The MAGIC Tether Experiment 15 July 2015 University of Colorado Friday, April 02, 2004 The MAGIC...

The MAGIC Tether Experiment April 19, 2023

University of Colorado

Friday, April 02, 2004

The MAGIC Tether Experiment

A Demonstration of DINO’s MAGIC Boom

Colorado Space Grant Consortium & DINO

2


The MAGIC Tether Experiment

• Special Thanks To the KC-135 Team for All of Their Hard Work and Great Contributions– Cook, Evan – Martinez, Mike– McArthur, Grayson – Mohler, Andrew – Parker, Jeff– Seibert, Mike– Stamps, Josh – Worster, Kate


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Background – DINO

• Nadir Pointing– Gravity Gradient Stabilization

• Deployable Boom– Primary Satellite

» 25 kg– Tip Mass

» 5 Kg– MAGIC Tether

» Mechanically-Actuated Gravity-Induced Control

» Stanley Tape Measure» 6m Long

– Lightband» 2 +/- .5 ft/sec» Full deployment after 10 sec

Tip Mass

Tether

DINO


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Why do This Test

• Is this System Even Feasible?– Dynamics of the Semi-Rigid System are Poorly

Understood– Experimental Results of Energy Dissipation

• Over damping will result in inadequate deployment– Poor gravity gradient stabilization

» Science objectives

» ADCS power Draw

• Under damping would shock the system– Could damage Electronics and Cameras

– Could recoil, causing a collision


5


Expected Results

• The MAGIC Tether team expects the following things:– Four standard springs will accelerate the relative velocity of the

tip mass with respect to the primary satellite to approximately 1.7 ft/s (0.518 m/s).

– The tip-off rate of the deployment to be less than 1°/s in each axis.

– Given a deployment velocity of 1.7 ft/s, the optimal value of x0 to be approximately 0.66” to critically damp the system’s motion as the tether is fully deployed.

– The semi-rigid tape to be deployed in a controlled fashion without any recoil at the end of its deployment.


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Experiment Objectives

1. To measure the large-scale and small-scale dynamics in the deployment

• Linear and angular accelerations

2. To empirically measure how the energy in the system can be dissipated

• Spring force in the slow-down mechanism• Critically damp tip mass’ motion

3. To demonstrate a successful deployment of DINO’s MAGIC Boom


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• KC-135• Heavy Sat

– 14.6 kg (32.2 lbs)

• Light Sat– 8.1 kg (17.8 lbs)

• Tether– Two lengths of Stanley

Tape Measure (1.0 in)– 4 ft (1.22 m)

• Sensors– 6 Accelerometers– 6 Rate Gyros

• Equipment Containment System

Overview of the Experiment

Safety Straps

Light Sat

Heavy Sat

Tether


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Structure

• The structure on each of the two satellites (Heavy and Light Sat ) is composed of two 1/8” 6061Al plates connected by 4”-tall 1/4" 6061Al box walls.

• All sharp edges will be covered with pipe insulation

Damping System

Foam Padding

TAZ


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Heavy Sat

• Circular inner plate • Male mating adapter • TAZ • Deployment springs• Data loggers• Dummy loads• Sensors and batteries

Containment box • Hand holds• Pipe insulation

The Heavy Sat will have an overall mass of approximately 14.6 kg and dimensions of 18” x 18” x 6”.

Data Logger

Data Logger


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Light Sat

The Heavy Sat will have an overall mass of approximately 14.6 kg and dimensions of 18” x 18” x 6”.

• Circular inner plate • Female mating adapter • Spring Adapters• Data loggers• Dummy loads• Sensors and batteries

containment box • Hand holds• Pipe insulation• Braking System

Data Logger

Data Logger


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Entire Assembly


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Push off Springs x 4

• Based on Planetary System’s Lightband springs

• K = 22.5 lb/in (Per Spring)

• Finitial = 60 lb (Total)


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Tether Description

• The semi rigid tether (SRT) – Two face-to-face Tape Measures– Commercial, off the shelf part


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Tether Mounting

• Deployment / Braking System mounted in Light Sat (Tip Mass)

• Boom mounted to Heavy Sat (Main Satellite) with a tether attachment system (TAZ), designed to maintain the rigid natural shape of the tether, while providing a secure attachment.


