Build with the physics engine

A small, key-authenticated HTTP API over the same momentum-theory engine the app uses. Analyze any build, read the parts catalog and airframe types, and manage your own saved builds — from your scripts, notebooks, or apps.

Import the OpenAPI file into editor.swagger.io or any client to get a full interactive reference, or load the Postman collection and set base_url + api_key.

Quickstart

1 · Create your key

Sign in, open My account → API access, and click Create API key. The key is shown once — copy it somewhere safe. It looks like rl_…. You can hold one active key; regenerating replaces it.

2 · Authenticate

Send your key as a bearer token (the header X-API-Key is also accepted). Base URL for this instance is /api/v1.

Copycurl -H "Authorization: Bearer rl_your_key" \
  http://127.0.0.1:8765/api/v1/version

3 · Analyze a build

Copycurl -X POST http://127.0.0.1:8765/api/v1/analyze \
  -H "Authorization: Bearer rl_your_key" \
  -H "Content-Type: application/json" \
  -d '{"airframe_type":"Quad X","motor_count":4,"prop_diameter_in":7,"motor_kv":1700}'

The response has out (headline numbers — AUW, TWR, hover/cruise endurance, currents, top speed…), charts (inline SVG), and checks ([level, message] pairs).

Python

Copyimport requests
BASE = "http://127.0.0.1:8765/api/v1"
h = {"Authorization": "Bearer rl_your_key"}

r = requests.post(f"{BASE}/analyze", headers=h,
                  json={"airframe_type": "Quad X", "motor_count": 4, "prop_diameter_in": 7})
out = r.json()["out"]
print(f"AUW {out['auw_g']:.0f} g · TWR {out['twr']:.2f} · hover {out['hover_min']:.1f} min")

# save it to your library
requests.post(f"{BASE}/builds", headers=h,
              json={"name": "My quad", "params": {"airframe_type": "Quad X", "motor_count": 4}})

JavaScript (fetch)

Copyconst BASE = "http://127.0.0.1:8765/api/v1";
const h = { "Authorization": "Bearer rl_your_key", "Content-Type": "application/json" };
const res = await fetch(`${BASE}/analyze`, { method: "POST", headers: h,
  body: JSON.stringify({ airframe_type: "Quad X", motor_count: 4, prop_diameter_in: 7 }) });
const { out } = await res.json();
console.log(out.twr, out.hover_min);

Endpoints

All paths are under /api/v1 and scoped to the calling user. Builds you don't own return 404.

Quotas, credits & purchasing

Every request except version and usage spends one unit. Your plan sets a daily quota (resets at 00:00 UTC), spent first. Once it's gone, requests draw from your credit balance — credits come included with some plans, can be granted by an admin, or purchased from My account when monetization is enabled. When both are exhausted the API returns 429.