entry, descent, and landing systems short course subject:cpas parachute testing, model development,...

Entry, Descent, and Landing Systems Short Course

Subject: CPAS Parachute Testing, Model Development, & VerificationAuthor: Leah M. Romero

JETS/Aerodyne, LLC

sponsored by

International Planetary Probe Workshop 10

June 15-16, 2013

San Jose, California

International Planetary Probe Workshop 10 Short Course 2013

2

Agenda

• CPAS Overview• Airdrop Testing• Parachute Test Analysis• Development of a Parachute Model• System Verification & Validation• Future of CPAS

June 15-16, 2013


3June 15-16, 2013

CPAS OVERVIEW


4

CPAS Overview

• Capsule Parachute Assembly System (CPAS) is the human rated parachute system for the Orion vehicle used during re-entry– Similar to Apollo parachute design– Human rating requires additional system redundancy

June 15-16, 2013

• A Government Furnished Equipment (GFE) project responsible for:– Design– Development testing– Performance modeling– Fabrication– Qualification– Delivery


5

MainPilots

Mains

1st Stage

2nd Stage

Full Open

Mortar Deployed

Pilot Deployed

Mortar Deployed

Forward Bay

Cover Pilots

Blunt End Forward Launch Abort

System Jettison

CPAS Concept of Operations

June 15-16, 2013

Drogues

Pilots

Mains

1st Stage 2nd StageFull Open

Full Open

1st Stage

2nd Stage

Mortar Deployed

Mortar Deployed

Pilot Deployed

Mortar Deployed

FBCPs

Nominal Mission and High Altitude Abort

Deployment Sequence

Low Altitude and Pad Abort Sequence (direct to mains)


6

CPAS Requirements

• The CPAS Project Technical Requirement Specification (PTRS) levies requirements on the system

• To verify the design and validate the requirements– Some system aspects are modeled– Some rely on demonstration

• 155 requirements total with 104 completely or partially verified by analysis

• Verification and Validation Document (V&VD) – Contains success criteria for verification of each requirement– Identifies the method and pass/fail criteria

June 15-16, 2013


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CPAS Analysis Focus• CPAS analysis team responsible for verification and validation of 23

requirements– Functional and performance

• Meet all other requirements when in deployment envelope• Meet all other requirements with specified vehicle mass

– Rate of Descent (ROD)• Crew and vehicle structure safety

– Parachute Loads – single riser and cluster loads• Individual parachute failure• Vehicle structural failure

– Rotation Torque and Flyout Angle Limit• Main risers induce rotation• Orient vehicle edge into water for landing

• Develop models anchored to flight tests• Conduct Monte Carlo analyses to examine possible failure

conditions and compare results to requirements– Parachute canopy or riser failure– Failure to deploy– Parachute flagging or skipped stage

June 15-16, 2013


8June 15-16, 2013

AIRDROP TESTING


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CPAS Parachutes

• Forward Bay Cover Parachutes (FBCPs) (~7 ft)– Pulls off Forward Bay Cover (FBC) from vehicle.

• Drogue Parachutes (~23 ft)– Stabilizes the vehicle for Main deployment.

• Pilot Parachutes (~10 ft)– Pulls out the Main chutes.

• Main Parachutes (~116 ft)– Slow the vehicle to landing.

• Test Support Parachutes– Extraction Chutes (~28 ft)

• Pulls the vehicle out of the aircraft. Used for testing only.

– Programmer Parachutes• Used to create the proper test conditions for the Drogue, Pilot, or Main

chutes. Used for testing only.• Can sometimes be an identical chute as the Drogues, but the use is

different.

June 15-16, 2013

Extraction Chute

Programmer Chute

Main Chute

Drogue Chute

FBCP

Pilot Chute


10

Engineering Development Unit (EDU) Test Vehicles

• Mid-Air Delivery System (MDS) & Cradle Platform Separation System (CPSS)– Allows the PCDTV and PTV to be deployed from an aircraft cargo bay

• Parachute Compartment Drop Test Vehicle (PCDTV)– Tests the full CPAS system utilizing an aerodynamically stable vehicle– Dart shape based on the Solid Rocket Booster and Ares booster parachute test program

• Allows for achievement of high dynamic pressure

• Parachute Test Vehicle (PTV)– Tests the full CPAS system with representative flight like wake environment– Unable to achieve nominal entry environment with current test techniques

June 15-16, 2013


11June 15-16, 2013

Extraction from a C-130 at 25,000 ft MSL

Separation

One reefed Gen II Drogue as Programmer Deploy

Drogues Deploy

Pilot Deploy

Main 1st StageMains 2nd Stage

MainsFull

Open

PCDTV/MDS Test Sequence


12June 15-16, 2013

Extraction from C-17 at 25,000 ft with two 28 ft Extraction Parachutes

Smart Separation after Ramp Clear

Two full-open Gen II Drogues as Programmers deployed

Programmer cut One Drogue

deployed

Smart Drogue Release using SDR

3 Pilots lift 3 Mains with

nominal reefing

PTV Touchdown

Programmers Inflated

Drogue Inflated

PTV/CPSS Test Sequence


13

Video

• For more videos, search for NASACPAS user on YouTube

June 15-16, 2013


14June 15-16, 2013

PARACHUTE TEST ANALYSIS


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Parachute Analysis: Preflight

• No single end-to-end simulation available therefore multiple simulations used to model different phases

• Define test objectives: number and configuration of programmers

June 15-16, 2013

• Assesses risk of test through Monte Carlos: loads, altitude, range safety, etc.


