tommayer wrote:
Paul,
There has been a lot of bad mouthing of rotaries on the Mustang website.
I wrote off this rebuttal in haste. It probably contains inaccuracies, and
is surely not complete. I wish I had remembered to say that you are well
advanced in solving the constant speed prop issue, and that turbo charging
is obviously doable by somebody with your experience and knowledge. I don't
know if you think it worth the time to enlighten these people. My feeling
was that it is a shame for the website of a popular, rather good homebuilt,
one that ought to be a prime candidate for rotaries, to be the forum for
such misinformation, if not prejudice.
-----Original Message-----
From: Morrison, John <johnm@vcc.victoria.bc.ca>
To: Morrison, John <johnm@vcc.victoria.bc.ca>; 'tommayer'
<tommayer@cybermesa.com>
Date: Friday, April 28, 2000 2:11 PM
Subject: RE: Engine Weight
Tom has some valid points, and I am quoting parts and rebuild figures
directly from Mazda Canada, who ships cores to a plant in Texas. I spent
7
months hunting for parts across North America, and I will tell you that
Mazda have "washed their hands" of the 12A and 13B engines. If your
intention is to rebuild a rotary from a core to some semblance of quality,
you will hunt and scrounge and end up spending the equivalent of a 1/2
time
Lycoming.
I agree that the rotary is lighter (it's only saving grace in it's
history),
and I agree that aircraft engines are not bulletproof (though lets look at
statistics, not testimonial evidence)
The appeal of the rotary engine is not just weight, it is considered a
cheaper alternative to certified aircraft engines. My point is...that to
make a rotary airworthy is an expensive undertaking. You will hunt for
parts, you will start collecting spare rotor housings and you will not
receive any support from Mazda. There are certified aircraft engines that
will run on high-test auto fuel, though I won't continue arguing the point
of efficiency, as it's a distraction.
If I can pull together one coherent point, let it be this: "Don't think
that your neighborhood rebuilt rotary engine is anything close to the
purpose built, all-new, and rigorously-tested rotaries you see in the
Kitplane engine directory." Rotaries are extremely-complex, with very
tight
tolerances. They are not dangerous!...they run fine in the perfect
operating environment. But what motivation is there other than weight
savings? I support some auto conversions, such as well-done EA-81's and
V6
derivitives, because the parts are plentiful, the technology is widely
understood, and the tolerances permit flucuations in operating conditions.
Of course, this is just another opinion right?
-----Original Message-----
From: Morrison, John <johnm@vcc.victoria.bc.ca>
To: GEORGE B. <georgeb043@webtv.net>; mustang-list@n9.org
<mustang-list@n9.org>; 'tommayer' <tommayer@cybermesa.com>
Date: Friday, April 28, 2000 1:04 PM
Subject: RE: Engine Weight
The hairs on the back of my neck stand up every time I hear the word
rotary.
I just finished converting a Mazda RX-7 from rotary to V8, and the
reliability of the Wankel product is only as good as your ability to
keep
it's operating environment perfect. For example, let it overheat
briefly
and your in big trouble, a particle of dust in the right oil passage
will
have the same effect. Once you wear the chrome off the rotor housings,
they're scrap metal...once you unbolt the housings to inspect the
chrome,
they warp and they're scrap metal...Wankel rotaries are disposable
engines,
don't even bother trying to find the mulitudes of apex seals and rotor
fittings needed for a rebuild. Don't be fooled into thinking they're
like
turbines, with few parts...the seals alone account for over $1700 in
parts.
If you know the Wankel rotaries, you know that they run extremely hot,
and
will demand nothing less than perfect cooling...you'd better have two
if
you're working out the bugs in your cowl inlet design, the first one
will
buy the farm during testing. Aircraft installations also bring up the
risk
of shock cooling, likely just as deadly.
Also, due to the rotary engine's very nature, fuel economy is not good,
not
two-stroke mind you, but not good.
In conclusion, I would say the rotary has a better chance of success in
aircraft than it did in cars, as we tend to take care of aircraft and
abuse
cars, but the consequences of failure are much more severe...
The cost of a Lycoming 180hp on the used market can't be that mush more
than
a professionally rebuilt rotary with psru, I'll go on a diet and steal
some
titanium to save weight.
I think it might be a good idea if all of you that have an opinion or experience
with the rotary engine send a message to mustang-list@n9.org and refute these
exaggerations, un truths and opinions.
Tom has done this to a certain extent but he needs some help. Send a copy to
Tom just in case it does not find its way to the right place.
tom mayer <tommayer@roadrunner.com>
Paul Lamar
The Aircraft Rotary Engine Newsletter. Powered by Linux.
http://home.earthlink.net/~rotaryeng/ http://www.linux.org