HIGH ALTITUDE BALLOON EMERGENCY COMMUNICATIONS Elizabeth Kalbacher Matthew Woytek Mitch Hubbs Andrea Herman Faculty Advisors: Joseph Slater, PhD, PE Mitch Wolff, PhD April 19, 2016 Group 2

Outline ■Introduction ■Background –High altitude winds –Previous flights data analysis ■Design Criteria –Station keeping and automation ■Project Scope ■Approach and Expected Results –Ascent Method Design Concept Options –Helium Venting Valve Concept –Command Module ■Next Steps ■Budget ■Summary ■Questions

Introduction ■WSU has 35 previous flights focusing on ballute ■ originated station keeping ■Amateur radios for emergency communications –Limited by range –Repeater stations can increase range ■Goals: Maintain altitude for 24 hours within 100 mile radius ■Problems: Ascent method, environmental conditions, and retrieval ■Target: 3 successful launches next semester

Background: High Altitude Environment ■Stratosphere (between 65,000 – 160,000 ft) ■Can be divided into layers of winds with different speeds and direction ■Lower speed winds between 60,000 – 80,000 feet Figure 1: Wind Velocity Plot (1)

Background: Previous Flight Data ■Near space versus ground environmental conditions ■Affect on flight (ascent rate, groundspeed)

Background: Previous Flight Data

Design Criteria ■Stop ascent at 70,000 ft. ■Maintain altitude for 24 hours. –100 mile radius ■Transmit location and save data during the flight. ■Automated cut down of control module, with manual backup ■Recover control module ■FAA regulations ■Environmental conditions

Project Scope ■Goal: Complete three launches that remain at 70,000 ft for 24 hours. –Stop ascent (helium valve) –Small altitude changes to take advantage of wind layers ■Helium and ballast valves. –Decision making capability –Mathematical model for the ascent of the balloon. –Cut down in extenuating circumstances –Position tracking and backups to retrieve the command module. ■Does not include repeater equipment –Dummy load

Ascent Method Concepts ConceptDescription Pro’sCon’s Fan/Pump with Venting Valve Fan can move air into the balloon to increase the balloon density, acting as ballast. No liquid ballast (weight) Better altitude control (no limit on ballast) Polyethylene film balloon needed Most complex concept Tow Balloon Two balloons lift the payload instead of one. Cut-down of second balloon close to 65,000 ft. Controlled ascent rate Neutral buoyancy after tow balloon cut-down Rubbing between balloons Rigging issues Accurately measure Helium inflow rate Can’t change altitude Helium Vent Valve (Low Pressure Valve) Valve at the mouth of balloon to vent Helium to reduce lift. Previous successful station keeping Can overfill balloon Serves as maintenance altitude control (with liquid ballast) Potential sticking at -40 °C Liquid ballast needed Adds weight to payload

Selected Ascent Method Concept: Helium Venting Valve ■Zero pressure ballooning for station keeping involves: –Expensive polyethylene film balloon –Specific volume of a low-density gas –Designed to maintain a desired altitude based on a predetermined volumetric capacity of the balloon and the weight of the payload ■Goal: Provide altitude control by simulating a "zero-pressure" flight with a latex balloon ■Description: Venting valve at the bottom of the balloon that receives commands from the payload. ■Controls lift by letting helium out of the balloon

Prior Work: Montana University Figure 2: Montana University's Altitude vs. Time Flight Data with "Zero-Pressure" Valve (2)

Model Support for Helium Venting Valve ■Feasibility of Helium Venting Valve Concept –Helium would not release at ground level –Changes in external pressure, volume, and strain on balloon ■Pin – Pout α Stress in Balloon ■Nonlinear strain for elastic materials ■Determined change in pressure difference v. altitude

Command Module Design ■Decision making –Initiate helium valve to stop ascent based on altitude –Control helium valve duty cycle based on ascent rate compared to model –Control helium and ballast valves to alter altitude to control drift –Be able to terminate flight on its own ■Power supply ■GPS tracking ■Locating pay-load after flight

Next Steps ■Complete command module –Programming –Hardware ■Design and build Helium vent valve and ballast system ■Testing: temperature, vacuum, drop ■Successfully launch and receive data to improve launch

Budget Item DescriptionCost Per Item Needed Cost Per Item In Possession Quantity Needed 1600 g Latex Balloon$120-3 Helium Tank$ Radios-$ Arduino Pro 328P 5V/16 MH-$ *Material for Helium Valve$ Rtrak-HAB v1.10-$ FTDI Basic Breakout-5V-$ *Rechargeable Battery Pack$ *Material for Ballast$ *Subject to Change Total Cost of Items Needed Total Cost $568.50$2,839.00

Summary ■Introduction ■Background –High altitude winds –Previous flights data analysis ■Design Criteria - Station keeping and automation ■Project Scope ■Approach and Expected Results –Ascent Method Design Concept Options –Helium Venting Valve –Command Module ■Next Steps ■Budget

References ■(1) Department of Atmospheric Science. University of Wyoming. College of Engineering. (2016). Retrieved from: ■(2)Basta, T., Miller, S., Motley, J., Murray, N., Larimer, R., Knighton, B., (2014). Developing a Zero-Pressure Flight System. Montana State University, Bozeman, MT: Academic High Altitude Conference, June 27, North Dakota ■(3)Eziolisa, Odera., Hardacre, Dale., Wilson, Kaneisha. "High Altitude Balloon Proposal," (2012), P31-32, Retrieved from:

Questions?