cheap engine and prop ideas

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kansaswildman

Active Member
Joined
Jun 25, 2009
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31
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Pawnee Rock, Ks
Im designing a ultralight aircraft on a budget so my engine choices are very limited i think i am going to use two five horse direct drive chainsaw engine (unless you have any better ideas) what size prop should i use.
I can upload a book on building ultralights, if you want.
 

proppastie

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Feb 19, 2012
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4,558
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NJ
Old snowmobiles had rotex 277, Might get one cheap with a snowmobile attached. Maybe 100 or 300.
You will have to know your way around engines though to make it work.
 

kansaswildman

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Jun 25, 2009
Messages
31
Location
Pawnee Rock, Ks
Here ya go:

Moderator note: The book, "How to Build Ultralights" has been deleted from this post. Please do not upload copyrighted materials without the permission of the author. The book is still available from the author's website,

I left the appendices as they are part of FAA Advisory Circular AC103-7, which is public information.
 

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PMD

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Apr 11, 2015
Messages
242
Location
Martensville SK
I used a Cuyuna 430 snowmobile engine in my Lohele Parasol, it was easy, and 40 HP.
I forget who manufactured it, but the gearbox that Cayuna sold with their engines was good for over 100 HP (I have used it at that power level). If you find one, I would consider it a diamond.
 

Urquiola

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Aug 23, 2013
Messages
96
Location
Madrid, Spain
Even if I don't fly, and I don't build, I've collecting info abut this. Perhaps you may find cheap 2-Stroke engines in eBay and other sites, but a 2-Stroke engine, also torsional vibrations and other issues, killed the BD-5 and some pilots.

2-Strokes go seized, or have the plug fouled much more easily than 4-Strokes,, there are not many engines in the 48 kW, 64 HP the Rotax 582 delivers, but in eBay, there is this: Mazda RX7 Wankel rotary engine custom SINGLE ROTOR mower boat motorcycle mazda rx-7 rx7 wankel rotary engine custom SINGLE ROTOR mower boat motorcycle | eBay it's a bit above the power of Rotax, needs the cooling parts (See 'How to cool your Wankel', by Paul Lamar), but Kevin Landers has a good reputation as Rotary engine tuner; the brand new engines from www.wankelsupertec,de may be more expensive, the www.Aixro.de and www.austroengine.at are also below the power of Rotax, but Rotaries are safer.
www.wankel-ag-de or www.rotronuav.com is another choice.
Please provide feedback, if you have time and will doing it. Blessings +
 

Dana

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Apr 3, 2007
Messages
9,251
Location
CT, USA
2-strokes have come a long way since the days of the BD-5 and early ultralights. Not only have the engines improved, but so has pilots' awareness of how to operate them. I haven't looked at the numbers, but I'd bet that the reliability of aircraft-designed 2-strokes (which essentially means Rotax) is probably better than any automotive conversion, with the possible exception of VWs.

Not that an auto conversion couldn't be just as reliable (or more); it's just that only the Rotaxes and VWs have the long history of working the bugs out.

But we're drifting far from the cheap engine for an ultralight that the OP was interested in.
 

simflyer

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Joined
Sep 24, 2015
Messages
185
Location
Moravia
... You could probably get, 250cc ish, is probably going to be bare minimum. With a drive. 350cc Range is better. 1/2 VW is probably the best home grown solution.
627ccm small block Briggs & Stratton 23HP Vanguard would work better for You, as is used in SD1 Minisport and also in MC30 Luciole. Direct prop is 116cm, but PSRU is good choice.
Interresting are some 2strokes as STRATOS 400 - STRATOS 400 - Prodotti
 
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b7gwap

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Joined
Sep 1, 2014
Messages
265
Location
UT
Hirth Engines has sort of taken over the small aviation two stroke market from Rotax. I don’t own one but many ultralight manufacturers install hirth engines as factory options. They all have gear reduction systems for the prop.
 
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