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Parachute Analysis: Post-flight

• Reduce and plot test data against prediction• Photogrammetric analysis used to

characterize parachute behavior

June 15-16, 2013

0 50 100 1500

10

20

30

40

50

60

70

80

90

Se

pa

ratio

n

Pro

gra

mm

ers

Re

lea

se

Dro

gu

e S

/N 6

Dis

ree

f to

Fu

ll

Dro

gu

e R

ele

ase

Ma

in s

tea

dy-

sta

te

PT

V T

ou

chd

ow

n

Time (s - RC)

Qb

ar

(ps

f)

Aircraft Tray SPAN-SESPAN-SE Raw IMUBest Estimate Trajectory (GPS/IMU)DSS Preflight (12/11/2012)

Circular Sector

Ring 4

Sail 1

rRing


17June 15-16, 2013

DEVELOPMENT OF A PARACHUTE MODEL


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Parachute Modeling

• Parachute parameters – Drag area: CDS

– Fill constant: n– Opening profile shape

exponent: expopen

– Overinflation factor: Ck

– Ramp down time: tk

June 15-16, 2013

Dra

g A

rea,

CDS

Time, t

expopen = 1expopen < 1expopen > 1

expopen = 0.5

expopen = 1.5

0

10

20

30

40

50

60

70

80

90

100

0.0 0.1 0.2 0.3

Drag

Are

a (s

q ft

)

Time (sec)(CDS)i-1

(CDS)itfp

tf

tk

(CDS)peak

Time, t

Dra

g A

rea,

CDS

ti


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Model Development

• Determine appropriate parachute parameter through test data reconstructions– Run simulations varying parachute parameters until test

data is matched– Can be subjective

• Do this for each test, parachute type, and stage

June 15-16, 2013

CDT-3-4 CDT-3-5 CDT-3-6

Drogue A Drogue B Drogue A Drogue B Drogue A Drogue B

Clean Reefed Drag Area per canopy, (CDS)R (ft2) 128 128 146 158 133 134

Over-inflation Factor, Ck 1.2 1.3 1.2 1.3 1.3 1.4

Fill Constant, n 3.4 6.9 5.4 4.9 7.5 5.2

Opening profile shape exponent, expopen 0.90 2.1 2.1 2.2 2.8 1.9

Ramp down time, tk (s) 0.69 0.13 0.03 0.06 0.14 0.11


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Model Development• Generate dispersions for each parachute type and stage• Dispersion bounding: caps or polygon

June 15-16, 2013

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

2.5

3

3.5

4

-1

+1

-2

+2-3

+3

Canopy Fill Constant, n

Fre

qu

en

cy

Test Data

Best Fit of Test Data

Median: 2.35Mean: 2.79

Bounds: 0.90063 6.7474

Bounds(formerly uniform

dispersions)

TMIN(1-EF) TMAX1+EF)

Test Data

logn: 0.9209 0.44781

Bounds: 0.90063 6.7474

Median: 2.41

Test Data

logn: 0.14547 0.21556Bounds: 0.76275 1.8689

Median: 1.17

0 2 4 6 8 100

0.5

1

1.5

2

2.5

3

EDU Main Stage 3 n

ED

U M

ain

Sta

ge

3 e

xp

op

en


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Model Development

• Redraw dispersions until inside polygon

• Deliver parachute model: 200K dispersions via 21 text files

June 15-16, 2013

Points within boundary are retained; outside points (green) are re-

drawn until acceptable (circled red)


22June 15-16, 2013

SYSTEM VERIFICATION & VALIDATION


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System V&V Introduction

• CPAS must meet its requirements to ensure the system functions as intended, individually and with other Orion systems

• V&V plan is a “list of activities that establishes the compliance” with the requirements

• Analysis team requirements are verified via analysis• Instructions provided through NASA Standard 7009

“Standard for Models and Simulations”– Model must be credible

• Determine through Model Credibility Scoring Guidelines• Completed for each model and simulation

– Current primary simulation: Decelerator System Simulation (DSS)– Future primary simulation: Flight Analysis & Simulation Tool (FAST)

June 15-16, 2013


24June 15-16, 2013

Level Verification Validation Input Pedigree

Results Uncertainty

Results Robustness Use History M&S

ManagementPeople

Qualifications

4Numerical error small for all important features.

Results agree with real-world data.

Input data agree with real-world data.

Non-deterministic & numerical analysis.

Sensitivity known for most parameters; key sensitivities identified.

De facto standard.

Continual process improvement.

Extensive experience in and use of recommended practices for this particular M&S.

