1McCauleyRBSP/EFW CDR 2009 9/30-10/1 EFW AXB Jeremy McCauley Aerospace Engineer Space Sciences...

1McCauley RBSP/EFW CDR 2009 9/30-10/1

EFW AXB

Jeremy McCauleyAerospace EngineerSpace Sciences Laboratory, [email protected]

AXB

AXB

Spacecraft +Z

EFW AXBOverall Flow

228 July 2009 EFW INST+SOC PEER REVIEW

DesignETU Build

ETU Test

Flight DWG Release

Flight Build

PDRPeer Review

July 28

CDR

•PDR•RFAs: 6 AXB related, 6 Closed

•Peer Review•AIs: 4 AXB related, 4 implemented•Suggestions: 11 AXB related,

11 implemented

•CDR•RFAs: 0 (?)


EFW AXB Overview

• Design Drivers• Design Description

– Concept

– Heritage

– Assembly Breakout

– Thermal

• ETU Integration and Testing (I&T)• Changes Since ETU


EFW AXB Design Drivers

• Deploy spherical electric fields probes up to 7 meters from center of spacecraft with an E-Field sensor and preamp at the end.

• Length adjustable (longer only) on orbit with a resolution of +/- 0.5 cm

• Interface to spacecraft to support deployable booms.• Meet straightness requirement (< 1° from spin axis).• Provide relief for CTE mismatch between Gr/E Tube and SC

body.• Provide a connector for test input to the sensor accessible

during all integration phases.• Total Mass not to exceed 8.57 kg (Each AXB Unit to not exceed

3.64 kg; AXB Tube to not exceed 1.29 kg)• Interface Operational Temperature Range: -25 to +55C (TBR)• Interface Survival Temperature Range: -30 to +60C (TBR)


EFW AXBConcept

• Axial Boom Unit (AXB)– Sensors Extended from SC on Stacers

• Compact for Launch

• Rigid after Deploy

• Adjustable Length

Upper Boom Unit (+Z)

Lower Boom Unit (-Z)


EFW AXB Heritage

• Heritage Unit– Primarily AXB from THEMIS, modified for length and to fit RBSP SC

• Including Tube, Structure, Stacer, DAD design and springs

• Similar to units on STEREO (6), THEMIS (10), POLAR and FAST

– More than 60 years of on orbit operation

– Whip from Rockets

• replaces THEMIS Whip Stacer

– Direct Drive Unit from THEMIS SPB

• Added Refinements– Direct Drive Unit on a Stacer

– DAD Lock Wheel Assemblies

– Sphere Caging Mechanism


EFW AXB Order of Deploy

Stowed Unit

•Unpowered

•Fully RestrainedStep 1: Whip Deploy

•Frangibolt Actuated

•Spring Powered

Step 2: Stacer Deploy

•Frangibolt Release

•Motor Driven (3 cm/s)

•Length Adjustable

•Fault Analysis in Backup Slides

+Z SC Axis


EFW AXB Design Description: AXB

• Structural Design– End Supported Tube with Aluminum End Fittings– Two (2) Identical Boom Units

• Stationary Deploy Assembly• Moving DAD• Stacer• Whip and Spherical Electric Fields Probe

Upper Boom Unit (+Z)

Lower Boom Unit (-Z)

Dimensional Scale

Tube Diameter

6” [15 cm]

Deck Separation

43.5” [108 cm]

Whip Length

13” [33 cm]

Sphere Diameter

3.2” [8.0 cm]


EFW AXB Tube Assembly

• Structural Design– End Supported Tube: Graphite Epoxy,

M55 (Layup: -60/60/0/0/60/-60 [quasi-isotropic])

– Fixed-Fixed First Frequency: 257 Hz

– Tube Static Stress Margin: 10

– End Fittings: Al 6061-T6

– Lower Support includes a drumhead flexure design

• Currently 89.1 lbf @ 52ºC dT

– Joint Epoxy: Hysol 9309NA

– Bond Shear Stress Margin: 30.3

Tube

End Fitting

Flexure

Flexure atdT=52ºC

EFW AXB Tube Testing

• Structural Testing– Thermal cycling

– Static loads

– Structural loads testing• Integrated to SC



EFW AXB Design Description: Booms

• Boom Design– Stationary

Deploy Assy– Moving DAD– Stacer– Whip and Spherical

Electric Fields Probe

Whip

DAD

Stacer

Deploy Assy

Stowed Configuration

Deployed Configuration



• Stationary Deploy Assy– Sphere Caging Mechanism

– Direct Drive Assembly

– Roller Nozzle #1

Sphere CagingMechanism

Roller Nozzle #1

Direct Drive Assy




EFW AXB Design Description: Cage

• Sphere Caging Mechanism– Protect Spherical Electric Field

Probe– Release Whip on Orbit

• Frangibolt Actuator (Next Slide)

