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Author Topic: Overheating and its consequences  (Read 1731 times)

Offline Matt Piatkowski

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Overheating and its consequences
« on: July 04, 2017, 01:58:14 PM »
Hello,
Today, I have made three patterns with my RToucan with EVO60 NX tuned for stunt
The engine's launch RPM are 10,380 with 13x4 MAS propeller. Fuel: raw Omega 10% nitro, no castor added. Lap time ~5.1-5.2 sec. on 61' 0.018" braided lines (eyelet to eyelet). The distance from the Brodak's handle to the C.G of the plane is 64'.

The ambient temperature was: 26 deg. C (79 deg.F.) during the first flight, 30 deg.C. (86 deg.F.) during second and 33 deg.C (91.4 deg. F.) during third.

The performance of the engine was getting progressively worse with the engine struggling more and more in the OH maneuvers and loosing power.
I could not finish the clover in the third flight as the lines were going seriously slack and I run around to save the plane.
The head was very hot ( 89 deg.C. (192 deg.F.) after third landing and there was no compression for a long time. The compression returned after 15 minutes when I put the plane in the shaded area.

The engine is completely exposed to the ram air (attached) and run beautifully yesterday ( four full pattern flights) when the ambient temperature was 22-23 deg.C (73.4 deg.F).

I suspect serious overheating.

Is there anything that can be done or I have to wait for cooler weather?

I can try running Omega 15% nitro or higher what is the common method to maintain the performance in warmer weather.

Anything else?

Please comment,
Thanks,
M

P.S: this engine must be run at high RPM (more than 10,000) with the low pitch prop otherwise the RPM in the air are erratic. It will not run consistently in the air with, say, 12x6 APC prop. at 8,500 2-4-2 launch RPM. I have tried it before. This is NOT the EVO 60 C/L engine - it is EVO60NX R/C engine with the exhaust timing ~155 deg. that has been tamed by me after two years or trying and erring to fly the pattern with RToucan.



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Offline Tim Wescott

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Re: Overheating and its consequences
« Reply #1 on: July 04, 2017, 02:35:07 PM »
Try some castor in your fuel, to carry away heat.  I recently saw Brett Buck suggest higher nitro + richer needle as a way of running cooler, but that was more in terms of keeping the performance the same at varying altitudes.  Dunno what else to suggest -- you certainly seem to have the engine sticking out in the airflow.
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Offline RandySmith

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Re: Overheating and its consequences
« Reply #2 on: July 04, 2017, 04:56:47 PM »
that prop may be a bit much, try a 12 1/2 x 4 prop, or  try a 13 x 5  prop, you will be able to run both richer... so less  heat
it sounds like you were running so lean it was sagging lean, this will cause massive heat.
also it will not hurt to add  2 ounces of castor in your fuel

Randy
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Offline Tim Wescott

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Re: Overheating and its consequences
« Reply #3 on: July 04, 2017, 05:14:40 PM »
Quote from: RandySmith on July 04, 2017, 04:56:47 PM
that prop may be a bit much, try a 12 1/2 x 4 prop, or  try a 13 x 5  prop, you will be able to run both richer... so less  heat
it sounds like you were running so lean it was sagging lean, this will cause massive heat.
also it will not hurt to add  2 ounces of castor in your fuel

Randy

Wait -- either a smaller diameter prop or same-diameter but more pitch?  The higher-pitch prop because he can run it significantly richer and slow it down?

I is confuséd.
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Offline Brett Buck

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Re: Overheating and its consequences
« Reply #4 on: July 04, 2017, 06:30:27 PM »
Quote from: Tim Wescott on July 04, 2017, 05:14:40 PM
The higher-pitch prop because he can run it significantly richer and slow it down?


   Exactly, a more efficient prop (slower) will reduce the shaft HP required and thus the heat generated.

The only issue is that this will also reduce the fuel draw. I guess we will see if it is overheating, or not able to draw fuel when the air thins out, because it will make that worse. It's right on the edge of something, if it works in the morning but not in the afternoon. Can't tell the difference from the explanation.

       Brett
     
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Offline RandySmith

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Re: Overheating and its consequences
« Reply #5 on: July 04, 2017, 07:42:21 PM »
Quote from: Tim Wescott on July 04, 2017, 05:14:40 PM
Wait -- either a smaller diameter prop or same-diameter but more pitch?  The higher-pitch prop because he can run it significantly richer and slow it down?

I is confuséd.