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Deployment System


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Damping System• 42 Teeth per Rotation

• 366 Teeth per Full Deployment

• 3.1 J Total Energy• .0085 J / Tooth

• Two 2.5 inch spools

• Geared to counter rotate• Ratchet and Pawl

• Pawl Spring Loaded• Adjustable Initial Compression


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Damping System


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Mechanical Dial

• In Flight Spring Adjustment

• .55in - .75in

• Linear Transducer


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Release System

• Deployment initiation – Mechanical System– Hand held actuating lever

• Bicycle brake

– Release cable – Switch

• Incorporated into handle

• Initiates data collection


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Testing

DAY 1• Set Spring to maximum

compression, .75in (Over Damped)

• Position Test Equipment• Deploy• Reset• Decompress spring .05in• Repeat until .55in

compression is reached (Under Damped)

DAY 2• Set Spring to maximum

compression in range of interest

• Position Test Equipment• Deploy• Reset• Decompress spring

desired amount• Repeat until minimum

compression in range of interest is reached


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Data Collection

• There will be four sources of data in the MAGIC Tether Experiment: – Qualitative observations by the flyers and by the

digital video camera– Quantitative measurements of acceleration by the six

single-axis accelerometers– Quantitative measurements of angular velocities by

the six single-axis gyroscopes– Quantitative measurements of braking spring

compression by the linear transducer


22


Safety

• Restraint Straps– Four cinch straps to hold satellite to base plate during Takeoff/landing– Two Velcro straps for satellite securing during flight– Velcro connection between Heavy Sat and base plate during flight

• Safety straps– 10’ straps connected from the base plate to each satellite– 6’ strap connecting each satellite– Braided steel rated to 1000 lbs.

• Safety pin– Prevent accidental deployment

• Padding on all metal edges• Four handholds per satellite• Safety straps attached to all tools• Fuses installed on electrical lines


23


Results

• Trends will be extrapolated and scaled to DINO’s full Deployment length and weight.

• What will happen to the satellite if the damping system does not perform precisely as planned?

• What are the risks to the Satellite?• Does the Tether “explode” violently?• Is the deployment controllable?• Does the damping occur as expected?

• Real world experience• Will result in a safer, more reliable system for DINO


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Appendix


FEA for KC-135 Experiment

Grayson McArthur


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G-Load Specs

Takeoff/landing- Forward 9 g’s

- Aft 3 g’s

- Down 6 g’s

- Lateral 2 g’s

- Up 2 g’s

3 g’s in any direction - Randomly picked 3 configurations to simulate the structure being dropped


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FEA Setup

Program used for analysis → CosmosWorks

Takeoff/landing

- Load acts through the center of gravity

- Outer face of the outer panel on the light side restrained as immovable/no translation to simulate attachment to base plate

- Global size of nodes set at 0.44469 in. with a tolerance of 0.02223 in.

- Yield strength of Al 6061 used as max. load = 145 MPa or 21030.51 psi

- Factor of safety set at 2 based on the yield strength


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FEA Setup Con.

3 g’s in any direction - Load acts through the center of gravity

- Global size of nodes set at 0.44469 in. with a tolerance of 0.02223 in.

- Yield strength of Al 6061 used as max. load = 145 MPa or 21030.51 psi

- Factor of safety set at 2 based on the yield strength

► Thin edge faces of outer plates set as immovable/no translation to simulate the structure being dropped on those two edges


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Results

Stress: Von Mises (VON)- Measured in pounds per square inch- VON = (0.5[(P1-P2)2+(P1-P3)2+(P2-P3)2])1/2

- P1,P2,P3 are principle stresses- Measures stress intensity required for a material to start yielding

Strain: Equivalent Strain (ESTRN)Displacement: Resultant (URES)- Measured in inches- Adds displacement vectors in X,Y,Z direction to get a resultant vector

Design Check- FOS < 2 area shows as red- FOS > 2 area shows as blue


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Stress


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Strain


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Displacement


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Design Check


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Conclusions

The structure will be able to withstand all the prescribed loads as indicated in NASA document AOD 33897 Experiment Design Requirements and Guidelines NASA 931 KC135A

Structure will survive a 3 g impact such as being dropped by the flight crew during transition from 0 g to 2 g


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Issues and Concerns

Mesh resolution was limited due to computer memory and time limitations

Boundary conditions being appropriate for load case


Onboard Support Equipment

Equipment Containment System

(ECS)


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Entire Assembly


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Base Plate

• .125-.25in Al 6061 sheet

• Note, Current design requires heavy hand construction… It will not fit within the CNC

• 4 Aircraft mounting location

• 7 handhold, accommodating up to 4 handlers

• Experiment restraint harness

• Safety cable attachment


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Tool Box

• Store bought

• Plastic and steel construction

• Round plastic edges

• Lockable


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Stand Off

• Al 6061

• Industrial strength Velcro

• Non permanent attachment

• Only for stability, not critical for LD/TO


Mechanisms

Michael Martinez


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Mechanisms

• Contents:– Tether Description– Deployment System– Braking System


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Tether Description

• The semi rigid tether (SRT) is constructed of 2 COTS spring metal "tape measures", four feet length by 1 in wide, curved along their width.