• Top Opens• Cam Releases Arm• DAD Plunger with Kickoff

Spring Starts Whip– AC Test Contact for Ground

Operations– Torque Margin: 40.9

• Spring to Friction Drag– Green Tag Enable Plug/

Ground Test Plug



DAD Plungers

AC Test Contact

Enable Plug

Frangibolt


EFW AXB Design Description: Frangibolt

• TiNi Frangibolt– 500 lb Retention Force

• For Launch Loads Only

• Static Margin: 14

– Resettable

– 25 W @ 28 Vdc

– 95°C Actuation Temperature

– Trending Data

http://tiniaerospace.com/fbt/fbfc2-16-31sr2.html


EFW AXB Design Description: Direct Drive

• Direct Drive Assembly– Stacer Frangibolt Release– Harness Spool: Max Capacity 6.66 meters 0.068” diameter cable– Motor Drive Mechanism: Globe A1430 Motor (1000:1 gear ratio)– Sense Switches: Stacer Release, End of Wire and Turn Counter (Newark, 1HM19)– Slip Ring (Airflyte CAY-1398)– Length Resolution: 0.65 cm/click BOT, 0.52 cm/click EOT, 5.2 clicks/s– Torque Margin: 7.6 (Motor Torque to Torque to Retract Stacer)

Frangibolt

Sense Switches Spool

Harness

Motor Slip Ring


EFW AXB Cable Load Path

• Cable Force Path– Force is carried completely in Kevlar overwrap– Static Margin: >100

Tie Off Point

Glue Joint


EFW AXB Design Description: Nozzle

• Roller Nozzle #1– Centering of the Stacer– Resist SC Forces

• Springs designed to 1.6 lb minimum radial force

Rollers

Rocker Arms


EFW AXB Design Description: DAD

• Moving DAD– Deployment Assist Device

(DAD) with Kickoff Springs– Lock Wheel Assemblies

• Increase Unseat Force from 6 lbs to 15 lbs axial from 1.6 to 4.5 lbs radial

– Roller Nozzle #2• Springs designed to 1.6 lb

minimum radial force

– Force Margin: 2.1• DAD Springs to

Friction

Stowed Configuration Deployed Configuration

DAD Springs

Lock Wheel Assy

Roller Nozzle #2


EFW AXB Design Description: Stacer

• Stacer– Helical Spring– Deployed Acts as a Rigid Tube

• Spin Adjusted Resonance: 26.5 RPM

– Force Margin: > 3 • Stacer Force to Friction

MAIN STACER PROPERTIES

[in] [mm]

STRIP THICKNESS 0.004 0.10

STRIP WIDTH 5.000 127.00

TIP DIAMETER 0.700 17.78

BASE DIAMETER 1.128 28.65

EQUIVALENT DIAMETER

1.005 25.54


Stacer


EFW AXB Design Description: Whip

• Whip and Spherical Electric Fields Probe– Hinge

• Torque Margin: 3.6• Hinge Spring to Friction• DAG 213 Coated

– Whip Tube• FOS (Bending on Deploy): 2.0• DAG 213 Coated

– Sphere• Probe and Preamp Assy• DAG 213 Coated

– Cannot Clean DAG 213 surfaces– All Three Isolated for Potential Control– Fundamental Frequency: 23.0 RPM

• (> 4x SC Spin Rate Rigid)

StowedConfiguration


SphereInternal View

Whip

Sphere

HingePreamp


EFW AXB Design Description: Stress Margins

Critical Part Stress Margin

Stacer Frangibolt 14

Mounting Flexure 0.9

Mounting Flange 2.7

Mounting Tube 10

Tube Bond (Top) 30

Whip Tube 128

Whip Hinge Pin 34

EFW AXBGlue Bond Margins

* Joint Strength is derated according to surface preparation requirements as discussed in HTN-102050-017, dated 06/15/2000, as received from Chris Smith, UCB/SSL.


