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Down Draft Cooling


niceez

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Fellow builders:

 

 

 

DD cooling is a subject that interest me also. When I first considereded it I felt as others do that it would be just naturally better. After several years of watching developments I have come the following conclusions:

 

1. DD cooling is better for the basic cooling job of cooling the cylinders.

 

2. DD cooling ends up being much more complex because the NACA scoop is still required to cool the oil cooler and provide air for the CARB or fuel injection. So you end up with two systems to provide air for instead of one.

 

3. The promise of less cooling drag is still only a theory and has not be proven. Logically the fact that a NACA scope under the airplane,even if it is smaller, and NACA scopes on top of the airplane increase the odds that cooling drag will not be reduced.

 

4. DD cooling causes overheating during extended taxi and during ground operation that has never been a problem with updraft cooling.

 

5. DD cooling causes the oil sump and carb. area to be heated if extensive baffling is not used below the engine to get the hor air out. This brings the question, is the baffling really simipler and easier?

 

6. DD cooling will probably cause the exahust pipe to run hotter. This will shoten their life. How much?

 

5. It appears that what we really need is a engine designed for updraft cooling. Intake on the bottom and exhaust on the top.

 

I feel that the jury is still out on DD cooling. Any opnions that don't agree with mine are very welcome. I am still trying to take my own decsion on down draft cooling versus updraft cooling.

 

Excuse any misspelled words please. No spell checker!

Jack Wilhelmson

www.EZnoselift.com

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Jack and All,

 

While I don't want to constantly try and defend DD cooling, I think many of you might want do a little more research. :rolleyes: Our own Terry Schubert's system is very good and he uses his right top inlet for cooling air to the oil cooler.

 

At this point I feel if I make a duplicatable system, I should be able to market it with a big price tag since many folks seem to think it so hard to accomplish.

 

IMO, one must just not consider cooling drag. If it were the same as updraft and the dd system allowed for less parasite drag you would be getting more speed from the plane and actually if you wanted to fly the same speed and reduce the power and perhaps save extra wear and tear on the engine and be consuming less fuel one might want to consider the savings that way.

 

This will be my last post here for sometime as it appears those who have the system are not eager to share and I can better use the time building the DD cooling system then debating it.....:confused:

 

DD most likely isn't for everyone but then again neither is flying.

 

Cheers, :)

--

Dale Martin, 509-780-7320

LEZ

Lewiston, ID

EAA Technical Counselor

Owl Eagle Aerial Composites

=====================>

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I haven't seen much discussion of my own main objection to DD cooling which is the exhaust (and oil pan, etc.) preheating the cooling air. Maintenance access is clearly better, and baffling is much simplified. There are any number of ways to address oil cooling that don't involve the NACA duct. Bottom line: I'm impressed by what I see and I want to try it.

 

But I'm repeating myself. I guess it's all been said .... Jim S.

...Destiny's Plaything...

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  • 3 weeks later...

I think I have found a great place for ther oil cooler however, it will require the top of the baffling to be of the "dog house" style. This is the kind where the entire engine is covered with a material. I plan to use aluminum.

 

The place will be centered on top of the case with the oil vanes of the cooler perpendicular to the aircraft C/L. A rectangular hole will be made on the dog-house just aft of the engine mount ears (like that makes sense) and the cooler mounted to the doghouse. Air will flow from the inlets up to the cut-out, throught the cooler and out the back of the cowl. No holes in the top cowl to slow us down!

 

The goal wih this design is to allow anyone with any kind of fire layout to adapt his to there EZ without challenges. ( I can also move my oil cooler from its spot on the firewall which will allow for greater access to other accessory case equipment). This position will also allow cooling when the aircraft is shut down and the majority of oil to drain from the oil cooler when parted nose down.

 

More later,

 

Dale:D

--

Dale Martin, 509-780-7320

LEZ

Lewiston, ID

EAA Technical Counselor

Owl Eagle Aerial Composites

=====================>

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  • 6 years later...

I am building an AeroCanard with a IO-360 and I am using the Velocity plenum and two Naca type ducts on top to feed it. I didn't have room to make a real Naca so mine are shorter and steeper 12degree floor. I opened up the front to 3 " to try to get more air. We'll see how it all works. Sorry I have picts but can't seem to attach them.

Long Ez, AeroCanard

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well this flying thing is just a lot of fun for me and I just love the old P-51 look and my engine temps are AOK here in the Havasu heat with updraft cooling, and as for speed it goes a lot faster than my ultralight weight shift which is liquid cooled,so chill out guy's:) :)

Rebel Wallace

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