Anyone have any recommendations for a 15 hp engine under $1000?

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DavidBooks

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I have a very low budget to start building my plane. originally I was going to go with a structure made of metal tubing, but then I did the pricing on that and discovered that it was way out of my pay range. Now I'm going with something a whole lot cheaper and not nearly as strong, but it will (probably) get the job done. long story short, my structure is around 150 pounds lighter than my previous design, and now I only need around 15hp to get the thing off the ground. I'm on a shoestring budget, and I'm looking for the bare minimum at this point, so anyone have any recommendations for a 15-20 hp engine, or two 7.5-10 hp engines that aren't too costly? under $1000 dollars would be nice, but I could go up to $1500 possibly. Keep in mind that I don't even have that much money saved up, so the cheaper the better.
 

TiPi

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you should be able to find a used small V-twin in the 500-650cm3 range, they will do 15-20hp. Best bet would be a B&S 38-series, make the prop for a max rpm of 3,100-3,200 and you will have a reasonable thrust for what is most likely a draggy airframe.
 

Victor Bravo

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David you have access to a lot of people here who are highly experienced, and have the ability to offer about a million dollars worth of aviation and airplane design advice (honestly) at no cost. Please let us all know what type of material you are trying to work with, and how you are designing it. Listening to one idea or piece of advice here from guys with a lot of experience can save you hundreds or even thousands of dollars. This is money you might have wasted if the material will not do what you need it to do. There are several of us here who can help you know exactly where and how you can save money on using materials the right way, and where you have to use another material because it gives you more strength and safety for less money. 90% of us on here are very budget-conscious with our experimental planes... you're in the right place to learn how to save money and still have a plane that flies right!
 

DavidBooks

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Alrighty, well let me explain everything in more detail. So, by "shoestring budget" I mean that I have less than 600$ saved at the moment. Long story short: the only way I can obtain money for my project is crowd funding or doing odd jobs (which are few and far between becuase there aren't many people in my neighborhood). I figure that I should try to build a following or at least grab people's attention before I can really start any type of crowd funding endeavor. So, I'm gonna build a wooden ultralight (metal is too expensive) from a steel wheel barrow. The wheel barrow weighs 30 lbs, and I don't have a clue what the rest of the structure will weigh yet, and I don't have any type of experience with this kind of thing so I can't make any estimates either. The only thing that I have done so far are some basic initial sketches of what I think it should look like. From here I'm gonna find the power loading, then the wing loading, then the tail geometry and sizing. If anyone has any questions feel free to ask.
 

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TFF

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Wheelbarrow is an interesting conversion to flying machine. I would consider building this. Primary Glider Plans
The plans are cheap, it is successful flying, and a few have been converted to engines. I say first build it completely as a glider and before you cover it, decide how to finish it. It will take a lot of guesswork out of how to build something and at the same time creating some new questions.
 

DavidBooks

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I'll consider it, but (however idiotic it may be) I am quite married to the idea of creating and designing my own plane.
 

Protech Racing

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Cuyuna 215 , Rotax 277, Big single Honda clones, The 627 V twin, all could be well under 1500$. Use some sort of redrive on the first 3.
When you lack cash, you must be innovative. Stubborn helps but often will kill you.
 

TFF

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Designing your second plane when you have experience of what you liked and what you don’t from a design from the first is helpful. No one says you can’t build another. Yours is very similar already to this other one. It can fill in the blanks on what yours needs.
 

Stephen Asman

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To answer the original question, here is an engine that is over 15 HP and costs less than $1000:


It has been discussed some here but folks are leary of it because:

1. At 110 lbs it's a bit heavy
2. The 1" PTO shaft might not handle prop loads.
3. Harbor freight's reputation.

Personally, after looking into V-twins, I've decided to go with a 1/2 VW build.
 

TFF

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I think I would be more inclined to find a pair of used 150-200cc model plane engines a la CriCri. Converting a lawn engine is not easy without some fancy tools and is going to take more money and expertise to do the conversion. Low horsepower means the plane will need to be lighter than 254 maximum weight. If not I would be more inclined to spend the money on a 1/2VW. That would require being able to machine stuff yourself and not buy off the shelf stuff for that price. $1000 does not go far. $2000 is almost as hard. Hopefully once the airframe is finished a better cash flow situation will help finish it, and there is a long way to go to even get to the point of needing an engine.
 

Jsample40

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I have 3ea twin cylinder horizontally opposed KFM aircraft engines in good working order for sale. Complete with factory designed belt reduction, alternators, electric starters, ready to bolt on an ultra light/ home built aircraft. Entire engine package weighs approx. 50 lbs. I flew this model engine for 8 years & found them to be exceptional in design, performance, power to weight ratio. The 25 hp are $1000.00, and the 30 hp is $1500.00. First come, first served. Cash only. Spare parts available.
Jay W. Sample
 

jedi

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10 hp Tillitson (dynos at 9.5 hp) 212 cc can be upgraded to 225 cc or purchased complete to go to 17 hp at higher intermittent rpm. Stock 212 is $200 or $270 with electric start. 225 cc purchased complete is $750 IIRC.

My son is working with this engine. His design will use two of the lower power engines with the ability to upgrade if more power is required (or desired). The stock twin engine gives good thrust efficiency without a redrive. It also is suitable with a much less expensive prop. The high rpm upgrade is to much rpm for a direct drive and then requires a much more expensive prop as it is out of the large model aircraft sized prop.

Weight depends on how much stuff you add or remove, etc. so no numbers unless there is much more discussion. It comes down to a $/# equation so each application has it own unique solution if any.
 
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Vigilant1

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10 hp Tillitson (dynos at 9.5 hp) 212 cc can be upgraded to 225 cc or purchased complete to go to 17 hp at higher intermittent rpm. Stock 212 is $200 or $270 with electric start. 225 cc purchased complete is $750 IIRC.