Epoxy: Hysol 9309NA Lap Shear Strength (psi): 4000

Joint Area (in^2)

Strength(lbs) *

Force(lbs)

Margin

Whip to Sphere 0.244 155 0.051 3010

Whip to Hinge 0.196 124 0.051 2418

DAD Rod to DAD Tip 0.349 221 2.17 101

Tip Tube to Tip End 1.077 683 3.17 214

Tip to Tip Tube 1.077 683 3.17 214

Tip to Safety Pin 1.127 715 3.17 224

EFW AXBGlue Bond Margins


Tip to Safety Pin

Tip to Tip Tube

Tip Tube to Tip End

DAD Rod to DAD Tip

Whip to Hinge

Whip to Sphere

EFW AXBDesign Spreadsheets

• Caging Spring Torque

• DAD Lock Spring

• DAD Telescoping Spring

• Deploy Motor

• Frangibolt Firing Times

• Hinge CTE

• Hinge Spring Torques

• Large Fine Pitch Bolt Torques

• Mass Properties

• Roller Nozzle Spring

• Sense Line Resistances

• Tube CTE

• Whip Torsion Spring

• Wire and Spool



EFW AXB Thermal

• Thermally Coupled to the SC

• Spherical Electric Fields Probe, Whip and Hinge:

– Coated with DAG 213

• Stacer:

– Mill Finish Elgiloy

• Moving DAD:

– Alodine (1500, Clear, 300s immersion)

– Electroless Nickel Plating with Teflon Impregnate

• Stationary Deploy Assy:


– Electroless Nickel Plating with Teflon Impregnate

• End Supported Tube

– M55 Graphite Epoxy

• Aluminum End Fittings


EFW AXBLong Lead Items

• Frangibolts– Ordered: August 2009

– ~10 week lead

• Gore Cable– In House

• Motor– In House

• Stacer– In House


EFW AXBOrder of Assembly


Paint: Whip, Stacer and

Sphere

Paint: Whip, Stacer and

Sphere

Assemble Doors

Assemble Doors

Assemble StacerAssemble Stacer

Assemble Stacer Assembly

Assemble Stacer Assembly

Assemble Whip

Assemble Whip

Preamp Mech

Assembly

Preamp Mech

AssemblyAssemble

Sphere, Whip and Preamp

Assemble Sphere, Whip and Preamp

Test Preamp PWB

Test Preamp PWB Integrate Whip

and CageIntegrate Whip

and Cage

Motor Burn InMotor

Burn InHarness

MotorHarness

Motor

Harness SW1

Harness SW1

Assemble Direct Drive (-500)

Assemble Direct Drive (-500)

Harness Diode Block

Harness Diode Block

Assemble DAD

Assemble DAD

Assemble Caging Mech

Assemble Caging Mech Whip and

Cage Mechanical Functional

Whip and Cage

Mechanical Functional

Assemble Stacer Mechanism

Assemble Stacer Mechanism

Harness AssemblyHarness

Assembly

Stacer Mech Functional,

Length & Runout Measurement,

Continuity Check



Continuity Check

PER

Whip and Cage

Electrical Functional

Whip and Cage



EFW AXB I&T: Environmental Test Matrix

EFW AXBEnvironmental Testing


Integrate Stacer, Whip

and Cage


and Cage


Test


Test

Science CalibrationScience

Calibration

Whip and Cage Mechanical Functional

Whip and Cage Mechanical Functional



Continuity Check



Continuity Check

PER

Mass Properties

Mass Properties

Integrated Vibration

Test

Integrated Vibration

Test

Electrical Functional Test




Dis-Integrate Stacer, Whip

and Cage

Dis-Integrate Stacer, Whip

and Cage

Whip and Cage TV Hot

Deploy

Whip and Cage TV Hot

Deploy

Whip and Cage TV Cold

Deploy

Whip and Cage TV Cold

Deploy

Stacer Mech TV Hot Deploy,


Continuity Check



Continuity Check



Continuity Check



Continuity Check


and Cage


and Cage

PSR


EFW AXB I&T: Deployments

• Functional Deployments– Expected number of deployments on the instrument at launch: 4

• Functional

• Post Vibe Functional (“test as you fly” exception)

• Thermal Vacuum Hot

• Thermal Vacuum Cold

• Deployments of Whip and Cage

at SC Level after Vibe

All stacer deployments include:

Frangibolt and Motor trending,

EOT Switch verification,

Continuity verification,

Runout and

Stiffness testing.


