Hello Paul,

Thanks for a great website. I am likely to build a Vans RV4 soon, but
prefer to use a new Belgian engine you may have heard of, the UL Power
350iS. The information on your website concerning design of a new engine
mount is going to be so useful ! I am interested in gaining performance
and keeping fuel burn down, by reducing weight and frontal area a little.
A slight stretch in the nose will be needed to maintain the correct C of G
limits.

I was also interested in your rotary engine stuff. I hate to see many
slightly scaled down homebuilt warbird lookalikes ruined by badly fitting
Lycomings or Continentals. A Mazda conversion is exactly what is required.
Low frontal area with liquid cooling, rather like the real thing.

Please would you sign me up to your rotary engine newsletter. I promise no
spam !

Kind regards,

Justin Adams
Trosa
Sweden
http://spitfire3d.com/

A direct drive aircraft piston engine like the UL Power 160 ci
rated at 3300 RPM is not the same 97 HP as a direct drive AC engine
rated at 2700 RPM.

That is because of the smaller prop diameter required for
the 3300 RPM. For a 70 inch prop at 3300 RPM tip speed would be well
above transonic. Propeller efficiency is a strong
function of prop diameter. My guess is the prop efficiency
is off about 10 to 15 percent so the real rating
is more like  the 82 HP claimed for the engine running
at 2800 RPM. Don't be fooled by direct drive AC engines
rated at 3300 RPM. That is an unrealistic RPM for a
direct drive AC engine.

If they had increased the displacement to the same ci as
the Continental 200 ci  O-200 from the current 160 cubic inches
then they would get a real 97 HP. However my guess is it
would weigh about what a real O-200 weighs and that
is 200 pounds instead of the claimed 160 pounds.

The Mazda P-port 1 rotor on the other hand running a 2.85:1 PSRU
and 7500 RPM for take off would be turning a high efficiency
prop at only 2613 RPM and would be generating 125 HP.
It would weigh about the same with aluminum end housings.
Maybe a bit more for the liquid cooling system.

AIXRO is working on a 2 rotor AC version of their well known
kart engine of about 100 HP that would weigh a lot less.
It would be smoother than a Mazda one rotor and have
less frontal area.

Woelfle Engineering GmbH
Randstraße 109
D - 47804 Krefeld
Tel. +49 2151 151020
Fax +49 2151 151019
www.woelfle-engineering.com
ph.woelfle@woelfle-engineering.com

Paul Lamar



Many thanks for you detailed reply.

Kind regards,
Justin