space shuttle day-of-launch trajectory design and verification

Space Shuttle Day-of-LaunchTrajectory Design and Verification

Operational Concepts

Brian E. HarringtonBrian. E.HarringtonCausa-spaceops.com

281-282-3762

AIAA-Houston Annual Technical SymposiumApril 30, 2010

Copyright © 2010 by United Space Alliance, LLC. These materials are sponsored by the VNational Aeronautics and Space Administration under Contract NNJ06VA01C. The U.S.

April 30, 2010 Government retainsapaid-up, nonexclusive, irrevocable worldwide license in such materials,to reproduce, prepare, derivative works, distribute copies to the public, and perform publicly

Brian_ Harrington_ATS2010-DOLILU.ppt and display publicly, by or on behalf of the U.S. Government. All other rights are reserved bygsr^nt / descentthe copyright owner. ^^gi^t [les^gn

useUnited Space Alliance

Objective• Review Space Shuttle day-of-launch trajectory optimization operational

concepts• Demonstrate how the Day-of-Launch Initialization-Load Update process, or

DOLILU, can improve launch probability three-fold• Offer Shuttle DOLILU methodology for future launch vehicles to build on

April 30, 2010Brian_Harrington_ATS2010-DOLILU.ppt

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Background• Space Shuttle is not certified to lift-off in all weather conditions• Vehicle's trajectory is optimized to that day's wind and environmental

conditions• Designed trajectory must be rigorously assessed to ensure crew and vehicle

safety, while accomplishing mission objectives• DOLILU process results in a trajectory that protects vehicle structural margins

and maximizes performance given other factors• Similarity will transition to future launch vehicles


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Cape JSC JSC

Balloon Data TrajectoryDesign

TrajectoryVerification(Prime)

DOLILU Overview

Since the environment (wind) changes, the DOLILU design and assessmentprocess is repeated every hour from about launch minus 6 hours to lift-off

Boeing

TrajectoryVerification(Independent)

Loads & DOLILUOfficer

Final DOLILUGo/No-Go

MSFC

Wind-OnlyAssessments




Jimsphere-Radar tracked, no package-Measures Wind Speed and Direction

High-Res-G PS tracked, attached to clear Jimsphere-Measures Wind Speed and Direction

Low-Res• GPS tracked-Measures WindSpeedandDirection-MeasuresThermodynamicd ata

Balloon Systems• Shuttle makes use of weather balloon data on Day-of-Launch (DOL)

— Wind speed and direction from 0 to 58,000 ft.— Thermodynamic atmosphere data (temperature, humidity, 0

density) from 0 to 100,000 ft• Weather Balloons are released about 10 miles from the launch pads

by Air Force contractors



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Balloon Timeline

L-6:15

L-4:50

L-3:45 Contingency

L-3:35

/

L-2:20

L-1:25 Contingency

i Balloon Rise

MDesign, High-Q & Roll Assessments

q High-Q & Roll Assessments

n Roll Assessment

L-1:08

L-0:50 Con

6:00 5:30 5:00 4:30 4:00

3:30 3:00 2:30

2:00 1:30 1:00 0:30 0:00

Time to Launch (H:MM)




DOLILU Design• Shuttle first-stage is "Open-loop"; "Closed-loop" second-stage will fly itself to

a target

• DOLILU software optimizes the first-stage trajectory in order to minimizevehicle structural loads and maximize abort capability

— Targets angle of attack (Alpha), angle of sideslip (Beta), and dynamicpressure (Qbar)

— Targets staging conditions: altitude rate and optimum azimuth

• Design consists of two elements— "Shaper" software uses a low pass filtered wind to obtain

• Initial pitch and yaw steering commands• Throttle up and down table• On-board wind table

— "Biaser" software uses the actual wind to fine-tune the pitch and yawcommand by centering the wind-induced Alpha and Beta spikes



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2750.0

2.75

2500.0

2.50

2250.0

.asured Wind 2.00

1750.0 j'1.75

"Shaper"Filtered Wind hA

1500.0 1.50

A

1.25

250.0

H

too

000.0

0.75

750:

I

0.50500.0 11

EFT - RIGI^IT250.0 0.25

80000 .

70000 .

80.0

60000 .

GMi

E 50000 .70.0

T

40000 .w

60.0

S 30000 .

50.0 E

C 20000 .

