pe reivers

In picture one, close the side louvers up front, so all very turbulent air hits the cylinder middle. You don't want any air to pass by the sides. The louvers are scale functional, so leave them in place and close them from the rear so they won't let air pass through them..
Adding functional louvers to the cowl sides (red markup) to extract cooling ait is a good idea.
Be sure to have the carb connected to a static port or static tube if you make setups like this.

3136

Thanks Pe

Marinep51

pe,

pe reivers

That is hogwash! More airflow (more air mass) means better cooling - period-. (air amount times temperature difference equals amount of heat carried away). The slow moving air myth stems from reducing internal cylinder flow air speeds at higher air density to reduce drag. The air speed is increased at the end of the duct again to provide extra plane thrust. Spitfires gained a few miles top speed by incorporating this.

General rule for cylinder temperature of 150° is to have 10 liters of air each second for each 1000 watts of engine power.
The 58cc engine pictured in this thread has about 5000 Watts power. Depending on weather and propeller and tune (richer or leaner) I get cylinder temperatures ranging between 150°C and 180°C peak during glider tow measured against cylinder wall topmost cooling fin. This means I do indeed get about 50 liters/second air flow per second (5000/1000x10 liters Or about 10 gallons per second)
I run a 23x10 wood JXF prop at about the same rpm that a zenoah 45 runs a 20x10 Menz-S prop. The zenoah has about the same cooling area, but has about half the power, so it needs only 5 gallons of air per second to stay running well. No special ducting needed there.

rexbirk

Old post I know but can someone tell me what department at Walmart or Home Depot I could find these louvers in?

Poffit

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Rexbirk
You need to walk into your local lumberyard and ask for soffit vents for a wood soffit and I think you will get what your after. They are made out of aluminum, measured around 5" by 12" and had 2 or 3 rows of louvers. The vents are not as common as they once were because most soffits and fascias are aluminum anymore. Hopefully you find what your looking for.

Pat

Lifer

My Feedback: (1)

Try Thunderbolt RC for these type of vents.

3136

Rex, just go to the hardware store, there will be a section where they have central heating duct covers and ventillation grates.
Even in my backwater part of Australia we have a good selection at the hardware shop, surely in America you guys must have them.
Also caravan/mobile home shops will have them too.

Lifer

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Here:

http://www.thunderboltrc.com/index.p...roducts_id=899

AlW

My Feedback: (17)

Valley View sells some very nice aluminum louvers - they have two different sizes.
Al

asaad_civic99

Hi,

I have 70 inch zlin 50 with a magnum 1.20 nitro engine installed on its side. The engine runs great without the cowl but when I install the cowl it has bad transition and always quits inflight. I think that my engine is overheating due to no air is flowing inside the cowl and through the head. I did some reasearch and found a lot of threads on baffles and I came accross this thread. Unfortuantely the sketches in the 1st post have broken links. I would appreciate any ideas backed up with some sketches on the best way to baffle a side mounted nitro engine. My cowl has a big cur underneath for the pitts muffler. Im planning on closing the front openning of the cowl that doe not have the engines head behind it.

1QwkSport2.5r

It's a pity the photos are gone now; the OP hosted them on his own site and he has since passed away. Pé was an incredible asset to our hobby that is now lost. Perhaps someone else on the forum saved some of those photos?

mmattockx

Some photos of your setup would help a lot in suggesting some improvements


Mark

aerobear

My Feedback: (4)

Here they are. All drawings and photos are from his old website.

1QwkSport2.5r

Thank heavens those are still available. Last I checked, MVVS.nl was down. Has the data from Pé's site been moved elsewhere on the net or did you have these saved away?

aerobear

My Feedback: (4)

I had them saved. I don't know of any website hosting his old info. Too bad he is gone.

1QwkSport2.5r

Amen to that. +1. Thanks for re-posting those photos. Perhaps if a moderator catches this, maybe there can be some of these photos added to the gasoline engines thread sticky?

asaad_civic99

Thanks. These pictures were helpful in letting me know what to do woth my setup. I will post before/after pics after I finish.

SWORDSN

My Feedback: (13)

Looks like the air dam is a big part of cooling.

speedracerntrixie

My Feedback: (29)

Yes, you have to get the air through the cooling fins. Air will always travel the path of least resistance, with an engine that is just sitting out in the open this usually means the air will slip around the cylinder and remove very little heat. The exit area is just as important as the intake, the air must be pulled through as it's much more efficient then trying to push air. Too many times it's thought that simply because an engine is receiving air that it is cooling correctly, usually not the case. We see guys asking how to keep their mufflers from coming loose. They are surprised when I state that it's usually a cooling issue that is making the muffler come loose. The answer is almost always the same " It's getting plenty of cooling" yet when a picture is posted it's just a cylinder head poking out of the cowl.

3136

Yep good idea, also make a downward angled plate at the front of that muffler opening, that will create a low pressure area that will suck air out of the cowl.
If you can block off as much as you can inside the cowl, so all the air goes through the head that will improve your result.

I was going to suggest an onboard temp sensor, but it looks like they are discontinued http://www3.towerhobbies.com/cgi-bin...0p?&I=TRAG4091

Most of the companies are going with on board telemitry, I'm not sure what radio you have, this could be an option.
Otherwise call around, I bought one just a few months ago, new in pack, a few shops should still have some.

Post some pics of your install, that will help.

Flyfast1

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To All:

I am currently designing a cooling system for a 1/4 scale supermarine spitfire that I am building, and have a question that I hope someone will answer. I am planning to use cross-flow cooling with a separator structure down the center of the two inline cylinder heads to force cool air through the cooling fins of the cylinder heads. The separator structure will be attached to the front of the firewall, but what do others do about the periphery of the separator structure. Does it just butt up against the cowl, or is it fit against the cowl with a rubber gasket or other material to provide a seal?

Here is an image showing the general idea:

Thanks,

-Ed B.

speedracerntrixie

My Feedback: (29)

Ed, what you have done here is very close to the same as what I do. The difference is that I separate the cowl into an upper chamber and lower chamber. Air comes in the upper chamber and in order for it to flow to the bottom of the cowl it has to pass through the cylinder fins. The key to it working is to create a low pressure area in the bottom chamber so the air is pulled through. On your spit you will want to create some ducting to the bottom of the cowl that will pull air from one side to the other. I don't completely seal the cowl chambers a fairly good fit is all that is required.

Flyfast1

My Feedback: (1)

Thanks,

-Ed B.

asaad_civic99

Here are some photos of the current setup: