THEMIS Instrument PDRRob Duck 1 UCB, October 15-16, 2003 EFI Axial Booms (AXB) Preliminary Design...
-
Upload
sammy-pepper -
Category
Documents
-
view
213 -
download
0
Transcript of THEMIS Instrument PDRRob Duck 1 UCB, October 15-16, 2003 EFI Axial Booms (AXB) Preliminary Design...
THEMIS Instrument PDR Rob Duck 1 UCB, October 15-16, 2003
EFI Axial Booms (“AXB”)
Preliminary Design ReviewRob Duck
Mechanical Engineering Department
and Space Sciences Laboratory
Univ. of Calif., Berkeley
THEMIS Instrument PDR Rob Duck 2 UCB, October 15-16, 2003
Requirements & Specifications
THEMIS Mission Design Requirements• Axial boom designed in accordance with the THEMIS Product
Assurance Implementation Plan (“PAIP”)
• Mechanical design and test environments as outlined in Mechanical-Verification-Spec-1c by Swales Aerospace
• Deployed axial boom shall be repeatable and stable to and L/L = 1%
• Axial boom shall be designed to be deployed between 0 and 25 RPM
• Axial boom deployed stiffness shall be greater than 0.75 Hz
• Axial sensor baseline will be ~10 m, tip to tip
THEMIS Instrument PDR Rob Duck 3 UCB, October 15-16, 2003
Requirements & Specifications
Mechanical Design Objectives• Axial boom shall be modular and removable from probe with minimal
probe disassembly• Axial boom test and safe plug shall be externally accessible to probe• Each individual boom shall have a single point of actuation• Axial boom design shall be based on heritage designs from previous
launches
Mass• 2 Kg per boom
Deployment execution is critical• Proper stowing of wire cable• One time deployment• Full boom extension
THEMIS Instrument PDR Rob Duck 4 UCB, October 15-16, 2003
Axial Boom Overview
AXB are integral part of THEMIS probe• Primary probe structure provided by Swales Aerospace• AXB located along center axis of probe• AXB deployment through top and bottom decks of probe.
Test & Safe Plug
Lower Deck Mount
Composite Tube
Antennae Mount (TBD by Swales)
AXB relative to THEMIS Probe Internal View
AXB Assembly
THEMIS Probe
Upper Deck Mount
Upper AXB
Lower AXB
AXB Housing
THEMIS Instrument PDR Rob Duck 5 UCB, October 15-16, 2003
Design Heritage
AXB Base Design has flown before• POLAR• FAST
UCB Heritage• Test data from previous flights• Design engineers still at UCB• Using the same vendors• Consistent assembly and test procedures
AXB Heritage Design• Double boom deployment• Stacer booms• Double cantilever design• Deploy Assist Device
THEMIS Instrument PDR Rob Duck 6 UCB, October 15-16, 2003
Axial Boom General Assembly
Whip Canister (Whip Sensor Inside)
Double Deploy Assist Device
(“DDAD”)
Tube Mounting Brackets
Preamp
Cable Bobbin
Stacer Canister (Stacer inside)
INDIVIDUAL BOOM IN STOWED CONFIGURATION
SMA/Ball détente Actuator
Whip Doors
DDAD Doors
STACER
Design Modifications• Stacer length• Double deploy assist device• SMA/Ball détente actuation• Whip sensor
Roller Nozzles
Whip Posts
THEMIS Instrument PDR Rob Duck 7 UCB, October 15-16, 2003
Theory of Operation
Integration & Loading• Whip Sensor is loaded into whip canister
• Whip canister is locked to the preamp by the whip clamp
• Stacer is loaded into stacer canister, DDAD doors hold the DDAD, and whip doors hold the whip canister
• Removable stacer pin is inserted through stacer tip piece, which locks the stacer, DDAD, and Whip canister to the boom assembly
• Cable is spooled around the cable bobbin
• Ball détente mechanism is clamped to the stacer tip piece
• Stacer pin and whip clamp are removed
• Boom is loaded into housing
Deployment• SMA wire is actuated and ball détente mechanism is engaged
• Stacer tip piece is released
• DDAD extends and initiates stacer deployment
• DDAD separation opens whip doors, initiating whip sensor deployment
Science Ops• Deployed boom configuration unchanged
THEMIS Instrument PDR Rob Duck 8 UCB, October 15-16, 2003
Whip Sensor
Theory of Operation
Deployed Properties• Whip sensor deployed length: 40 inches • Stacer deployed length: 150 inches• Option to change length
Stacer
Stacer Pin
Ball Détente Mechanism
Cable Bobbin with Cable
DDAD
DDAD Doors
SMA Actuator
Stowed Boom Deployed DDAD
4”
4”
Stacer Cansiter
Stacer Tip Piece
Whip Canister
Whip Doors
Roller Nozzle
Deployed Boom
Deployed Whip Sensor
150”
40”
THEMIS Instrument PDR Rob Duck 9 UCB, October 15-16, 2003
Goals 1. Initiate Stacer deployment.