My son is working with this engine. His design will use two of the lower power engines with the ability to upgrade if more power is required (or desired). The stock twin engine gives good thrust efficiency without a redrive. It also is suitable with a much less expensive prop. The high rpm upgrade is to much rpm for a direct drive and then requires a much more expensive prop as it is out of the large model aircraft sized prop.

Weight depends on how much stuff you add or remove, etc. so no numbers unless there is much more discussion. It comes down to a $/# equation so each application has it own unique solution if any.
Interesting. It looks like these weigh about 40 lbs each, though I'm not sure what is included in that. Surely not a prop hub.

Is your son trying to get under US Part 103 weight? Do you know of other folks using these direct drive?

IMO, a three-engine plane with these/similar engines would be a fun challenge (something like a micro version of Blane's Tri-Mower idea). $600-$800 for 30 HP isn't bad, 120 lbs is a lot but might be acceptable, and flight on 20 hp (one engine out) might be possible with enough span and attention to weight. The larger singles (Honda clones and B&S of 440cc+) might also be good from $/hp and lbs/hp perspective.
Multi-engine with singles: "Whole lotta shakin' goin on."
 
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REVAN

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Interesting. It looks like these weigh about 40 lbs each, though I'm not sure what is included in that. Surely not a prop hub.

Is your son trying to get under US Part 103 weight? Do you know of other folks using these direct drive?

IMO, a three-engine plane with these/similar engines would be a fun challenge (something like a micro version of Blane's Tri-Mower idea). $600-$800 for 30 HP isn't bad, 120 lbs is a lot but might be acceptable, and flight on 20 hp (one engine out) might be possible with enough span and attention to weight. The larger singles (Honda clones and B&S of 440cc+) might also be good from $/hp and lbs/hp perspective.
Multi-engine with singles: "Whole lotta shakin' goin on."
I am trying to be 103 compliant with my design.

My Tillotson 212cc test engine has the electric starter and the steel fuel tank on top. It is stock, with the only modification being a prop flange and propeller attached to the engine shaft. On the test stand, I've got about 40 hours on the engine so far. The test engine as it stands weighs in at 42 pounds with oil.

I'm intending to just use recoil start on my ultralight (at least in the beginning). Dropping the starter, steel fuel tank and oil from the engine's empty weight should get it down below 39 pounds. Then if I want to shed more weight, I'll replace the iron fly wheel with an aluminum one. That will cost about $100, and should bring the engine+propeller weight down into the 35 to 36 pound range. Cost for the engine with aluminum flywheel and propeller will be around $500 for about 10 Hp, or $50/Hp.

If it is too underpowered, one option is to upgrade to the 225cc engine. I figure I can prop it to de-rate the 17.5 Hp engine down to about 14 or 15 Hp and still direct drive the propeller. This will provide more margin on heat rejection than running it at 17 Hp. The downside is the 225cc engine is more expensive and drinks premium fuel instead of regular. I'll be looking at more like $1000 for engine+propeller, or about $70/Hp. So, for about double the installed cost and also more noise and more expensive fuel, I can get about 40% to 50% more power.

My first choice is to try to build a design that is efficient enough to be able to operate effectively with the 10 Hp engines. Hopefully, it will work.
 

Vigilant1

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I'm intending to just use recoil start on my ultralight (at least in the beginning). Dropping the starter, steel fuel tank and oil from the engine's empty weight should get it down below 39 pounds. Then if I want to shed more weight, I'll replace the iron fly wheel with an aluminum one. That will cost about $100, and should bring the engine+propeller weight down into the 35 to 36 pound range. Cost for the engine with aluminum flywheel and propeller will be around $500 for about 10 Hp, or $50/Hp.

If it is too underpowered, one option is to upgrade to the 225cc engine. I figure I can prop it to de-rate the 17.5 Hp engine down to about 14 or 15 Hp and still direct drive the propeller. This will provide more margin on heat rejection than running it at 17 Hp. The downside is the 225cc engine is more expensive and drinks premium fuel instead of regular. I'll be looking at more like $1000 for engine+propeller, or about $70/Hp. So, for about double the installed cost and also more noise and more expensive fuel, I can get about 40% to 50% more power.

My first choice is to try to build a design that is efficient enough to be able to operate effectively with the 10 Hp engines. Hopefully, it will work.
Thanks for the helpful info, sounds like a fun project.
The relationships between $, HP, and lbs definitely aren't linear, so it can be a challenge to find the best mix.

Just another mark on the wall: As you're likely aware, the 810cc twins cost about $1000 new, and require some internal work to allow them to run with a horizontal crankshaft and drive a prop. Weight after modifications is about 77 lbs with starter and a slightly lightened flywheel, and they make 26-30 HP in aircraft use (so, 2.6 to 3.0 lbs/hp). If it winds up at $2k total, that would be $67-$77 $/HP.
 

cluttonfred

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A brand new Radne Raket 120 ES-RD runs about $2,000 including redrive, electric start, and your choice of muffler or just $1,750 or so for the pull start version. That's about as cheap as it gets in terms of new, off-the-shelf solutions with a proven track record. That said, I am sure you could find a serviceable used paramotor package for that much, get it checked out for safety, and then just go flying (with the proper training).
 

REVAN

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My design will accommodate a single engine with minor airframe modifications. If the Tillotson project fails to be viable, I've been keeping an eye on the 35 Hp. Vaxell V-Twin engine. They haven't listed a price for this engine yet, but I'm hoping it will be somewhat competitive with my cost model of using the Tillotson engines. Several different paramotor engines will also be viable, but I'm hoping to find a good 4-stroke solution.

VX 40I (V-2 / 90°) - VAXELL
 
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