EFW AXB I&T: Alignment

• Alignment Testing– Requirement: <1° from spin axis– Testing Total: <2.2” Runout < 0.46° from spin axis

• Stacer Runout is <1.2” (0.88”, 0.73”, 1.2”, 1.2”, 0.94”)– Unit deployed horizontally on a g-negating track, then lifted to floats.

• RSS Analysis of Tolerance Stackup: 0.20 degree (0.8 inches at Sphere)• Hinge, Whip and Sphere Runout is <0.1”• Loose Stacer on Tip 0.1”

– Stiffness: 0.003 lb/in– Fund. Frequency: 0.43 Hz


EFW AXB I&T: Vibration

• Vibration Testing– ETU Vibration to Qualification levels per 7417-9019 Section 5.4.5 – Self-shock survival from boom deployment actuations– Force Limiting (C^2 = 5, f(0) = 1.1 X f(n), CG response = 4.25 X TLL)– First Frequency: X, Y = 180 Hz, Z = 275 Hz– Flight Units Random to GEVS Workmanship Levels as these are higher than the

SC loads predicted by early SC acoustic testing.

CONTROL ON TABLE X - AXIS

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0020.00 100.00 1000.00

0.5248

3.98E-06

1.00E-05

0.0001

0.0010

0.0100

0.1000

Frequency (Hz)

(gn)²/Hz


EFW AXB I&T: TV

• Thermal Vacuum Testing– 2 operational cycles plus 1 survival cycle, per the requirements and limits

indicated in 7417-9019 section 5.3.2– Deployment tests successful at hot and cold levels

COLD DEPLOY

HOT DEPLOY

COMPONENTOPERA-TIONAL

MIN

OPERA-TIONAL

MAX

SUR-VIVAL

MIN

SUR-VIVAL MAX

Whip & Caging Mechanism -25 65 -30 70

Deploy Mechanism -25 55 -30 60

EFW AXBRadiation Dose Testing

• Three samples were analyzed:– a 2 square inch sample of Aluminum with Electroless Nickel

Plating with Teflon Impregnate (Microlube, by Micro Plating, Inc.),

– approximately 2 feet of AXB harness with Tefzel overwrap (Gore Cable, RCN8818, July 2008), and

– a hemisphere coated with DAG-213.

• Total dose of 10 Megarads at 18 rads/s, • Average gamma ray photon energy is 1.25 MeV.• APL Space Departments Cobalt 60 Irradiator

• Maintained integrity, adhesion and surface properties.



EFW AXB Mass Properties Testing

• Mass Properties Testing: to be completed– Mass: 3.065 kg (2.97 predict, 3.40 NTE)

• 11% Margin

– Ixx = 0.160 kg-m2 (0.407 kg-m at Tube COM)

– Iyy =

– Izz =


EFW AXB HYPOT Testing

• HYPOT Testing: to be completed– Connectors need testing for resistance to High Potential (HI POT)

– Not reasonable on a part by part basis

– Harness will be tested in unit, prior to Preamp installation

Sphere

Whip Hinge

Whip Harness

EFW AXBAnomaly Reports

• CLOSED– RBSP_EFW_AXB_018 Disposition of Deploy Catch 090417

• Improved Stacer Packing• Tip Grip Accommodated in Alignment

– RBSP_EFW_AR_003 AXB Motor Gap• Washer on ETU to fill gap• No modification to Flight Motors

– RBSP_EFW_AR_004 Frangibolt Overtemp in Hot TV• Switches with Timing Backup

• OPEN– RBSP_EFW_AR_002 AXB Spool Wiring

• Open conductor• Pending further testing


EFW AXBChanges Since PDR

Increase deploy length from 12m to 14m tip to tip. Maintaining extra coils in Stacer Can. Removed Deploy Heater and Thermostat.

• Determined unnecessary in EFW/SOC PDR AI #29. Change Roller Nozzle Springs.

• Lowered contact force.


EFW AXBChanges Since ETU Testing

Add Frangibolt Switches



Add Science Cable support on Direct Drive Assembly

Spool Wheel Well Finalize Spool Sizing



PreAmp Harness Support Additional travel range added

to Sphere Clamps Improve bonding features

around Omnetics connectors Add clearance to parts near

stacer Add Sleeve for Sphere Cage

Stop


EFW AXBShipping Containers

• Designed and Assembled– Vibration Shipping Crate– Tube Shipping Crate

• To Be Completed– Final Crate for Shipment to

APL• 2 Whips

• 2 Cages

• 2 Deploy Assemblies

• Not Assembled

• Most likely an update to the Vibration Shipping Crate



EFW AXB Backup Slides

• Back up slides– Redundancy is Key….