• To be configured ‘face to face’, provides greater stability.


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Deployment System


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Deployment System (cont)

• The MAGIC Tether deployment system consists of two 2.5 inch spools, geared to counter rotate and unwind the spring metal boom in a controlled manner.


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Deployment System (cont)

• Deployment / Braking System

– The stowed SRT will be wound on the two spools such that when deployed the two tape measures will be face to face, forming a rigid structure.

– Tape to spool connection recessed to reduce stress at connection


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Braking System

• Velocity control is provided by a 48 tooth, 2.0 inch ratchet and pawl system, with the ratchet shafted to the geared spool, and the pawl spring loaded to provide a loading / braking force against the ratchet.

• Initial k for spring

~ 0.245 N/mm


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Release System

• Deployment initiation – Mechanical System– Hand held actuating lever

• Bicycle brake

– Release cable – Switch

• Incorporated into handle

• Initiates data collection


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Tether Reset Device

• Tether reset device• Two options

– Manual crank– Electric drill

• Flexible extension used to reach the drive shaft easily

• Attached to the toolbox by a steel cable tether


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Tether Mounting

• Deployment / Braking System mounted in Light Sat (Tip Mass)

• Boom mounted to Heavy Sat (Main Satellite) with a tether attachment system (TAZ), designed to maintain the rigid natural shape of the tether, while providing a secure attachment.


Sensors

Kate Worster

Michael Seibert


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Sensors: Objectives

• The Sensors Subsystem is designed to measure the large-scale and small-scale dynamics of the experiment during its deployment, including linear and angular accelerations imparted by the tether

• Sensors and Data Acquisition– Onboard storage of science and engineering data– Provide data for post-flight analysis


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Sensors & Data Acquisition System Functional Diagram

Data Signal

Power lines

Data Logger

HVY_AZHVY_AYHVY_AZ HVY_G3HVY_G2HVY_G1

KS

9V15V

Heavy Side

KSKill Switch


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Sensors & Data Acquisition System Functional Diagram

Data Signal

Power lines

Data Logger

LHT_AZLHT_AYLHT_AZ

LHT_G3

LHT_G2

LHT_G1

KS

9V15V

LHT_T_D

Light Side


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Functional Requirements

Requirements Accelerometer Rate Gyro

Linear Transducer

Data Logger

Laptop

Measure acceleration

Measure twist & rotation

Measure spring

compression

Data acquisition &

analysis


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Gyro Specifications-ADXRS150EB

• Surface-mount package of 7mm x 7mm x 3mm and mass of 0.5 grams.

• Each rate gyro has a resolution of 0.05/s/Hz and a dynamic range of 150/s.

• Input voltage of 5.00v DC from onboard power supply and a quiescent supply current between 6.0-8.0 mA.


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Accel. Specifications-ADXL150

• Nominal sensitivity: 38.0mV/g and a maximum sensitivity of 43.0mV/g.• The functional voltage range 4.0V - 6.0V and a quiescent supply current of

1.8mA for nominal operation and 3.0mA as the maximum supply current.• Resolution: 1.0mg/Hz• Dynamic range: 80dB• Each can withstand 2000 g’s when un-powered and 500 g’s when powered


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9V Power Supply Specifications

9V ZnMn2 battery• Average voltage of 9.0 volts • Average capacity of 655mAhr (0.8 volts per cell • Weighs 45.6 grams (1.6oz) and has a total volume of 21.2cm3 (1.3in3).


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15V Power Supply Specifications

1.5V Alkaline Zinc-Manganese Dioxide (ZnMn2) battery• Average voltage of 1.5 volts • Average capacity of 3135mAhr (0.8 volts per cell• Weighs 23.0 grams (0.8 oz) and has a total volume of 8.1cm3 (0.5in3).


