Launch Vehicles System Design

Launch Vehicles System Design - Vertical Launch Vehicles

Introduction to Vertical Launch Vehicles

  • Definition: Launchers are space systems dedicated to the orbit insertion of other space systems.

  • Categories of Launchers:

    • Expendable Launch Vehicles (ELV):

    • More common type of launcher.

    • Examples include: Ariane, Vega, Soyuz, Proton, Atlas, Delta, Dnepr, Long March, Pegasus.

    • Reusable Launch Vehicles (RLV):

    • Only a few launchers are reusable.

    • Example: Space Shuttle.

  • Qualification for Human Flight:

    • Only a few vehicles are qualified for human flight, including Space Shuttle and Soyuz.

Mission Management and Support

  • Covers all aspects of launch activities and preparation from contract signature through launch.

  • Responsibilities include:

    • Systems engineering support and analysis.

    • Procurement, verification, and delivery of the launch vehicle and associated hardware.

    • Ground range and support (GRS) for customer activities at launch site.

    • Combined operations at launch site including launch vehicle and spacecraft integration.

    • Telemetry and tracking ground station support and post-launch activities.

    • Assistance and logistics support, including insurance, customs, and export licenses.

    • Quality and safety assurance activities.

    • Insurance and financing services.

Launch Vehicle Family

  • Ariane Programme: Includes different types of European heavy launch vehicles, such as Vega, Ariane 5 GS, Ariane 5 ECA, etc.

  • Russian Heavy Launchers: Mention of the FFA & DORMA Car 20.

  • Payload to GTO (Geostationary Transfer Orbit) (kg):

    • Capacity details of various vehicles, with specific examples like the USA Launcher Family - Delta Programme.

Detailed Technical Specifications

  • Payload Fairing:

    • Diameter: 5.4m

    • Height: 17m

    • Mass: 2675 kg

  • Cryogenic Upper Stage (ESC-A):

    • Size: 5.4m x 4.711m between I/F rings.

    • Dry mass: 4540 kg.

    • Configured with HM7B engine, 14.9 tons of LOX + LH₂.

    • Thrust: 67 kN and Isp: 446 s.

  • Cryogenic Main Core Stage (EPC):

    • Size: 5.4m x 23.8m (without engine).

    • Dry mass: 14700 kg.

    • Propellants: 170 tons of LOX + LH₂.

  • Solid Rocket Booster (EAP):

    • Size: 3.05m x 31.6m.

    • Structure: Stainless steel case.

    • Propulsion: 240 tons of solid propellant per SRB.

    • Significance of mean thrust and combustion time parameters.

Constraints on Launch System Design

  • Influencing factors on spacecraft design before reaching orbit include:

    • Launch Loads:

    • Steady state acceleration.

    • Dynamic loads due to thrust and maneuvering.

    • Acoustic and pressure loads.

    • Random mechanical vibrations and sine-equivalent loads.

    • Design Drivers for Structure:

    • Shock loads due to stage separation.

    • Impulsive loads for array deployment.

Reusable Launch Systems

  • Importance of cost in space activities.

  • Example: An Ariane 5/6 launch costs comparable to an Airbus plane (~90-150M$).

  • Costs associated with reusability include:

    • Refurbishment of thermal protection.

    • Abort sites for potential engine failure safety.

    • Re-certification processes after each flight.

  • Advantages sought from reusable launch vehicles include:

    • Reduced operations costs.

    • The capability for robust abort situations.

    • Decreasing inspection times between flights.

Challenges of Reusable Vertical Launch Systems

  • Key challenges include thermal load management.

  • Temperature challenges during reentry, potentially reaching 600-700°C over major airframe areas, with peaks of 1600°C.

  • Trade-offs between hot and cold structure design strategies regarding thermal protection.

  • Need for superior aerodynamic configuration integrating tank volume, engine systems, and control surfaces.

Liquid Rocket Engine Thrust Chamber Performance

Correction Factors

  • Correction Factors for LRE:

    • Combustion chamber correction factor adjusts performance parameters based on real combustion processes.

    • Nozzle correction factors account for friction and divergence losses.

Performance Parameters

  • Relevant performance characteristics:

    • Specific impulse, thrust coefficient, specific energy ratios, and operational efficiency.

    • Flaws such as boundary layer effects and multi-phase flow are critically analyzed.

Thrust Chamber Dynamics

  • Detailed performance assessment models coupled with thermodynamic principles to predict chamber behavior under various operational conditions.

Turbopumps Overview

  • Purpose of Turbopumps:

    • Deliver propellant under high pressure from storage to combustion chamber.

    • Allow efficient energy transfer for optimal performance.

Components of a Turbopump

  • Pump Functionality:

    • Impellers increase fluid velocity; diffusers convert that into pressure.

  • Turbine Role:

    • Extracts energy from combustion gases and drives the pump via a shaft system.

Turbopump Operating Principles

  • The conversion of chemical energy to mechanical work formed through high-pressure gas propulsion, effectively moving liquid propellants to the combustion chamber.

Design Parameters of a Turbopump

  • Pressure Limits: Pump must attain and maintain necessary pressures per operational requirements, measured by specific formulas.

    Cycle of operation captures essential aspects of thermal dynamics, aerodynamic pressures, and structural responses under significant loads.

Summary

  • Turbo pumps are paramount in ensuring reliable and efficient propellant delivery in rocket engines.

  • Continuous advancements in materials and engineering methods are anticipated to enhance performance significantly for future missions.

Recommendations for Further Study

  • Delve into specific turbine-seal systems and their unique operational characteristics in high-stress environments.

  • Study advanced techniques integrating new materials for turbo pump assemblies, particularly in cryogenic conditions.