Spacecraft Design with the Metric System

Don't you think that the use of imperial units gives Transhuman Space a steampunk flavour which doesn't fit in the ultra-modern setting? This page is an attempt to adapt the TS spacecraft design rules to the modern world. The conversion is based on the following:

• 1' = 30 cm;
• 1 space = 13.5 m³;
• 1 ksf = 90 m² (hsm for hecto square metre);
• 2000-pound ton ~ 1000-kg tonne.

It was tempting to set 1 sp = 15 m³ and 1 ksf = 100 m² but this generates conflicts between the two systems, i.e. up to a 10% discrepancy or more. But it doesn't matter that a unit area or volume doesn't correspond to a round number. With this method, the conversion becomes really simple: there are few things to modify. And there is only about 1 per mil discrepancy between the two systems.

For the record, note that 1 space approximately corresponds to a 8' / 2.4 m side cube, or a 10' / 3 m diameter sphere.

Hull Design

• Sphere: V = R³ × 0.296, A = R² × 0.139.
• Cylinder: V = L × W² × 0.0593, As = L × W × 0.0356, Ab = W² × 0.0089.
• Streamlined Delta: V = (L / 7.5)³, A = (L / 7.5)² × 0.5.
• Box: V = L × W × H / 13.5, As = [(L×H) + (L×W)] / 45, Ab = Af = W × H / 90.
• Torus: V = R × r² × 1.48, A = R × r / 2.25.

Pseudo-Gravity Generation

• Maximum: Spin radius / 90 metres.
• Spin theter: 180 m long

Habitat Modules

• 1 acre = 4000 m²

Accessories

• Space Dock Hangar Volume = H × W × L / 13.5 m³
• Space Dock Hangar Area = H × W / 90 m³

Performances

• ΔV = sAccel(g) × Burn_Endurance(h) × 17.6
• Realistic ΔV = 0.0048 × Isp × ln( LMass / DMass )

In km/h:

• Stall Speed: Rs = 21.5 if responsive structure, 29 if not
• Air Speed = square root of ( 38,400 × Thrust / Drag )

Welcome to the 22^nd century!