Parametric Design -...
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Parametric DesignPrinciples of Space Systems Design
Parametric Design
¥ The Design Process¥ Example: Project Diana
Parametric DesignPrinciples of Space Systems Design
AkinÕs Laws of Spacecraft Design - #3
Design is an iterative process. Thenecessary number of iterations is onemore than the number you havecurrently done. This is true at anypoint in time.
Parametric DesignPrinciples of Space Systems Design
Overview of the Design Process
System-level Design(based on discipline-
oriented analysis)
Vehicle-level Estimation(based on a few
parameters from prior art)
System-level Estimation(system parameters based
on prior experience)
Program Objectives ✑System Requirements
Parametric DesignPrinciples of Space Systems Design
Project Diana - Mission Statement
Design a system to return humans tothe moon within the shortest feasibletime span for the minimum achievablecost.
Parametric DesignPrinciples of Space Systems Design
Project Diana - Requirements Document (1)
¥ System must be based on the use ofAmerican launch vehicles in operationalstatus as of 2005
¥ System shall be at least as capable forlunar exploration as the G-mission ApollosystemÐ Two landed crewÐ 24 hour stay time, 3 hour EVAÐ 100 kg of science payload (each way)
Parametric DesignPrinciples of Space Systems Design
American Heavy-Lift Vehicles (2005)
¥ Space Shuttle -25K kg to LEO
¥ Delta IV Heavy -25K kg to LEO
Parametric DesignPrinciples of Space Systems Design
DV Requirements for Lunar MissionsTo:
From:
Low EarthOrbit
LunarTransferOrbit
Low LunarOrbit
LunarDescentOrbit
LunarLanding
Low EarthOrbit
3.089km/sec
LunarTransferOrbit
3.089km/sec
0.808km/sec
3.046km/sec
Low LunarOrbit
0.808km/sec
0.022km/sec
LunarDescentOrbit
0.022km/sec
2.247km/sec
LunarLanding
2.861km/sec
2.062km/sec
Parametric DesignPrinciples of Space Systems Design
Mission Scenario 1
¥ What can be accomplished with a single shuttlepayload (25K kg)?
¥ Assume d=0.1, Isp=320 sec¥ Direct landing
Ð LEO-lunar transfer orbit DV=3.089 km/secÐ Lunar transfer orbit-lunar landing DV=3.046 km/secÐ Lunar surface-earth return orbit DV=2.861 km/secÐ Direct atmospheric entry to landing
Parametric DesignPrinciples of Space Systems Design
Scenario 1 Analysis¥ Trans-lunar injection
¥ Lunar landingÐ r=0.3786Ð mLS=1897 kg
¥ Earth returnÐ r=0.4016Ð mER=572 kg
r eTLI
V
gITLI
sp= =-D
0 3724.
m m r kgTLI o TLI= -( ) =d 6809
This scenario would work for amoderate robotic sample returnmission, but is inadequate for ahuman program.
Parametric DesignPrinciples of Space Systems Design
Mission Scenario 2
¥ Assume a single shuttle payload is used to sizethe lunar descent and ascent elements
¥ Assume d=0.1, Isp=320 sec¥ Direct landing
Ð LEO-lunar transfer orbit DV=3.089 km/secÐ Lunar transfer orbit-lunar landing DV=3.046 km/secÐ Lunar surface-earth return orbit DV=2.861 km/secÐ Direct atmospheric entry to landing
Parametric DesignPrinciples of Space Systems Design
Scenario 2 Analysis¥ Lunar landing
Ð r=0.3786Ð mLS=6965 kg
¥ Earth returnÐ r=0.4016Ð mER=2101 kg
¥ Trans-lunar injectionÐ r=0.3724
Payload mass still too low forhuman spacecraft. Need a betterfit to launch vehicle constraints.(Ideal situation is to ensure 100%load factors.)
mm
rkgLEO
TLI
TLI
=-( )
=d
91 780,
Parametric DesignPrinciples of Space Systems Design
Mission Scenario 3
¥ Assume three shuttle missions carry identicalboost stages which perform TLI and part ofdescent burn
¥ Fourth shuttle payload completes descent andperforms ascent and earth return
¥ All other factors as in previous scenarios
Parametric DesignPrinciples of Space Systems Design
Scenario 3 Standard Boost Stage
¥ mo=25,000 kg¥ mi =2500 kg¥ mp =22,500 kg¥ LEO departure configuration is three boost
stages with 25,000 kg descent/ascentstage as payload
¥ mLEO =100,000 kg
Parametric DesignPrinciples of Space Systems Design
Scenario 3 TLI Performance¥ Boost stage 1
Ð VTLI remaining=2290 m/sec
¥ Boost stage 2Ð r=0.7; DV2=1119 m/secÐ VTLI remaining=1171 m/sec
¥ Boost stage 3Ð r=0.55; DV3=1875 m/secÐ Residual DV after TLI=704 m/sec
DV gIm m
mm
spLEO prop
LEO1 799= -
-æ
èç
ö
ø÷ =ln sec
Parametric DesignPrinciples of Space Systems Design
Alternate Staging Possibilities
¥ Three identical stages¥ Serial staging (previous chart) DV=3793 m/sec¥ Parallel staging (all three) DV=3525 m/sec¥ Parallel/serial staging (2/1) DV=3750 m/sec¥ Pure serial staging is preferred
Parametric DesignPrinciples of Space Systems Design
Scenario 3 Ascent/Descent Performance
¥ 704 m/sec of lunar descent maneuver performedby boost stage 3
¥ Remaining descent requires 2342 m/secÐ r=0.4738Ð mLS=9346 kg
¥ Earth returnÐ r=0.4016Ð mER=2818 kg
Return vehicle mass iscomparable to the Geminispacecraft - should be adequatefor adoption as initial baseline.
