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Critical Design Review: SR-1 (Skybreaker I)

Document Ref: OMSA-SR-1-CDR
Program: Early Sounding Rockets
Vehicle: Skybreaker I
Target Launch: February 1951

STATUS: Skybreaker I APPROVED for SR-1

1. Vehicle Configuration​

1.1 Components & Dimensions​

The vehicle utilizes a single-stage liquid fuel configuration.

  • Mass: 285 kg
  • Height: 4.1 m
  • Diameter: 0.3 m
  • Payload: Science Core (0.3m) with Nose Cone
  • Propulsion: 1st Generation Aerobee
  • Tankage: Steel High Pressure Liquid Fuel (Aniline/Nitric Acid)
  • Comms: 2W UHF Telemetry Unit

1.2 Drawings​


2. Performance Analysis​

2.1 Propulsion Profile​

  • Burn Time (tburnt_{burn}): 47 - 52s (Nominal: 50s)
  • Launch TWR: 2.02
  • Total ΔV\Delta V: ~ 1200 m/s

2.2 Stability Analysis​

Stability is achieved via passive aerodynamic forces.

  • Center of Mass (CoM): Shifts forward during burn (Stable trend).
  • Center of Pressure (CoP): Located at tail fins, behind the CoM
  • Static Margin: Positive throughout flight.

3. Subsystem Design​

3.1 Payload​

  • Science Core: 1st Generation Science Core - total mass 0.3 kg.
  • Sensors: Barometer & Temperature.
  • Power: Internal battery - total mass 0.3 kg.
  • Recovery: None.

3.2 Power​

  • Load: 102 W (Avionics + Comms).
  • Power Supply: 30 kJ Chemical Battery.

3.3 Communications​

Analysis of the 2W UHF downlink to Ground Station (G/S) using data from RealAntennas

ParameterValue
Tx Power+30 dBm
Tx Gain1.5 dBi
Rx Gain+3 dBi
Path Loss-105.1 dB
**Received Power **-70.6 dBm
  • Noise Floor: -131.4 dBm
  • Link Margin: −70.6−(−131.4)=+60.7 dB-70.6 - (-131.4) = \mathbf{+60.7 \text{ dB}}

The link margin is sufficient for the mission

3.4 Guidance, Navigation, and Control (GNC)​

  • Active Control: None.
  • Passive Stabilisation: Tail fins angled at 5 degrees, generating spin stabilisation from aerodynamic forces.

3.5 Propulsion​

4. Risk Register​

SerialRiskMitigatationSeverity
1Uncontrolled catastrophic failure (explosion)All personnel to be clear of pad.High
2Engine failureEngines are static tested prior to flight.Medium
3Debris striking personnel or structresVehicle to be launched at a small angle towards the sea. Range safety device to be installed if possible.Medium

5. Manufacturing and Launch Constraints​

  • LC-1 being developed with ground support equipment (GSE) for handling fuels for Skybreaker. Currently under construction - due to complete February 1951
  • Vehicle must be launched east over the Atlantic.