OpenEarth and OpenWind - ROCKET SIMULATOR TOOLS

Simulador 02

Atmospheric wind profile for OpenRocket · MOST + Pasquill-Gifford + Ekman

GFS · Historical Forecast Monin-Obukhov Open-Meteo API Ekman Spiral

📖 About

⚙ Configure

📄 CSV

🌡 Atmosphere

🚀 OpenRocket

01 — The problem

Why does wind matter in rocket simulations?

OpenRocket simulates ballistic rocket trajectories. Wind is the main factor for lateral deviation — especially in the first seconds, when speed is low. A constant profile ignores the fact that wind changes completely with altitude.

In practice, wind at 10 m AGL can be 3× lower than at 500 m AGL, and the direction can rotate 20–40° between the surface and apogee. Using a single value underestimates deviation in unstable conditions.

🎯
Landing precision
Real profile reduces impact zone prediction error by up to 60% vs. constant wind
📐
Stability margin
Gusts and shear affect angle of attack — critical for rockets with low CP-CG margin
🛡️
Range safety
Simulating with a realistic profile defines the fall ellipse with much more confidence

02 — Data pipeline

Where does the data come from?

OpenWind combines two global numerical weather prediction sources (NWP) with a proprietary boundary layer model. The source is automatically selected by date.

GFS — Global Forecast SystemNOAA / today +15 days

NOAA global spectral model, 4×/day. ~13 km grid, 127 vertical levels. Available for 0 to 15 day forecasts.

api.open-meteo.com/v1/forecast

Historical ForecastArchive since 2022

High-resolution GFS/ECMWF-ERA5 reanalysis. 1-hour temporal resolution. Dates 2022–today.

historical-forecast-api.open-meteo.com

Pressure levels30 ISA levels

30 isobaric levels: 1000 to 10 hPa. Each level is converted to AGL altitude. Levels below terrain are discarded.

hPa → m MSL: 44330·(1−(p/1013.25)^0.1903) − elevação

Boundary layer synthesis — OpenWindProprietary model

NWP models have coarse vertical resolution exactly where wind changes the most (0–500 m AGL). OpenWind fills this gap with MOST, power law, and Ekman spiral. Adaptive spacing: 5 m up to 50 m, 10 m up to 200 m, 25 m above.

Synthesized levels marked [SYNTHESIZED PG:X] in CSV

OpenWind_File.csv — final outputOpenRocket ready

Synthetic levels + observed levels, sorted by AGL altitude. Columns: altitude (m AGL), speed (m/s), direction (°), stddev (m/s).

altitude,speed,direction,stddev

03 — CSV anatomy

How to read the generated file

OpenWind_File.csv — annotated structure

# OpenWind_File.csv — OpenWind # Fonte obs.: GFS Seamless (NOAA via Open-Meteo) ← NWP source used # Terrain: Open field (z0=0.03 m, alpha=0.15) ← roughness and exponent # Location: 22.0000°S, 46.5000°W | Terrain: 850 m MSL # Date/time: 2025-11-15T15:00Z UTC # Obs. levels: 12 | Synth. levels: 18 ← how many of each type altitude,speed,direction,stddev # [SYNTHESIZED - terrain:open z0=0.03m PG:C] ← stability class 2,1.823,248.3,0.241 287,5.120,252.0,0.410 ← first observed level

04 — Physical model

Boundary layer equations

4a. Pasquill-Gifford: based on local solar time and reference wind speed.

Class	Condition	Obukhov L (m)	Aσ
A	Daytime, <2 m/s — very unstable	−10	2.7
B	Daytime, 2–3 m/s — unstable	−25	2.5
C	Daytime, 3–5 m/s — slightly unstable	−80	2.3
D	Strong wind — neutral	±∞	2.2
E	Nighttime, 2–4 m/s — slightly stable	+100	1.9
F	Nighttime, <2 m/s — very stable	+30	1.6

MOST — wind speed in surface layer (<200 m AGL)

u(z) = (u★ / κ) · [ln(z / z₀) − ψ_m(z/L) + ψ_m(z₀/L)]

u★ — friction velocity · κ = 0.41 · z₀ — terrain roughness · L — Obukhov length

Ekman Spiral — wind direction

H_E = 0.25 · u★ / f Δφ(z) = Δφ_max · e^{−z / H_E}

f = 2Ω·sin(|φ|) — Coriolis parameter · H_E — Ekman depth

Maximum altitude AGL

Maximum altitude (m above ground)Only levels with altitude ≤ this value are included.

Launch site

Latitude (°)South = negative

Longitude (°)West = negative

Terrain altitude (m MSL)MSL altitude of the point

Launch date and time (UTC)

Data

UTC Time

Terrain type

Select a terrain type above.

Automatically selected source

—

Select a date above

○Configure and click "Generate OpenWind_File.csv" in the ⚙ Configure tab.

🌡

Generate the profile first to see atmosphere data.

Follow the steps below to import the profile into OpenRocket.

── Step 1: Import the wind profile Edit › Simulation options › Wind › Custom wind → Click Import CSV → Select the file OpenWind_File.csv ── Step 2: Configure the import dialog CSV file has a header row: ✓ MARCADO Field Separator: , (comma) Altitude → column: altitude unit: m Speed → column: speed unit: m/s Direction → column: direction unit: ° Std Dev → column: stddev unit: m/s ALTERAR ALTITUDE REFERENCE: ABOVE GROUND LEVEL (AGL) ── Step 3: Configure the atmosphere Edit › Simulation options › Atmosphere OpenRocket requires only two values — temperature and pressure referring to the ground at the launch base: → Temperatura: — (generate the profile first) ↳ air temperature at ~2 m height at the launch site → Pressão: — (generate the profile first) ↳ atmospheric pressure at ground level at the base (terrain level, not sea level)

⚠ [SYNTHESIZED] lines in the CSV are produced by the physical boundary layer model: MOST (Monin-Obukhov) with Businger-Dyer correction, power law above, Ekman spiral for direction, and Pasquill-Gifford classification. For recreational rockets (< 3 km) they are physically and statistically realistic.