Ask in your own words — or tap one of the common problems. The Flight Doctor works out what's actually wrong and how to fix it before your next flight.
After enough crashes, you learn that almost every "it just won't fly" ends up being one of a handful of causes. The troubleshooter above walks you to the specific one. Here's the short version of what it's looking for.
Pull back on the stick and the elevator goes down — the plane leaves your hand and dives straight in. It's the single most common first-flight crash there is, and it's free to prevent: stand behind the plane before every flight and confirm stick-back raises the elevator, stick-right raises the right aileron.
Tail-heavy planes zoom, stall, and flop over no matter how good your thumbs are. Nose-heavy planes won't rotate and land hard. The CG belongs about 25–30% back from the wing's leading edge, and the Airplane Designer gives you the exact number for your wingspan and style.
A backwards prop makes plenty of noise and hardly any thrust. The raised numbers on the blade — 9×4.7, for example — always face forward, toward the nose. If they already do and the air still blows the wrong way, swap any two of the three motor wires at the ESC.
If it lifts off and mushes back down, the wing is overloaded. Weigh the plane, then check wing loading in the calculators. A lighter battery is the fast fix; a bigger wing is the right one.
Foam board hides its injuries. A crease you can barely see can cut a wing's strength in half — that's exactly how my slow flyer folded a wing mid-air days after a small crash. If the plane has been in a wreck since it last flew well, flex-test the wings before you trust it.
New to all of this? Start with the beginner path, or design a plane that flies on the first toss with the Airplane Designer.
CG, wing loading, thrust, and control throws — worked out before you cut any foam.
Open the Airplane DesignerSee the exact hookup for your battery, ESC, receiver, and servos — and the mistakes that fry parts.
Open the Wiring DesignerEvery fix on this page came from something breaking on camera first.
See the build projectsFound the problem? Re-check the design so it doesn't come back, or grab the right part from the gear guide.
