Design of Space Launch Vehicles

Lecture

Subject. (number) refers to chapter number in Design of Rockets and Space Launch Vehicles

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(1)Introduction to Launch vehicles (LVs). Anatomy of a LV, launch & ascent phases, worldwide launch sites. The global space economy, market & need for LVs. LV terminology & vocabulary.

(2) Technical history of rocketry & LVs: early events, WWII, the Cold War, ICBMs.

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(2) History of LVs (cont.): moon race, space shuttle, oddities. Current LVs; future developments.

(3) Mission requirements, top-level performance analysis for LVs. Orbits & trajectories: due east, direct orbits, polar, sun-synch, Molniya. LV design velocity estimation including gravity, drag, & other losses. Effects of launch site location. Ground launch vs. air drop, launch direction calculation, launch windows, orbit injection & shutdown conditions.

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(4) Propulsion: exhaust speed, mass flow, calculation of thrust & ∆v. Solid motors: grain, thrust profiles. Liquid engines: mixture ratios, performance vs. altitude, specific impulse, room-temp vs. cryogenic propellants, hypergolics. Engine thrust-to-weight ratio. Aerospike engines, hybrid rockets. Effective specific impulse during ascent.

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(5) Performance estimation using dimensional and dimensionless parameters of mass ratio and structural fraction. Three LV mass categories. SSTO & benefits of staging. Four types of staging, including series & parallel. Performance of series & parallel staging, optimization using Lagrange multipliers & “brute force” methods. All hydrogen Saturn V! Propellant crossfeeding. LV design sensitivities/trade-off ratios: where is the best place to improve performance? Recovery calculations: energy to dissipate, drag vs. propulsive recovery, flight profiles, additional propellant required, recovery system mass.

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(6) Flight through the atmosphere. Simplified LV equations of motion with aerodynamic lift & drag, gravity, buoyancy. Moving vehicle coordinate system, local horizon frame, pitch-plane trajectory simulation, gravity turns & other types of guidance.

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(6 cont.) LV trajectory optimization: Newton & 1^st optimization problem. Conflict between gravity & drag/thermal loads. Importance of thrust-to-weight ratio. Lofting, other optimization techniques, optimization software (including public domain). Ten LV trajectory profiles: Falcon 9, Ariane, Delta III, Saturn I/V, Space Shuttle, others.

(7) LV structures. Tank layouts, bulkheads, dome shapes, propellant feed line routing, toroidal tanks. Examples from Atlas, Delta, Saturn, Ariane, Zenit, & Shuttle. Multi-engine arrangements. Payload accommodations: payload fairings, payload attach fittings, including ridesharing. Types of structures: skin & stringer, sandwich, waffle/isogrid/orthogrid. Materials include metals (aluminum, Al-Li, steel), composites (graphite/epoxy). Material usage guides.

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(8) LV inboard profile. Propellant mass & volume calculation by ∆v & specific impulse including “real-life” additions for startup, ullage, thermal contraction. Sizing of tanks and domes including ullage and shrinkage, intertank/interstage structures, skirts, thrust structure. Two-stage-to-orbit (TSTO) vehicle sizing example. Engine selection: existing vs. “rubber” engines. Mass properties: calculation of center of mass & inertias when loaded, empty, after stage separation.

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(9) LV ground, transportation (handling/road/rail/ship/plane), & ascent loads: effective load from distributed loads, ground winds on pad, in-flight aerodynamic & inertial forces during trimmed flight at max-q. Why max-q and max-qa are important. Calculation of moments, shears, axial loads. Detailed Saturn V example. Load curve rules-of-thumb. Measuring atmospheric winds, Jimsphere. Load relief.

(10) Stress terminology. Thin-wall cylinder stresses due to axial & bending loads. Tank positioning vs. increased tank mass. Reduced allowable stress due to structural stability/buckling. 7 ways to improve structural stability. Internal stresses induced from aero loads, internal & hydrostatic pressure, geysering.

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(10 cont.) Overall stress state & required wall thickness calculation for tanks, skirts, adapters, interstage. Simple rules for LV structures. Property variations with temperature. Table of selected material properties.

(11) Launch environment: vibration, shock, acoustics, thermal loading. Engine startups & cutoffs. Explosive/ordnance & non-explosive separations. Payload fairing separation dynamics. Payload separation via clamp bands, pyro shocks. Acoustics: ignition overpressure, liftoff & max-air acoustics, acoustic suppression. Thermal environment from aero heating, plume radiation, protection systems. Payload structural design verification, coupled-loads analysis. Payload environment, acoustics, thermal; isolation.

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(12) Stability & Instabilities. Stability & control vs. guidance & navigation. Attitude determination. Stability & control: how to stabilize unstable vehicle. Flight control system elements. Thrust vector controlled (TVC) vehicle equations of motion in pitch plane. Tank positioning vs. stability and CG travel. LV block diagrams, transfer functions. Introduction to complex variables & root locus diagrams. Wind gust response. Instabilities from LV flexibility, “tail-wags-dog,” sloshing, pogo, resonant burn.

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(13) Manufacturing. Metal structures: conventional vs. friction-stir welding. Fabrication of tanks, connecting structure. Composite materials: layups, fabrication techniques. The future: 3D/additive printing, fiber placement. Production flow and LV stacking.

(14) LV systems: onboard & launch pad facilities. Propellant loading & conditioning. Pressurization systems, hydraulics, thrust-vector control. Avionics, data systems, electrical, telemetry basics: transducers, data handling, multiplexing. Ordnance & non-pyrotechnic separation systems. Launch pad facilities: umbilicals, swing arms, propellant loading, lightning protection, vehicle hold-downs. Acoustic suppression. Examples from Saturn V, Shuttle, Falcon 9, others. Logistics/equipment needed for recovery & re-use of payload fairings, boosters, upper steps.

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(15) Testing: reasons for testing. Ground & flight wind tunnel, structure, pressure, vibration, shock, acoustic testing. Radio frequency/RF & software testing. Hot gas & plume testing. Redundancy, reliability, k-out-of-n system reliability with multi-engine examples. NASA Safety definitions.

(16) Failures: examples & lessons learned. Most common failures, case studies. Five mistakes to look for. Failures of propulsion, structure, avionics/software systems. Flight termination systems, range safety. Abort trajectories, ascent shaping to avoid “black zones.” Best practices to avoid failures.

(17) LV Financial analysis, project management, cost estimation. Design decision-making, cost engineering, cost-estimating relationships, inflation. Recommendations & Atlas V cost example. Software cost. Fallacy of “cost per pound” or “per kg”. Propellant costs. Economics of re-use.