what engines are making successful aero engine conversions?

I think the topic (40hp engine) is of sufficient interest
internationally to justify some form of permanent address on the
internet. The problem is only going to become worse.

-R.S.Hoover

"Stealth Pilot" wrote

rotec is not in consideration. my target is a light 40 hp engine for
single seat aircraft.

How about a Harley Davidson motorcycle engine? I see some guy has been
using one for airplane use.

It seems like it would have a lot of things going for it. Air and oil
cooled, power output shaft designed to drive a primary drive belt, just like
could be used to drive a prop. Light and should have plenty of power for
your use. Plenty engines available, different sizes, and good supplies of
aftermarket parts.

The only drawback is the uneven drive pulses, and only two cylinders-at
that. Still, it seems to work for at least one guy.

I saw a three cylinder Harley-like engine on a TV motorcycle show once. I
wonder how that would work.

And, it sounds cool for a bonus!
--
Jim in NC

Morgans wrote:
How about a Harley Davidson motorcycle engine? I see some guy has been
using one for airplane use.

It seems like it would have a lot of things going for it. Air and oil
cooled, power output shaft designed to drive a primary drive belt, just like
could be used to drive a prop. Light and should have plenty of power for
your use. Plenty engines available, different sizes, and good supplies of
aftermarket parts.

The only drawback is the uneven drive pulses, and only two cylinders-at
that. Still, it seems to work for at least one guy.

I saw a three cylinder Harley-like engine on a TV motorcycle show once. I
wonder how that would work.

And, it sounds cool for a bonus!

I don't think a HD engine has sufficient cooling fins on the cylinder
heads to run at a steady power output and not melt. It's the VW problem
all over again. And as has already be discussed, casting cylinder heads
is no easy job.

If someone were to custom build an engine, there are HD parts that would
make the project go a bit quicker. I once sketched up an opposed twin
using parts from the all aluminum head HD engine back in the mid 1980s.
It was a somewhat doable project but I wasn't thinking of it as an
aircraft power plant but rather an modernization of the very rare WWII
military Harley XA.

Tony

On May 16, 11:42*pm, Anthony W wrote:
*It's the VW problem
all over again. *And as has already be discussed, casting cylinder heads
is no easy job.
----------------------------------------------------------------------------------------------------------

Ummm.... well, not necessarily. If we could come up with a
professional pattern for a Lost Foam Casting we can come up with a
single-piece, one-cylinder cylinder head having nearly TWICE the
cooling-fin are of the stock VW cylinder head.

No, not like the Scat head, but similar to it, with regards to one-
head-per-cylinder. What makes it different is that you need TWO
castings... because the Volkswagen's exhaust valves are on the
corners.

The main advantage here is the high precision you can get using Lost
Foam Casting. Plus, there's no need for any DRAFT in the pattern.
That means you can produce up to ten fins per inch (!) from a
casting. But you're looking at a minimum run of about 5000 units to
get the price down to where it's affordable.... and it STILL doesn't
address the main issue, which is the fact we are running out of VW
engines. But if we DID have such heads we could assemble a 140cid
engine capable of delivering an honest 65 hp.

-R.S.Hoover

Bob wrote:
On May 16, 11:42 pm, Anthony W wrote:
It's the VW problem
all over again. And as has already be discussed, casting cylinder heads
is no easy job.
----------------------------------------------------------------------------------------------------------

Ummm.... well, not necessarily. If we could come up with a
professional pattern for a Lost Foam Casting we can come up with a
single-piece, one-cylinder cylinder head having nearly TWICE the
cooling-fin are of the stock VW cylinder head.

No, not like the Scat head, but similar to it, with regards to one-
head-per-cylinder. What makes it different is that you need TWO
castings... because the Volkswagen's exhaust valves are on the
corners.

The main advantage here is the high precision you can get using Lost
Foam Casting. Plus, there's no need for any DRAFT in the pattern.
That means you can produce up to ten fins per inch (!) from a
casting. But you're looking at a minimum run of about 5000 units to
get the price down to where it's affordable.... and it STILL doesn't
address the main issue, which is the fact we are running out of VW
engines. But if we DID have such heads we could assemble a 140cid
engine capable of delivering an honest 65 hp.

-R.S.Hoover

I don't know what it cost this guy to have his engine parts cast but the
article is certainly enjoyable to read...
http://www.flashbackfab.com/pages/excel00.html

I wasn't thinking of continuing to use VW engines, I was talking about
making a boxer twin out of Harley-Davidson engine parts. The 80cid
engine of about 1984 on would be the one I was thinking about but the
newer 88cid engine would be worth looking at too.

when I was first thinking about this project I had the opportunity to
pick up a damaged BMW R90 engine and my crazy idea was to start with the
Beemer crank and built something custom from there. However that was
long ago and I don't have the resources now that I did back then...

Tony

On May 16, 5:26*pm, Brian Whatcott wrote:

Car engines often feature a crank damper on the front end.
This stops the angular oscillations that lead to crack ups.

