Tenshock GDM1520B Planetary Gear 4.75:1 135g

Tenshock GDM1510B Planetary Gear Drive Motor – 1KW Power, Precision, and Performance without the price tag.

The Tenshock GDM1520B is a game-changing planetary gear drive motor that delivers 1 KW of premium performance at a fraction of the cost. Featuring a compact, ultra-efficient 4.75:1 planetary gearbox paired with a high-performance brushless inrunner motor, it punches well above its weight—matching the output and reliability of systems priced three times higher.

Designed for pilots who demand exceptional performance, smooth operation, and easy maintenance, the GDM1520B offers all the advantages of a geared setup - without breaking the bank.

Engineering highlights

• All-metal 3-planet gearbox – shot-peened steel gears and needle-roller planet carriers for ISO class-6 concentricity and long life under 50 A burst loads.
• High-density 15 mm inrunner – 0.1 mm laminations and N35SH magnets keep core losses low at 50 k RPM.
• CNC-machined 6061-T6 case – ribbed exterior for efficient heat shedding without excess mass.
• 30mm motor diameter and 24mm front flange diameter allowing installation in the narrowest of fuselages.
• Field-replaceable gearset – front cover removes with four screws; a full rebuild averages <10 minutes.

Typical applications
3m - 4m F5J ballasted sailplanes needing sub-140 g front ends and 3 kg+ launch thrust (or 2kg thust with 130 kph pitch speed).
2m - 3m Hotliners needing 1KW powertrains
F3G / GPS-light models on 4S - 5S LiPo where climb rate matters most.
High-performance sport gliders or electric retrofits where nose ballast can be replaced by power.

What you get
GDM1520B motor with factory-installed 4.75 : 1 gearbox
Hardened 5 mm output shaft (flat-ground)

At much less than half the cost of premium gear drives—and weighing less than many direct-drive outrunners—the Tenshock S-GDM1520B delivers competition-ready punch without punishing your budget or wing loading. Drop it in, spool it up, and watch your model rocket skyward.

(c) 2025 Neil Stainton


From a post by Jo Grini on Facebook:

Some of you might have noticed I used the new Tenshock geared motor in the World Masters GPS Triangle light class competition (using the 2PK Pro). I asked for 2 of the motors with the new gear that should be very strong and durable. This is the new version after they learned a lot from the last one. I really like that they still use needle bearings that gets lubrication with the gears instead of the usual closed bearings.

So for GPS I ordered a Tenshock 1520 with 3850KV and a AX60 controller. My preferred prop is the CCM13x9 but they provided also a Falcon 14x9.5 (very stiff actually) and a cute carbon spinner i opted to use. All flights were done with 2600g model and 4S900mah battery. Beware a 4S1200-1400mah would be more safe if you need a lot of climbs but it was sufficiant for me as usage was max 400-450mah on first climb to 250-300m and I had a few extra climbs now and then. I like the motor/controller and will continue to use it since it very efficient for GPS use since we are flying very heavy models almost always. Next might be Radolfcell were we might see new rules and 3000g models. So will use some 4S2P1200mah probably since usage will for sure go up. Amps are around 50A and 60A startup (first seconds untill the plane moves). Motor is not getting hot. On one occation I had to be very fast to reach the start window. 250m was reached in less than 30seconds and that is nice with a 2600g model ;-)

For F5J use I ordered the Tenshock 1510 4550kv (or might actually work in GPS also but needs to test with temerature probe). Have had about ten flights on it and today I did a few extra tests to see if I gained anything by using a smaller prop. The amps go down but time up off course. Each test with 5-10min beetween but motor was not hot and had no problems touching it (I get my finger in but did not use a temp probe). Controller (AX40) was barely feeling hot so about 35-40C probably. I used a Alti's with altimiter switch on 250m for fun as I have an old one with bad display. The usual 4s900mah Gensace and CCM 12x6 prop gives 37A startup and around 30-32A while climbing. 4s900 and CCM13x9 or Falcon 14x9.5 gives 60A startup and around 45-50A climbing on max. Have to meassure again with logger to be sure but the amount of mah used (220-230mah) seems to verify that. Overall very happy with the motors. It was also very easy to direct solder to esc and shave off a few grams.

On a side note I can say I am not sponsored by neither Dualsky, Xpower or Tenshock. But I enjoy testing all brands. For F5J with lighter planes one might say that a direct drive is plenty enough since planes are generally light and motor time short. But for GPS light class flying with heavy 4m models my idea is that a geared motor is reducing the need for extreme batteries and I can use bigger diameter props that will allow very safe launches. Yet I am still using much higher power than most actually need. Just because I like it ;-)