crankpin

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Dle-35RA here, Pilot 26% Yak. Just mounted it, cutaway for head. Any thoughts here on cooling area. Open up more ? The 35 mounted OK on the firewall, this plane, thrust line on target. Only mod with the standoffs, on the bottom L & R out just a little from what the DLE30 mounted at on other plane.

Any comments appreciated, not an expert here.

Crank

irocbsa

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That's more than enough.

crankpin

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Thanks Iroc. Got little carried away with the dremel. I am sure that IROC means: Int'l. Race of Champions, (Camaro, Vette)? BSA, as in BSA motorcycles ?

Crank

irocbsa

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Happy to help. As far as my user name, I kinda hate it now but it's been my forum name for 15 years so I just stick with it. My first car was an 87 IROC-Z Camaro which of course was named after the competitive racing class you mentioned. BSA are my initials. Seemed like a good user name when I was 18, not so much anymore. Ha!

irocbsa

My Feedback: (12)

Double post.

pe reivers

Lots of holes. I hope your engine will survive this. Run it slobbering rich and you may get lucky.
I miss the air guiding system to force it to do cooling work.
I miss the air EXTRACTION system that creates a low pressure zone behind the engine, and pull the air through the air guiding system.

airraptor

My Feedback: (66)

I agree with Pe this will not cool the engine properly. the guys that say you need 2,3, even 4 times the inlet area are just clueless on how to cool an engine.

irocbsa

My Feedback: (12)

Fair enough, we all have our own opinion of what works. I have run plenty of planes with the exact same configuration as the OP and I have had zero overheating problems. Zero. IMHO, that head is hanging out there in the airstream and will get more than enough air passing over it.

crankpin

My Feedback: (15)

Thanks guys for the input. I put a DLE30 in the other 26% Yak, Bison Pitts muffler, had to cut a lot from the cowl. Looks like DL addressed this on the 35. The head fins are deeper, and a few mods internally. I also attached the pie plate on the other plane. Any issues with this, I am going to do the same here.
I am a beginner on gas, will step up, near future. Vents here, Valley View RC.
Crank

pe reivers

Invest in a temperature measuring device and use it. Only then you will know what works, and what does not.
Having zero issues is no way to describe a cooling issue.

irocbsa

My Feedback: (12)

That's pretty darn presumptive of you to imply that I'm not measuring temperature. But you're probably right, never having an engine overheat is no evidence of my engines not overheating. [&:]

pe reivers

you did not post temperatures, nor how they were obtained. I just went by the information provided.

MTK

What temperature are you measuring? Where exactly are you pointing you IR temp gauge? When are you doing that? On the ground (throttle setting?) or in the air with telemetry feedback (again, throttle setting)? Is the model pointed straight up, down or sideways? What exactly are you trying to achieve by knowing a specific temperature?

Why is it inadequate to have a full throttle,non-sagging, unlimited vertical up performance in hot weather? Or a set-up that keeps on ticking over hundreds and hundreds of flights?

I'm curious to know.....I want to learn something here...

pe reivers

On several occasions I posted my recorded temperatures of well baffled engines.
In short, I have two types.
Using Venom gauges topmost rib against cylinder wall, well shielded from cooling air:
Normal flight, engine well tuned, 155°C peak temperature. Towing duty 200°, test stand , no shrouding, 220°C

Using a thermocouple under the plug seat and data logging:
Normal flight 200°, towing duty 220°C, test stand 240°C

All temperatures corrected for 20°C ambient. measured temperatures follow ambient temperature differences almost exactly.

PS
I never measure after landing. It's useless.

zacharyR

My Feedback: (5)

ok stupid question wouldnt the scale cowl oil cooler thingy thats on the bottom rear of the cowl creat low pesure exhust air exit ?


I do see he cut the opening of the " oil cooler full scale " thingy so via Cuting the opening i guess he would get rid of any vacum affect that thing would have ...

i still voet go fly the airplane .. i am just guessing but your probably a crycle flyer

just don't hover the thing for a loing period of time .. your frist few flights ..

MTK

Yes....it is!

So in every case, full throttle setting of a well tuned engine, bench running an unshrouded engine results in higher temperature. What doesthe 20Chigher tempof the bench runs mean to the engine?

A shroud surrounding the cylinder's top, bottomand sides and with an opening to allow ram air in should work better. Should the shroud completelycover the side fins or can it simply lead the cooling air to the front?

