High Altitude Engine Runs in DG powered sailplanes
It is a frequently asked question - especially from customers of South America -, how a SOLO-Engine runs in high altitude.
In Germany it is forbidden to fly higher tan 3,050 Meters, but the runway of Quito, the capital of Ecuador is already more than 2,800 meters high.
So when Wilhelm Dirks was asked about that question again, he answered to the customer:
Betreff: DG-500MB CALCULATIONS
As we are not allowed to go higher than FL 100 in Germany. So we don't have much experience about engine performance and handling at high altitude.
We never could try to start a cold engine at FL100 for instance, although I don't believe, that there will be any problems.
Otherwise I can say that the DG-500MB can be operated under power like a power plane, but fuel consumption is quite high for a 2 stroke at reduced power compared to a 4 stroke engine.
We have several customers who operate a DG-505MB or a DG-800B/DG-808C (same engine) from Minden Nevada who should have much more high altitude experience than we. You may contact Jim Herd for more information about this item.
with best regards
Wilhelm Dirks
DG Flugzeugbau GmbH
The customer asked Pete Williams and he answered as following:
Dear Sirs:
Takeoff runs and climb outs from Minden, NV USA (4,700' msl with a summer density alt normally over 7,000 ft) are no problem with the Solo engine.
Typically a ground run of less than 800 ft for the DG-800B and about 1,000 ft for the 505MB. Climb rates: 500 fpm+ for the DG-800B and 350 fpm+ for the DG-505MB on summer days.
Continued climb to above 10,000 ft msl yields a lower climb rate but I have climbed as high as 13,000' with no problem. In one instance, on a November day, to 17,000' msl.
Providing the engine attains its specified static rpms on a ground run-up, both aircraft have no problem with high field elevation operations. Just make sure the carb settings are adjusted for the field altitude using the EGT for max output and always opt for a slightly rich mixture.
Best Regards,
Pete Williams
DG-800B N885N
So you can see: No Problem!
Here is another statement of our Chief Designer Wilhelm Dirks concerning Carburetor Adjustment:
Carburetor adjustment at higher altitudes
The data in the maintenance manual for the EGT values DG-800B is 640° +-10°C. This value applies for the engine warmed up until the EGT values don't increase any further and is valid for an altitude of 100m above sea level. If the crab's are adjusted at a higher location the EGT's must be adjusted to lower values.
Subtract 5° per 200m altitude from the value of 640°C. So for an altitude of 1500m above sea level the limits are 605°C +-10°C. With this setting the DG-800B may be operated at sea level up to min. 3000m above sea level.
The objective for the given values is, that we want to have smooth engine run at least up to 3000 m above sea level (about 550°C EGT at this altitude).
If you intend to take off from higher airfields, the fine adjustment screw may be turned clockwise to lean the engine. As the fine adjustment screw is a standard Mikuni part, it is not possible to allow more than the given 1/4 turn. If the 1/4 turn is not sufficient for very high altitude airfields, the fine adjustment screw cap may be removed and the needle turned in further.