On Nov 19, 7:04*am, Darryl Ramm wrote:
On Nov 19, 5:29*am, Nigel Cottrell wrote:





Rotax specifically say that 100ll should only be used if 95 ron
unleaded is unavailable due to increased wear and unsuitability
to their 2 stroke engines. We have never used 100ll in our 505
due to this advice from Rotax.
The sooner an unleaded aviation petrol spec is agreed and the
fuel widely available the better.
This would also be of great help to the large number of light
aircraft powered by engines originally designed to use 80/87.

At 07:11 19 November 2010, Alan wrote:

In article *Jim *writes:

You spend enough to buy a house on your motorglider and
are trying to
save a few bucks on fuel?

*Avoiding 100LL is often not about trying to save money.

*If you spent that much money on the motorglider, you
probably want to
feed
it the best fuel for it, which may not be 100LL.

*I don't know about the engines used in motorgliders, but the
Rotax
engines
used in many of the light sport aircraft "prefer" mogas over
100LL, as the
lead content results in shorter service intervals for things like
oil
changes,
gearbox servicing, and possible engine overhaul.

* *Alan

Ah the devil is in the details and the question about concerns with
Ethanol blend fuels that are an issue in the USA may not be in the UK.

The real question is what do Rotax or the aircraft manufacture say
about Mogas with Ethanol blends? And what experience do people
actually have operating at high Ethanol blends E10, E15 etc. Its not
just an automatic extrapolation that because non-blended or low-blend
(5%) Mogas is "better" (for some definition of what better means)
than 100LL that all ethanol blends of Mogas will be. In many cases I
suspect that the motorglider manufacturers do not have enough
experience with Ethanol blended fuels to know what the answer should
be.

Let alone the question of what Ethanol blends might do to fuel tanks
and hoses etc. there is the question of whether the Engine and carb
etc. are suitable for higher blend ethanol fuels. To take the example
offered of Rotax/light sport example further Rotax themselves have
qualified some (but not all of their) engines to use up to E10 blends
but no more. Other engines are limited to E5. (seehttp://www.rotax-aircraft-engines.com/portaldata/5/dokus/d04851.pdf).
So if you live in the USA in a state where fuel is pushing E15 you
might really want to consider AVGAS.

For example see how Remos handle this issue herehttp://www.remos.com/media/news/notification-use-ethanol-blended-fuel
... Use Mogas over 100LL but Mogas is not recommended if it contains
Ethanol. Not exactly clear from this at what blend ratio it might be
better to use 100LL.

The rotary engines in Schleicher motogliders run better on Avgas 100LL
than Mogas so its a non-issue. The Solo engines in DG motorgliders and
others have traditionally had Mogas recommended, but again that advice
may not necessarily apply if the Mogas is a high Ethanol blend. Check
with DG or Binder for their advice - and be clear you are asking
specifically about Ethanol blends not conventional Mogas.

Having drained enough water out of AVGAS tanks in light aircraft to
scare me I would be concerned about dissolved water contamination in
high Ethanol blends.

Darryl- Hide quoted text -

- Show quoted text -

Alan and Nigel are right, several rotax powered motogliders DO prefer
Mogas. Metal tanks in the HK-36.

Lead in 100LL can cause plug and gearbox problems. I know because I
do the support for two HK -36 research birds

aerodyne