Using store bought engine(s)

[ultra]

Would it be possible to use one of these engine to fly an XL or maybe two of them? 

https://www.princessauto.com/en/detail/420cc-ohv-gas-engine-with-electric-start/A-p8628265e

[Tom XL-7]

I understand the desire for an off the shelf solution. These engines are made in large quantities and are priced accordingly.
However one  of these would not do it. Two is a bit of a stretch and how in the world would you mount two. Sounds like some serious engineering and weight gain.
There has been some success with the larger V-twin engines. Often found on generators. They start around 22HP and go up. One is commercially available, ready to go, with prop and reduction.
look up culver props big twin engine.
It may represent a bargain with all the work done, but it is not cheap.
Tom XL-7

[ultra]

I understand the desire for an off the shelf solution. These engines are made in large quantities and are priced accordingly.
However one  of these would not do it. Two is a bit of a stretch and how in the world would you mount two. Sounds like some serious engineering and weight gain.
There has been some success with the larger V-twin engines. Often found on generators. They start around 22HP and go up. One is commercially available, ready to go, with prop and reduction.
look up culver props big twin engine.
It may represent a bargain with all the work done, but it is not cheap.
Tom XL-7

Would something like this work? http://www.northerntool.com/shop/tools/product_200514299_200514299

I don't want to spend $5,000 canadian on a hummel engine and it looks like this guy used that engine with a reduction drive for his aircraft https://www.youtube.com/watch?v=WNeLtU9sGCU

40HP at 5500 rpm doesn't sound too bad for $2000.

[Dan_]

Once you get your plane built, and it comes time to fly it for the first time, you will regret not having spent what ever it costs to get a proven, reliable engine.

It is always better to be on the ground wishing you were in the air, rather than being in the air wishing you were safe on the ground.

Get a 3VW radial for it and never look back. 

 

[stevejahr]

Would something like this work? http://www.northerntool.com/shop/tools/product_200514299_200514299

I don't want to spend $5,000 canadian on a hummel engine and it looks like this guy used that engine with a reduction drive for his aircraft

40HP at 5500 rpm doesn't sound too bad for $2000.

Hmm.  First thing is 108 lbs shipping weight suggests this engine is on the heavy side for a UL type airplane.  Next where are you getting 5500 RPM when the specified maximum is 3600?  It is unfortunate that power output is specified in HP here and torque there, thus making comparisons difficult.

Unless you want to spend the time to experiment and develop (with potential extra money for parts that break or do not work), then you best spend the money to get something where it is all done.  The hard facts are that aircraft DO have some rather special requirements and so require a bit more or different tradeoffs than a basic power engine.  Lowest possible weight is just one example.  Ability to run wide open for hours at a time is another.  Then there are vibration and torsional working loads to deal with.

I have wondered at the Culver Big Twin though... they have spent some time developing that one and working kinks out.  Still seems a bit heavy though.

[Tom XL-7]

Steve, you are right on the big twin weight. At 120 pounds they are close to the 4A-084 engine. Maybe 125 pounds. 4 cyl smooth and balanced and can often be had inexpensively.

 Culver put the big twin on an aluminum framed ultralight. Other than that I see them powering parachutes like the one in the video. not a lot of weight in a parachute.

Tom XL-7

[Dan_]

Gene and Larry Smith, (who own Culver props) tested their V twin and re-drive on a dune buggy and air-boat before flying behind it on the Legal Eagle they bought from the 1/3 Corvair engine designer Fletcher Burns.  


It was legal weight with Honcho wings, Culver Big Twin, and parachute.

They sold the LE after their testing.  


They sell the re-drive for the 1/2 but you have to have electric start.   Larry Smith had a trip to the hospital (broken thumb) hand propping the 1/2 VW with the re-drive on it...

[canterbury]

Just my two cents. If you are wanting to not use the VW engine, I would go with a Rotax or a Hirth. Anything else will require some major engineering.