A Simple Auto Engine Conversion

"Bill Daniels" bildan@comcast-dot-net wrote

Would I put this thing in an airplane and fly it over the mountains at
night? Not at first - not by a long shot. I'd build it on a trailer so I
could run it in non-noise sensitive areas. I'd take it to air shows to
entertain but mainly I'd just run it on the trailer trying to break it.

How about putting on an airboat, and have fun, while trying to break it.
The chopping at the waves would put some gyroscopic loads on it that would
imitate, of even exceed the types of conditions that it would see on an
airplane, that you could not duplicate on a trailer.

I saw someone did that while developing a system, just recently. I plan to
do just that.

If after a few years I still couldn't break it, then maybe in an airplane.
Ground testing is the expensive part. 2000 hours at 10GPH = 20,000
gallons at $4 each = $80,000. Nobody said it was cheap.

While I agree with the need to thouroughly test a unit, I do question the
need to do 2,000 hours, unless you are going for certification. Running it,
tearing it down occasionally and carefully inspecting (including
magnafluxing) will give you all the information you need for deciding
whether it is going to go the distance, IMHO.
--
Jim in NC

On Aug 28, 4:05 pm, "Morgans" wrote:

I recall that while it is important to vary ratios in a toothed gear redrive
away from exact ratios like 2:1, so different teeth mate with both gears
(prevents wearing a certain pattern in each other) that is not a necessary
condition for toothed belt redrives. I recall that in fact, it is not
desirable to do that, but again, my recall is incomplete.

Rotax two-strokes are available with a variety of gearbox
ratios, among them 2.0:1, 3.0:1 and 4.0:1. The others are odd, like
2.24:1 and 3.47:1. They've been building these things for a long time
and I expect they've figured out what the problems with even ratios
are and how to fix them.
http://www.rotax-aircraft-engines.co...n.Data_503.pdf
I have a Hummelbird that I want to get finished someday, and
I've considered the Rotax 503 for it. I don't like the rum-rum-rum
sound made by the odd ratios, and would choose an even number,
probably 3:1 or 4:1 so I could swing the largest prop possible for
better takeoff and climb performance.
The Hummelbird is supposed to use the half-VW, but after
Veeduber's advice about the VW's inadequate cylinder head finning and
its resulting propensity to burn its valves regularly, I think maybe
I'll stay away from it, even though I prefer the sound of a four-
stroke over the whine of a two-stroke. My first car was a VW Bug and
it burned its valves on a long uphill pull. It just wasn't made to put
out 100% power for any length of time.

Dan

"Peter Dohm" wrote in message
. ..

I was only thinking of the exact ratios that place the same teeth in use
on each successive rotation of the belt.

Torsional resonance can be extremely difficult to monitor andI am glad
that you were able to identify it before it became a dissaster. For the
moment, my own project and the decision to build around a PSRU or use a
direct drive aircraft engine has been pushed further into the future. But
I have wondered whether the elimination of critical speeds might be the
true purpose of those little springs in the driven plate of a manual
clutch.


I think their primary purpose it simply to reduce or eliminate chatter when
engaging the clutch. Most high performance clutches don't even use them.

Ramsey wrote:
"Peter Dohm" wrote in message
. ..

I was only thinking of the exact ratios that place the same teeth in use
on each successive rotation of the belt.

Torsional resonance can be extremely difficult to monitor andI am glad
that you were able to identify it before it became a dissaster. For the
moment, my own project and the decision to build around a PSRU or use a
direct drive aircraft engine has been pushed further into the future. But
I have wondered whether the elimination of critical speeds might be the
true purpose of those little springs in the driven plate of a manual
clutch.


I think their primary purpose it simply to reduce or eliminate chatter when
engaging the clutch. Most high performance clutches don't even use them.





http://www.rotaryaviation.com/PSRU Zen Part 2.html

On Aug 27, 7:19*pm, flybynightkarmarepair wrote:
On Aug 27, 7:01*pm, "





wrote:
On Aug 26, 11:14*pm, Ron Wanttaja wrote:

On Tue, 26 Aug 2008 21:07:46 -0700 (PDT), "

wrote:
everyone says "ooh -- auto...dangerous" but no
one can explain exactly why.

1. Ignition systems with insufficient redundancy.
2. PSRU failures.
3. Difficulty in implementing efficient liquid cooling systems.

