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Figure 1. The Effects of Scaling and Size on Spaceplane Payload Performance.

 

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Figure 2. Typical Result of a Sensitivity Study Using the Spaceplane Equation
Airbreathing/Rocket Engine Combinations to Maximize Orbital Velocity and
Payload Delivery Capability.

 

Mission Application Areas Payload Mass Flow (Tonnes/Year) Cost of Access to Space ($ / kg)
Information Missions Communications, Meteorology, Navigation, Earth Resources 100 20,000 - 2000
Mass Missions (Near Tern) Space Tourism Space Manufacture 1000 - 100,000 2000 - 200
Mass Missions (Far Term) Space Solar Power
Space Colonization Mining in Space
100,000 to Ten Million 200 - 10
Table 1. The Cost of Access to Space for Different Missions.

 

Parameter Parameter Hyperplane (M8) with Skylon Parameters (SF=1) Hyperplane (M8) with Skylon Parameters (SF=0.5) Hyperplane (M8) with Skylon Parameters (SF=0.25) Avatar (M8) with Skylon Parameters (SF=0.09)
Take-off Mass Take-off Mass 275 137.5 68.75 25
Mass in Orbit Mass in Orbit 115.50 57.75 28.88 10.50
Payload Mass Payload Mass 25.03 8.27 3.31 0.87
Lox Stored / Required During Airbreathing Phase Mlox-A 207.35 107.66 55.83 21.75
Vehicle Weight at End Airbreathing Phase MA 364.32 186.95 95.87 36.60
Mass Addition Ratio in Airbreathing Phase RA=MA/M0 1.32 1.36 1.39 1.46
Specific Impulse Ratio (Airbreathing to Rocket Phase) i=IsA/IsR = 3000/470 (Hypl) 6.52 6.52 6.52 6.52
Vehicle Mass Ratio Multiplier Factor (ζ) ζ = (RA)^i 6.26 7.41 8.74 12.00
Vehicle Mass Ratio (Rocket Phase) RR RR = MA/ME 3.15 3.24 3.32 3.49
Overall Vehicle Mass Ratio (R) R= ζ x RR 19.74 23.99 29.01 41.84
Table 2. Use of the Spaceplane Equation and Excel Spread Sheet Methodology to Determine the Effect of Scaling of
Spaceplanes with No Lox (Skylon) at Take-off (Hyperplane/Avatar Spaceplane Concepts).

 

Parameter Symbol Skylon (M5) (SF=1) Skylon (M5) (SF=1/2) Skylon (M5) (SF=1/4) Skylon (M5) (SF=0.09)
Take-off Mass Mo 275 137.5 68.75 25.00
Mass in Orbit ME 67 33.50 16.75 6.09
Payload Mass MPL 12 4.80 1.54 0.26
Lox Stored /Required During Air breathing Phase 30.57 15.29 7.64 2.78
Vehicle Weight at End Airbreathing Phase MA 306 152.79 76.39 27.78
Mass Addition Ratio in Airbreathing Phase RA=MA/M0 1.11 1.11 1.11 1.11
Specific Impulse Ratio (Airbreathing to Rocket Phase) i=IsA/IsR = 3000/470 (Hypl) 6.22 6.22 6.22 6.22
Vehicle Mass Ratio Multiplier Factor (ΞΆ) ζ = (RA) ^i 1.94 1.94 1.94 1.94
Vehicle Mass Ratio (Rocket Phase) RR RR = MA/ME 4.57 4.57 4.57 4.57
Overall Vehicle Mass Ratio (R) R= ζ x RR 8.88 8.88 8.88 8.88
Table 3. Use of the Spaceplane Equation and Excel Effect of Scaling of Spaceplanes with 50% Lox at Take-off (The Skylon Concept).

 

Spaceplane Concept Take-off Weight Fuel weight at Take-off (Tonnes) Type of Mass Addition System

Mode   |   Oxidiser
O/F Mixture Ratio Mass Addition Ratio Specific Impulse Ratio Overall Vehicle Mass Ratio Payload Weight (Tonnes)
Black Horse (Ref.5) 22 Tonnes (Original Concept) Aviation Kerosene 14.6 Tonnes (66.4%) Density: 800 kg/m^3 External Means: Aerial Refueling from KC-135 Tonnes Tanker at Mach .85,at 14.1 kms alt Hydrogen Peroxide Density: 1432 tonnes/m^3 Qty filled: 19.90 tonnes Fill Time: 445 secs 7.38 3.8 1.038 44.9 0.52
Skylon (Ref. 6) (Original Papers: 196/275/345 tonnes take-off weight) 25 Tonnes

Scaled Down concept by Equation only for Comparison
Normal Hydrogen 6.36 Tonnes (25%)

Density: 70 kg/m^3 0-28 kms alt
Virtual Oxidiser Collection & on-board storage Air-breathing Rocket Engine Mach 0-5.0 Liquid oxygen Density: 1100 tommes/m^3 Qty filled (Virtual): 2.78 tonnes Airbreathing phase: 645 secs 3.5 (Sabre Engine Is 450 in rocket phase) 1.11 6.52 8.9 0.26
Avatar (Ref: 7) 25 Tonnes (2001 concept; 271 tonnes, 1996 concept; 100 tonnes 1987 concept) Slush Hydrogen 14.5 Tonnes (58%) Density: 80 kg/m^3 Internal Means: aerocryogenic technologies; lox mass addition from Mach 3.5 to Mach 8 28-30 kms alt Liquid oxygen Density: 1100 tommes/m^3 Qty filled 17.4 tonnes

Lox collection time: 1200 secs
5.0 (P&W Expander Cycle Engine Is=470) 1.46 6.52 41.24 0.87
Table 4. Comparison of Three Different Means of Mass Addition in Flight In SSTO Spaceplanes.