Free · Runs in your browser

Preliminary aircraft design, for builders and engineers

Size your airplane, then check the wing spar that carries it. Two free tools for Part 103, Light Sport and Experimental amateur-built designs, with no spreadsheet to maintain and no account to create.

Start designing → How it works
First-pass numbers to start from, not a certification.

Two tools, one workflow

Start with the airplane, then take the same design into the structure. Everything you enter is kept in your browser, and a share link reopens any design.

01

Aircraft Sizing

Nine steps from category to a complete sizing summary.

  • Weight, wing loading and wing geometry
  • Airfoil, fuselage, tail and power
  • Compared against reference aircraft, with flags for numbers that look wrong
Open Aircraft Sizing → 02

Structural Sizing (V-n)

Takes your design and checks the wing spars in six steps.

  • Load factors and the V-n diagram
  • Bending, shear and torsion checks on main and rear spars
  • Compare two spar options side by side
Open Structural Sizing →

What you get

Built for the stage before you cut anything.

Instant feedback

Change a number and see how it moves everything downstream.

Flags that point to the fix

Click a warning and jump straight to the input that causes it.

Export anywhere

CSV, JSON or a PDF report, ready for OpenVSP, XFLR5 or your own spreadsheet.

Share a design

One link reopens your design exactly as you left it.

Honest about its limits

A first-pass tool earns trust by saying exactly where it stops.

Good for
  • Sizing a design from a blank page
  • Sanity-checking your numbers against reference aircraft
  • A first-pass check of the wing spars
  • Comparing two options before you commit
Not for
  • Certification compliance or airworthiness analysis
  • A structural sign-off, since lift distribution and section properties are simplified
  • Replacing CFD or finite-element analysis
  • Cutting material
  1. 1Size it hereGet a defensible baseline
  2. 2Validate itXFLR5, OpenVSP, CFD or FEA
  3. 3Have it reviewedA qualified engineer signs off
  4. ✈Then buildOnly after all three
Feedback

Tell me where the numbers don't match your aircraft.

This tool is built in the open, and your design is the best test it will ever get. A two-minute note shapes what gets built next.

  • Did a result look off compared with a design you know?
  • Which step slowed you down or confused you?
  • What would you want the next tool to check?
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