Ron Wanttaja

i heard the e racer had an inflight engine fire and eventually the
designer through in the towl on auto engines. *anyone remember why?

Sure do.

"From: Dorothy Dickey
Sent: Monday, January 24, 2000 8:46 PM
To: Young, Ryan
Subject: Engines for E-racers
There is nothing wrong with the Buick engine it's just that I no
longer favor
auto engines for aircraft applications. This is because it is not
possible
to achieve equivalent reliability and performance of an aircraft
engine for
the same or less money... So why do it? Shirl"

Remember, this is a guy who designed an airplane around an auto
conversion, and devoted serious time, money, and twice, almost his
life to making this idea work. *If you think you can do better, step
right up.

This whole thread smacks of TROLL, but you can read what more of what
I think, along with the E-Racer guy (Shirl Dickey), and a little from
the Belted Air Power reduction guy (Jess Myers) he

http://users.lmi.net/~ryoung/Sonerai/BOP.htm

You can also search this newsgroup for anything by Corky Scott, and
watch his chronicle. *He never flew his auto engine conversion, after
working on it for years.- Hide quoted text -

- Show quoted text -

Sorry, but that quote does not say the specific technical reason(s) he
gave up, just the basic economic idea that i've already heard -- hence
the original post. I wanted to hear a really good reason to not use
an auto engine, give readily available magnetos. Someone eventually
said propellor loads on the auto crankshaft. Thanks to that person
for answering the question. It's time to look at the aircraft engines
again (maybe the Walters)... I don't have any other questions.

"Ernest Christley" wrote in message
...

http://www.rotaryaviation.com/PSRU Zen Part 2.html

Bad link.

Zebulon wrote:
"Ernest Christley" wrote in message
...
http://www.rotaryaviation.com/PSRU Zen Part 2.html

Bad link.




The link is correct, you just have to use the whole thing.

http://www.rotaryaviation.com/PSRU Zen Part 2.html


Charles

"Zebulon" @###@.^net wrote in message
...

"Ernest Christley" wrote in message
...

http://www.rotaryaviation.com/PSRU Zen Part 2.html

Bad link.




Ok, got it now, but what's your point?

Is this what you are referring to?

"At this point it should be obvious that our original assumption about the
intended purpose of the damper is wrong. The engineers in Detroit are not
stupid and they don’t put in relatively expensive parts for no reason, so
why do manual transmission equipped cars have a damper? The main reason is
to absorb unexpected torque overloads. This happens only on rare occasions
like when someone gets overly aggressive with the throttle and suddenly
releases the clutch. The springs store the energy of the shock load and
release it in a more controlled fashion in order to avoid breaking
drive-train parts. "

"Zebulon" @###@.^net wrote in message
...

"Zebulon" @###@.^net wrote in message
...

"Ernest Christley" wrote in message
...

http://www.rotaryaviation.com/PSRU Zen Part 2.html

Bad link.




Ok, got it now, but what's your point?

Is this what you are referring to?

"At this point it should be obvious that our original assumption about the
intended purpose of the damper is wrong. The engineers in Detroit are not
stupid and they don't put in relatively expensive parts for no reason, so
why do manual transmission equipped cars have a damper? The main reason
is to absorb unexpected torque overloads. This happens only on rare
occasions like when someone gets overly aggressive with the throttle and
suddenly releases the clutch. The springs store the energy of the shock
load and release it in a more controlled fashion in order to avoid
breaking drive-train parts. "



The damper, which is indeed a relatively expensive part, is on the other end
of the engine and is intended to eliminate resonance within the engine. A
breif treatise, which probably started as an an internal document at one of
the big three auto makers, has been included on this forum a number of times
and is probably in an issue of Contact! Magazine as well; but I can't find a
copy on my current computer.

I could easily be incorrect about the purpose of the springs, but another
article from Contact! regarding the development of the BD-5 drive train
(which I also can not find) does provide some food for thought.

Peter

On Aug 31, 10:29 pm, "
wrote:
Sorry, but that quote does not say the specific technical reason(s) he
gave up, just the basic economic idea that i've already heard -- hence
the original post. I wanted to hear a really good reason to not use
an auto engine, give readily available magnetos. Someone eventually
said propellor loads on the auto crankshaft.

What? We didn't mention cooling issues, weight issues, PSRU issues,
cost issues or anything else? Aren't these good things to consider?

Dan