Sound Test

1
Sound Test
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Testing and Integration of a Rocket-Launched
Video Imaging Platform

• IniTech Engineering

Apoorva Bhopale Susan Schmidt Rob Wingo Brian
Love
1 May 2002
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Project Background

• Project is sponsored by Applied Research Labs
• Main Objective
• Prove the validity of a rocket launched balloon
  as a telecommunications platform
• Possible uses, disaster relief, drug
  interdiction, inexpensive throwaway satellites
• Rocket is to be launched this summer

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Overview of the Presentation

• Goals to accomplish
• Description of each goal
• Work completed for each goal
• Future work
• Questions

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Semester Goals

• Design and build payload canister with mountings
  for electronics
• Size and build drogue chute
• Test balloon buoyancy
• Test Electronics
• Test balloon deployment

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Flight Profile
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Chute Sizing

• Brian Love

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Drogue Chute

• Required to deploy balloon after ejection
• Will be used to slow descent after operations

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Sizing

• Previous work concluded that a small chute will
  deploy the balloon
• Limiting factors for design are descent
  constraints

• Considerations
• Weight of payload
• Altitude
• Allowable impact velocity

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Algorithm
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Calculations
Standard Atmosphere
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Chute Design
108
116
Weight 14.2 oz.
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Balloon Tilt

• Weight drop of 11 oz. from 25 to 14 oz.
• Balloon used was 1/4 scale

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Neutral Buoyancy
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Calculations
Need mass air inside balloon 4kg less than the
STP value for neutral buoyancy
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Temperature Difference
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Considerations

• Absorbed solar energy
• Air circulation inside balloon
• Descent rate of inflated balloon vs. chute
• Thermal updrafts
• Need experimental data to prove theoretical
• Testing difficult on ground

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Payload Canister

• Susan Schmidt

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Initial Avionics CanisterDesign

• Canister made of 4.25 inch
• PVC pipe
• Covered in carbon fiber
• Electronic components
• secured with bubble wrap
• Plexiglas bottom
• for camera

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Previous Canister Design Changes

• Components hit canister walls and each other
• Bubble wrap was not sufficient vibration control
• Foam was then used to secure items

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Issues with Past Designs

• Carbon fiber blocks radio waves
• Electrical components not secure
• Plexiglas fogs at higher altitude
• Plexiglas cracks easily
• Component constraints cannot handle temperatures
  of high altitudes

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Requirements for the Avionics Canister

• Structural integrity
• Limit component vibration
• Airtight seal
• Temperature control

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Structural IntegrityExternal Material Options

• Metals
• Possible Shrapnel
• Weight
• Porous materials, i.e. wood
• Airtight seal
• Plexiglas
• Cracks easily
• Lexan
• High cost
• Availability
• And the winner is

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PVC

• Weather Resistant
• High strength to weight ratio
• Corrosion Resistant
• Good thermal insulator
• Self-extinguishing
• Low cost!!

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Internal Structure

• High impact resistance
• Used to stabilize internal components
• Used for the camera viewing area

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Limit Component Vibration

• Two 0.09 thick Lexan perpendicular
• boards
• Secured components with nuts and bolts
• Ends capped with hobby plywood

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Airtight Seal

• Change in pressure from sea level to higher
  altitudes cause fogging on the Lexan
• Seal end of canister with Teflon Tape
• Teflon tape for extruding connections
• Pump in Nitrogen through a gas fitting
• Inert gas replaces the water vapor

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Temperature Control

• Cameras operating range
• -1.1C to 37.77C
• Above 8,000 feet the temperature drops below this
  operating range
• The rocket test in summer will not reach this
  altitude
• The temperature limits of the components must be
  evaluated for higher flights

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Electronics

• Rob Wingo

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Electronic Components

• Accelerometer board
• GPS/Video Overlay board
• GPS receiver
• Video camera
• Telemetry system
• Batteries

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Semester Objectives

• Connect all of components and make work
• Range test telemetry system
• Find problem with power source
• Determine how to use accelerometer board as an
  event trigger
• Mount electronics in canister

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Component Connectivity

• Successfully connected all components

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Range Test First try

• Unsuccessful
• Assumed power problem

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Range Test Second try

• Made adjustments to power supply and connectivity
  board
• Still unsuccessful

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Range Test Third try

• Re-soldered connectivity board
• Still unsuccessful
• Contacted transmitter manufacturer
• Discovered range can be drastically reduced by
  ground effects

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Ground Effect Problem

• Transmitter designed for aerial use only
• Will not be able to accomplish range test on
  ground

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Balloon Deployment

• Apoorva Bhopale

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Balloon Deployment

• Objectives
• Determine a method to pack the balloon
• Determine an adequate amount of black powder to
  eject the canister

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Balloon Size
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Suggested Method
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Pyrotechnic Ejection

• Advantages
• Reliable
• Lightweight
• Used extensively

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Possible Failure Modes of the Ejection

• Too Little Black Powder
• Does not clear ejection tube
• Inhibits the rockets main chute deployment
• Payload crashes with the rocket
• Too much Black Powder
• Rocket tube explodes
• Drogue chute rips from balloon
• Burnt drogue chute or balloon

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Theory of Pyrotechnic Ejection

• Wp Weight of Black Powder (lbs)
• dP Ejection Charge Pressure in Psi
• V Free volume in cubic inches
• R Combustion gas constant 22.16 ft-
  lbf/lbm-R
• T Combustion gas temperature, 3307 degrees
  R

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Test Footage
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Conclusions From Test

• Place Canister closest to the ejection charge
• Use 7 grams of Black Powder

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Conclusion

• Design and build payload canister with mountings
  for electronics
• Size and build drogue chute
• Test balloon buoyancy
• Test Electronics
• Test balloon deployment

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Future Work

• Verify range of the transmitter another way
• Possibly send it back to manufacturer
• Test the deployment method in a rocket
• Determine a way to sever connection between
  balloon and canister
• Neutral Buoyancy test
• Setup accelerometer board to be used as event
  trigger

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Acknowledgements

• Dr. Ronald Stearman
• Dr. Martin Barlett
• Dr. Jennifer Lehman
• Danny Linehan
• Daniel Parcher
• Rick VanVoorhis
• Lixin Gong

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Questions