How to cool an outboard motor without using water?

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Mario
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How to cool an outboard motor without using water?

Post by Mario » Wed Aug 18, 2010 9:24 pm

I am wanting to build a personal ultralight helicopter. First issue here is to find a suitable engine. Outboard motors have the 40+ horsepower I need and can be found pretty cheaply on places like craigslist.

One thing I know about these engines is that they use a water pump to suck up water and cool the engine. It is important that this water is present and can the engine can be wrecked if it is run without water for more than a minute or two.

Short of including a water tank on this helicopter, do any of you have any practical solutions to keep an engine like this cool?

(Just so you know, an "ultralight" helicopter must weigh under 249 pounds without the passenger. In the US, you can fly ultralights without a pilots' license. 40hp outboard motors weigh around 160lbs so I don't have a lot of room for heavy water.)
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Re: How to cool an outboard motor without using water?

Post by Metallica Man X » Wed Aug 18, 2010 9:40 pm

Not an easy call...You could use either a very large (and very un-aerodynamic) heat sink, or you could pump something different..

let's see...a quick google search around and I found this:

http://www.evanscooling.com/assets/Uplo ... talog2.pdf" onclick="window.open(this.href);return false;

Says the stuff is more efficient than water for cooling--which means you will need less to keep that engine cool, reducing weight hopefully lol.

Otherwise, best I can think is using a non boat engine.
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Re: How to cool an outboard motor without using water?

Post by Triton » Thu Aug 19, 2010 8:53 am

your best bet for an ultralight motor would probably be to try and find a used aviation engine like a rotax or similar. outboard engines are powerful and light but a watercooled engine on an ultralight wouldnt be very good, too much additional weight for radiators and coolant etc.
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Re: How to cool an outboard motor without using water?

Post by Steamdnt » Thu Aug 19, 2010 8:43 pm

I really hope you have Plans for this, You can't build a helicopter freehand (without plans). You are going to need to do do tons of research and either find or create your plans.
That said, I have seen a good couple ultralite airplanes made with 650 Katana engines. But, I have also seen a person crash and have part of their femur sticking through their skin.
If you want to fly around it would probably be best to make a plane rather than a helicopter, A plane has a LITTLE more room for error than a helicopter.
Also, don't build this with an outboard, you WILL kill yourself.
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Re: How to cool an outboard motor without using water?

Post by Triton » Thu Aug 19, 2010 11:56 pm

personally i would go with an autogyro. you have some of the manuverability of a helicopter and shorter takeoffs than a plane, and there are plans available for ultralight autogyros i am pretty sure
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Re: How to cool an outboard motor without using water?

Post by Metallica Man X » Fri Aug 20, 2010 12:49 am

Yeah, an autogyro! that's the way to go! I think I have an old issue of Popular Mechanics (circa 1960's) that has a plan for an autogyro! I'll see if I can dig that up...
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Re: How to cool an outboard motor without using water?

Post by Bino Gas » Fri Aug 20, 2010 7:08 am

I would love to see those plans!
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Re: How to cool an outboard motor without using water?

Post by bentendo64 » Sun Aug 22, 2010 5:48 pm

You could get an old air-cooled outboard, I have one, and all I am supposed to do is add a bit richer mix of oil to the gas.
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Re: How to cool an outboard motor without using water?

Post by Steamdnt » Sun Aug 22, 2010 9:10 pm

Regardless, you need high torque and low revs for an aircraft, Not High revs and low torque,
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Re: How to cool an outboard motor without using water?

Post by Triton » Mon Aug 23, 2010 8:34 am

Steamdnt wrote:Regardless, you need high torque and low revs for an aircraft, Not High revs and low torque,
if the old OMC (johnson/evinrude etc) outboards were lighter and air cooled they would make great aircraft engines. the 70hp evinrude has enough torque to propel a 16 foot aluminum boat with 6 people in it like 35mph easily, while pulling somebody on skis. they are great motors, just not suitable for an ultralight
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Re: How to cool an outboard motor without using water?

Post by Mario » Mon Aug 23, 2010 6:21 pm

Yeah, I've decided on a different engine. (Not sure exactly what kind yet, but probably a motorcycle engine.)

I figured it was cheap, so maybe it could work. :roll:
All my life I've been trying to save money on projects, etc, but I realize this is NOT something I should try to be cheap on. I am putting my life in this engine, and if it seizes up because of a cooling problem, I probably won't make it out alive, depending on how high I'm flying.

I would do a plane or autogyro but there is absolutely no place to take off or land for that kind of thing where I live. It's all roads. :? It'll have to be a helicopter.
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Re: How to cool an outboard motor without using water?

Post by mako321 » Mon Aug 23, 2010 6:41 pm

Maybe you should sell one of your portable n64s for money :S

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Re: How to cool an outboard motor without using water?

Post by Snow_Cat » Mon Aug 23, 2010 10:09 pm

mako321 wrote:Maybe you should sell one of your portable n64s for money :S
I didn't know that you could sell things for anything other than money. :o

Also, engines aside, what do you plan on using ducts or open props for thrust?

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Re: How to cool an outboard motor without using water?

Post by Triton » Tue Aug 24, 2010 9:50 am

Mario wrote:Yeah, I've decided on a different engine. (Not sure exactly what kind yet, but probably a motorcycle engine.)

I figured it was cheap, so maybe it could work. :roll:
All my life I've been trying to save money on projects, etc, but I realize this is NOT something I should try to be cheap on. I am putting my life in this engine, and if it seizes up because of a cooling problem, I probably won't make it out alive, depending on how high I'm flying.

I would do a plane or autogyro but there is absolutely no place to take off or land for that kind of thing where I live. It's all roads. :? It'll have to be a helicopter.
you live in california and you dont have any kind of airfield anywhere nearby? i live in the middle of NOWHERE and we still have a small airport lol.
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Re: How to cool an outboard motor without using water?

Post by weaponepsilon » Thu Aug 26, 2010 9:18 pm

Perhaps I am retarded, but can you just use a radiator and connect it to the water pump intake, and recycle from the exhaust, while the air flow would cool the water.
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