Ultralight motors?

UltraJohn wrote:
wrote:

But there isn't any regulation that prohibits using a 2
stroke on a light sportplane or experimental is there?
Mixing gas and oil may well be worth the minor hassle
to many pilots given the weight savings. Could that
engine be used on an aerobatic plane?


I'd think you could especially with the fuel injected model. Still IMHO
there are too many other options out there to have to mess with mixing oil.
Even if I built just for the short haul eventually (like in 4+ years when
I retire!) I'd like to mousy (SP) around the country a bit and not have to
lug that 2 stroke oil around !
John

One quart of oil will do for 4 or 5 fill ups depending on the size of
your tank. One thing that I find peculiar is that Hirth doesn't list
any expansion chamber exhaust systems. A good expansion chamber can
easily double the HP and one more mildly tuned would add another 25% no
problem.

Not that I can afford one of these at the moment but if I could, I'd be
working on a way to stuff one of these in an old BMW motorcycle chassis.
;o) Talk about go like stink...

Tony

Morgans wrote:
"Anthony W" wrote


Not that I can afford one of these at the moment but if I could, I'd be
working on a way to stuff one of these in an old BMW motorcycle chassis.
;o) Talk about go like stink...


That would be a real trick, since the BMW motorcycles use the engine case as
part of the frame.

Only the new ones do. I've seen a 1600cc VW bug engine in an older BMW.

Tony

"Anthony W" wrote

Use avgas and
mineral based 2 stroke oil and they shouldn't separate for the working
life of stored fuel.

That is not what I recall. I think it was the two stroke ultralight group
that gave me that information, but I don't remember for sure where it was.
It seemed quite definite.

I don't think it was a separation problem, but rather the performance of the
oil suffering, or the octane level lowering, or something. I think it was
the Rotax opinion that said you should always use freshly mixed gas, or risk
ruining the engine.

Anyone have a clue what I am remembering? I didn't commit to total recall,
because I will never fly behind a 2 stroke. I would rather not fly, if that
is the only choice.
--
Jim in NC

"Anthony W" wrote

Not that I can afford one of these at the moment but if I could, I'd be
working on a way to stuff one of these in an old BMW motorcycle chassis.
;o) Talk about go like stink...

That would be a real trick, since the BMW motorcycles use the engine case as
part of the frame.
--
Jim in NC

Hmm, I thought it said "Tips for building UltraLight"?

Yes I noticed the grin so I guess you know there was a LOT of claims out
there that were no where near right!
John

Ok, mea culpa a little bit too.

While on the subject, didja notice how many "Sport Legal" airplanes
there were
before the specs were even decided?


"A man believes what he wants, and disregards the rest."
Paul
Simon

One quart of oil will do for 4 or 5 fill ups depending on the size of
your tank. One thing that I find peculiar is that Hirth doesn't list
any expansion chamber exhaust systems. A good expansion chamber can
easily double the HP and one more mildly tuned would add another 25% no
problem.

Tony

Expansion chamber exhaust get their power increases over a very narrow
range. Generally designed on a motorcycle to give max power at near max
rpm. This is not what you want in an airplane where you plan on cruising at
75% power (then again if your working on a race airplane. . .).
I think they said 40 or 50 to one so that makes 1 quart per 10 to 12 gallons
so probably 1/2 to 2 quarts per fill up depending on tank (5 gal UL to 25
gallon regular plane (had to resist saying "real plane")).
John

Richard Lamb wrote:

Hmm, I thought it said "Tips for building UltraLight"?

Yes I noticed the grin so I guess you know there was a LOT of claims out
there that were no where near right!
John

Ok, mea culpa a little bit too.

While on the subject, didja notice how many "Sport Legal" airplanes
there were
before the specs were even decided?


"A man believes what he wants, and disregards the rest."
Paul
Simon

Yes but at least with the "sport legal" they could control max speed with
prop changes and set the gross weight at whatever the regs stated. So at
least they had the capability of having a "sport legal" when the standards
did come out ( and some did ie 601XL for starters).
John

UltraJohn wrote:


One quart of oil will do for 4 or 5 fill ups depending on the size of
your tank. One thing that I find peculiar is that Hirth doesn't list
any expansion chamber exhaust systems. A good expansion chamber can
easily double the HP and one more mildly tuned would add another 25% no
problem.

Tony


Expansion chamber exhaust get their power increases over a very narrow
range. Generally designed on a motorcycle to give max power at near max
rpm. This is not what you want in an airplane where you plan on cruising at
75% power (then again if your working on a race airplane. . .).
I think they said 40 or 50 to one so that makes 1 quart per 10 to 12 gallons
so probably 1/2 to 2 quarts per fill up depending on tank (5 gal UL to 25
gallon regular plane (had to resist saying "real plane")).
John

It depends on the design of the pipe. I used to build expansion
chambers and you can either design them for max out put on one end of
the scale or a broad power-band. The street pipes I used to build were
somewhere in the middle leaning toward broad power-band. It would be
easy to pick up 20% over straight exhaust pipes on a well made engine
like the Hirth or Rotax within the normal operating RPM.

I think one of the Hirth 4's with fan cooling might have been able to
keep mini-500's in the air but this is pure speculation.

If you ever find a copy, read the Two Stroke Tuners Handbook by Gordon
Jennings. He could be a real butthole at times but he knew his stuff.
I loaned my copy out and never got it back. It took me 20 years to
track down another copy...

BTW, bike engines need a broader power-band than airplane engines. A
bike engine has to make usable power from 3k to red-line. I don't know
for sure but don't most aircraft engines run within a 2k RPM range in
flight?

Tony

"Anthony W" wrote

Only the new ones do. I've seen a 1600cc VW bug engine in an older BMW.

Must have been real old. I know the '75 60R did not have a real frame.
--
Jim in NC

Richard Riley wrote:
On Sat, 22 Oct 2005 23:48:49 GMT, Anthony W
wrote:

:If you ever find a copy, read the Two Stroke Tuners Handbook by Gordon
:Jennings. He could be a real butthole at times but he knew his stuff.
:I loaned my copy out and never got it back. It took me 20 years to
:track down another copy...

Ain't the internet wonderful? It took me 20 seconds to find it here -
http://tinyurl.com/e2wwh

but the cheapest copy is $96!! Someone needs to put this one back
into print!

There's a copy on Ebay at http://tinyurl.com/exsup, $15 right now.

One of the customers to my motorcycle parts biz eMailed me a copy in PDF
format. If you're real nice, I'll eMail it to you one file at a time.
I was thinking of adding it to my website but I don't want yo get into
problems with royalties.

Tony