Form factor comparator
Put up to three sizes side by side. Each value is computed in your browser with the first-order models of the PocketQube review, for a spacecraft at the mass limit of its standard.
F10.7 = 140 sfu, Ap = 12
Isometric, common scale 0.99 px/mm
| Quantity | 1PPocketQube | 3PPocketQube | 1UCubeSat |
|---|---|---|---|
| Envelope(mm) | 50 × 50 × 50 | 50 × 50 × 178 | 100 × 100 × 113.5 |
| Volume(cm³) | 125 | 445 | 1,135 |
| Mass limit(kg)Mass limit of the standard; a typical value where the standard sets none. | 0.25 | 0.75 | 2.00 |
| Bulk density at the limit(g/cm³) | 2.00 | 1.69 | 1.76 |
| External surface(cm²) | 150 | 406 | 654 |
| Surface per gram(cm²/g) | 0.60 | 0.54 | 0.33 |
| Mean projected area(cm²) | 37.5 | 101.5 | 163.5 |
| Ballistic parameter(m²/kg)C_D·A/m with C_D = 2.2 and the mean tumbling area A_tot/4. | 0.0330 | 0.0298 | 0.0180 |
| Orbit-average power(W)Eq. 1: body-mounted triple-junction cells (η = 0.28), packing factor 0.6, eclipse at β = 0° for the chosen altitude. | 0.53 | 1.44 | 2.33 |
| Specific power(W/kg) | 2.13 | 1.93 | 1.16 |
| Thermal time constant(min)Eq. 2: c_p = 900 J/(kg·K), ε = 0.8, T₀ = 290 K. | 56 | 63 | 104 |
| Principal moments of inertia(kg·m²)Homogeneous box; smallest and largest principal moments. | 1.0 × 10⁻⁴ | 3.1 × 10⁻⁴ – 2.1 × 10⁻³ | 3.3 × 10⁻³ – 3.8 × 10⁻³ |
| Lifetime from 500 kmKennewell density model, re-entry at 180 km. | 20.4 months | 22.6 months | 3.1 years |
| Highest altitude for a five-year lifetime(km) | 559 | 553 | 525 |
| Δv per year to hold 500 km(m/s) | 17 | 16 | 9.4 |
| Standard | PocketQube Standard, Issue 1 (2018) | PocketQube Standard, Issue 1 (2018) | CubeSat Design Specification Rev. 14.1 (2022) |
| Deployers | AlbaPod, MRFOD, PicoBus | AlbaPod | P-POD, ISIPOD, NRCSD, EXOpod |
Assumptions
- Spacecraft at the mass limit of its standard, homogeneous, tumbling randomly; drag coefficient 2.2 and mean projected area A_tot/4.
- Lifetime from a circular orbit with the Kennewell density model at constant solar activity; re-entry at 180 km.
- Body-mounted power from Eq. 1 of the review; deployable arrays and pointing are not modelled.
- These are first-order estimates for comparing sizes. Mission analysis needs empirical atmosphere models, solar-cycle forecasts and real mass properties.
DETERMINISTIC PHYSICS & DATA METHODOLOGY
How This Calculator Works
Source modules: lib/data/form-factors.ts, lib/physics/decay.ts, lib/physics/power.ts, lib/physics/thermal.ts
Compares up to three standardized small-satellite form factors side by side across geometric scaling (L, L², L³), Cauchy drag area, ballistic parameter, orbit-average body-mounted solar power, linearized thermal time constant, principal inertia, and orbital lifetime.
Governing Equations & Physical Model
P̄ = S₀ · η · p · (A_tot / 4) · (1 − f_e)Uses S₀ = 1361 W/m², triple-junction efficiency η = 0.28, cell packing factor p = 0.60, and cylindrical-shadow eclipse fraction f_e(h).
τ_th = (m · c_p) / (4 · ε · σ · A_tot · T₀³)Evaluated at c_p = 900 J/(kg·K), ε = 0.80, and T₀ = 290 K to quantify eclipse cooling speed.
I_xx = m·(y² + z²)/12, I_yy = m·(x² + z²)/12, I_zz = m·(x² + y²)/12Computed from outer envelope dimensions (x, y, z) and maximum standard mass limit (or reference flight mass).
Inputs, Parameters & Units
| Parameter | Unit | Physical definition |
|---|---|---|
| Form factor IDs | — | Up to three selections from PocketQube (1P, 1.5P, 2P, 3P, 6P), CubeSat (0.5U–12U), ThinSat, TubeSat, and ChipSat. |
| h | km | Circular reference altitude used simultaneously for eclipse fraction, orbital lifetime, and annual drag make-up Δv. |
| Solar activity | sfu / Ap | Low (F10.7 = 70), moderate (140), or high (210) thermospheric density regime. |
Assumptions & Validity Limits
- Mass defaults to each standard's maximum allowable deployer mass (e.g., 0.25 kg for 1P per AlbaPod/PQ standard, 2.0 kg for 1U per CDS Rev. 14.1) or reference flight mass where unstandardized.
- Solar power assumes body-mounted cells only (no deployable wings) at fixed 60% packing factor across all faces.
- Inertia assumes uniform mass density across the rectangular or cylindrical envelope.
Worked Default Reference Case
Doubling linear edge L from 50 mm to 100 mm quadruples external surface area (150 → 600 cm²) and orbit-average solar power (0.53 → 2.13 W), while an 8× mass ratio halves thermal cooling rate and nearly doubles orbital lifetime.
- Cauchy drag area (1P vs 1U)
- 37.5 cm² vs 150 cm²
- Orbit-average power (500 km)
- 0.53 W vs 2.13 W
- Thermal time constant τ_th
- 56.5 min vs 113.0 min
- 5-year ceiling (moderate)
- 559 km vs 525 km