SP-28 Series

The 2-stroke single cylinder SP-28 CR with 28 ccm is the longest standing engine in our lineup and well known by industry veterans for its robustness and longevity for many years.

The Sky Power SP-28 CR is still our most requested system and particularly suited for fixed wing aircraft on the upper end of the “below 55 lb” or “up to 25 kg” class UASs. The 3W-International SP-28 CR engine is equipped in the standard configuration with one spark plug and a single ignition unit. The carburetor is rear (CR) mounted.

The cylinder and crankcase are casted aluminum and have been manufactured in its current form for over a decade. One customer is running this propulsion system for 10+ years and accumulated more than 1,000,000 flight hours, it is a reliable work horse in all operational scenarios.

SP-28 CR

Additional information


1-Cylinder gas engine


28 ccm / 1.71 cu in


2.2 hp / 1.6 kW @ 6600 rpm

Speed Range

2500 – 10000 rpm


2.95 lbs (1.34 kg) incl. ignition


3 ball bearings

Oil/Gasoline ratio

1:50 / 2 % mix

Operating Voltage

6 – 8.4 V DC

Bore diameter

1.42 inch (36.00 mm)


1.10 inch (28.00 mm)


2.3 Nm @ 6600 rpm