Budget Ultralight

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Basil

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The 810cc Briggs is a fairly new engine and will exceed your budget but the 23hp Briggs as used in the Luciole seems to be widely available used so as long as you can convert it for aircraft use yourself it should be within your budget.
 

TiPi

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Aug 25, 2019
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Mackay (AUS)
the 810 Briggs is the best power/weight/cost ratio of all 25-35hp V-twins. It is only available as vertical engine.
The 2CV usually ends up at around 50kg.
The only other option is the small Briggs (38-series/627cm3). It is the base engine for the Luciole conversion and also for the Parazoom, Solo etc conversions. Most of them use performance parts to increase the rpm to 4,500-4,800 and add a reduction drive. With a bit of work the 38 will deliver 25-27hp at 3,600rpm.
 

Nichoxx

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Jul 6, 2020
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Hi guys, thank you for all your replies, busy looking around to see what I can find based on your suggestions. Just out of curiosity, has anyone used a motorcycle engine? They dont seem to weight to much more and give alot more power (would definitely need a reduction drive). Also need to find a propeller seller in the UK
 

Hot Wings

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Just out of curiosity, has anyone used a motorcycle engine?
Back in the early days of US ultralights cut down motorcycle 2 strokes were pretty common. 2 stroke Kart engines, like the Yamaha KT-100, are another option.
 

Bille Floyd

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Sep 26, 2019
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Back in the early days of US ultralights cut down motorcycle 2 strokes were pretty common.
...
The YZ250f 4-stroke, will put out around 42 Hp ; how much engine weight
would we be talking , after a grinder job to the transmission parts that aren't
needed ? I see that type dirt-bike; going for kinda cheap on craigslist, at times !

Bille
 

Victor Bravo

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The small 2-stroke motorcycle engines are not designed to survive at the "duty cycle" or power level that is used on aircraft. This lesson has been learned hundreds and hundreds of times over the last 50 years. I'm sorry, but you are walking down a road that many people have wanted to walk, and learned it is a lot more difficult and more expensive than they wanted it to be. A lot of engine experts here on HBA can provide the technical details and knowledge I don't have..
 

JamesF

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Mar 30, 2015
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Clovis, NM
Hi,
I suggest that you search for the discussion “The Ranger, an easily built high wing LSA runabout” started by a brilliant guy named Fritz. The title indicates an LSA plane but it could easily qualify as a ultralight in the US. It appears that it would fly well on 25 HP. It will give you some very good ideas on light weight construction that is also very strong. Also search the web for the Sky Pup ultralight. Great engineering and quite strong. If I can think of other examples I’ll send them along. You might need a re-drive to get enough power to fly well but you can certainly try direct drive. Good luck and be safe.
 

Bille Floyd

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Sep 26, 2019
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242
The small 2-stroke motorcycle engines are not designed to survive at the "duty cycle" or power level that is used on aircraft.
...
The YZ250f , 250 cc , is a 4-stroke ; and the kawasaki kx250f , is
also a 4 stroke with duel EFI for low and high rpm.

Was just wondering how much weight could be cut off the engine, if
the transmission had a grinder job done to it ?

Bille
 
Last edited:

Chilton

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Jun 28, 2014
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Jersey, channel islands
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.



Mathew, unfortunately due to stall speed issues (real speed checked in flight) neither the Turbulent or the Jodel D9 meet the SSDR rules, neither does the Chilton! This was a finding from CAA and LAA at the time of the weight increase on the category.
 

cluttonfred

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For an off-the-shelf design that will suit the UK SSDR regulations and do fine with a modest four-stroke engine, check out Don Stewart's Headwind. Listed stall speed at gross is 38 mph, which corresponds exactly to my calculations for 110 sq ft of NACA 2412 and 650 lb gross weight. Sea level rate of climb with just 35 hp is a respectable 850 fpm per the same performance spreadsheet, so it would be a perfect candidate for an industrial V-twin with an Ace redrive. I didn't find it on the LAA approved list or find any listed in G-INFO, but it's such a conventional and long-established design I can't imagine that approval would be problematic. And it has such a nice vintage look (Aeronca C-2 style!) that you'd be welcome at the antique fly-ins as well as the amateur-built ones!
8034424276_ee4ee880c0_c.jpg
 

Basil

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The aircraft in the UK SSDR catagory don't require any design approval. They simply have to meet the max weight and stall speed requirements (and nobody checks the stall speed if the wind loading and configuration seem plausible.
 

nestofdragons

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Jun 8, 2016
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Near Antwerp, Belgium
I see you willing to keep costs down and need for technology too. My advise would be: go for car-towed gliders. It does not have to be a HUMMER to pull the glider up. We used a old Renault to tow our Bi-Swift (two-seater). Theere are good plans on the internet of primary gliders. Mike Sandlin has very good and proven plans. Goat and Bug is a good glider of him.
Gliding is pure fun. OK, you need to be a team to have flying days. A pilot, somebody in the car, somebody maybe at the wingtip (might be that it is not needed on GOAT and BUG). The flying is more pure and you will have NO trouble with neighbours who complain about your noisy lawmower engine on your airplane. So ... go soar the sky in a glider and have fun at the lowest cost possible.
Disadvantage: you need a large field to take off due to the length of cable and the car needing to ride. If you have a abandoned road, you are very lucky.
 

Hephaestus

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Jun 25, 2014
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YMM
I see you willing to keep costs down and need for technology too. My advise would be: go for car-towed gliders. It does not have to be a HUMMER to pull the glider up. We used a old Renault to tow our Bi-Swift (two-seater). Theere are good plans on the internet of primary gliders. Mike Sandlin has very good and proven plans. Goat and Bug is a good glider of him.
Gliding is pure fun. OK, you need to be a team to have flying days. A pilot, somebody in the car, somebody maybe at the wingtip (might be that it is not needed on GOAT and BUG). The flying is more pure and you will have NO trouble with neighbours who complain about your noisy lawmower engine on your airplane. So ... go soar the sky in a glider and have fun at the lowest cost possible.
Disadvantage: you need a large field to take off due to the length of cable and the car needing to ride. If you have a abandoned road, you are very lucky.



Just saying that there are alternatives in this day and age. And we do have some pretty awesome remote control gear available too.
 
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