3 Formal numerical error estimation.

Results agree with experiemental data for problems of interest.

Input data agree with experiemental data for problems of interest.

Non-Deterministic analysis.

Sensitivity known for many parameters.

Previous predictions were later validated by mission data.

Predictable process.

Advanced degree or extensive M&S experience, and recommended practice knowledge.

2 Unit and regression testing of key features.

Results agree with experiemental data or other M&S on unit problems.

Input data traceable to formal documenation.

Deterministic analysis or expert opinion.

Sensitivity known for a few parameters.

Used before for critical decisions. Established process.

Formal M&S training and experience, and recommended practice training.

1 Conceptual and mathematical models verified.

Conceptual and mathematical models agree with simple referents.

Input data traceable to informal documenation.

Qualitative estimaes.

Qualitative estimates. Passes simple

tests. Managed process. Engineering or science degree.

0 Insufficient evidence.

Insufficient evidence.







M&S Development M&S Operations Supporting Evidence

Model Credibility Score for DSS (January 2011)


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CPAS V&V Cycle

1) Design the parachute subsystem2) Test the design through flight and ground tests3) Development and Qualification test data is gathered4) Document the test data and advancements in parachute physics knowledge5) Verify the parachute subsystem meets flight performance requirements

a) If No, update the document for requirement clarificationb) If No, update the design so that it can meet the requirement

6) Validate flight performance requirements at the integrated Crew Module level7) Conduct integrated flight tests8) Run-for-the-record simulations

June 15-16, 2013


26June 15-16, 2013

FUTURE OF CPAS


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Future of CPAS

• Development Testing– EDU (plan as of May 20, 2013)

• 2013 (remaining): 2 tests – 1 PTV, 1 PCDTV

• 2014: 4 PTV tests• 2015: 2 PTV tests

– EFT-1 in fall 2014

• Qualification Tests

June 15-16, 2013

Lockheed Martin’s MPCV• Simulation & model development

• Transition to end-to-end simulation in an independent parachute model• Refinement of statistically derived dispersions• Determine and document Model Credibility of simulation used for run-for-

the-record V&V


28June 15-16, 2013

CPAS Analysis TeamPat GalvinJohnny BlaschakKristin BledsoeJohn DavidsonMegan EnglertUsbaldo FraireFernando GalavizEric RayJoe Varela

Koki Machin

Entire CPAS team

SPECIAL THANKS


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For More Information…• 2009 AIAA ADS Conference

– Overview of the Crew Exploration Vehicle Parachute Assembly System (CPAS) Generation I Drogue and Pilot Development Test Results, R. Olmstead

– Overview of the Crew Exploration Vehicle Parachute Assembly System (CPAS) Generation I Main and Cluster Development Test Results, K. Bledsoe

• 2011 AIAA ADS Conference – Proposed Framework for Determining Added Mass of Orion Drogue Parachutes, U. Fraire– Summary of CPAS Gen II Testing Analysis Results, A. Morris– Load Asymmetry Observed During Orion Main Parachute Inflation, A. Morris– Challenges of CPAS Flight Testing, E. Ray– Verification and Validation of Requirements on the CEV Parachute Assembly System Using Design of Experiments, P.

Schulte– Development of Monte Carlo Capability for Orion Parachute Simulations, J. Moore– Photogrammetric Analysis of CPAS Main Parachutes, E. Ray– A Hybrid Parachute Simulation Environment for the Orion Parachute Development Project, J. Moore– Measurement of CPAS Main Parachute Rate of Descent, E. Ray– Development of the Sasquatch Drop Test Footprint Tool, K. Bledsoe– Development of a Smart Release Algorithm for Mid-Air Separation of Parachute Test Articles, J. Moore– Simulating New Drop Test Vehicles and Test Techniques for the Orion CEV Parachute Assembly System, A. Morris– Verification and Validation of Flight Performance Requirements for Human Crewed Spacecraft Parachute Recovery

Systems, A. Morris

June 15-16, 2013


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For Even More Information…• 2013 AIAA ADS Conference

– Extraction and Separation Modeling of Orion Test Vehicles with ADAMS Simulation, U. Fraire– An Airborne Parachute Compartment Test Bed for the Orion Parachute Test Program, J. Moore– Application of a Smart Parachute Release Algorithm to the CPAS Test Architecture, K. Bledsoe– Application of Statistically Derived CPAS Parachute Parameters, L. Romero– A Boilerplate Capsule Test Technique for the Orion Parachute Test Program, J. Moore– Testing Small CPAS Parachutes Using HIVAS, E. Ray– Improved CPAS Photogrammetric Capabilities for Engineering Development Unit (EDU) Testing, E. Ray– Reefing Line Tension in CPAS Main Parachute Clusters, E. Ray– Skipped Stage Modeling and Testing of the Capsule Parachute Assembly System, J. Varela– Reconstruction of Orion EDU Parachute Inflation Loads, E. Ray

June 15-16, 2013


31June 15-16, 2013

QUESTIONS?


32June 15-16, 2013

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entry, descent, and landing systems short course subject:cpas parachute testing, model development,...

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