The Automatic Refueling System
If you want to refuel a motor glider you usually have four choices:
1. You can fill gasoline out of canisters directly into the aircraft. We would urge you not to use this method. It's too easy to get dirt particles into the tank even if the funnel has a fine-mesh sieve in it. Dirt is especially problematic because in aircraft you cannot use paper filters that would filter out almost everything. Such paper filters can suddenly disintegrate, causing a real problem.
2. You can use an electric pump and filter to fuel out of canisters and could even assemble such a rig yourself. All you need from an automotive supply house is a suitable pump, filter, quick connects, hoses, switches, plugs and cables - quite a few parts that have to fit together. Also, the pump has to remain filled with gasoline, so that the membrane does not dry out. And of course the remaining gasoline contaminates your trailer.
3. It's a lot simpler to buy the refueling system from DG. It would even be suitable for motor gliders of other manufacturers. All you have to do is connect the pump, stick the supply hose into the canister, and watch so that the tank does not overflow.
4. The simplest method is the fully automatic refueling system we developed for the DG motor gliders:
In the aircraft one sees only the hose ending with quick connect in the baggage compartment of the sailplane and a switch on the back rest. A third fuel pump and filter is permanently mounted in the sailplane. (The first one is powered by the battery and is needed for a ground start. The second one is powered by the generator as added safety in case of a power failure. The third on is used only for refueling.)
All you have to do is connect the hose by quick connect (come with the unit) and hold it into the canister. Flip the switch, and the pump starts.
A pressure switch in the tank signals the DEI when the tank is full. The pump switches off and the DEI resets itself to 22 liters. That's it. You don't have to do anything else. And what do you do with the filler funnel and the large nylon tank cap? Seal it off because you don't need it any more!
That is how we think of the little things that make the fueling of a motor glider as simple as possible.
- friedel weber - 
translated by Al Schreiter, CDN
A Short Note:
The pressure switch that signals that the tank is full is asymmetrically installed. Because of this, the tank can be filled more when the right wing tip is on the ground.
And like every technical device it should be checked occasionally. After filling the tank and having it shut off automatically, the fuel level should be visible at the inlet. At the very minimum, you should be able to detect some fuel with a short dip stick.
You should make this test before a long distance flight. Otherwise, the pressure switch is very reliable if it has been installed correctly.
An Enquiry
It makes sense to fill up the tank by use of a nozzle. It eases up the filling process on a multiple stop cross country flight. There is no further need to detach tape – except if you do not have either a canister or a petrol pump close by.
Therefore – to make things even more clear. The DG-800B is equipped with an additional filler neck – an is therefore the sole glider with a retractable engine capable of stopping at a fuel pump at any airport.
We on the other hand have our doubts whether we went to far in our struggle for perfection – is the filler neck actually used by our customers?
We would be more than happy to receive a feedback and your thoughts on this matter... Please let us know.
weber@dg-flugzeugbau.de
Result:
We got quite a lot of answers to the a. m. question. Of course these opinions were quite different. Some of our customers wrote, they had never used the filler neck for several years. Others praised this additional comfort for cruising flights and for the case that the fuelling pump should fail.
Well, obviously there are at least some pilots who want to use such a filler neck and so we decided to continue offering such a filler neck for the DG-808B.
This decision was also supported by a nice photo, which was sent to us by our representative Bert de Wijs. He made this picture in Spain during his recent holidays:
