An elevon is a control surface on the trailing edge of a tailless aircraft — a delta wing, flying wing, or blended wing body — that combines the functions of ailerons (roll) and elevator (pitch) in a single pair of surfaces.
Mixing logic: The flight controller mixes pitch and roll commands to drive the two elevons:
- Pitch up: Both elevons deflect trailing-edge-up (symmetric).
- Pitch down: Both deflect trailing-edge-down (symmetric).
- Roll left: Left elevon up, right elevon down (differential).
- Combined: Superposition of pitch and roll commands. A simultaneous pitch-up and roll-left command deflects the left elevon further up while the right elevon is near neutral.
Elevons are the standard control system for delta-winged expendable drones (Shahed-136, LUCAS, and derivatives), flying-wing stealth UAVs (RQ-170, nEUROn), and many hobbyist flying-wing designs. They reduce part count to just two servos — the minimum for controlled fixed-wing flight.
The limitation of elevons is coupling: a large pitch command reduces the roll authority available (the elevons are already near full deflection for pitch), and vice versa. This limits the total control authority compared to a conventional layout with independent surfaces. For most UAV flight envelopes, this limitation is not operationally significant — the flight controller manages the mixing and saturates gracefully.
Split elevons (each elevon divided into upper and lower halves that can deflect independently) provide rudder-equivalent yaw control through differential drag — opening one split elevon like an airbrake while the other remains closed. This adds two more servos but provides three-axis control without a vertical tail.
Related terms
- Aileron — the dedicated roll surface on conventional aircraft
- Elevator — the dedicated pitch surface on conventional aircraft
- Control Surface — the general category