Outboard Motors

[facthunter]

There's nothing new in trying to adapt other motors to aircraft but nothing beats designing one from scratch. Getting the drive from them is difficult "what is strong enough to mount it to? Same with mounting the engine. Where do you place the carburettor(s)? ALL import considerations. not easily dismissed if you're serious. Nev

[dreemhi]

Not an outboard but the Yamaha Phazer snowmobile engine has been used as a replacement for the 503 and 582 engines.  With performance similar or exceeding the 582 and slightly lighter weight this 4 stroke, fuel injected and liquid cooled engine sounds almost ideal.  On the down side, to get the power this under 500cc engine revs up to 11000 rpm, something I would worry about and I don't believe it is currently in production.  

This may be wishful thinking but I would like to see more ultralight aircraft, Challenger, Chinook, Quicksilver and the like, back in the air and fun flying again.  I think for that to happen there is a need for a replacement for the now defunct 40 - 70hp 2strokes, Yamaha, if they are so inclined may have the answer.

[skippydiesel]

5 hours ago, facthunter said:

There's nothing new in trying to adapt other motors to aircraft but nothing beats designing one from scratch. Getting the drive from them is difficult "what is strong enough to mount it to? Same with mounting the engine. Where do you place the carburettor(s)? ALL import considerations. not easily dismissed if you're serious. Nev

All true Nev - what attracted me (in a complete theoretical sense) is that the Yamaha engines I looked at appear to have  the ability to maintain sustained high rpm/power ,in just the right band to be geared down (eg Rotax) for an excellent prop speed and all in an already compact/light package.

 

Nothing is ever simple but I suspect carburation is not one of the issues, as the engines are fuel injected.

 

I agree with your principal - cant just turn an engine 90 degrees, mount it with what into an airframe, drive a g box capable of supporting a prop and probably other fasters that would need to be addressed /solved

[facthunter]

Powerplants are a challenge. So many come on the market with high hopes and fade away.. I've flown a few with high revving engines and  their "busyness" gets to you. Same with a high revving motorcycle.. Radials have the most character. They often seem to be just loafing along..Nev

[Old Koreelah]

16 hours ago, facthunter said:

... Radials have the most character. They often seem to be just loafing along..Nev

Nev I’m just watching a round engine being ground-run and at idle its popping every second or so. Any ideas?

[facthunter]

They don't do things like that normally so wouldn't be serviceable if they did. There are extra precautions to take when starting them. They idle smoothly usually but don't idle the big ones too slow as they have dynamic counterweights on the crank and you need oil to fling to the pistons.  Nev

[Old Koreelah]

Thanks Nev. Its a big old 9-cylinder unit on a 301. Uneven popping at idle, some pops while speeding up.

After some work behind the engine, they have it running better, fewer pops.

[facthunter]

air leaks gummy valve stems, broken valve springs. Has it sat for a while.? Nev

[Thruster88]

1 hour ago, Old Koreelah said:

Nev I’m just watching a round engine being ground-run and at idle its popping every second or so. Any ideas?

He has probably just leaned the mixture excessively to make it pop. The most lean cylinders would be miss firing.  

[onetrack]

I love the note of the Nakajima Sakae radial in the Zero, they sound like they mean business. I understand there's only one surviving operational Nakajima Sakae engine.

[facthunter]

The look well made including the prop.

 . Re leaning the radial, let it be known it is foolish as a backfire into the manifold, supercharger and carburetter can do a lot of damage to the motor.. There's quite a lot of combustible mixture in  there. You stop the motor on the mixture lever and it goes to idle cut off fairly quickly. You don't muck about with slowly stopping the fuel flow... Nev

[Old Koreelah]

3 hours ago, onetrack said:

I love the note of the Nakajima Sakae radial in the Zero, they sound like they mean business. I understand there's only one surviving operational Nakajima Sakae engine.

I’ve read that the Allies were quite impressed with the build quality of the Zero, or at least those made early in the war. Saburo Sakai was skilled at leaning his radial engine for economy and claims he once flew for over 12hrs.