Spacecraft SPB’s AXB’s Mag Booms

S3-2 4

S3-3 4 2

ISEE 2

VIKING 4

FREJA 6

FIREWHEEL* 2

CRRES 2

POLAR 4 2

FAST 4 2 2

CLUSTER I* 16

CLUSTER II 16

THEMIS 20 10 10

SPARES 26 6 2

Lunar Prospector 1

Sounding Rockets ~50

----- ----- -----

110 26 (+ 50) 15

* LAUNCH FAILURE

SSL History / Heritage

UCB/SSL HERITAGE (courtesy F. Mozer)



EFW AXB Design Description

ID Req. Title Priority Requirement Body or Section Heading 3 Functional Requirements

3.1 Functional, performance and general design requirments

EFW-1 Instrument Design life shall be designed for a total lifetime duration of 2 years plus 60 days.

EFW-200 Instrument Calibration shall be calibrated prior to launch, and be designed to accommodate additional in-flight calibration

EFW-6 Instrument Orbit Inclination Operability

shall be capable of operating in an orbit with an inclination of 10° ± 0.25°.

EFW-7 Instrument Orbit Perigee Operability

shall be capable of operating in an orbit where perigee altitude is between 500 km and 675 km (TBR).

EFW-8 Instrument Orbit Apogee Operability

shall be capable of operating in an orbit where apogee altitude is between 30,050 km and 31,250 km (TBR).

EFW-201 Instrument Accommodation of Observatory Sun Off-Point Angle (Component)

shall shall be capable of collecting required science measurements under the condition where the off-pointing angle between the spin axis of each observatory and the Sun-Earth line during nominal operations does not exceed 25 degrees North or South of the ecliptic plane, or 25 degrees East or West in the ecliptic plane, where "north" and "south" are with respect to an ecliptic coordinate system.





EFW-202 Instrument Accommodation of Observatory Sun Off-Point Angle (Composite)

shall be capable of collecting required science measurements under the condition where the total off-pointing angle between the spin axis of each observatory and the Sun-Earth line during nominal operations is greater than 15 degrees, and does not exceed 27 degrees.

EFW-9 Instrument Accommodation of Observatory Operational Spin Rate Range

shall be capable of operating nominally within an observatory spin rate range of no less than 4 rpm and no more than 6 rpm.

EFW-10 Instrument Accommodation of Observatory Selected Operational Spin Rate

shall be capable of collecting required science measurements at a specific, optimal spin rate selected for both observatories that is within the specified allowable range

EFW-11 Instrument Accommodation of Observatory Selected Spin Rate Stability

shall be capable of collecting required science measurements at an observatory spin rate that is maintained to within +/- 0.25 rpm of the in-flight selected value, except during maneuvers.

EFW-203 Instrument Accommodation of Observatory Commissioning Spin Rate Range

shall be capable of accommodating an observatory spin rate during commissioning period activities within a range between 3 RPM (TBR) and 15 RPM (TBR).





EFW-12 Instrument Accommodation of Unattended Mission Operations

shall be designed to accommodate periods of unattended mission operations (unstaffed MOC) during the operational phase of the mission of up to TBD hours

EFW-21 EFW Instrument Complement shall consist of four orthogonally oriented, boom-mounted spin-plane boom-mounted sensors, an Electronics Box, and two axial boom mounted sensors with harness as defined in the Spacecraft to EFW ICD.

EFW-22 Functionally Identical EFW Instrument Suites

shall be functionally identical.

EFW-23 EFW - Spacecraft ICD Compliance

shall comply with the EFW-to-Spacecraft interface control documents (ICDs).

