DG Flugzeugbau GmbH / Passion, Power + Performance

AVGAS, super petrol, leaded or unleaded?

For the usage of a two-stroke-engine the lead addition is completely unnecessary, as it is used to seal up the valves in older engines. But there are no valves in a two-stroke-engine. The problem is not the engine nor the fuel pipes. The problem might be found in the tank, knowingly made of Epoxi-resin. Unfortunately the stuff used in unleaded petrol for the anti-knock also is a very good dissolver for synthetics.

The easiest and safest recommendation is to use AVGAS in future. In the sense of environmental awareness of the engine it would be a giant step backwards, and very expensive too.

We launched a special investigation, to find out in a laboratory test whether in future it will be possible to use unleaded petrol, such as Euro-Super for example.

The results of a laboratory test show, that you can use the unleaded gasoline, "EURO95".
The use of leaded gasoline or "Super Plus" is unnecessary.

- w. dirks -

Addendum:

As far as we know a number of our customers wanted to be "good to the motor" and regularly used AVGAS. That is possible in principle, but actually does more damage than good.

AVGAS causes a harsher combustion than MOGAS, because of its high octane rating. One could see this with the Porsche Aircraft engine some time ago. This increases the vibrations of the engine, and that is critical in retractable motor gliders. This is why we want to recommend strongly to all customers: gas up with EURO Super of lead-free 95 and avoid AVGAS whenever possible.

In other countries this type of fuel is widely available, but may go under another name. For instance, in the USA the octane number is expressed as "ROZ" or "MOZ", so that regular fuel has an 82-octane rating. Super probably corresponds to our EURO 95, but please inquire first. (As far as I know, it es o.k.!)

Again the request, not to fill up out of canisters, but always to use a pump with a filter. It's hard to believe how many unwanted engine stops are cause by dirt getting into the carburetor.

And that once in a while the tank should be drained would not have to be repeated. One customer with a DG-400 was asked after an unscheduled motor stop if he had drained the tank. "Drained? I never drain the tank" he said.
So he tore his gear out in an emergency out landing. And that really was not necessary.

Two Stroke Oil

According to the specifications of SOLO-Company we highly recommend the two-stroke-oil:
Castrol Super TTS, TTS, ACT>EVO 2T, Power 1RS 2T or other oil with the specification "JASO FC".

Please avoid to use synthetic oil!

Allan Martini wrote an excellent Explanation - especially for US customers:

There is no difference between octane measurements in the US and Europe but the emphasis in specifing may be different. I will give a summary first and then some details  There are four commonly used ways to measure and state octane values. These are:

RON    Reaserch Octane Number.  This is the value commonly used by DG, Stemme, etc to specify an octane requirement. NOTE  I don't have my DG manuals anymore and I haven't been able to find anyone here that has heard of  ROZ, but I have the question still out to some of my friends in Chevron.

MON   Motor Octane Number. This value is determined in a different way. It is often considered to be more sensitve to changes in operating conditions and their effect on the engine than RON.

AKI    Anti-Knock Index.  This is the number that is posted on the gas pump in the USA as "Octane". It is derived as  (RON + MON)/2  In other words, an average of RON and MON values.

RON is typically 8 to 10 points higher than MON.  Therefor, the average is typically 4 to 5 points above MON and 4 to 5 poins lower than RON.  Thus, a requirement for 95 RON gasoline should be met by 91 "octane" fuel in the US.  This explains Gary Evans information.

RdON  Road Octane Number.  Not generally used but mostly related to fine tuning fuel for racing engines.

Some background:  The term octane for fuel anti-knock qualities was developed, I believe, by General Motors in the early 30's.  The RON is the percentage mixture of two gasoline components, iso-octane (C8H18) which has very good compression/antiknock qualities and heptane (C7H16) which has poor compression/antiknock qualities. If the mixture contains 80% iso-octane it is deemed to have an RON of 80.

The test fuel is then burned in a single cylinder test engine with variable compression and rigid conditions of rpm, air temp, spark advance, barometric pressure, etc and the antiknock qualities measured.  Any other mixture of hydrocarbons which has the same antiknock qualities will also be considered to have an RON of 80.

MON is measured in the same type of engine using several changes in rpm, temp, throttle position, etc which make the operating conditions much more severe (and possibly more realistic) and the octane numbers are lower.

RdON is measured in multi-cylinder engines, usually at wide open throttle, and usually on an engine dynamometer.  The procedure is used to develope racing fuels.

All that is probably more than you wanted to know, but I hope it helps.

Regards,
Allan Martini

Fuel pipes

Fuel pipes in our planes are security-relevant parts and have to be changed every few years.

Since some years there exists a new type of fuel pipe made from PU material (polyurethane material) which is supposed to have no run-time limit. We only use this type of fuel pipes in new gliders due to the following reasons:

 

 

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