2. Provide double cantilever design at deploy.
3. Maintain minimal boom length while stowed.
4. Single locking contact point.
Design1. Two stage nested spring push rod.
2. Roller nozzle for beam support.
3. Double doors to stow Whip and Main Stacer.
Theory of Operation1. Stacer tip piece is released.
2. Double spring extends roller nozzles.
3. Roller nozzle pulls stacer from canister
4. Stacer deploys.
5. Whip doors open as roller nozzles separate.
6. Whip deploys.
7. Roller nozzles maintain contact on stacer.
Double Deploy Assist Mechanism
STOWED DDAD DEPLOYED DDAD DDAD PUSH ROD
ROLLER NOZZLE STOWED
ROLLER NOZZLE DEPLOYED
Roller Nozzle
Locking Contact Face
Whip Doors
DDAD Doors
Stacer direction
THEMIS Instrument PDR Rob Duck 10 UCB, October 15-16, 2003
Goals 1. Single actuation point.
2. Safe reload operation for testing.
3. Minimal activation stroke.
4. Minimal activation force.
Theory of Operation1. Applied current contracts SMA wire.
2. SMA wire pulls lever up.
3. Lever pulls deploy pin down.
4. Lower ball detent drops into cavity and release spring rod.
5. Spring extends and pulls locking sleeve down.
6. Upper ball detent drops into cavity.
7. Stacer pin is released and stacer deploys.
Axial Boom Deploy Mechanism
STOWED CONFIGURATION
SECTION VIEW
DEPLOYED CONFIGURATION
SECTION VIEW
Stacer Tip Piece
Cable Bobbin
Locking Sleeve
Spring Rod
Lever
Deploy Pin
Upper Ball DetentSMA Wire
Lower Ball Detent
THEMIS Instrument PDR Rob Duck 11 UCB, October 15-16, 2003
Assembly & Materials
Standard Flight Materials• AL 6061 T6• SST 440• Elgiloy• PEEK• M55J Graphite Composite
Standard Flight Coatings• DAG-213• DAG-154• TYPE 3 Hard Anodize
Long Lead Items• Stacer – Ordered• Multi-conductor wire
THEMIS Instrument PDR Rob Duck 12 UCB, October 15-16, 2003
Electrical Connections
Boom Connectors• 1 connector per boom• Located at base of boom• SMA actuator cable• Preamp sensor multi-conductor wire
Test & Safe Connector• External to boom, located on top deck of probe• AC test• Safe - Deploy deactivation
THEMIS Instrument PDR Rob Duck 13 UCB, October 15-16, 2003
Mass & Power
List Mass Target & Actual• MASS
– Target– 2 Kg per Boom including Housing
– ActualHousing 1.70 lbs 0.772 kg
Upper Boom 3.58 lbs 1.625 kg
Lower Boom 3.58 lbs 1.625 kg
Total 8.86 lbs 4.022 kg
• POWER– 1 AMP
THEMIS Instrument PDR Rob Duck 14 UCB, October 15-16, 2003
Thermal - AXB
Heat Transfer
Power Dissipation
• 80 mW dissipated at preamp, irrelevant to bus temperatures
• Essentially inert hunks of metal after deployment
Conduction
• Top Deck reaches –93 °C in long eclipse
• AXBs are a heat leaks for the bottom deck so they are isolated with 1/8 inch G10 spacers.
Radiation
• All surfaces covered with low ε VDA tape or blankets
• Black body open end of the tube dominates the heat leak
THEMIS Instrument PDR Rob Duck 15 UCB, October 15-16, 2003
Thermal - AXB
Temperature Limits
• Steady state predictions from UCB based on top and bottom deck temperatures from Swales
• Cold prediction from cold orbit, not long eclipse
• Hot prediction from hottest orbit and attitude
• Will not deploy in extreme cold case
• Better predictions await more complete instrument thermal models
Deployment (°C)
Predictions
(°C)
Margin
(°C)
Cold Hot Cold Hot
0 30 -7 5 -7 25
THEMIS Instrument PDR Rob Duck 16 UCB, October 15-16, 2003
Thermal - AXB
Temperature Monitoring and Control
• Modified Interface Monitoring
• None required at this time
• Instrument Monitoring
• IDPU will process additional thermistors if needed
• Heaters
• No operational heaters are required
• No survival heaters needed after deployment
• Unlikely to need deployment heaters
THEMIS Instrument PDR Rob Duck 17 UCB, October 15-16, 2003
Engineering Model Objectives
Engineering test unit designs are critical
• Boom length repeatability
• DDAD stiffness and length
• Actuation reliability
• Boom reloading
• DDAD roller nozzle design
THEMIS Instrument PDR Rob Duck 18 UCB, October 15-16, 2003
Axial Boom General Assembly
Axial Boom Installation process• Goal to allow easy removal of boom without probe disassembly
• Process1.Lower mount ears aligned with upper deck cutout.
2.Boom inserted through upper deck.
3.Boom rotated to line up bolt pattern.
4.Boom bolted with 8-32 screws