Which type of sUAS is best suited to be powered by an internal combustion engine?

• A. Multirotor
• B. Rotorcraft
• C. Hybrid VTOL
• D. Fixed wing

Answer: (D)

Fixed-wing sUAS are best suited for internal combustion engines because they gain the most from the high energy density of liquid fuels during sustained, forward-flight operation. In fixed-wing flight, lift comes from the wings as the aircraft moves through the air, so propulsion efficiency during long cruise is what matters most. Liquid fuels provide long endurance and greater payload potential without needing frequent refueling or heavy battery mass, making ICEs advantageous for longer missions.

Multirotor and rotorcraft rely on electric motors to enable stable hover and vertical takeoff/landing; adding an internal combustion engine would add weight, vibration, cooling and fuel logistics challenges, and would not improve hover efficiency. Hybrid VTOLs can use ICE for cruise, but for the straightforward, efficient long-endurance role, fixed-wing designs benefit most from an ICE.