Everybody that wants a 100 HP  24 KG, 35 KG (77 pound) with Hirth
gear box, rotary send email to my friend Poul Henrik Woelfle AIXRO


   ph.woelfle@woelfle-engineering.com


If they get enough request they might market an existing engine in
the US.

Paul Lamar


A quick look at their web site does not reveal much about engine
cooling on these little hot-rods.

A couple of friends of mine owned Arctic Cat snowmobiles with
rotary engines (stock) back about 40 years ago.
They ran nicely, sounded neat, and were air-cooled (admittedly ... the ambient temperatures were almost always sub-freezing.)

I would guess that air-cooling at the power densities required
for aviation is out of the question, huh?

Robin Berglund

They have my book "How to Cool Your Wankel so everything
will be OK. Not to worry. They will not be selling a firewall
forward package anyway. That is up to the aircraft builder.

It is not that air cooling a Wankel is out of the question.
Plenty of small one rotor air cooled Wankels out there.
Mostly built by Sachs. Too small for aircraft use however.

The difficulty is air cooling a multi-rotor design.
It is tough to get enough air between the rotors
to cool the side plates. If you separate the rotor
sections for more room you will add undesirable length to
the e-shaft and lower its resonant frequency.
However something like heat pipes might work.

Using an engine driven blower is counter productive
as that reduces the net HP out and increases
the fuel burn. Austro engines use such a blower
to air cool the rotor.

The best thing to do is focus on the cooling drag
and the easiest way to do that is design the heat exchanger
diffusers properly and use cowl flaps.

The main competition is the Rotax 912 some of which
is liquid cooled so why pursue air cooling?


Paul Lamar