Weight-Budget Builder

Module 10's core habit — build the weight budget in a spreadsheet before ordering anything — as a live tool. It opens pre-filled with the reference build (420 g dry, 650 g all-up), so the numbers you see first are the ones the modules derive by hand: TWR 9.2, ~33 % hover, ~11 min hover endurance.

Edit any weight, add or remove parts, swap the pack — and watch the whole chain react. Hover power is scaled from the reference build's 122 W by the $m^{3/2}$ law from Module 2, so estimates stay honest for builds in the 5″ neighbourhood; for a very different airframe, do the full disk-area math in Module 2 instead.

Component	Grams

Battery weightgCells in series (S)SCapacitymAhMax thrust per motorgMotors×

Dry weight420 g

All-up weight650 gover 250 g — registration territory (Module 13)

TWR9.2freestyle band (8–12)

Hover≈ 33 %≈ 122 W

Hover endurance≈ 11.4 minfreestyle: divide by 2–3

Reading the results:

• Every gram costs three times — thrust-to-weight, hover power and endurance (Module 10's what-if table walks the classic cases: +120 g of GoPro takes the reference build to 770 g and TWR 7.8).
• The regulatory note is a design input, not trivia — crossing 250 g or 900 g changes your legal category entirely (Module 13).
• Predict, then verify: Module 10's mastery bar is predicting your finished AUW within 5 %. Weigh the real build and compare — the pre-maiden checklist has a line for exactly that.

Thrust numbers are the soft input

Weights are exact — a scale settles arguments. Thrust-per-motor comes from manufacturer tables and is optimistic by nature (Module 2's caution applies). When in doubt, enter the table value and treat the resulting TWR as an upper bound.