Desktop utility for aerospace engineers and designers. Replaces ad-hoc Google searches for unit conversions, atmospheric data, and FEM/CFD solver unit systems. Bilingual — CS / EN.
28 categories, ~145 units — SI and imperial, covering the units found in Niu and Bruhn literature.
Live recalculation as you type. Entire table of all units updated at once — one glance answers "100 KTAS = ? m/s = ? km/h = ? ft/s". Double-click any table row to copy the value. Type a unit into the search box (e.g. psi) to jump straight to its category.
| Category | Notable units |
|---|---|
| Length | m, mm, in, ft, NM |
| Speed | m/s, kt (KTAS/KIAS/KEAS), ft/min, mph |
| Pressure / Stress | Pa, MPa, psi, ksi, psf, kgf/mm² |
| Force | N, kN, lbf, kip, kgf |
| Mass | kg, slug, slinch (lbf·s²/in) |
| Density | kg/m³, t/mm³ (Abaqus), lb/in³, slug/ft³ |
| Second Moment of Area | m⁴, mm⁴, in⁴ |
| Fracture Toughness | MPa·√m, ksi·√in |
| Areal Weight | kg/m², g/m², oz/yd² (fabric) |
| Temperature | K, °C, °F, °R — plus a separate ΔT category (no offset!) |
| Running Load / Shear Flow | N/mm, kN/m, lbf/in, lbf/ft |
| Mass Flow | kg/s, kg/h, lb/min, lb/h |
| SFC | TSFC g/(kN·s), lb/(lbf·h) · BSFC g/(kW·h), lb/(hp·h) |
| … and more | moment, energy, power, viscosity, spring stiffness, angular velocity… |
Pick a solver → see consistent unit system combinations with reference material values:
- Abaqus — SI (m), SI (mm/t/s), US (in/slinch), US (ft/slug)
- Nastran — same +
WTMASSnote for lb/in³ density models - OpenFOAM — SI only; note on kinematic pressure p/ρ for incompressible solvers
- PAM-CRASH — (mm/g/ms) → MPa and (mm/kg/ms) → GPa crash systems
Each table includes reference material properties (steel, aluminium) in every unit system.
US Standard Atmosphere 1976, 0–86 km.
- Input: altitude in m / ft / km / FL — geometric or pressure altitude (toggle), optional ΔISA offset
- Output: T, p, ρ, speed of sound (m/s + kt), dynamic and kinematic viscosity, σ, δ, θ, 1/√σ (TAS↔EAS factor), geometric / geopotential / density altitude
- Built-in σ/δ/θ profile plot with a marker at the current altitude (native canvas — no plotting library needed)
Compressible subsonic conversions tied to the ISA model:
- Input: altitude (pressure or geometric) + ΔISA + speed as CAS / EAS / TAS / Mach in kt, km/h, m/s, mph, ft/s
- Output: all four speed definitions side by side, dynamic pressure q = ½ρV² (Pa + psf), impact pressure q_c, speed of sound, 1/√σ
- Honest about IAS: IAS = CAS + instrument/position error — the app says "IAS ≈ CAS" instead of pretending to know your calibration curve
29 common aerospace materials with SI and imperial side by side, full-text search, and user-editable library:
Al 2024-T3, 2014-T6, 6061-T6, 6082-T6, 7075-T6/-T73, 7050-T7451, 5052-H32 · Mg AZ31B · Ti-6Al-4V, Ti-3Al-2.5V, Ti Grade 2 · Steel 4130, 4340, 300M, 17-4PH, 15-5PH, 304 · Inconel 718 · C/epoxy UD, fabric and quasi-isotropic · E-glass/epoxy · Kevlar 49/epoxy · Sitka spruce · Birch ply · Rohacell 51 IG · Divinycell H80 · Balsa
Add your own materials — saved automatically to user_materials.json. Export/import JSON libraries to share with colleagues.
Any table (converter, solver systems, ISA, airspeed, materials) can be copied to the clipboard as TSV (pastes straight into Excel) or saved as CSV — two toolbar buttons, always acting on the active tab.
⚠️ Indicative typical values only. For structural substantiation use MMPDS / CMH-17 or the material data sheet.
Requirements: Python 3.11+, Windows (primary); Linux/macOS may work for development.
pip install -r requirements.txt
python main.pyUser settings and custom materials are stored next to the sources in development, or in %APPDATA%\AE_UNITS for frozen builds. Place an empty file named portable next to the .exe to keep data beside the executable instead.
Pre-built .exe releases are available on the Releases page.
To build yourself (PyInstaller):
pip install -r requirements-build.txt
BUILD_EXE.batOr equivalently:
python -m PyInstaller --noconfirm main.spec(main.spec collects CustomTkinter assets and produces dist\AE_UNITS.exe.)
Nuitka alternative: BUILD_EXE_NUIT.bat
AE_UNITS/
├── main.py
├── requirements.txt
├── requirements-build.txt
├── main.spec # PyInstaller (collects CustomTkinter)
├── core/
│ ├── units.py # unit definitions and conversion engine
│ ├── isa.py # ISA 1976 model + pressure/density altitude inversion
│ ├── airspeed.py # CAS/EAS/TAS/Mach compressible conversions
│ ├── formatting.py # global number format state
│ ├── i18n.py # localization engine (CS / EN)
│ ├── paths.py # resource / writable dirs (dev, PyInstaller, Nuitka)
│ ├── settings.py # persistent user settings (settings.json)
│ └── user_materials.py # custom material persistence
├── data/
│ ├── solver_systems.py # FEM/CFD unit system tables
│ └── materials.py # built-in material database (CS + EN)
├── lang/
│ ├── cs.py # Czech UI strings
│ └── en.py # English UI strings + quantity map
├── gui/
│ ├── app.py # main window, toolbar (format, theme, language, export)
│ ├── theme.py # dark/light palette for native Tk widgets
│ ├── export.py # table → CSV / clipboard
│ ├── tab_converter.py
│ ├── tab_solvers.py
│ ├── tab_isa.py
│ ├── tab_airspeed.py
│ ├── tab_materials.py
│ └── dialog_material.py
├── docs/
│ └── screenshot.png
└── tests/
├── test_units.py
├── test_isa.py
├── test_airspeed.py
├── test_materials.py
├── test_user_materials.py
└── test_settings.py
All conversion factors are exact SI / NIST 2019 values where defined:
| Factor | Value |
|---|---|
| 1 in | = 0.0254 m (exact) |
| 1 lb | = 0.45359237 kg (exact) |
| 1 lbf | = 4.4482216152605 N (exact) |
| g₀ | = 9.80665 m/s² (exact) |
The test suite checks 36 known values from aerospace literature (Niu, Bruhn), runs a roundtrip test across all units in all categories, and validates the airspeed calculator against the classic M 0.80 / FL350 ≈ 272 KCAS reference point.
- Dynamic pressure calculator (q = ½ρV²) from ISA + airspeed → Airspeed tab
- Export table to CSV / clipboard
- Pressure-altitude input and density altitude in the ISA tab
- Unit search across categories
- ISA atmosphere profile plot (σ/δ/θ, native canvas)
- More materials (29 entries: further Al alloys, Ti, steels, composites, cores)
- v0.42 — ISA endpoint/ΔISA fixes, EN materials & OpenFOAM labels, portable/APPDATA data dir, packaging fixes
MIT