EFW-24 EFW Instrument Availability shall be designed to be available for the collection of its required measurements at least 99% of the time during the operational phase of the mission

EFW-209 EFW Spin Axis Measurement Sensitivity Validty

shall meet Spin Axis measurement sensitivity requirements outside time periods defined as follows: the interval where the aft axial boom is shadowed by the spacecraft or solar panels, and 25 seconds after the end of such periods. (TBR)





EFW-51 Measure Spin Axis DC Electric Field (Survey)

shall measure axial electric field components (survey), as follows: -- frequency range: DC to 15Hz; -- magnitude range: 2 mV/m - 500 mV/m; -- cadence: 32 vectors/second; -- sensitivity: 4 mV/m or 20% for R > 3.5 Re, 6 mV/m or 20% for 3.5 Re > R > 2.5 Re, 12 mV/m or 20% for R < 2.5 Re.

EFW-52 Measure Spin Axis DC Electric Field (Burst)

shall measure axial electric field components (burst), as follows: -- frequency range: DC to 256 Hz; -- magnitude range: 0.4 - 500 mV/m; -- cadence: 512 samples per second; -- sensitivity: 1 mV/m or 10% @ 50 Hz (TBR).

Required Components to Achieve Above

EFW-54 EFW Axial E-Field Booms shall be capable of deploying 6 meters with an E-Field sensor preamp at the end capable of measuring E-Fields to 400 kHz





Required Components to Achieve Above

EFW-54a EFW Axial E-Field Booms shall Deploy the AXB sensors within +/- 1 degree of the AXB deployment system axis

EFW-56 EFW Harnessing shall connect the SPB, AXB, IDPU, EMFISIS/MAG and EMFISIS/SCM units together as detailed in the ICDs

EFW-61 EFW Power Control shall contain circuitry to open SPB and AXB doors and deploy sensors

3.2 Power allocations and related requirements

EFW-65 EFW Main Power Max Voltage shall tolerate without damage a maximum input voltage of 40V indefinitely as defined in the ICD

EFW-66 EFW Main Power Turn Off shall tolerate without damage having power removed without notice as defined in the ICD

EFW-68 EFW AXB Deployment Power shall not exceed 4.0 Amps from the EFW AXB Deployment Service

EFW-69 EFW Survival Heaters shall accommodate survival heaters up to 1/2 nominal power at 22V bus voltage, or approximately 113 Ohms.




3.3 Performance budget sub-allocations with respect to system budgets

EFW-72 EFW AXB Whip Release Power shall not exceed 2.0 Amps at 28VEFW-73 EFW AXB Stacer Release

Powershall not exceed 2.0 Amps at 28V

EFW-74 EFW AXB Motor Power shall not exceed 0.2 Amps at 28V (1.5A startup) 3.4 Operational requirements

EFW-77 EFW AXB Operational Temp Range

shall perform as designed from -25 to +55C (TBR)

EFW-80 EFW AXB Survival Temp Range

shall survive without damage from -30 to +60C (TBR)

3.6 Interfaces to the spacecraft bus

EFW-90 EFW AXB ICD Compliance shall comply with the requirements and constraints imposed by all relevant instrument-to-spacecraft interface control documents (ICDs).

3.8 System test Interfaces

EFW-92 AXB Signal Test Input shall provide a connector for test input to the sensor accessible when the top and bottom of the spacecraft are accessible.




3.10 Fault detection and correction considerations/requirements

EFW-100 EFW AXB Deployment Enable shall not deploy AXB booms or fire AXB actuators without the AXB and Main power ON.

3.11 Redundancy description

EFW-101 EFW Boom Pair Redundancy shall be capable of powering each Efield axis separately.EFW-102 EFW Safing by subsystem shall separately current-limit each axis and the front end

electronics required for EMPHASIS EFI signal, and the remainder of the EFW electronics

3.12 Mass allocation

EFW-103 EFW Total Mass shall The EFW shall not exceed the total allocated mass budget of 31.17kg (or as allocated in RBSP System Mass Budget).

EFW-106 EFW AXB Mass shall not exceed 3.64 kgEFW-107 EFW AXB Tube Mass shall not exceed 1.29 kgEFW-108 EFW Harness Mass shall not exceed 2.50 kg (TBR) 3.15 Contamination control requirements

EFW-132 Instrument Compliance with Contamination Control Plan

shall comply with the requirements and constraints imposed by the RBSP Observatory Contamination Control Plan, APL document no. 7417-9011




3.15 Contamination control requirements

EFW-133 Instrument Compliance with EM Environment Control Plan

shall comply with the requirements and constraints imposed by the RBSP Electromagnetic Environment Control Plan, APL document no. 7417-9018.