 

https://en.wikipedia.org/wiki/Saburō_Sakai#/media/File:Saburo_Sakai_Zero.jpg

 

I have a part-built 75% replica in my shed, based on the one in Canberra. (Wikipedia claims it was Sakai’s plane, but John White, in charge of restoring it, never mentioned that to me.)

[facthunter]

You run them at low revs and high boost  in principle and at a height where the throttles are full open if you can. It's not smart to throttle back and then compress the charge in the supercharger. There's fuel flow figures for all output settings..  The power you need varies with weight. Your airframe has a most efficient angle of attack so you will be adjust power as you burn fuel off. If there's a headwind it pays to up your TAS to get best ground distance for fuel used. Nev

[Old Koreelah]

An early round engine:

https://youtu.be/0I-xLhLquMA?list=RDCMUCOC84qwgDHkUPwfeLKL40tQ

[facthunter]

Proper rotary. Nice flying too. Nev

[Russ]

Chap central coast Qld, has been running a mercury engine for yrs now in his gyro, goes like the clappers, has an exhaust note that catches your attention, last I heard he has never had issues.

gyros have been running soob engines ( several models ) for decades now, EA81 was the beginning, up to EJ25’s, all reliable……ALL heavy

Many FW flyers are running the 6cyl soob, there is a dedicated FB group of these guys

Edited September 11, 2021 by Russ
Added

[skippydiesel]

4 hours ago, Russ said:

Chap central coast Qld, has been running a mercury engine for yrs now in his gyro, goes like the clappers, has an exhaust note that catches your attention, last I heard he has never had issues.

gyros have been running soob engines ( several models ) for decades now, EA81 was the beginning, up to EJ25’s, all reliable……ALL heavy

Many FW flyers are running the 6cyl soob, there is a dedicated FB group of these guys

Well there you go - not such an outrageous idea after all. Thanks Russ.

[howe]

John Stevens from Redcliffe Brisbane, ran a outboard motor with belt reduction, pusher, on a amphibian 95.10 he designed, an incredible little A/C , doubt if there will be any footage of it. Cooling shouldn't be a problem. We raced a Peugeot 404 in a Hydroplane, water feed was 1/4 inch copper pipe scoop on one sponson and we had difficulty getting it to run hot enough. It was doing 80 MPH though.

[BrendAn]

The mercury inline 4 cylinder was designed to power motor gliders and later became an outboard. Thats why the tower of power and 4 cylinders were all jug blocks. So if an aircraft engine can morph into an outboard why not the other way around.  7 marine outboards have closed cooling system but have the advantage of water to exchange the heat .

Edited September 25, 2021 by BrendAn

[turboplanner]

https://www.pinterest.com.au/pin/363665738636752864/

 

[onetrack]

Nothing's impossible. How about a Volvo powered by a 300HP Evinrude V8? Of course, the idea came to these blokes when they were drunk.

 

https://www.whichcar.com.au/features/two-stroke-marine-v8-powered-volvo-amazon-video

[onetrack]

Interestingly, Honda see fit to utilise many automotive  components in their outboard engines. With their biggest outboard engine, a 250HP V6, the crankshaft, connecting rods, pistons, camshafts, and valvetrain are all "derived" from their automotive 3.5L Honda Odyssey engine.

But the block and heads are different castings for the outboard, because the engine operates vertically, and has to cope with salt water. So the heads and block get an anodic film coating and sacrificial anodes for corrosion control.

In addition, the rings are specially-designed marine rings that control the higher amounts of oil that end up in the cylinders of the vertical marine engine.

 

https://www.caranddriver.com/features/a33610119/the-engine-youre-driving-might-live-a-cooler-life-on-the-water/

[facthunter]

I doubt it would be exactly the same engine. Mountings are something that varies a lot depending on the application. With car engines often only two mountings are on the block and other(s) are on the gearbox. Mountings for aero engines are a bit critical. as is the front bearing (near the prop).It must have thrust loads catered for as well as prop out of balance etc. Nev

[BrendAn]

My honda bf90  uses a 1.6 lt civic engine.  But the head is marine only . Built in exhaust manifold and single cam 3 valve.

[BrendAn]

The seven marine outboard has a complete gm ls3 alloy block same as car model. It has freshwater cooling and sits horizontal .