Budget Ultralight

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Nichoxx

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Jul 6, 2020
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Hi,
As the title says, me and a group of friends are looking for advice on how we could power a small ultralight 1 seater aircraft we plan on building. This plane would not be going from airport to airport and never taken more than 500ft up, it is simply for field hopping. Unfortunately we are based in the UK so both our choice of parts is limited and we only have a budget of around £800 (for the engine). We have looked at small horizontal engines up to 25Hp as it seems the only way to obtain a reasonable amount of power cheaply (how we would go about attaching a propeller will likely be improvised) however if anyone knows of any cheaper solutions or would like to offer us any advice on completely from scratch builds - then it is incredibly welcome.
 

BBerson

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You might find a used 25hp lawnmower. Remove the engine and convert it to horizontal shaft.
 

Topaz

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Have you considered no motor at all? If you have any terrain around you - hills, a coastline with cliffs or other vertical features - and any kind of a steady breeze, you could stay up for possibly hours with no engine, and save a considerable amount of money and effort on your build. Another alternative is to tow a glider aloft using a car. If you can find thermals after launch, you can also stay up for as long as your skill and luck provide.

This ultralight, and the others flying with it, are all motorless gliders. Something to think about.

 

Nichoxx

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Have you considered no motor at all? If you have any terrain around you - hills, a coastline with cliffs or other vertical features - and any kind of a steady breeze, you could stay up for possibly hours with no engine, and save a considerable amount of money and effort on your build. Another alternative is to tow a glider aloft using a car. If you can find thermals after launch, you can also stay up for as long as your skill and luck provide.

This ultralight, and the others flying with it, are all motorless gliders. Something to think about.

I'm afraid the land around us is all flat pretty much
 

Nichoxx

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You might find a used 25hp lawnmower. Remove the engine and convert it to horizontal shaft.
Would a horizontal lawnmower engine work? Or would we need to create a reduction gear? Just wondering if the force of the propeller pulling would damage a generic engine
 

BBerson

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Would a horizontal lawnmower engine work? Or would we need to create a reduction gear? Just wondering if the force of the propeller pulling would damage a generic engine
Direct drive. Lots of folks are converting the vertical shaft Briggs and Stratton 810 to horizontal. Search for SD-1 discussion here or elsewhere.
 

bmcj

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If you are only doing short hops, electric might be an option for you. One of the current shortcomings of electric is that they don’t have much range/duration, but it doesn’t sound like range or duration is a requirement for you. Of course, I have no idea what an electric setup costs.
 

Victor Bravo

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I believe there are several lawnmower engines that have been used on the SD-1 and Luciole aircraft that started out as horizontal engines. On a low-drag airplane you can run them direct drive, on a high drag airplaneyou're go ing to want a reduction of some sort.
 

cluttonfred

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Keep in mind that the OP is discussing a UK single-seat deregulated type (SSDR) so a maximum takeoff weight of 300 kg/661 lb and a stall speed under 35 kt/40 mph/65 kph, so a very different beast than a Part 103 ultralight. I would suggest a basic design capable of meeting the SSDR specs with a modest VW but repowered with an industrial engine and an Ace redrive. The MiniMax V comes to mind, and because there is an allowance up to 390 kg for amateur-built aircraft permitted before 2003 you might also look for an derelict Luton Minor, Druine Turbulent, or Jodel Bébé to restore as an SSDR type.



 
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Aerowerx

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Have you looked into the availability of used BMW motorcycle engines? IIRC they are popular in Europe for homebuilt aircraft.
 

Bille Floyd

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Sep 26, 2019
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...
This plane would not be going from airport to airport and never taken more than 500ft up, it is simply for field hopping.
...
300 to 500ft is about the minimum you need , for a reserve parachute
to work , with decent odds for opening ; in other words , (1000ft is Safer) !

I'm afraid the land around us is all flat pretty much
For your budget the open sailplane , suggested by, "Topaz", would be
your best option , because ya don't need hills or mountains to catch
a thermal ; just 500 feet up from a rope attached to a car would
do the trick. You can put a pusher engine on it later , (like a Paraglider uses)
when ya get more money. Flat land, usually means More Landing options
which is a Good thing. The Goat glider is open source ; just go find the plans.

Bille
 

Victor Bravo

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Lawnmower engines are vertical crankshaft. They are converted to horizontal.
Oops, I meant industrial V-twin engines that have the horizontal shaft. That may be pressure washers, generators, etc.

I had been under the impression that the majority of power output levels, brands and build quality levels were available in both H and V configurations. Is that not the case?
 

akwrencher

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No personal experience, but from following the threads, it is my impression that the 810 vertical is converted to horizontal for a reason, power to weight and perhaps cost play into it. Maybe other reasons I can't remember at the moment.
 

pictsidhe

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I'd suggest sticking to direct drive. The Briggs 810 converted to horizontal is a budget option. Another option for Europeans are the Citroen 2CV and sibling engines. There are 800cc barrel kits available. If flying on low power, don't skimp on the span or climb will suck. Have a look at some of the 20s low power designs. A trip to Shuttleworth would be good research
 

galapoola

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That's a slick looking powered glider. If I recall, the goats are mono wheel, is that your design?
 

BBerson

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I had been under the impression that the majority of power output levels, brands and build quality levels were available in both H and V configurations. Is that not the case?
Yes, most can be ordered in either version. There is various reasons for choosing one or the other.
 
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