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COTS Parts Status

Part Availability Status

ADXL150 In stock on Analog Devices website

Not yet ordered

ADXRS150 In stock on Analog Devices website

Not yet ordered

Inhibits Available at CSGC and JB Saunders

Have some, others will be purchasing next week

Sensor housing, 18 gauge wire, prototype board

Available at JB Saunders Purchasing next week


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Data Collection

• Omnidata Polycorder and Data Fielder loggers

• 415K on board storage• 25Hz sampling rate• Start/Stop trigger capability• 10 analog input channels• 0V-5V, 0V-10V & 0V-15V

input ranges


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Data Collection

• Heavy Sat– 6 Inputs

• 3 Accelerometers• 3 Rate Gyroscopes

• Light Sat– 7 Inputs

• 3 Accelerometers• 3 Rate Gyros• 1 Linear Transducer


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Data Collection

• Configuration– Omnidata DF200 GUI– RS-232– Variables

• Sampling Rate

• Saving Rate

• Channel Input Voltage Range

• Data Retrieval– Omnidata DF200 GUI– RS-232– Data Retrieval Options

• Histogram

• Spreadsheet


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Ground Support Equipment Requirements

• Laptop– RS232 Capability

• Serial Port• USB to Serial adapter

• Spring Set Screw Calibration– Calipers

• Initial state displacement measurement


Procedures

Jeff Parker


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In-Flight Procedures

• Preparations for the First Parabola• These procedures must be followed to set the experiment up for the first

parabola:1. Flyer B: verify that the digital video camera is on and working normally.2. Flyer A: verify that the sensors’ wiring harness is connected to the first data logger on

each satellite.3. Flyer A: turn on power to both satellites by switching the kill switch into the on

position. Flyer B: verify that power has been turned on. An LED will indicate normal power for each battery system onboard. Flyer B: replace any battery packs that require replacing.

4. Flyer A: configure each of the two data loggers using a brief set of instructions attached clearly to the equipment containment toolbox. Flyer B: verify every instruction as they are entered.

5. Flyer B: verify the setting of the slow-down mechanism.6. Flyer B: remove the four cinch straps from the experiment and stow them in the

equipment containment toolbox. Flyer A: assist as necessary. This leaves two Velcro straps still attached to the experiment system.

7. Flyers A and B: visually inspect the experiment to make sure that everything is in working order, including the Velcro straps, the safety straps, the deployment system, the safety deployment pin, and the slow-down mechanism.


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• Free-Fall minus three minutes8. Flyer A: remove the safety deployment pin and Velcro it to the side of Heavy Sat (it

also has a short tether attached to it to restrain it from possibly floating away).9. Flyer B: check the temperature of the cabin using the thermometer attached to the

toolbox.10. Flyer B: record all settings and activities in the logbook. The ambient temperature, air

currents, and other environmental factors should be noted.• Free-Fall minus one minute11. Flyer A: release one of the two remaining Velcro hold-down straps. If the experiment

behaves in an unexpected manner, immediately replace the straps and inspect the deployment system. This may sacrifice the parabola, but it could avoid releasing an uncontrolled deployment.

12. Flyer B: prepare the active data logger on each satellite. This requires about eight key-strokes that will be easily visible near the data logger on the system.

13. Flyer A: release the last hold-down Velcro strap (the satellite system still has Velcro attached to its base to keep it still on the base plate).

14. Flyers A and B: situate yourselves such that your feet are restrained by the foot-restraints and you are on opposite sides of the flight system. Make sure that Flyer A will be near Heavy Sat and Flyer B will be near Light Sat upon deployment completion.


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• Free-Fall15. Flyers A and B: make sure you are stable in the foot-restraints and prepared for the experiment.16. Flyers A and B: lift the experiment off of the base plate and maneuver into the correct position

over the base plate. During the deployment, the Light Sat will move approximately 2.5 feet and the Heavy Sat will move approximately 1.5 feet. Hence it is important to deploy the system in the proper location in space such that the full deployment occurs within the specified experiment volume. This position is marked on the base plate.

17. Flyer A: hold and stabilize the satellite system from the side such that the deployment action will occur sideways and that Flyer A will be near Heavy Sat and Flyer B will be near Light Sat upon deployment completion.

18. Flyer A: take hold of the deployment trigger.19. Once all personnel are clear from any interference with the MAGIC Tether’s deployment (keeping

in mind that both the primary and tip mass systems will move upon deployment), then Flyer A: carefully release the system and trigger the deployment. Keep hold of the deployment trigger, both as a safety and because letting it go might induce added dynamics into the system.

20. The separation springs activate and the deployment proceeds.21. The tether is reeled out from the Light Sat; accelerometers and rate gyros on both bodies

measure the linear and rotational accelerations experienced by both systems; the data are recorded on the data loggers.

22. The slow-down mechanism removes energy from the moving system from the moment of deployment until the system comes to a stop.


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23. The Light Sat either comes to a halt with respect to the Heavy Sat or it recoils after the tether stretches taut. Flyer B records the resulting dynamics in the logbook. Flyer B then records the distance that the tether deployed by observing the tic marks on the tether.

