Moki S250 with Planetary Drive SP-250-X by Mario Seidel and Seidel-Props


Please contact for possibly lower shipping rates outside the US.


The planetary gear-drive for the Moki S250!
Available immediately.


The price is a total for:

New Moki S250, inspected and tuned

SP-250-X Planetary Geardrive by mario Seidel, 3:1 ratio, free first year inspection included

Tuning parts (among many other HS carbon pushrods, HS custom valve springs, intake tube)

Break-in in Germany

Seidel-Props SP-250-X geardrive

This gear-drive is available as a per-installed combo, mated to a tuned Moki S250 using Heilemann parts such as carbon pushrods and custom valve springs.
This will enable you to use 4-blade propellers starting at 35inch diameter on all of your projects.

There is THE engine for the job as it has install diameters identical to the regular Moki S250. Imagine to finally be able to outfit your scale warbirds and other projects with museum scale propellers at SCALE size.

This is a first in the hobby and opens up new doors.

Dr Vogelsang will be flying the SP-250-X on his BAHS true quarter scale Corsair this year here in the USA, you may be able to catch him at one of the east coast events as of this summer.

The Moki and the gear-drive will of course be serviced here in the USA by us should the need arise. Annual service intervals are required.

The motor with gear-drive comes to 6595 gr, just 780 gr more than the regular S250, or 1.7lbs.

We are still testing prop variants, that is what this years testing is mostly about, right now we are looking at

3-Blade Props 38" and larger, for example FW-190, Wildcat, Corsair

4-Blade Props 35" and larger, for example Corsair, Thunderbolt, Bearcat

5-Blade Props 34" and larger, for example Seafury

Additional information:

Planetary drive:
As with most Aviation products low weight was of utmost importance, hence the planetary drive needs to be inspected once a year, with the first inspection being free of charge. You see the same in turbines, for example. High load at low weight leads to higher stress. The system is maintenance free for the owner but does need to be inspected at an interval.

The planetary drive builds very short and is mounted to the front of the engine, replacing a lot of the stock components, yet the complete gear driven motor ends up being just a hair longer than the stock motor.

These motors are tuned and inspected before the assembly of the planetary drive by our partner Heilemann in Germany. Tuning parts such as carbon pushrods (to decrease drive-train inertia) and custom valve springs (made custom for this project by one of Germany's biggest spring manufacturers) are being added to the setup.

Redesigned spark plug caps are being installed to improve contact and reliability.
An improved velocity stack has been added to decrease loss of mixture at the carb and to increase motor performance, it furthermore keeps the inside of your cowl cleaner.
The planetary drives are made and installed in Germany but serviced here by us in the USA

The assembly of this drive requires special tools, machinery and know-how. Any tampering with the unit can lead to failure of the drive and/or motor.  Hence all work needs to be done by us here in house.

MUSEUM SCALE PROPS: For all projects we will be able to offer you CUSTOM made and museum scale flying props furthermore pushing the limits of what is possible in the hobby.


Allow us to quote an enthusiast from France:
 "Congratulations Mario ! This device is the best thing since years in the R/C Giant Scale A/C world !Curious to see the result with more load on the engine. Regards from France"


Mario Seidel is not affiliated with Seidel engines. - Same last name, same country even,  completely different individual.