40.1 kW start-motor UAV engine with low-vibration opposed-cylinder design, electronic injection, lightweight construction, 2 kW onboard power generation, auto-brake safety shutdown, and optional high-thrust carbon fiber propeller—ideal for fixed-wing, composite-wing, and target drone applications.

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UAV Engine ModelsQS27A 20KWQS27B 20KWQS55A 40KWQS55B 40KW

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📘 PRODUCT DESCRIPTION

The QS55B Start-Motor Engine is a powerful and lightweight propulsion system engineered for medium-class UAVs seeking high thrust performance, fast deployment capability, and exceptional flight stability.
Delivering 54.5 hp (40.1 kW) of rated power, the QS55B supports a wide 1500–6500 RPM operating band optimized for climb, cruise, and high-speed tactical maneuvering.

Designed around a horizontal-opposed cylinder architecture, the QS55B significantly reduces vibration, improving payload stability and extending airframe life.
Its electronic injection system ensures consistent fuel-air delivery, supporting fuel consumption below 350 g/kWh when using 92# gasoline and above, with a 50:1 oil-fuel ratio.

The QS55B integrates a quick-disassembly module, enabling rapid maintenance in field operations.
Its auto-brake shutdown system actively stops propeller rotation after engine cutoff, improving ground-handling and landing safety during mission cycles.

Weighing less than 20.7 kg, the engine provides an exceptional power-to-weight ratio suitable for 150–300 kg-class UAVs.
Although this version does not include an integrated start generator, it supports 2 kW @ 28V onboard power generation, ensuring steady supply for avionics and mission payloads.

An optional high-performance carbon fiber propeller delivers >89 kgf static thrust and >60 kgf dynamic thrust at 50 m/s, adding only +1.0 kg, ideal for heavy-load or high-altitude applications.

⭐ Key Advantages

• High Power Output (54.5 hp / 40.1 kW)

Provides strong propulsion for takeoff, climb, high-load missions, and rapid-response target drone operations.

• Horizontal-Opposed Low-Vibration Engine

Stabilizes sensitive surveillance payloads and minimizes structural fatigue during long-endurance missions.

• Lightweight Design (<20.7 kg)

Optimized for UAVs requiring strong thrust-to-weight performance.

• Intelligent Electronic Injection System

Delivers efficient combustion and stable performance across the 1500–6500 RPM band.

• Auto-Braking Safety Shutdown

Immediately halts propeller rotation for safer landing and maintenance operations.

• Quick-Detach Maintenance Structure

Supports fast field servicing and high mission availability.

• Optional Carbon Fiber Propeller

• Static thrust: >89 kgf

• Dynamic thrust: >60 kgf @ 50 m/s

• Additional weight: +1.0 kg
  Ideal for target drones and tactical fixed-wing platforms.

📊 Technical Specifications

✈️ Application Scenarios

• Fixed-Wing UAVs

Long-range ISR, maritime patrol, and tactical surveillance missions.

• Composite-Wing UAVs

Aerodynamic hybrid configurations requiring efficient, stable propulsion.

• Target Drones

High-speed maneuvering, rapid acceleration, and responsive tactical flight training.

• 150–300 kg UAV Platforms

Designed for medium-class military and industrial UAV systems.