Yes the smaller diameter will rev higher, go faster, so he can richen the mixture, same most times with the higher pitch, he will be able to richen the mixture, both will result in lower temps.
I could not tell for sure from his post, but I would guess  he is just having to run the engine Too lean,  that will cause massive heat
It would help to have more info from him on this, plus any feedback from using different props

Randy
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Offline Matt Piatkowski

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Re: Overheating and its consequences
« Reply #6 on: July 05, 2017, 11:53:30 AM »
Breaking News...Literally.
The muffler disintegrated in the air in the morning after ~20 seconds flight. The reason: fatigue crack generated by vibrations.
Please see the attached.

Randy,
I was using 13x5 Zinger prop. Launch ~9,200 RPM was a bit wet 2 cycle. I have added some castor to Omega 10% nitro.
I managed to finish the wingover (the plane was a bit sluggish compared to 10,380 RPM on 13x4 MAS) when the muffler fell off.

Finished the pattern with seriously roaring engine in full 2 cycle but the OH maneuvers were excellent with good lines tension. Did not measure the lap times but it was too fast...4.8-4.9 seconds/lap I believe. No overheating though in 80 deg F. ambient temperature.

"Learning never stops and when it stops this means you are dead"

Regards,
Matt
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Offline Tim Wescott

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Re: Overheating and its consequences
« Reply #7 on: July 05, 2017, 12:01:03 PM »
Too fast will mask all sorts of line tension issues, so you have to put that aside.

I take it that the muffler fell apart on the same flight that you first changed the prop and the fuel?  So there's no way to tell if the new fuel and/or prop cured the overheating.
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Offline RandySmith

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Re: Overheating and its consequences
« Reply #8 on: July 05, 2017, 03:12:29 PM »
Quote from: Matt Piatkowski on July 05, 2017, 11:53:30 AM
Breaking News...Literally.
The muffler disintegrated in the air in the morning after ~20 seconds flight. The reason: fatigue crack generated by vibrations.
Please see the attached.

Randy,
I was using 13x5 Zinger prop. Launch ~9,200 RPM was a bit wet 2 cycle. I have added some castor to Omega 10% nitro.
I managed to finish the wingover (the plane was a bit sluggish compared to 10,380 RPM on 13x4 MAS) when the muffler fell off.

Finished the pattern with seriously roaring engine in full 2 cycle but the OH maneuvers were excellent with good lines tension. Did not measure the lap times but it was too fast...4.8-4.9 seconds/lap I believe. No overheating though in 80 deg F. ambient temperature.

"Learning never stops and when it stops this means you are dead"

Regards,
Matt


Matt

Let us know when you get more flights,  the motor must have gained  Rs in flight  because  a 13x5  at 9500  RPMs  yeilds a 5.1 to 5.2 lap time here??  but at least your moving in the right direction, and  maybe a little richer launch.
Try a couple of different setups and the  2  props  i suggested, I think you will be there  soon

Randy
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Offline Steve Helmick

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Re: Overheating and its consequences
« Reply #9 on: July 05, 2017, 08:36:22 PM »
I see a pressure tap on the remains of the muffler, but can't see a hose going to the muffler in the first picture of the engine installation. However, if it did have muffler pressure, as the muffler fracture got bigger, the engine leaned out. As much as I like muffler pressure on some engines, you've GOT to make sure stuff isn't going to come loose or otherwise fail, causing a reduction in muffler pressure. Engine goes lean and the engine won't survive too much of that mistreatment.

Matt, you'd help us a lot if you'd just post jpegs instead of all these pdf files. We could more easily refer to multiple pictures, etc.

Another thing...have you been using a pitch gauge, or are you going off the nominal pitches of the props you use? The MA props are VERY much below nominal, while the APC's at least act like they're a bit higher than the label. Different animals, for sure.

I'd like to see you get a pitch gauge, and would like to see you stick to either APC or XOAR for awhile, because they're consistent and most seem to work pretty good for stunt, if you're anywhere close to correct in size and pitch. Not everybody is ready for CF props; that's just the way it is. If you don't get a pitch gauge and use it, CF props generally won't work very well. Price of doing business, I guess. Get one or make one. Howard appears to check his prop pitch with his cell phone...I haven't really paid much attention to that, because I'm sure my flip-phone wouldn't do it. But it does fit in my pocket better, and it makes calls just as well.  ;) Steve
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Offline Matt Piatkowski

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Re: Overheating and its consequences
« Reply #10 on: July 06, 2017, 03:30:14 PM »
The problems with Evo60NX have been solved.
Completely.
Due to sudden loss of power in the horizontal eight, the plane hit the circle almost vertically and disintegrated.

The engine survived in one piece but must be carefully checked by somebody who wants to use it.

I do not.

My next attempt to use ICE will be Ro-Jett76 in Tiger Shark. Project completion: April 2018.

Thank you,
Matt

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