40.0

1000030.0

20.0

10.0 0

80.0

G

E70.0

T

60.0

S

50.0 E

C

40.0

30.0

20.0

10.0

Example Wind

In-Plane Wind

Out-of-Plane Wind

TRAJ RUN: TRAJ RUN:

N

2.75

2500.0 J70a00 .. ........... ... ..

-2.50

2250.0

,000

2000.0200

50000

1750.0° OShaper"Filtered Wind 15

40000

1500.0 1.50

Measured Winc30000

250.0

\ H

20000 ................. 1.00

000.0

0.7510000

0.50soa.o ^

AIL ^ HEA250.0 0.25

0

60

V

a

0-200 -175 -150 -125 -100 -75 -50 -25 0 25

-200 -175 -150 -125 -100 -75 50 -25 0 25

12-01-2004 13:55:54

IN-PLANE WIND SPEED (FPS) 12-01-2004 13:55:26

OUT-OF-PLANE WIND SPEED (FPS)

FLIGHTAZIMUTH - 43 DEG FLIGHTAZIMUTH - 43 DEG


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vMeg

(D if

Alpha Miss

/Nw^ ""', J-\,

Alpha &Alpha Target

Nind

►Xis)

BetaYLJ

0j I J iv^ :^^W,M1r N^I t ` r^

Irf,

isured'

ferent )

Resultant Alpha, Beta, Qbar

In-Plane Wind &

Out-of-Plane Wind &

Resultant Alpha

Resultant Beta

0

Altitude

60,000 ft 0

Altitude

60,000 ft

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Now with a wind 3 '/2 hours laterIn-Plane Wind

Resultant Alpha

Al ^

I r+IY

a.^,1 ;

1 ^

ii

^t v

Non-optimized Alpha

---- ----- ----- ----- -----0 Altitude 609000 ft

Out-of-Plane WindResultant Beta

i

Design

^Get this win

11

I1

1 Iv l 1

1

Non-optimized Beta

0 20000 30050000

ude 60,000 ft


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Constraints: Alpha/Beta/Qbar• "Q-Planes" constrain the flight

envelope to alleviate structuralconcerns

• Each trajectory point is Mach

dispersed by the Root SumSquare of wind persistence,flight derived systemdispersions, and atmospherepersistence (Qbar only)

• Limits are reduced for engineout and gust effects

Alpha-Beta varies with Mach

Alpha-BMargin

Alpha-Beta Slice or Plane

>

(deg) (deg)

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Constraints: Structural Loads and Trajectory

• Structural Load Indicators (SLI) protect critical load points on the vehicle— Each SLI is dispersed for the Root Sum Square of wind persistence,

system dispersions, and gust• Trajectory System Rules protect staging limits, pitch/yaw/roll rates, Range

Safety limits, and throttle limits• Trajectory Experience Rules assess attitude errors, angular accelerations,

SSME and SRB commanded positions, and on-board wind table

Aft 9T., n 2RITFD


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Wind Persistence

• Wind will continue to change after the final assessment• Wind Persistence statistically accounts for the change on a

constraint caused by the wind• Shuttle uses a statistical distribution using a minimum

marnin methodLC^G

W

Q.

Q

N

r

O^.E


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MSFC Wind-Only Assessments

• Wind Shear Limits protect the Orbiter Tail• Measurement Reasonableness Assessment ensures the balloon represents

the current environment• Wind Change Redline Assessment ensures that no late-in-the-count large shift

in the wind might invalidate the design:

In-Plane Wind Example

7OW

60*0

cuuuu

40*0

3U*U

i0*0

10*n

9

K" _300 k 200 _1S0 -100 0 100 156 -k.

TAIL TN-P] AN

_'PFF rp [(F]

IMAD

r Al INn'FLIG HT 17 MUTH 4.3 [dqj

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Ascent Performance Margin (APM)• APM is remaining propellant in excess of that required to reach orbit• DOL performance uncertainties influence pre-launch payload manifesting

• DOLILU designs tends to normalize APM which reduces in-flight dispersionprotection

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec




Launch Probability• With the DOLILU process, the probability of launch increases over an average

monthly wind design• For example, what if Shuttle did not redesign on launch day, but used the

monthly average windlatmos design?- In February, the launch probability would be reduced from 90% to -30%

Mean Wind Design Beta DOLILU Design

0.8 7.d 1 1.2 1.4 1.e 1.8

0.6


H 0.8 t 12 1.4 1.8 U 2 2.2

2.2 0.6 2.2 Mach

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Summary

• Day-of-launch design and assessment is important because it increases theprobability of launch

• Winds always change and the Space Shuttle must have some means toaccount for those changes

— Space Shuttle trajectory is redesigned on day-of-launch to minimize loadswhile maximizing performance

— Many safety improvements and assessment refinements have been made• The Shuttle concepts of operation can serve as a good basis for future NASA

vehicles



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space shuttle day-of-launch trajectory design and verification

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