Parametric DesignPrinciples of Space Systems Design
Baseline System Schematic - Project Diana
Boost Stage 125,000 kg
Boost Stage 225,000 kg
Boost Stage 325,000 kg
Descent/LandingStage
15,650 kg
Ascent Stage6528 kg
Crew Cabin2818 kg
Parametric DesignPrinciples of Space Systems Design
Variation 1: Lunar Orbit Staging¥ Assume same process as baseline, but use lunar
parking orbit before/after landing¥ Keep boost stage scenario as before
Ð Residual DV=704 m/secÐ Additional 104 m/sec required for braking into LLO
¥ Add LOI completion to descent stageÐ Descent DV=2269 m/sec + 104 m/sec LOI (r=0.4692)Ð Ascent DV=2084 m/sec (r=0.5145)Ð TEI DV=808 m/sec (r=0.7729)
Parametric DesignPrinciples of Space Systems Design
Variation 1 Results
¥ Lunar landed payload = 9625 kg¥ Payload returned to lunar orbit = 3990 kg¥ Earth return payload = 2685 kg¥ Net loss of 133 kg for crew cabin/entry
vehicle¥ Simplistic approach (includes taking earth
return propellant to/from lunar surface)basically adds another stage, but reducesuseful payload
Parametric DesignPrinciples of Space Systems Design
Variation 2: Lunar Orbit Rendezvous¥ Use specialized vehicle for descent/ascent¥ Keep boost stage scenario as before
Ð Residual DV=704 m/secÐ Additional 104 m/sec required for braking into LLO
¥ Leave TEI stage in lunar orbit duringascent/descentÐ Descent DV=2269 m/sec (r=0.4850)Ð Ascent DV=2084 m/sec (r=0.5145)Ð TEI DV=808 m/sec (r=0.7729)
Parametric DesignPrinciples of Space Systems Design
Variation 2 Mass Calculations
¥ TEI stage inert mass=2500 kg (d=0.1)¥ Propellant for LOI completion=815 kg¥ Desired quantity=crew module mass (mcm)¥ Ascent vehicle mass=2.412 mcm
¥ Descent vehicle mass=2.597 mascent =6.265 mcm
¥ Trans-earth injection maneuverÐ Initial mass=25,000-815-5.265 mcm
Ð Final mass=2500+mcm
Ð r=0.7729 --> mcm=3194 kg (gain of 376 kg = 11%)
Parametric DesignPrinciples of Space Systems Design
Variation 2 System Schematic
Boost Stage 125,000 kg
Boost Stage 225,000 kg
Boost Stage 325,000 kg
Descent Stage12,310 kg
TEI Stage4990 kg
Ascent Stage4510 kg
Crew Cabin3194 kg
Parametric DesignPrinciples of Space Systems Design
Variation 3: Maximal LOR¥ Use specialized vehicle for descent/ascent¥ Keep boost stage scenario as before
Ð Residual DV=704 m/secÐ Additional 104 m/sec required for braking into LLO
¥ Leave earth-return hardware (heat shield,parachutes - assume 1000 kg) and TEI stage inlunar orbit during ascent/descentÐ Descent DV=2269 m/sec (r=0.4850)Ð Ascent DV=2084 m/sec (r=0.5145)Ð TEI DV=808 m/sec (r=0.7729)
Parametric DesignPrinciples of Space Systems Design
LOR Component Definitions
¥ Five components to vehicle at lunar arrivalÐ Boost stage 3 (jettisoned during lunar orbit
insertion)Ð TEI stage (also performs final LOI burn)Ð Descent stageÐ Ascent stageÐ Crew module/entry vehicle, composed of
¥ Earth entry hardware (assumed 1000 kg)¥ Crew module
¥ Arrival mass 25,000 kg
Parametric DesignPrinciples of Space Systems Design
Variation 3 Mass Calculations
¥ TEI stage inert mass=2500 kg (d=0.1)¥ Propellant for LOI completion=815 kg¥ Desired quantity=crew module mass (mcm)¥ Ascent vehicle mass=2.412 mcm
¥ Descent vehicle mass=2.597 mascent =6.266 mcm
¥ Trans-earth injection maneuverÐ Initial mass=25,000-815-5.266 mcm
Ð Final mass=2500+mcm +1000Ð r=0.7729 --> mcm=2997 kg --> mentry =3997 kg
Parametric DesignPrinciples of Space Systems Design
Revised Baseline System Schematic
Boost Stage 125,000 kg
Boost Stage 225,000 kg
Boost Stage 325,000 kg
Descent Stage11,550 kg
TEI Stage5220 kg
Entry Hardware1000 kg
Ascent Stage4232 kg
Crew Cabin2997 kg
Parametric DesignPrinciples of Space Systems Design
The Next Steps From Here
¥ Perform parametric sensitivity analysesÐ Inert mass fractionsÐ Specific impulseÐ Size of entry package left in orbit
¥ Investigate reduction from 3 to 2 boost stagesfor minimal system
¥ Examine growth options allowed by systemÐ One-way cargo variantsÐ Larger module with more boost modules
Parametric DesignPrinciples of Space Systems Design
Overview of the Design Process
System-level Design(based on discipline-
oriented analysis)
Vehicle-level Estimation(based on a few
parameters from prior art)
System-level Estimation(system parameters based
on prior experience)
Program Objectives ✑System Requirements