Pre-Burst Chaos
description
Transcript of Pre-Burst Chaos
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Pre-Burst Chaos
Howard L. Brooks
Dept. of Physics and Astronomy
DePauw University
Greencastle, Indiana
www.depauw.edu/acad/physics/base
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Indiana Space & Earth Workshop Flight 12 Nov.2009 video
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72,000’ first wind sheer76,000’ Payloads are stable82,000’ Payloads go horizontal
Taylor University Flight October 2009
Flight for college student experiments including my son
Photos were shared by Jeff Dailey, Taylor University
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82,400’
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82,500’
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82,600’Payload and Command are above balloon
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82,625’Chute on top of balloon
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82,625’Command flies through balloon
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82,625’Post burst start
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Memsic 2125 Dual-Axis Accelerometer
Measures ±3 g on each axis
Simple pulse output of g-force for each axis
TTL/CMOS compatible 100 Hz PWM output signal with duty cycle proportional to acceleration
www.parallax.com
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Heated gas bubble rises inside sensor. When tilted the temperature sensors read different values.
Theory of Operation
http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/28017-Memsic2Axis-v2.0.pdf
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BASE 28 Ascent
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BASE 34 Ascent
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Freescale MMA7361L3-Axis Accelerometer
• ±1.5g, ±6g
• Operates on + 3.3 VDC
• Micromachined dual capacitors
• Voltage proportional to acceleration
• Zero acceleration = 1.65 Volts
www.sparkfun.com
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BASE 43 Ascent
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Acce
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Clear Air Turbulencehttp://www.turbulenceforecast.com/clear_air_turbulence.php
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Atmospheric Gravity Waves
• Surface features (mountains)
• Convection (thunderstorms)
• Frontal Systems
• Jet Stream Interface
• Energetic Particles / Solar Radiation
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Wavelengths of 10 – 100s of kilometers
Periods of 10 minutes – several hours
Seen in some cloud formations:
Nacreous clouds in troposphere (15-25 km)Noctilucent clouds in mesosphere Airglow, Kansas in thermosphere (90 km+)
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Wind - Flight String Interaction
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Wind - Flight String Interaction
Force due to wind is proportional to air density and cross-sectional of object
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Wind - Flight String Interaction
Force due to wind is proportional to air density and cross-sectional of object
Payload boxes are fixed size
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Wind - Flight String Interaction
Force due to wind is proportional to air density and cross-sectional of object
Payload boxes are fixed size
Balloon gets larger
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Altitude(feet)
Volume(cu ft)
Area(m^2)
Air Density(kg/m^3)
4.5m/s Wind Force
(N)
0 300 5 1.22 6236,000 1,300 14 0.36 5066,000 5,500 35 0.09 31
105,000 35,000 120 0.01 16
Force on Expanding Balloon
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Simulations with Interactive Physics Version 2.5
Assumptions: 1.5 kg Balloon 300 cu. ft of He is 1.5 kg
3 payloads on 3 meter strings Top payload of 0.4 kg Middle payload of 0.5 kg
Bottom payload of 2 kg
TOTAL WEIGHT OF FLIGHT STRING = 58 Newtons
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Wind Force = 1/3 TOTAL WEIGHT
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Wind Force = TOTAL WEIGHT
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Wind Force = 3 times TOTAL WEIGHT
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RECOMMENDATIONS
Fly accelerometers
Carefully review all flight videos
Expect the unexpected