Hello again good sir,

   Just as the topic says, after looking into the cost of converting an aircraft
to a Mazda engine or a commercially available alternative such as those produced
by Powersport Aviation or Mistral Engines (not to mention a host of smaller companies)
I feel that my business partner and I have the potential to produce a rotary power
plant with comparable performance (lbs/hp) at a competitive price. The problem is
our lack of in depth knowledge of what aviators actually prefer in an engine aside
from what common sense dictates (reliable, cheap, powerful, cheap.) What would you
look for in a *perfect* rotary aviation engine Mr. Lamar? Would you prefer the
efficiency of water cooling or the reliability of air cooling, gasoline carburetion,
gasoline fuel injection, or diesel high pressure injection? Design aspects such as
these are what my partner and I are having a hard time determine. If you wouldn't
mind, please endow me with knowledge of what you and other
aviators would do given the chance to design their own engine.


Best thanks,

Vladimir


It would have to meet this criteria.

Paul Lamar

By Kenichi Yamamoto from his book "Rotary Engine" 1981

1.3     REQUIREMENTS FOR A PRACTICAL ROTARY ENGINE
       Although various types of rotary engines have been
developed to date, there are few that do not qualify as internal
combustion engines or do not qualify as a practical engine even
if they satisfy the qualifications of an internal combustion
engine.
       The requirements for a rotary engine to be qualified
as a practical internal combustion engine can be summed up in
the following five items. The practicality of various ideas on
rotary engines can be judged by evaluating them by these
criteria:

(1) Every moving part, including the timing mechanism, should
make a rotating motion. A mechanism having a reciprocating
inertia will increase mechanical noise and vibration, and will
work against high speed and high revolution.  [In addition
mechanisms that reciprocate generate reversing loads. Reversing
loads lead to reversing stresses. Reversing stresses lead to
metal fatigue and limited life. The Wankel rotary engine has no
reversing stresses therefor the life of the major parts such as the
eccentric shaft and rotor are unlimited unlike, crankshafts, connecting
rods, pistons and poppet valves. Paul Lamar]  Accordingly, structures
that require intake and exhaust valves and mechanisms using the rotors
oscillatory motion are not desirable.

(2)     Gas seals or the working chamber should be three
dimensionally reliable.  The gas seal mechanism of a rotary
engine should be constituted by connecting the individual seals
three dimensionally. Among the many ideas we come across are
those that don't show such three dimensional thoughts.

(3)     Appropriate gas exchange of intake and exhaust should
take place. Together with having a mechanism that can correctly
open and close the ports, sufficient time for intake and exhaust
should be provided especially for high speed and high
revolution.  Among the ideas on rotary engines, there are some
that ignore this point.

(4)     Every component part should have the strength to endure
high speed and high pressure.  As the component parts are
exposed to high pressure, high sliding velocity and high heat
load, every part should have sufficient allowance in size and in
shape.

(5)     Sufficient cooling and lubrication should be provided.
In order to qualify as an internal combustion engine, although
this is related to above (4), durability against high heat load,
high sliding velocity, etc. are required. Therefore, the
structure should be simple, and the ideas on rotor cooling,
lubrication of seal parts, and oil seal structure should be
those that are given adequate thought.
       Also, it is desirable for a practical rotary engine to
have a simple and compact structure. When we evaluate the
various type's of rotary engines devised to date in view of the
above mentioned requirements, the NSU Wankel type rotary engine
is the engine that best satisfies the above mentioned
requirements.



[I]   Read the book and checked off all the requirements, however,
the items mentioned are but only basic concepts. For instance,
certainly an engine must have a sufficient cooling system,
however, as a aviator, would you prefer water cooled or air
cooled. While the basic requirements for a running engine are
easy to consider, the more detailed parts such as the type of
cooling system or gasoline vs diesel fuel depend more on the
application, in this case aviation. I am fully aware that to
have a practical rotary engine, all the criteria Yamamoto
mentions must be met, however, a practical rotary engine in
no way implies a practical aviation rotary engine. In any case,
thank you for your suggestions Mr. Lamar and please continue
to share your thoughts with me.

P.s. While Yamamoto may be regarded as a good source for
information and basic principals, Toyo Kogyo/Mazda are not
without their faults. Many of the concepts presented in both
the 1971 and 1981 books are now contradicted and some of the
basic formulas are flawed.

Vladimir

Really? Could you get specific on what is flawed and
what are the faults?

Paul Lamar