It's understood that itwill only work properly if the hot air is efficiently removed.I install hooded exits on the hot air cutouts for looks and function. I have photos in the pattern forum

Is there a reason not to use afull throttle, vertical up line engine sag (or lack of same) as the gauge?

airraptor

My Feedback: (66)

You guys counter back saying it will cool ok yes I may cool it enough so it won’t sag or lock up but it is in no way cooled as good as it could/should.
I use telemetry for mine. If it’s over 260 I look to improve the cooling.
Think of air as a fluid (it is). This fluid will flow to the shortest path or least resistance. SO
A hole in the front of the cowl is good. A hole in front of the cylinder on the cowl isn’t good. The air will hit the cylinder and exit the cowl IN FRONT of the cylinder. You are only cooling 30-45% of the cylinder at best. The engine cylinder has different heat ranges on it and causes the cylinder to not be round and seal as well as it should you lose power. Now just because it doesn’t sag doesn’t mean it’s cooled enough to perform at its best. It’s just cooled enough to not seize.
MTK I respect a lot of your work but you should try a telemetry set up on your planes you might be surprised on how much heat your engine is staying at.
I have seen many gas engines run 300 degrees on a vertical up line and not sag but obviously overheating.
Now if you look at how air flows around a cylindrical cylinder you will see there is a dead zone behind the airflow all ready. This is why you need some form of ducting. This will help force the air around the cylinder. Now this still isn’t the best set up either for best power. On a round engine cylinder the air will hit the front of it and flow thru the fins and generally cover 75% of the cylinder. This will have the coolest parts of the cylinder from 15 degrees from center to 165 degrees on each side. The back side of the cylinder will be much hotter. As most know the metal expands as it heats up. The back part of the cylinder expands more that the sides and now the cylinder is slightly out of round. This will cause the piston ring to not seal as well as it should.
Now to fix this you need to cool the cylinder evenly. Ok now go look at glow two strokes and you will see the MFGs already know this and it shows in their designs. Look at the old ST 4500, New OS AX series, Nova Rossi and few others. They have more cooling fins on the rear section of the engine. The OS AX engine even tapered the front of the fins.
Ok back to gas engines. For side exhaust engines the highest temp you will record will be at the 45 degree intersection between the exhaust flange and the back of the cylinder in a front to rear airflow arrangement. Side mounted engines are the hardest to cool set up this way. So work with baffling to direct the air to flow the most around this area. Have a baffle coming from the front of the cowl and wrap toward the exit as best you can for both sides.

I could spend all day typing on here.. I will also add that I am no expert but I do understand fluid dynamic and heat transfer. Do some research and look at full scale engine cowls.

pe reivers

You forgot to mention the effectivenes of a simple turbulator entry in front of the engine, combined with a decent pressure difference fore/aft, which is what makes air flow.

3136

Crankpin, are you planning on placing any baffling inside the cowl?
I use pliable foam ca glued to the cowl so the air flows through the fins rather than swirling all around in the cowl.
Can you post a frontal pic as well?

airraptor

My Feedback: (66)

yes PE I was going to but I was on lunch. I probably didnt make sense anyway lol. Its hard to explain something to those that dont want to listen.

Jim Branaum

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Somebody please tell me what the heck a 'turbulator entry' is! I already do more baffling than most.

airraptor

My Feedback: (66)

a turbulator swirls the air. it will help the air to "stick" to the cylinder better and will slow it down some.

crankpin

My Feedback: (15)

3136. The pie plate, comes with the kits. The pictures here are from the first 26% Yak, with the DLE30. I cut out sections for air flow. Reading these posts, and some darn good information here, I may open it up a little more. I ordered some vents from Valley View RC, and may put them on the cowl sides, opening up the fake closed vents that are molded on the cowl. This may be a little overkill here, as I do not use these planes as helicopters.

The attached pictures are of the first Yak with the 30cc engine. The plate has been cut at sections, then siliconed in. I was looking to do the same with the 35cc Yak. With my zero experience of gas engines, in planes, I always look for best info I can find, from others experience, and success. The 35cc engine has rear exhaust. The pictures here of the 30cc, has the Bison Pitts muffler.

pe reivers

In the DLE30 cooling, just leave the bottom opening open. In that case it will work as a turbulator which normally should work well, if good hot air extraction is available.
The other two openings will only reduce the amount of cooling air going directly over the engine, yet use up hot air extraction capacity.

airraptor

My Feedback: (66)

+1 block the other two holes. For an example on one of my 3D planes with a DLE 55 the inlet for cooling air is 1 3/4" wide by 2" high. I have seen a max of 262° on a up line when it was 92°