LaACES High Altitude Ballooning

1. LaACES High Altitude Ballooning Atmospheric Density By: Henry Hardee Sina Zarei Ian Walsdorf

2. PROJECT GOALS • To determine the density of the atmosphere throughout the flight using the P and T that we find assuming air is an ideal gas. • To better understand the effects that freezing temperatures and low pressures can have on equipment through the atmosphere. • To learn about circuits and electronics and attempt a hands on experiment.

3. Why pressure changes at different altitudes Atmospheric pressure reduces with altitude: -Due to gravity -The gravitational attraction between the earth and air molecules is greater for those molecules nearer to earth than those further away -Molecules further away from the earth have less weight but they are also 'standing' on the molecules below them, causing compression http://www.npl.co.uk/pressure/faqs/atmosaltitude.html

4. Density Simple density formula • ρ (rho) - is the density of the substance, measured in kg m^3 • m - is the mass of the substance, measured in kg • V - is the volume of the substance, measured in m^3 Boyle’s Law R - is the universal gas constant - we used 0.000082057 m^3/atm*K m - is the molar mass (in our we use air) kg P – pressure atm T – temperature K ρ – density kg/m^3

5. TEMPERATURE SENSOR • We are using the DS1621+ND temperature sensor.

6. PRESSURE SENSOR • We are using the same pressure sensor that was used on the HASP project last summer. We did this for a few reasons the main one being that we are familiar with the part already. • BASE -25°C SPAN -110°C • Part # 442-1026-ND

7. Data Acquisition

8. Connections

9. Altitude vs. Pressure

10. Standard Values for Pressure and Temperature

11. Our Expected Data

13. PAYLOAD CONSTRUCTION

14. Mechanical Design • We choose to do a double box design instead of using the pink insulation foam we used thin foam board because rigidity and thermal characteristics. • We used pink insulation and fiberglass insulation between the two boxes to further prevent heat escaping. • We mounted our temperature sensor outside our inner box and exposed it to the atmosphere to get accurate readings. • This design has so far been successful.

15. AUTOCAD DRAWINGS INNER BOX

16. AUTOCAD DRAWINGS BIG BOX

17. + Mechanical Design Weight Budget of the Pay Load: Weight limit:500 g • Balloon Sat W/ Sensors & Wires: ~82.40 g • One 9 v Battery: ~46.6.0 g • Outer Box ~126.5g • Inner Box ~74.4g 500 g -329.9 g= 170.1g

18. Pressure Test • Upon calibrating our pressure sensor we found to be a bias error of 2.05 psi. This is due to the fact that due to time constraints we were not able to reference our sensor to a 4 volt source so instead we referenced it to a 5 volt source. • We put our payload in a pressure chamber and it showed a linear output.

19. Temperature Test • We tested our payload by putting the box in an ice chest with dry ice for an hour. • All of our components were fine when we pulled it out and our data sheet was correct

20. Impact Test • The payload was dropped from a height of 10 feet to simulate the force felt upon landing this is because the nominal descent rate is approx. 20 feet/sec. • We did this test 3 times and nothing was damaged in the process

21. Acknowledgements • CSBF • Dr. Guo • Dr. Guzik • Dr. Wefel • Mr. Giammanco • Mr. Ellison • Jeff Kornuta • NASA