. At this altitude, I guess that is about right as we typically get an approx 15-20% performance decrease over sea level. I then put my OS 55AX MACs muffler on the Evolution. It fit the mounting bolt pattern OK, but I saw at least 1700-1800 RPM decrease over the stock muffler. The most I got out of it was barely 9000-9100 RPMs, but after about 2 minutes, the RPMs suddenly decreased to a “surging� 7600-7800. No amount of needle adjustments brought it back up and I even took off the muffler and remounted it two times just to be sure it was on correctly. Same results each time of upper 7K RPMs. So, in reality, I saw about 2800 RPM decrease from the stock muffler. This was just a gee whiz experiment with a muffler I had on hand. I hope another after market muffler designed for this engine will do better. You got to give the R&D guys credit, they designed the stock muffler for optimum performance.

Interestingly enough, I gained about 900 RPMs on the stock muffler by disconnecting the muffler pressure line. When the pressure line was on the muffler nib, the RPMs dropped to about 10000 but removing it caused an immediate increase to 10900-ish. Has anyone else seen this?

Dave

By taking off the line you leaned out the engine. Not getting as much fuel.

I am following this on FG and here. Nice work!

That was my first impression too. But w/the muffler pressure line attached, I tweaked the HS needle for about 150-200 RPM less than peak. I guess I convinced myself that a sustained 900 RPM difference wasn't it, especially since the change in RPMs was almost instantaneous. (Not like pinching the line and seeing a gradual RPM increase.) I'll experiment with leaning it out a little more to see if that is what it was. I learn something new every day. THANKS!

Dave

One word of caution...I wouldn't fly it with the muffler line disconnected. You will more than likely have a dead-stick and the engine will not run properly at different orientations because the engine cannot draw enough fuel without the muffler pressure.

That being said, experiment away!

Thanks,
Jimmy

Just a thught Redline Racing two Stroke or similar oil is good on these small engines - On the 26 I found th piston remained looking like new after a lot of running and the engines retained a nice loose feel with lots of compression As for amount of oil - do not skimp - you will kill it .
A 2025 to 1 ratio is good on racing bikes and I used 30 -1 on th Evolution 26's with no problems whatsoever -at recorded 10000 rpm rpms - almost all the time on he piped engines - the non piped we ran slower at 8000- Much less power !
For those who think less oil makes more power -the answer is NO.
also never lean the engines for maxpowre in level flight - that is too lean.
max power is for vertical glimbing - these carbs will NOT compensate for load -No internal power valve in the carb
The only compensation is the built in demand regulator and it is use in conjunction with the slight boost in fuel delivery provided by the tank pressure . It should make for smooth performance provided the engine is not over propped and or run lean.

When in doubt -always run a slightly smaller prop to breakiin and learn the engine
overpropping to slow the engines -just wrecks em.

The extra fuel seen with muffler pressure may not be from the HS circuit and hence why trimming the HS needle couldn't obtain the leaness obtained without muffler pressuring. It could mean that the LS needed leaned some when on muffler pressure. Keep in mind that electronic ignitions greatly aid idle and it could be that the idle was rich and not detected to be rich.


What we don't know from the observation is if no muffler pressure would have sustained adequate mixture with nose up.

Thanks to everyone for your expert insight. I’m not trying to drain every last RPM out of this engine but it did strike me as odd that I got so much extra RPMs w/o the pressure line. I bet the LS is still a little off, so I will take the time to do more experimenting with the LS and HS settings this weekend. I'll even try a larger diameter fuel pressure line to see it that helps.

Dave

Dave... Thank you for offering the videos. One of my issues with glow is the rpms needed to obtain good performance. I was greatly encouraged by HH reps offering that the power band was wide enough on this engine to run a prop that didn't have to scream to perform.

I thought the video of your use of a 13x6 was cool and the tach to me showed a pretty good number with the 13x6. It encouraged me that I might get away with a 14x4 funfly prop on a slow flying funfly plane and it not be a screaming meme... my nerves will greatly appreciate it.

Larry is right on...a Pawnee is hard to move or transport without wrecking them...you know how easy eggs break!!!! Larry, we are in Florida now...seems too warm...its above the 70 degree temp like in the house at home! Capt,n