Well, there are so many different Rotax engines, it depends on which
one. 2 cycle, 4 cycle, etc.. But their flat 4, four cycle engine has
some very suspicious similarities to the VW. The cylinders look very
much alike, and the Rotax is the only other engine besides the VW that
has the exhaust exiting the front of the cylinder on the forward end
of the engine. All others have the exhaust exiting vertically, either
up or down. There seems to be some obvious Rotax designs that are
from the VW. No doubt improved, to get aircraft reliabliity. I looked
the thing over at Reno at their display, and it looked very VW. The
gearbox is of course their own design. In short, a geared VW engine
is all it is.

On Tue, 26 Oct 2010 22:16:42 -0400, wrote:

On Tue, 26 Oct 2010 20:40:07 -0400, rich
wrote:

Looking at the various conversions, such as Limbach, Hapi, Revmaster,
Great Plains, and I'm sure there are some others, I'm wondering if one
or the other has a reputation of being the best for reliablity?
The Rotax seems based on the VW, although the company denies that,
just looking at some of their models, the resemblence is too much not
to be somewhat a derivative of the VW. Looking around on the web, the
Revmaster seems to be the only one with a stand alone engine for sale,
Great Plains seems to sell the parts to make the conversion, and
Limbach and Hapi I can't find any parts for them for sale. If they are
even in business any longer.
Rich
The Rotax is no more based on the VW than on the BMW twin or the
Lycoming/continental aircraft engines. Or for that matter, on the
Corvair.