Building a Fixed-Wing FPV Plane: Wing Loading, CG and Motor Selection
There is a special satisfaction in watching a fixed-wing plane you built yourself climb out on a calm morning, the video feed rock steady and the motor barely audible. Fixed-wing FPV offers flight times that quads can only dream of, and a well-built airframe rewards good engineering with hours of peaceful cruising. But fixed wings are less forgiving of sloppy decisions than quads. Three factors — wing loading, center of gravity, and motor selection — decide whether your build soars or stalls. Here is how to get each one right.
Wing Loading: The Number That Predicts Handling
Wing loading is the total weight of your aircraft divided by its wing area, usually expressed in grams per square decimeter. It is the single best predictor of how a plane will fly. A lightly loaded plane glides gently, stalls slowly, and is easy to launch and land. A heavily loaded one flies fast, needs more power to stay airborne, and can be a handful near the ground.
For a first fixed-wing FPV build, aim for a wing loading on the lighter side. Bigger wings, a modest battery, and a disciplined approach to adding gear all help. Every camera, servo, and gram of reinforcing tape adds weight that the wing must carry, so weigh components before you commit to them.
Center of Gravity: The Difference Between Flying and Crashing
Center of gravity, or CG, is the point where the aircraft balances. A plane that is nose-heavy flies stable but needs constant up-elevator and lands fast; one that is tail-heavy is twitchy and can pitch into an unrecoverable stall on the first launch. The manufacturer’s recommended CG is a starting point, not a law, but you should always begin there and move it back only in tiny increments.
Balance the plane with the battery installed, fingers under the wings at the marked point. Adjust by sliding the battery or adding small weights. Mark the final battery position so every launch is identical. A plane that balances the same way every flight will fly the same way every flight.
Motor and Prop Selection
Unlike a quad, a fixed wing spends most of its time at partial throttle, so raw thrust matters less than efficient cruise. Pick a motor sized for your plane’s weight — a rough guide is around 100 watts per kilogram for relaxed cruising, and more for aerobatics or heavy payloads. Match the propeller to the motor’s Kv rating and the battery voltage so the motor spins in its efficient range rather than screaming at full throttle the whole time.
An oversized motor on a small plane adds weight and current draw for no benefit, while an undersized motor means the plane barely climbs. Read the motor’s thrust table, choose a prop that gives comfortable thrust at around half throttle, and confirm the ESC is rated well above the peak current you will actually draw.
Servos and Control Surface Setup
Fixed-wing control depends on servos, and a stripped or sluggish servo is a common cause of mystery crashes. Choose metal-gear servos for anything that moves a primary control surface, and set mechanical throws so the surface reaches full deflection without the servo binding. Always test control surface direction from behind the aircraft — a reversed elevator on the maiden launch is a classic, avoidable disaster. A few minutes of careful servo setup on the bench saves an entire airframe in the field.
Putting It Together
Fixed-wing FPV rewards patience. Build light, balance carefully, and size the power system for cruise rather than brute force. Double-check control surface direction before every maiden flight, and do not be afraid to glide test without power first. Get these fundamentals right and your plane will reward you with the kind of smooth, efficient flight that quads simply cannot match.