{"openapi":"3.1.0","info":{"title":"Rocket Equation API","version":"1.0.0","description":"Rocket-propulsion maths as an API, computed locally and deterministically. The delta-v endpoint applies the Tsiolkovsky rocket equation, Δv = ve·ln(m0/mf) with the exhaust velocity ve = Isp·g0, to give the velocity change a stage can produce from its wet (fuelled) mass, dry (burnout) mass and specific impulse — the delta-v budget that determines which manoeuvres are possible. The mass-ratio endpoint inverts the equation to give the mass ratio m0/mf = exp(Δv/ve) and the propellant mass fraction required to achieve a target delta-v, and, given a dry mass, the wet mass and propellant needed — revealing the steep, exponential tyranny of the rocket equation. The burn endpoint computes the propellant mass-flow rate ṁ = thrust/ve, the burn time and the total impulse from the thrust and propellant mass, and the delta-v if the wet mass is given. Masses are in kilograms, specific impulse in seconds, exhaust velocity and delta-v in metres per second and thrust in newtons, with standard gravity g0 = 9.80665 m/s². Everything is computed locally and deterministically, so it is instant and private. Ideal for aerospace, model-rocketry, spaceflight-simulation and orbital-mission app developers, stage-sizing and trajectory tools, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is rocket propulsion; for orbital velocity and escape velocity use an orbital-mechanics API.","contact":{"name":"PremiumApi","url":"https://www.oanor.com/by/premiumapi"}},"servers":[{"url":"https://api.oanor.com/rocket-api","description":"oanor gateway"}],"tags":[{"name":"Rocket"},{"name":"Meta"}],"components":{"securitySchemes":{"oanorKey":{"type":"apiKey","in":"header","name":"x-oanor-key","description":"Get your key at https://www.oanor.com/developer/keys"}}},"security":[{"oanorKey":[]}],"paths":{"/v1/burn":{"get":{"operationId":"get_v1_burn","tags":["Rocket"],"summary":"Burn time","description":"","parameters":[{"name":"thrust","in":"query","required":true,"description":"Thrust (N)","schema":{"type":"string"},"example":"10000"},{"name":"propellant_mass","in":"query","required":true,"description":"Propellant mass (kg)","schema":{"type":"string"},"example":"600"},{"name":"specific_impulse","in":"query","required":false,"description":"Specific impulse Isp (s)","schema":{"type":"string"},"example":"300"},{"name":"exhaust_velocity","in":"query","required":false,"description":"Or exhaust velocity (m/s)","schema":{"type":"string"}},{"name":"wet_mass","in":"query","required":false,"description":"Wet mass for delta-v (kg)","schema":{"type":"string"}}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"Mass flow ṁ = thrust/ve; burn time = propellant/ṁ. Total impulse = thrust × burn time. A higher Isp burns propellant more slowly for the same thrust.","inputs":{"thrust":10000,"propellant_mass":600,"exhaust_velocity_ms":2941.995},"burn_time_s":176.5197,"total_impulse_ns":1765197,"mass_flow_rate_kg_s":3.399054},"meta":{"timestamp":"2026-06-05T11:30:28.929Z","request_id":"155d5c57-12bf-49f8-8bba-dace7e3b697c"},"status":"ok","message":"Burn time","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/delta-v":{"get":{"operationId":"get_v1_delta_v","tags":["Rocket"],"summary":"Tsiolkovsky delta-v","description":"","parameters":[{"name":"wet_mass","in":"query","required":true,"description":"Wet mass m0 (kg)","schema":{"type":"string"},"example":"1000"},{"name":"dry_mass","in":"query","required":true,"description":"Dry mass mf (kg)","schema":{"type":"string"},"example":"400"},{"name":"specific_impulse","in":"query","required":false,"description":"Specific impulse Isp (s)","schema":{"type":"string"},"example":"300"},{"name":"exhaust_velocity","in":"query","required":false,"description":"Or exhaust velocity (m/s)","schema":{"type":"string"}}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"Tsiolkovsky rocket equation Δv = ve·ln(m0/mf), with exhaust velocity ve = Isp·g0. The Δv budget determines what manoeuvres a stage can perform.","inputs":{"dry_mass":400,"wet_mass":1000,"exhaust_velocity_ms":2941.995},"delta_v_ms":2695.7228,"mass_ratio":2.5,"delta_v_kms":2.695723,"propellant_mass":600},"meta":{"timestamp":"2026-06-05T11:30:29.002Z","request_id":"58686881-d5a9-4a92-a24a-464976b13b9d"},"status":"ok","message":"Delta-v","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/mass-ratio":{"get":{"operationId":"get_v1_mass_ratio","tags":["Rocket"],"summary":"Mass ratio","description":"","parameters":[{"name":"delta_v","in":"query","required":true,"description":"Target delta-v (m/s)","schema":{"type":"string"},"example":"2695.7"},{"name":"specific_impulse","in":"query","required":false,"description":"Specific impulse Isp (s)","schema":{"type":"string"},"example":"300"},{"name":"exhaust_velocity","in":"query","required":false,"description":"Or exhaust velocity (m/s)","schema":{"type":"string"}},{"name":"dry_mass","in":"query","required":false,"description":"Dry mass to size propellant (kg)","schema":{"type":"string"},"example":"400"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK","content":{"application/json":{"example":{"data":{"note":"Required mass ratio m0/mf = exp(Δv/ve). 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