Dear Paul,

I have been reading many of the articles on your website, they are
very informative. I have been looking for a good engine for a
heavy duty gyroplane, and I was told a Subaru EJ25 is a good
choice. However, I have not been convinced. I would think the 13B
would be a much better choice. I owned a RX7 for many years, and
when I sold it after an accident it had well over 150,000 miles and
the engine was in perfect shape.

I have a couple of questions and hope you can help me out. First
of all, do they make brand new rotary engines? If not then we can
only buy old cars for the engines which is not easy to do in my
country as cars must be destroyed after 10 years. Second, how does
the power to weight ratio of the rotary compare with that of the
EJ25? The data I got just got me very confused. The power for the
EJ25 ranges from 165hp to 300 hp. This sounds rather strange, and
with such power range the EJ25 could have rather high power to
weight ratios too.

Best regards,

Gordon Gao

Mazda stopped production this year but they do that from time to
time as the market is currently saturated. They did that in 1995
but started up again in 2004. There have been 2.5 million sold
world wide so there is no shortage of engines.

The rotary is in no way comparable to a piston engine. There are
no stresses in the rotary that lead to metal fatigue unlike a
piston engine. A 300 HP Subaru is a hand grenade. If you are not
killed by the shrapnel in the explosion the resultant crash will do
it. :)

http://www.rotaryeng.net/What-is-a-rotary-engine4.html

http://www.youtube.com/watch?v=QOwb8QRHrMY


Paul Lamar


Does it fit a so powerful engine with such a lightweight flying
machines a Giroplane? I'ts just a question form a 100% novice, the
Austro engine with 40 KW sound good for that kind of Autogiro,
that probably with an engine so big would spend all the power just
taking up the engine weight.Can you give me some feedback?

Thanks, best regards, salut +

Jose Gros-AymerichE-28033 madrid, Spain

I don't understand the question.

Gyro's require high power as they are basically a powered
parachute :) They are in a continous state of auto rotation so to
speak. It is a brute force approach to flying.

Paul Lamar

Thank you Paul. For the 13B MSP, the 247 HP that people talk about
is sustained power?

GAO, Gordon

Yes. One must re think what you know about internal combustion
engines. A rotary is more akin to an electric motor. There are
thousands of 100 year old electric motors still working every day.

In a rotary, just like in an electric motor, there are NO REVERSING
STRESSES! It is reversing stresses that do the damage in the piston
engine.

Paul Lamar


Hello again!: I've just had a superficial look on the data regarding
the first Giroplanes (Autogiros) by Juan de la Cierva, who invented
it, itsmain contribution was the articulation in the root of blades
that allowedit automatically changing angle of attack depending on
which part of the turn the blade was, if counter-wind, of in the
direction of wind, this arrangement was what finally allowed building
a parctical helicopter.The Cierva C-8, you can see it in Wikipedia,
installed a 97 Kw, 130 Hp, Clerget engine, and the weight of the
whole flying machine was 1735 lb, 790 kg, it sound several orders of
magnitude above the tiny machineshown in the photos, that would not
need such a huge power as proposed from a Mazda conversion. There's a
paper publisehd in SAE Journal, sept 1929, pag 204, and another in
the June 1932 issue of SAE Journal, pages 241 to 253, by Agnew E.
Larsen, entitled: 'Engineering aspects of the modern Autogiro'; as
previously stated, SAE papers sell for around $24, but a full back
issue of SAE Journal containing the same article can be bought and
downloaded from SAE.org at around $15, you'll tell us about your
opinion on the adequacy of this article, and if it can make change
somebody's mind about the power requirements of an ultralight
autogiro, but once again, I'm just a theorist.Thanks for your
attention, best regards,

salut + Jose Gros-Aymerich28033 Madrid,
Spain

Regarding winds, may years ago, sailors that had crossed the
cape Horn in the south end of Argentina were entitled the rights of
wearing an ear ring, remain standing before kings, and urinate against
the wind.


Jose Gros-Aymerich


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