I've been mulling trying to use motorcycle engines for a while now but
have had dreadful luck at finding anything at all interesting on the
internet about the topic. I've found a few obtuse references to
snowmobile and water-craft engines but no solid leads. What should I
look at? I plan to implement a redrive, and I'm not sure what other
modification concerns I need to watch out for.

Price is the primary concern, followed by the ability to use mogas,
weight and fuel efficiency concerns.

I seem to remember there being one or two very popular forums online
for homebuilts, can someone jog my memory where I should be going?

rektide wrote:
> I've been mulling trying to use motorcycle engines for a while now but
> have had dreadful luck at finding anything at all interesting on the
> internet about the topic. I've found a few obtuse references to
> snowmobile and water-craft engines but no solid leads. What should I
> look at? I plan to implement a redrive, and I'm not sure what other
> modification concerns I need to watch out for.
>
> Price is the primary concern, followed by the ability to use mogas,
> weight and fuel efficiency concerns.
>
> I seem to remember there being one or two very popular forums online
> for homebuilts, can someone jog my memory where I should be going?

It would be helpful to know what size plane you are going to use this
engine on.

Tony

Let's see...

Try nine Kawasaki Ninja 4 Cyl blocks arranged around a custom radial crank,
rods and crankcase. Use a 4:1 reduction planetary gearset in the nosecase.

You'd get a screaming 36 cylinder, liquid cooled engine about 30" in
diameter producing roughly 1000 HP.

Oh, you probably didn't want that much power - try 7 Ninja blocks for only
28 cylinders.


"rektide" > wrote in message
...
> I've been mulling trying to use motorcycle engines for a while now but
> have had dreadful luck at finding anything at all interesting on the
> internet about the topic. I've found a few obtuse references to
> snowmobile and water-craft engines but no solid leads. What should I
> look at? I plan to implement a redrive, and I'm not sure what other
> modification concerns I need to watch out for.
>
> Price is the primary concern, followed by the ability to use mogas,
> weight and fuel efficiency concerns.
>
> I seem to remember there being one or two very popular forums online
> for homebuilts, can someone jog my memory where I should be going?

I'm looking at making a powered sailplane with a ducted fan and would
need at minimum 75HP. I'd much prefer something closer to 120HP, but
I dont know what size and weight tradeoffs that would entail.

On Aug 23, 1:00*pm, rektide > wrote:
> I'm looking at making a powered sailplane with a ducted fan and would
> need at minimum 75HP. *I'd much prefer something closer to 120HP, but
> I dont know what size and weight tradeoffs that would entail.

There is a Yahoo Group for using motorcycle engines in airplanes but
for the most part UL engines in the 40 HP + or - range are discussed.
The HD engine has been used but one person who used a newer engine in
a 701 pulled it and replaced it with a VW due to the vibration issues.
I think your best option may be one of the BMW engines that some
people in the Yahoo Group are beginning to use in their experimental
aircraft, it show's some good preformance features. One of the online
forums you inquired about that is very active is
homebuiltairplanes.com. I hope this little bit of information is
helpfull and look forward to reading about your progress.

Joe

On Aug 23, 12:00 pm, rektide > wrote:
> I'm looking at making a powered sailplane with a ducted fan and would
> need at minimum 75HP. I'd much prefer something closer to 120HP, but
> I dont know what size and weight tradeoffs that would entail.

Ducted fans are usually higher RPM and smaller diameter,
so a direct-drive auto engine might work OK. The Subaru 2.2 litre four-
bangers will deliver around 130 hp at 5600 RPM. Weight of engine + rad
+ coolant is going to be around 300 pounds, something a sailplane
can't afford unless it's a BIG sailplane, and the Vne of sailplanes
also will limit useable HP.
There have been experimenters using ducted fans, only to
switch to conventional props after they found no advantage with the
ducted setup. Be sure to find as much info as possible before
reinventing the wheel and experiencing a lot of disappointment. The
only ducted fans I can think of now are in wind tunnels, on turbofan
engines (necessary for higher cruise speeds than props can deliver),
or on model jets where some attempt at authenticity is expected.

Dan

In article
>,
rektide > wrote:

> I'm looking at making a powered sailplane with a ducted fan and would
> need at minimum 75HP. I'd much prefer something closer to 120HP, but
> I dont know what size and weight tradeoffs that would entail.

Why do you need so much power for a (self-launching?) sailplane?

"rektide" > wrote in message
...
> I'm looking at making a powered sailplane with a ducted fan and would
> need at minimum 75HP. I'd much prefer something closer to 120HP, but
> I dont know what size and weight tradeoffs that would entail.

I'm no expert in this, but I'm curious: Why so much power????

Peter

"Peter Dohm" > wrote in message
. ..
> "rektide" > wrote in message
> ...
>> I'm looking at making a powered sailplane with a ducted fan and would
>> need at minimum 75HP. I'd much prefer something closer to 120HP, but
>> I dont know what size and weight tradeoffs that would entail.
>
> I'm no expert in this, but I'm curious: Why so much power????
>
> Peter
>
Could be this motorglider is going to be a glider tow plane too.

Subaru has several sizes that could fit the bill and there are several
commercial companies producing different versions. Try a search with
subject lines like auto-conversions and automotive aircraft. You will
also find a subscription CONTACT! Magazine a helpful publication.

rektide wrote:
>
> I'm looking at making a powered sailplane with a ducted fan and would
> need at minimum 75HP. I'd much prefer something closer to 120HP, but
> I dont know what size and weight tradeoffs that would entail.