运载火箭气动外形和结构设计

• Martlet 4 orbital launch vehicle: 3 rocket stages (design study)
Gerald Bull’s Sad End
Launch Vehicle Structural Loads
• Static/quasi-static loads
– Gravity and thrust – Propellant tank internal pressure – Thermal effects
Horizontal vs. Vertical Launch
• Feasibility of “airline-like” operations? • Use of high Isp air-breathing engines • Rocket stages lifted above the sensible atmosphere • Flexible launch parameters
• Plug nozzle • Nozzle = Reentry Heat Shield • Fully recoverable
• 1-1/2 stage, fully recoverable • Recoபைடு நூலகம்ery at sea • Ducted rocket
Vertical Takeoff, Horizontal Landing Vehicles
• Lockheed Clipper
• Lockheed TAV
Venture Star/X-33
• Venture Star: Reusable, single-stage-toorbit, proposed Space Shuttle replacement • X-33: Sub-orbital test vehicle • Improved thermal protection system (compared to SSV) • Linear spike nozzle rocket (altitude compensation) • Cancelled following tank failure in testing
• Maximum payload -> lightweight structure, high mass ratio, multiple stages, high specific impulse • Perceived simplicity, improved range safety -> single stage • Minimum cost -> low-cost materials, economies of scale • Minimum environmental impact -> nontoxic propellant
• Specific Energy contributed by first stage of launch vehicle
– Less remaining drag loss (typical) – Plus Earth!s rotation speed (typical)
EarthRemaining Mach RelativeVelocity, Drag Loss, Earth Rotation Specific Kinetic Total Specific Percent Altitude, km Number km/s km/s Speed, km/s Energy, km Energy, km of Goal Scout 1st-Stage Burnout 22 Subsonic Horizontal Launch 12 Supersonic Horizontal Launch 25 Scramjet Horizontal Launch 50 Target Orbit 300 4 0.8 3 12 25 1.2 0.235 0.93 3.6 7.4 0.05 0.15 0.04 0 0.4 0.4 0.4 0.4 0.4 123.42 12.05 85.57 829.19 3403.34 145.42 24.05 110.57 879.19 3703.34 3.93% 0.65% 2.99% 23.74%
Specific Energy Contributed in Boost Phase
• Total Energy = Kinetic plus Potential Energy (relative to flat earth)
Specific Energy Contributed in Boost Phase
Nova-Class “Big Dumb Boosters” c. 1963
Objective: 450,000 kg to low earth orbit
• Douglas Single-Stageto-Orbit
• General Dynamics, Martin, and Douglas Concepts
– – – –
Bending and torsion “Pogo” oscillations Fuel sloshing Aerodynamics and thrust vectoring
• Acoustic and mechanical vibration loads
– Rocket engine – Aerodynamic noise
• Single-stage-to-orbit
– Carrying dead weight into orbit – High structural ratio for wings, powerplants, and reusability – SSTO has very low payload ratio
Pegasus Air-Launched Rocket
• Initial mass: 18,000 to 23,000 kg • Payload mass: 440 kg
• Three solid-rocket stages launched from an aircraft • Aerodynamic lift used to rotate vehicle for climb
mV 2 E= + mgh 2
• Specific Total Energy = Energy per unit weight = Energy Height (km)
!
V2 E'= +h 2g
Aerospace Planes (TransAtmospheric Vehicles)
• Power for takeoff
– Turbojet/fans – Multi-cycle air-breathing engines – Rockets
Trans-Atmospheric Vehicle Concepts
• Various approaches to staging
• Boeing TAV • Rockwell TAV • Rockwell StarRaker
Structural Material Properties
• • • • • • Stress, !: Force per unit area Strain, ": Elongation per unit length
"=E#
Structural Material Properties
Material Properties (Wikipedia) Young's Modulus, GPa Aluminum Alloy 69 Carbon-Fiber Composite 530 Fiber-Glass Composite 125-150 Magnesium 45 Steel 200 Titanium 105-120 Elastic Limit, Density, MPa g/cm^3 400 100 250-700 830 2.7 1.8 2.5 1.7 7.8 4.5
• Expendable Vehicle
– Low cost per vehicle – New vehicle for each launch – Low structural ratio – Continued production – Launch preparation – Upgrade in production
Delta Clipper
Expendable vs. Reusable Launch Vehicles
• Reusable Vehicle
– – – – – – – – High initial cost High structural ratio Maintenance and repair Non-reusable parts and supplies Launch preparation Return to launch site Upgrade Replacement cost
Copyright 2008 by Robert Stengel. All rights reserved. For educational use only. http://www.princeton.edu/~stengel/MAE342.html
Launch Vehicle Configuration Design Goals
Launch Vehicle Design: Configurations and Structures
Space System Design, MAE 342, Princeton University Robert Stengel
Launch Vehicle Configuration Design Goals
• Rocket • Cryogenic propellant • Aerodynamic heating
• Dynamic loads
•Post-HARP Development (1967-1990) •Proposed 200 kg to orbit or 2,000 kg to 1,000-km range •Babylon Gun (1-m bore, 156-m length) designed by Bull for Saddam Hussein •March 26, 1990: Bull assassinated in Brussels
• Martin Astro-Rocket • General Dynamics Triamese
Properties of Launch Vehicle Powerplants
• Heat shield-to-heat shield
• Three “identical” parallel stages
Delta Clipper
•Minimum weight -> sphere •Minimum drag -> slender body •Minimum axial load -> low thrust •Minimum lateral load -> sphere •Minimum gravity loss -> high thrust
Proportionality factor, E: Modulus of elasticity, or Young!s Modulus Strain deformation is reversible below the elastic limit Elastic limit = yield strength Proportional limit ill-defined for many materials
Jules Verne Redux
• High-Altitude Research Project (HARP, 19611967) • Two 16-in battleship cannon barrels placed end-to-end • Principal designer: Prof. Gerald Bull, McGill • Sub-caliber projectile fired to 180-km altitude (Martlet 2)