EFW-135 EFW ESC Control shall comply with the UCB Electrostatic Cleanliness (ESC) Plan

EFW-136 Instrument Compliance with Environmental Design and Test Requirements Document

shall comply with the requirements and constraints imposed by the RBSP Environmental Design and Test Requirements Document, APL document no. 7417-9019.

EFW-137 EFW Quality Assurance shall comply with the RBSP Performance Assurance Implementation Plan, as modified by the Compliance Matrix

EFW-211 Instrument Range Safety shall comply with all relevant requirements and constraints imposed by AFSPC 91-710, Range Safety User Requirements Manual.

EFW-212 Observator Naming Convention

shall use an observatory naming convention, as follows: -- Observatory A is the top observatory in the stacked configuration for launch; -- Observatory B is the bottom observatory in the stacked configuration for launch.


EFW AXB Design Requirements

• Mechanical Design Requirements– From 7417-9019 RBSP

Environmental Specification, Rev. H

– Quasi Static Limit Load: 25 g (5 kg to 25 kg)

– Factors of Safety: See Chart– Provide a fundamental

frequency of greater than 50 Hz (Stowed).

Factor of Safety (FOS)Type

STATIC

SINE

R / AA CN OD UO SM T I C

Metallic Yield 1.3 1.3 1.6

Metallic Ultimate 1.4 1.4 1.8

Stability Ultimate 1.4 1.4 1.8

Composite Ultimate 1.5 1.5 1.9

Bonded Inserts/JointsUltimate

1.5 1.5 1.9


EFW AXB Design Description: Materials

• Materials and Properties Assumed– Metals, Yield Stress:

• Brass 360, 49 kpsi• Aluminum, 2024-T8, 58 kpsi• Aluminum, 2117-T4, 24 kpsi• Aluminum, 5052-H32, 28 kpsi• Aluminum, 6061-T6, 40 kpsi• Beryllium Copper, #25 (C17200), 160 kpsi• Bronze C544, 35 kpsi• Copper (Oxygen-free, C10100), N/A• Elgiloy, Spring Temper• Steel, SS, 18-8, 70 kpsi• Steel, SS, 300 Series, 30 kpsi• Steel, SS, 400 Series, N/A• Steel, SS, 17-7 PH, CH900, C condition, 230 kpsi• Tantalum per ASTM-B365-98, 65 kpsi (Ultimate)• Titanium, 6Al-4V, 120 kpsi



• Materials and Properties Assumed– Composites:

• Graphite Epoxy - Fiberite Hy-E 1034C or eq (M55)– Plastics:

• Acrylic (Medium-high impact), 6kpsi• Black Delrin, 11 kpsi (Ultimate)• White Delrin, 11 kpsi (Ultimate)• Vespel SP3, 8 kpsi (Ultimate)• PEEK, 16 kpsi



• Materials and Properties Assumed– Adhesives:

• Hysol 9309NA, 4 kpsi (Tensile shear Strength)• Hysol 1C• Hysol 0151• 3M EA1838• 3M EA 2216

– Tapes:• Kapton Tape (acrylic adhesive)

– Lubricants:• Braycote 601 –or— Braycote 601 EF• DAG 154 Paint



• Coatings Used– Alodine per MIL-C-5541 CL 3 (Gold)– Black Anodize per MIL-A-8625 Type II, Class 2– Hard Black Anodize per MIL-A-8625 Type III, Class 2– Electroless Nickel Plating with Teflon Impregnate– Silver Plate per QQ-S-365 Type I, Grade A– Vapor Deposited Nickel– Braycote 601 –or— Braycote 601 EF– DAG154 Paint– DAG213 Paint

EFW AXB Deploy Operations, IPDR RFA #26

1. Fire Frangibolt to release the Cage and Whip

2. Fire Frangibolt to release the Stacer

3. Deployment proceeds by running the motor to pay out the boom (<2cm/sec). AXB boom deployment is initiated by ground command and monitored by EFW Flight and SOC software. Deployment typically proceeds in small increments. Boom length at any time is determined by a turns counter, and can also be checked based on motor operation time.