The damper is to stop the crank's "ringing", not to absorb power
pulses. If the crank gets to vibrating at certain frequencies it
usually breaks.

Manual transmissions feature sprung drive on the live clutch plate.
This can serve a similar purpose. Besides the fluid flywheel there is
also the rubber spider drive to the half shaft, on some sports coupes.

The clutch's springs are supplemented by the torque-pulse-absorbing
abilities of the quill shaft, drive shaft, and axle shafts. Most of
those aren't present in a redrive.


As an odd-ball thought, wouldn't it be nice if two tubes sized to fit a
fabric reinforced hose pipe between them, and epoxied to both tubes
were arranged with a gap in the inner steel tube, then a gap in the
outer tube alternately - arranged to provide angular give in 'series'
for a soft, vibration absorbing *drive shaft....

I've done that, on electric motors. It doesn't last very long.
There is too little arm involved. As the rubber flexes, it heats up
and delaminates from the fabric. Blows up like the flat tire on a
semi.

Dan

"Morgans" wrote in message
...

"Stealth Pilot" wrote

rotec is not in consideration. my target is a light 40 hp engine for
single seat aircraft.

How about a Harley Davidson motorcycle engine? I see some guy has been
using one for airplane use.

It seems like it would have a lot of things going for it. Air and oil
cooled, power output shaft designed to drive a primary drive belt, just
like could be used to drive a prop. Light and should have plenty of power
for your use. Plenty engines available, different sizes, and good
supplies of aftermarket parts.

The only drawback is the uneven drive pulses, and only two cylinders-at
that. Still, it seems to work for at least one guy.

I saw a three cylinder Harley-like engine on a TV motorcycle show once. I
wonder how that would work.

And, it sounds cool for a bonus!
--
Jim in NC

IIRC, the then current Harley was a recommended powerplant for some ot the
Mignet "Flying-Flea" aircraft of the period c1970.

Peter

Stealth Pilot wrote:


hoover you are proof positive that old dogs can learn new tricks!
I note the use of the word Holden :-) and punch that upturned thumb to
the sky thinking yesss hoover you are a champion :-) :-)


Personally, I want to see a flying commie-knocker ;')

Charles

wrote:

On May 16, 4:13 pm, bildan wrote:
Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. Ask one to handle only 100HP and
they should last forever. You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die. They need almost
zero lash, or some heavy flywheel on the engine, or the damping of a
torque converter.

Dan

I'm not sure that we can handle someone who knows what he is talking about, Dan.
Isn't this group about speculation and WAGs.

Seriously, Tracy Crook and others have done a lot of work on the planetary gear
redrive in conjunction with the Wankel rotary, which BTW is a much better
solution to the overall search for the optimal aircraft engine. Their
conclusions are similar to the ones you pointed to.

On May 18, 7:44*am, routund wrote:
wrote:
On May 16, 4:13 pm, bildan wrote:
Re. PSRU's

There is a gear reduction unit that handles massive torque and power
the size of a a one-pound coffee can - it's the planetary gearset from
an automatic transmission. *I have two in my Jeep Grand Cherokee
'airport car' transmission that have lasted 300,000 miles - so far.
These things are built to very tight tolerances and are VERY tough.

If you want still tougher, speed shops sell replacement planetaries
that can handle 1500HP or more. *Ask *one to handle only 100HP and
they should last forever. *You can specify just about any reduction
ratio you want.

All you have to do is machine a nose case from billet aluminum to hold
the planetary gearset and the thrust bearing.

* I wish it was so simple. Without a flywheel and/or torque converter
to damp the engine's power pulses, the engine's desire to run in a
vibratory fashion will conflict with the prop's desire to run
smoothly, and at some resonant RPM the gears can die. They need almost
zero lash, or some heavy flywheel on the engine, or the damping of a
torque converter.

Dan

I'm not sure that we can handle someone who knows what he is talking about, Dan.
Isn't this group about speculation and WAGs.

Seriously, Tracy Crook and others have done a lot of work on the planetary gear
redrive in conjunction with the Wankel rotary, which BTW is a much better
solution to the overall search for the optimal aircraft engine. *Their
conclusions are similar to the ones you pointed to.

I hear rumors of a Japanese motorcycle maker that will introduce a
500cc inline 4 with direct injection. If it lives up to its Japanese
reputation, it will produce about 50 very reliable HP.

Take 5 of these 4-cyl blocks and arrange them around a common case and
crank to make a 20 cylinder, 250HP liquid cooled radial. De-rate it
to 150HP for reliability. Since it uses direct injection, the
plumbing would be air in and exhaust out. Fuel lines would be 3mm
stainless tubing from a common rail to the cylinder heads.

20 cylinders would make the engine smooth enough that the crank itself
would be plenty of flywheel. (Ever see a flywheel on a geared
radial?) A planetary in the nose case would get the prop RPM down
below 2000 RPM.

BTW, I don't think casting has any place in prototyping. Design the
parts with SolidWorks, email the file to a CNC shop who will mill them
from billet and ship the parts in a week. Machined billet parts are
FAR better than castings - and cheaper.