Super Dimona Motorglider in Soaring magazine feb 2004

In article ,
Robert Ehrlich wrote:
Mark James Boyd wrote:

Interesting article. Too bad (for US pilots) it uses
the "despised in the US" rotax engine. But this is
a real favorite in Europe, I'm told.


I also despise this Rotax engine, although not being an
US pilot. Since we bought our Super Dimona 5 years ago
we never had a season without engine problem(s). The last
season we spent 26000 euros on repairs/exchange. We had
to hire another Dimona for towing during the long period
we had to wait for the replacement engine. The good news
is that hiring another tug was cheaper than using our
own one, but this opportunity is going to stop as the
owner is selling the plane.

Maybe the Rotax is a very good engine for ultralights,
or even for the Dimona used as a touring motor glider,
but when used as a tug, the stress seems to be to high
for this engine, at least in the conditions of my club
(20 club gliders and 5 private owners using aerotow, we
add the second tug, a Rallye, when more than the half
fleet is waiting for launch). The version of the Super
Dimona used as tug is model HK36 115 TTC (I think the TC
means turbo charged). The maximum time during which
the full power (115 HP) is allowed is 5 minutes, but during
a good soaring day, each flight is a 5 minutes climb at full
power followed by 1 minute descent and landing, and I can
understand that the engine doesn't like that.

You are preaching to the Pope. Turbocharging? Any
idiot can get more power out of an aircraft engine,
all the way up to the point the TBO = 0! Nothing new
there. Ever been to a local dirt racetrack?
Lots of noise, lots of HP, and lots of spare engines...
Oh, and LOTS of mechanics... :P

Working planes deserve engines with high TBOs. The
loss of availability to me is often worse than the
repair cost. Turbo AND constant speed prop too? Not
for me, brother...

Mark James Boyd wrote:

In article ,
Robert Ehrlich wrote:
Mark James Boyd wrote:
..
Working planes deserve engines with high TBOs. The
loss of availability to me is often worse than the
repair cost. Turbo AND constant speed prop too? Not
for me, brother...

But a well enginered engine (pleonasm ?) designed for use
with a turbo should work and spare a lot of weight. The
real problem is that the Rotax was not designed for use
with a turbo. Regarding the constant speed prop, it is a
real plus, allowing a smaller prop and lower noise for the
same result. This is really significative and we had some
financial support from fundings for noise reduction when
we bought this tug.