EFW AXB Deploy Operations, IPDR RFA #26

A typical sequence (after whip and stacer release) is:

1. EFW and APL agree on the next deployment increment

2. The MOC enables the AXB deployment power service

3. Wait until the AXB deployment mechanism is within thermal limits

4. EFW SOC commands the EFW DPU to deploy AXB a number of clicks

5. EFW flight software powers on the motor, counts clicks, and powers off the motor after the desired number of clicks

6. MOC powers off the AXB deployment power service

7. SOC software & EFW personnel monitor the deployment


EFW AXB Deploy Fault, IPDR RFA #26

• Single String Mission• Credible AXB deployment failure mechanisms which might result in an unintended or

over-long deployment and mitigations:

Item Failure Mitigation

1 EFW hardware or software failure outside of boom deployment intervals which would cause the system to attempt to deploy the AXB.

AXB deployment service normally powered off by the spacecraft

2 EFW software failure during AXB boom deployment resulting in motor continuing to operate past the desired number of clicks

1. EFW watchdog resets system to motors off state2. EFW team requests MOC to power off deployment service if

system not operating nominally.3 AXB deployment clicks switch failure EFW team sees no clicks (or off-nominal click rate) during

deployment and shuts off AXB power, resulting in a short deployment. Deployment length can be estimated based on motor on time.

4 AXB motor switch failure (fails ON) EFW team requests MOC to shut off AXB deployment service

5 Harness failure (breaks) resulting in unrestrained deployment.

1. Harness contains Kevlar element which is >100x stronger than the deployment forces.

2. Should the deployment jam, an over-tension switch cuts off the motor well below the force level which might damage the harness.


EFW AXB Worst Case Fault

• If no clicks are seen or the deployment runs longer than expected

– terminated by ground command

– MOC can terminate the AXB deployment service

• SOC and MOC team should be prepared to act swiftly to minimize the uncontrolled deployment time (at ~2cm/sec).

• Most anomalies would be identified prior to reaching the desired deployment length

• Worst case: ~5 seconds to command, ~10cm of length.



EFW AXB Tube

• Structural Design– Fixed-Fixed First Frequency: 257 Hz

– Tube Static Stress Margin: 10

– Buckling Force: 3600 lbs (max load: 1200 lbs)


RBSP AXB Stacer Deploy Force Ratio

0

1

2

3

4

5

6

7

8

9

10

11

12

0 2 4 6 8 10 12 14 16 18 20

Deployed Length (ft)

Fo

rce R

ati

o

Pu

sh

Fo

rce (

lb)

No

zzle

Dra

g (

lb)

Push Force (lb) Nozzle Drag (lb) Req'd Ratio Force Ratio




• Whip and Spherical Electric Fields Probe– Hinge

• Torque Margin: 3.6• Hinge Spring to Friction• DAG 213 Coated

– Whip Tube• FOS (Bending on Deploy): 2.0• DAG 213 Coated

– Sphere• Probe and Preamp Assy• DAG 213 Coated• Cannot Clean

– All Three Isolated for Potential Control– Fundamental Frequency: 23.0 RPM

• (> 4x SC Spin Rate Rigid)

StowedConfiguration


Whip

Sphere

HingePreamp

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 10 20 30 40 50 60 70 80 90

T-Spring (lb-in)

T-Measured (lb-in)

T-Required (lb-in)


EFW AXB Design Description: I&T

• ETU Flow: Stiffness Testing– Slope: 0.003 lb/in

inch

es

grams



• Stacer Fundamental Frequency Testing– Unit deployed horizontally, then suspended vertically.

• Gravitational component subtracted from frequency.

– ETU Unit: 0.43 Hz

– Flight unit will be tested horizontally in Runout Test Fixture.



• ETU Flow: Thermal Vacuum Testing– 2 operational cycles plus 1 survival cycle, per the requirements and limits

indicated in 7417-9019 section 5.3.2– Deployment tests successful at hot and cold levels

TEST COMPONENTOPERATIONAL

MINOPERATIONA

L MAXSURVIVAL

MINSURVIVAL

MAX

Rod Sphere Caging Mechanism

-25 65 -30 70

DDAD Mechanism and Stacer

-25 55 -30 60

EFW AXB Mate / Demate Tally


Connector: JA JB JC PC JD JE PE JF PF JH PH JI PI JJ PJ

Total: 23 10 5 1 1 11 11 13 10 7 3 0 0 11 5

EFW AXBBlind Mates

• Mate of JH to PH– During assembly of Whip to

Stacer Tip Piece– The mate is hidden– Alignment is checked beforehand– Harness is checked afterward



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1McCauleyRBSP/EFW CDR 2009 9/30-10/1 EFW AXB Jeremy McCauley Aerospace Engineer Space Sciences...

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