Design a plane from your requirements
Tell it the mission, size and stall speed. The designer then works out the airframe and the weight breakdown, and checks stability and performance with real (simplified) aerodynamics. It also matches a motor and prop, shows the plane in 3D, and hands everything to the Build page for printable templates.
Engineering estimates. The models are classical and simplified: weight build-up, Helmbold lift slope, tail-volume neutral point, Prandtl lifting line, a drag build-up, and a motor-constants model. They are useful for comparing options and catching mistakes. They do not replace XFLR5, eCalc, a watt meter, or a careful CG check before the first flight.
1Requirements & sizing
Weight breakdown Estimate
How the weight is estimated
2Airfoil
Import a real airfoil (.dat)
Download coordinates (Selig or Lednicer format) from the UIUC Airfoil Coordinates Database or Airfoil Tools, then load the file or paste the text here. Everything stays on your computer.
3Geometry & weight
Fine-tune the airframe the sizer produced. Every analysis below updates live.
4Stability & CG
Where to balance Estimate
How it was calculated
As built (measured) Physics
Weigh the finished plane and find its balance point (support it under the wing at equal distances from the fuselage). Enter the measurements here: the stability analysis, performance, 3D model and simulator then use your real plane instead of the estimate.
Multi-panel wing CG calculator Physics
For wings with several panels (for example a straight centre section with tapered or swept tips): integrates the planform for area, MAC and its position, then puts the CG at the target static margin. Neutral point is at the MAC quarter-chord (exact for a tailless wing; a tail moves it aft).
5Wing analysis (lifting line)
Prandtl lifting-line theory solves the spanwise lift on your tapered, twisted wing. It shows how close the wing is to ideal (elliptic) loading and where the stall starts: tip stall causes a wing drop, root stall is gentle. Sweep is not modelled.
Spanwise lift distribution at cruise
Normalised load cl·c / (CL·cmean) compared with the ideal elliptic shape.
Local cl ÷ clmax at the onset of stall
The first point to touch 1.0 stalls first. Add washout or reduce taper if this is near the tip.
How it was calculated
6Flight performance
Thrust available vs drag
Where the lines cross is the top speed; the gap is climb.
Electrical power required
The bottom of the curve is the most efficient (longest-endurance) speed.
Glide polar (motor off)
Sink rate vs airspeed. The lowest point is best for thermals.
How it was calculated
Flight logs & calibration Physics
7Power system matching
An eCalc-style motor model (Kv, winding resistance Rm, no-load current Io, battery resistance) finds the real operating point of each motor and prop combination. It keeps the ones inside the motor's limits and ranks them by how well they fit your plane.
Best matches Estimate
Motor database (typical class values + your own motors)
Built-in entries are typical values for each motor size class, not specific products. For accurate results add your motor from its data sheet (Kv, Rm in Ω, Io in A, limits).
83D model
A live 3D model lofted from your airfoil and geometry. Drag to orbit, scroll or pinch to zoom; with the model focused, use the arrow keys and + / −. STL export gives a shell for Fusion, Blender or slicers (a visual model, not a print-ready airframe).
Drag to rotate · scroll to zoom
9Save & compare designs
Saved designs live in this browser (localStorage). Tick up to four to compare side by side.