K550cc Two-Stroke Engine

Overview of the K550cc Two-Stroke Engine

The K550cc Two-Stroke Engine is a 550 cc, horizontally opposed four-cylinder powerplant designed for professional unmanned aerial vehicle (UAV) platforms that require consistent power output at altitude. The engine combines electronic fuel injection (EFI) with an ECU-controlled altitude compensation system and a turbocharger with a 1.2:1 boost pressure ratio to maintain power density as air density decreases. It produces a rated output of 40 kW (50.9 N·m) at 7000 rpm, with a continuous total output of 46 kW (52.8 N·m) and a peak total output of 51 kW (69.6 N·m) when the integrated hybrid assist motor is engaged. The engine has a dry weight of 22 kg, yielding a power-to-weight ratio of approximately 1.82 kW per kilogram in rated configuration. The engine is manufactured on an ISO 9001-certified production line and is offered with custom tuning and OEM configuration options for system integrators and UAV manufacturers.

Key Features of the K550cc Two-Stroke Engine

Electronic Fuel Injection with Altitude Compensation

The EFI system delivers precise fuel metering based on engine load, RPM, and ambient air density. The ECU continuously adjusts the air-fuel ratio as altitude changes, maintaining optimal combustion efficiency and reducing the risk of detonation or lean-run conditions at high operating altitudes.

Turbocharged High-Altitude Performance

A turbocharger with a 1.2:1 boost pressure ratio compresses intake air to compensate for reduced atmospheric pressure at altitude. This helps maintain volumetric efficiency and power output when operating above sea level, which is particularly relevant for long-endurance fixed-wing platforms that cruise at several thousand meters.

Integrated Hybrid Assist and Power Generation

The engine incorporates a 4 kW continuous-rated hybrid electric motor that can provide additional torque during takeoff and climb, or function as a 3 kW generator in generator mode to produce electrical power for onboard systems. The hybrid system is compatible with a 12S lithium battery pack. This dual-mode capability allows platform designers to reduce battery size for cruise flight while retaining electric boost for high-power phases.

Durable Construction and Materials

The crankcase is manufactured from aluminum alloy using low-pressure casting followed by T6 heat treatment for structural rigidity and thermal stability. The crankshaft is surface-hardened for wear resistance, and the pistons are phosphated-coated aluminum alloy. The cylinders are air-cooled with heavy-duty finning, and ignition is handled by a digital capacitor discharge (CDI) system. The engine has a rated time between overhauls (TBO) of 300 hours.

Technical Specifications of the K550cc Two-Stroke Engine

Applications for the K550cc Two-Stroke Engine

Long-Endurance Fixed-Wing UAVs

The engine's fuel efficiency, turbocharged high-altitude performance, and 300-hour TBO make it suitable for medium-altitude long-endurance (MALE) fixed-wing platforms used in surveying, mapping, and persistent surveillance missions.

VTOL and Hybrid Lift Platforms

The integrated 4 kW hybrid assist motor provides additional power for vertical takeoff and landing phases, while the combustion engine handles efficient cruise flight. This architecture reduces the required battery capacity and extends overall mission endurance.

Heavy-Lift Multirotor and Tilt-Rotor Platforms

For platforms requiring high power density and reliable combustion-based range extension, the K550cc engine can serve as a generator power source (3 kW continuous) or as a direct-drive propulsion unit with the recommended 34 to 35 inch propeller.

Industrial and Agricultural UAV Platforms

The engine's compatibility with both automotive-grade unleaded gasoline (94 RON minimum) and 100LL aviation gasoline provides operational flexibility for field deployments where fuel availability varies. The EFI system reduces carburetor-related maintenance in dusty agricultural environments.

FAQ About the K550cc Two-Stroke Engine

What type of fuel does the K550cc engine require?

The engine operates on 94 RON (Research Octane Number) unleaded gasoline or higher, or 100LL aviation gasoline. The fuel must be mixed with full synthetic two-stroke oil at a 50:1 ratio. The EFI system automatically adjusts fuel delivery based on ambient conditions and engine load.

Is the hybrid motor included in the base engine configuration?

The hybrid assist motor and generator are integrated components of the K550cc engine platform. The 4 kW continuous motor provides torque assist, and the system can generate up to 3 kW of electrical power in generator mode. A 12S lithium battery pack is required for hybrid operation and is specified by the platform integrator.

What is the recommended propeller size?

The engine is designed to operate with a 34 to 35 inch propeller. The exact propeller selection should be determined based on the airframe's flight profile, cruise speed, and static thrust requirements, and may require custom tuning of the ECU fuel map.

What is the time between overhauls (TBO)?

The rated TBO is 300 hours of operation. The major overhaul interval is also 300 hours. Actual service life may vary based on operating conditions, fuel quality, maintenance practices, and operating altitude.

Can the engine be customized for OEM integration?

Yes, custom ECU tuning, modified mounting configurations, and OEM-specific adaptations are available on request. Platform integrators should contact the engineering team with their airframe specifications, performance requirements, and production volume to discuss customization options.