Harley motor in a homebuilt?

Ken Sandyeggo wrote:
David Hill wrote in message .. .

I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.

Looks like with an 80 cid Evolution engine I can get ~40 hp at ~3400 rpm
(direct drive) or ~60 hp at ~4500 rpm (PSRU setup).

Has anyone here tried this? Or know of anyone who has done this? I'm
looking for caveats, tips, and techniques. Based on experience, not
opinion. Oh, sorry, I forgot where I was. grin


Second hand caveat: This topic has been beaten to death, buried,
resurrected and beaten to death several more times on the gyro forum.
As I recall, the problem is heat. Running at the rpm we need to spin a
prop is too much for a motorcycle engine. After initial acceleration,
they basically loaf down the road. The sustained revs will fry them.
This what I recall being posted by people who seemed to know what they
were talking about. Craig Wall had some very spirited and seemingly
logical and convincing posts as to why they won't work. But then
again, someone may prove them wrong and get one to successfully
perform. I don't believe anyone has a good handle on it yet, with
proven reliability over a substantial amount of hours.

Ken J. - SDCAUSA

I seem to recall all the same posts. Which is why I never seriously
considered it, until I got involved with this replica project. The
original plane first flew on 17 hp with the Indian Chief motor, then was
changed to a 28 hp Lawrance A-3 (talk about vibration!). Even if all I
get out the Harley is 40 hp, I'll be doing okay.

thanks,
--
David Hill
david at hillREMOVETHISfamily.org
Sautee-Nacoochee, GA, USA

"David Hill" wrote
I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.

Do you really want your airplane to go "potato-potato-potato..." ? :-)

And on a more serious note, isn't the 45 degree configuration a lousy design
for vibration (or an excellent one, depending on how you look at it ) ?

Eric

"Eric Miller" wrote in message .net...
"David Hill" wrote
I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.

Do you really want your airplane to go "potato-potato-potato..." ? :-)

And on a more serious note, isn't the 45 degree configuration a lousy design
for vibration (or an excellent one, depending on how you look at it ) ?

Eric

In the world of high performance hovercraft, motorcycle engines
have been looked at for years. The only situations where they have
been made to work is where they are installed complete with gearbox
and rigged with a complex chain to belt PSRU. Also, they need to be in
an application where full power is rarely needed. After starring at
these harsh realities, most people choose between 2 stroke power or
Kohler reliability. Or for larger craft, a junkyard 4 cylinder car
engine.

"Eric Miller" wrote in message .net...

Do you really want your airplane to go "potato-potato-potato..." ? :-)

You could pretend it was a P&W R-2800.... ;-

Eric Miller wrote:
"David Hill" wrote

I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.


Do you really want your airplane to go "potato-potato-potato..." ? :-)

And on a more serious note, isn't the 45 degree configuration a lousy design
for vibration (or an excellent one, depending on how you look at it ) ?

Eric



Actually, I'd LOVE for my airplane to go "potato-potato-potato..."!
That's about the only think I like about a Harley. :-)

Yes, the 45 degree configuration is lousy regarding vibration (although
Honda has managed to smooth it out, just add 40 lbs or so of
counterweights). However, it's not as bad as the second engine that was
used in the original plane, the 28 hp Lawrance A-3 -- a two cylinder
opposed with a single crank throw, and no counterbalancing.

The buyer of the plane in 1926 commented on the excessive vibration in a
letter he write in the '80s. I know that in the late '20s someone came
up with a two throw crank conversion for these engines, but I only know
of one of these engines still running. And I'd rather fly behind a new
Harley engine than an 87 year old engine.

Interesting note on the Lawrance A-3 -- it does not have engine mounting
lugs. It has a grooved area around the base of each cylinder where you
*strap* the engine to the airplane. yikes!

--
David Hill
david at hillREMOVETHISfamily.org
Sautee-Nacoochee, GA, USA

On 23 Sep 2003 09:26 AM, David Hill posted the following:

Interesting note on the Lawrance A-3 -- it does not have engine
mounting lugs. It has a grooved area around the base of each
cylinder where you *strap* the engine to the airplane. yikes!

That brings up another point, it might be a really good idea to make a
safety cable from the engine to a lug on the fuselage, in case vibration
gets to be too much for the engine mount...

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

There was a newer Harley engine spinning a prop on a stand down at Sun'n'fun
this year. Can't remember the guys name. However with the newer Evos and
there twin balanced setup it seemed very promising and ran very smooth. Once
again I emphazise it was a newer Evo twin cam 88 motor.
John

David Hill wrote ...
I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.

Why not a current production Indian? Can't say that I know anything
about motorsickles, but I noticed one of the new ones a couple weeks
ago & wondered.

... I can get ~40 hp at ~3400 rpm
(direct drive) or ~60 hp at ~4500 rpm (PSRU setup).

Better check your math (PSRU = more torque @ lower rpm, but the HP
stays the same).

Daniel

"Daniel" wrote in message
om...
Better check your math (PSRU = more torque @ lower rpm, but the HP
stays the same).

Daniel...........

Better check yours. He's talking about engine rpm. ;o)

Rich S.

On 20 Sep 2003 17:48:25 -0700, (Daniel)
wrote:

David Hill wrote ...
I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.

Why not a current production Indian? Can't say that I know anything
about motorsickles, but I noticed one of the new ones a couple weeks
ago & wondered.

... I can get ~40 hp at ~3400 rpm
(direct drive) or ~60 hp at ~4500 rpm (PSRU setup).

Better check your math (PSRU = more torque @ lower rpm, but the HP
stays the same).

Daniel
No, David was right. Engine torque output being the same, horsepower
increases proportional to speed. Since torque droops with RPM, the
difference is not truly linear - but running a PSRU ALLOWS the engine
to produce more horsepower with the same prop RPM.If it did not, there
would be no reason for the complexity of a PSRU.