X-Mozilla-Keys:
Howard Wilkinson wrote:
Paul:
I'm new to rotary engines... somewhat. My first rotary was a '74
Mazda pickup back in about '84. I was not impressed.... and when it
died I transplanted a Buick 225 V6 engine into it and a Toyota 5 speed
trans..... made a screamer out of it. The 13B to all reports is an
excellent engine with virtually all the bugs of the earlier versions
worked out.
My interest in Mazda power for aviation is in the possibility of
building a 1/2 rotary which looks not to be too large of a problem
with the exception of balancing. I've done engine work most of my
adult life if you could call it that... over 20 years, but in recent
years I have worked almost entirely on the big iron.... industrial and
agricultural diesels.... I do have "wrench will travel" and have been
self employed for 20+ years. Creative engineering is not new to me as
I often have occasion to design and build systems and conversions for
my customers. The only cut down engine project I've done was a 1/2
Subaru EA 71 I built about 7 years ago for a garden tractor as a
killing time project for winter evenings.... runs great!!
One issue which concerns me about rotary engines is the absurdly
heavy parts.... at least on the old Mazda engine. here are some
example weights...
front housing (cast iron) 32 lbs
middle housing (cast iron) 35 lbs
rear housing (cast iron) 40 lbs
crank shaft 18 lbs.
Is some of this stuff available in aluminum?
Yes, Racing Beat has some aluminum pieces. One of the reasons
Abel Ibbarra is able to get 800 HP is because these parts
ARE cast iron and almost bullet proof. If all you want is 65 HP a
one rotor Mazda is overkill. Try Wankel GmbH in Germany. See the
ACRE NL web site. http://home.earthlink.net/~rotaryeng/
I see very little
reason why it couldn't be built in aluminum with industrial hard
chrome surfaces for wear surfaces for the side seals. I presume that
the rotors need to be iron for expansion reasons, and the rotor
housings are already aluminum. Surely somebody has addressed this
matter and built replacements to improve power to weight ratio. I
have an application (aviation) which could use 65-75 horsepower (real
horses not Rotax horses each of which is actually only about .8 BHP
according to my calculations), and I need to keep total installed
weight under 150 lbs.... a near impossibility if the parts weigh as
much as these ones I've been looking at.
If the counterweight can run direct crankshaft speed I don't see
much problem with making it work. I know there are two or three
people out there who have done it already, but I have doubts that any
of them would be willing to share information... it seems that
everybody wants to go into business as soon as they make something
that works.
Are the newer Mazda engines so grossly heavy also? or do they have
aluminum sections?
H.W.
It may appear they are grossly heavy but the power to weight ratio
is excellent. The power to size ratio is outstanding.
800 HP out of a basic package 12.5 inches high by 12.5 inches wide by
24 inches long was unheard of until Abel Ibarra did it.
He is not burning nitro methane either.
The rotary is also a very heavy duty engine compared to the vast
majority of all aluminum car engines made today.
Paul Lamar
The Aircraft Rotary Engine Newsletter. Powered by Linux.
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