24. The maximum separation velocity between the two bodies is 1.7 ft/s, slow enough to grapple if need be. Therefore, if any recoil action exists that appears to threaten a collision between the two satellites, then Flyer A: carefully grapple the two satellites prior to impact. If, however unlikely, the system recoils at an unexpectedly high velocity, then Flyer A: remain in a safe position and wait until the system settles down before retrieving the hardware.

25. If not otherwise retrieved, Flyer A: take hold of the Heavy Sat.26. Flyer B: take hold of the Light Sat. 27. Flyer A: place the Heavy Sat onto the Velcro swath on the base plate to secure it

before the end of the free-fall.• End of Free-Fall28. Flyer B: keep hold of the Light Sat while the aircraft’s accelerations increase.29. Flyer A: use the tether-reset device to recoil the tether onto the spools.30. Flyer B: mate the Light Sat onto the Heavy Sat, compressing the separation

springs. The deployment device will not allow the springs to release until triggered, so there is no danger of accidental deployment during this phase.


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31. Flyer A: strap the system down using the two Velcro hold-down straps.32. Flyer B: command the two active data loggers to stop recording data.33. Flyer B: adjust the knob on the slow-down mechanism to set the slow-down spring to the next

desired value of x0. Flyer A: verify the set value.34. Flyer B: record all dynamics, activities, and new settings in the logbook. The ambient

temperature, air currents, and other environmental factors should be noted.35. Flyers A and B: while waiting for the next free-fall, visually inspect the system for signs of

fatigue, failures, or damage. If power sensors indicate a battery pack low on power, replace the battery pack at this time. If a data logger is nearing memory capacity, then switch the power and data cables from the active data logger to the spare data logger. Follow the startup procedure listed in line 4.

36. Return to step 11 and repeat.• End of Flight37. Flyer A: place the deployment safety pin into the deployment system.38. Flyer A: secure all four additional cinch straps on the system.39. Flyer B: shut the data loggers down following the simple procedures listed on the side of the

structure.40. Flyer B: flip the kill switch on each satellite, turning off power to each system.41. Flyer A and B: verify that all straps are in place and secure.42. Flyer A and B: verify that all components are stowed and secure.


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Emergency Procedures

• In the event of an emergency, the following procedures will be followed. These procedures will be posted directly on the experiment, detailing exactly how to shut the system down quickly.1. If either satellite is not strapped to the base plate, follow the

appropriate procedures here:• Flyer A: take hold of the Heavy Sat• Flyer B: take hold of the Light Sat• Flyer A: place the Heavy Sat on the base plate• Flyer B: mate the Light Sat on the Heavy Sat• Flyer A: strap the system down using the two Velcro straps

2. Switch the master kill switch on each satellite to shut off all power on each satellite.

3. Shut off the power to the data loggers.


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Safety

• Restraint Straps– Four cinch straps to hold satellite to base plate during Takeoff/landing– Two Velcro straps for satellite securing during flight– Velcro connection between Heavy Sat and base plate during flight

• Safety straps– 20’ straps connected from the base plate to each satellite– 6’ strap connecting each satellite– Braided steel rated to 1000 lbs.

• Safety pin– Prevent accidental deployment

• Padding on all metal edges• Four handholds per satellite• Safety straps attached to all tools• Fuses installed on electrical lines


Data Analysis

Jeff Parker


74


Data Types

• There will be four sources of data in the MAGIC Tether Experiment: – Qualitative observations by the flyers and by the

digital video camera– Quantitative measurements of acceleration by the six

single-axis accelerometers– Quantitative measurements of angular velocities by

the six single-axis gyroscopes– Quantitative measurements of braking spring

compression by the linear transducer


75


Data Reduction

• Accelerometers and rate gyros have biases and scale factors– Calibrated by temperature measurements and

specific calibration measurements

• Analog measurements between 0 – 5 Volts• Expected Dynamics:

– Large acceleration spike at beginning of deployment– Diminishing decelerations until end of tether or all

energy is dissipated– Possible dynamics due to tether’s deployment– Possible recoil dynamics due to excessive energy


76


Expected Results

• The MAGIC Tether team expects the following things:– Four standard springs will accelerate the relative velocity of the

tip mass with respect to the primary satellite to approximately 1.7 ft/s (0.518 m/s).

– The tip-off rate of the deployment to be less than 1°/s in each axis.

– Given a deployment velocity of 1.7 ft/s, the optimal value of x0 to be approximately 0.66” to critically damp the system’s motion as the tether is fully deployed.

– The semi-rigid tape to be deployed in a controlled fashion without any recoil at the end of its deployment.

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