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Nearspace Balloon

Project Summary

The idea is to create a high altitude balloon that will reach at least 70,000 feet. The balloon should meet the following requirements:

  1. Be designed to reach at least 70,000 foot altitude.
  2. Have a primary payload that is less than 6lbs.
  3. Primary payload and secondary payloads may not weight more than 12lbs combined.
  4. Take photographs on the way up and down.
  5. Transmit GPS coordinates so we can track it from the ground.

Project Members

Name Contact Callsign
Rick O rick (at) KE7SAL
Kevin K kd7ahu (at) KD7AHU
James H    


  1. Acquire GPS unit for payload. This needs a serial interface to talk to the TinyTrak3.
  2. Come up with a power supply for the GPS and TinyTrak.
  3. Get all of the electronics together and test them together.
  4. Figure out how much room we need in the chassis.
  5. Design and build the chassis.
  6. Find an easy way to mount everything inside the chassis so it is accessible but secured nicely (velcro?).
  7. Acquire the balloon.
  8. Build the balloon filling apparatus.
  9. Build and test the tracking station(s).
  10. Acquire everything else.
  11. Write and tripple check launch procedures.
  12. Document Build Process
  13. GO GO GO!

Balloon Components

Component Description Supplier Price Assigned to
Chassis Lightweight but strong chassis big enough to contain all electronics. Need to access internals for adjustments and need to be able to attach parachute/balloon. Need identifying information and make it VISIBLE.      
Balloons Needs to be big enough to lift the full weight of the payload and then some.      
Parachute Needs to be able to safely return the full payload weight to the ground, but quickly so it doesn't drift too far. Also must be VISIBLE.      
GPS Must work over 65,000ft. Many GPS units do not work at those altitudes. James $0 James
Primary GPS Radio 5 watts should be enough. 2 meters is preferable. Rick $0 Rick
Camera Needs to be able to take time lapse photos. Kevin ? Kevin
Power Supply Needs to power the GPS and TNC at least. Maybe also the radio and camera.      
TNC Using the TinyTrak 3. TEST to make sure it reaches digipeaters and transmits altitude before launch. Rick $0 Rick
Radio Antenna Can make a simple J-pole out of ladder line from RadioShack. Rick $0 ?

Payload Primary Radio

We are using an old HTX-202 2 meter HT originally made by RadioShack. This one has a strange glitch where you get an on screen error when power is applied. To bypass this, you have to hold the function key and the D1 key and then turn the power on. I'm not sure how to fix this permenantly. The radio has a BNC connector for the antenna. This radio is capable of ourputting 5 Watts and requires a 12 volt power supply. The radio has a small battery compartment that can hold 8 AA batteries. We have used 8 Lithium AA batteries in a previous balloon with success.

Payload Primary Antenna

We can make a simple J-Pole antenna from strong ladder line available at RadioShack. We will need the proper BNC connector in order to hook the antenna up to the HTX-202 radio. Here is a guide on how a proper antenna can be made from ladder line. We will probably also need a small piece of coax cable to connect the anteanna to the radio.

TNC Configuration

We are using the TinyTrak3. The TinyTrak requires a 7 to 30 volt power supply. It is also currently configured to distribute power to the GPS through the DB-9 connector. We may or may not be able to use this depending on how much power the GPS requires. I believe this feature can be disabled by moving (or removing) a resistor on the TinyTrak3 PCB.

Primary GPS

James has lent his Garmin eTrex GPS unit to the project. He has also donated his serial/power cable to the project. We need to figure out how much power the eTrex requires and is capable of accepting. Initial tests show that it may be expecting around 3 Volts but perhaps it can accept 5 Volts, which would make our power supply simpler. There is some useful information about Garmin eTrex connectors on this site.

Launch Site Components

Component Description Supplier Price Assigned to
Large Tarp This protects the balloon from the dirt, rockets, etc on the ground.      
Helium Need enough to fill the balloon to proper buoyancy. Twice that if we want a second chance.      
Weights We attach these to the balloon during filling to ensure that it doesn't float away and also that we have reached proper buoyancy.      
Helium tank regulator This allows us to control the speed at which we fill the balloon with helium.      
Hose To connect the Helium regulator to the balloon fill aparatus.      
Balloon fill aparatus Need something to insert into the neck of the balloon to pump the helium into. Small piece of PVC pipe could work.      
Pipe clamps/tape To clamp the balloon neck to the fill aparatus.      
Cotton gloves Anyone who handles the balloon wears these to protect the balloon from dirt and oil from hands.      
Extra Batteries Batteries for everything. Just in case...      

Tracking Station Components

Component Description Supplier Price Assigned to
Laptop Laptop that can run tracking software and possibly hook up to a GPS for simplified tracking.      
Power inverter Power inverter so we can power the laptop indefinitely from a vehicle. Rick $0 Rick
TNC Can be software or hardware. Must be able to decode APRS packets for plotting on a map.      
Tracking software For tracking the balloon's position in real time on a map.      
Digital Maps Need maps for the tracking software. These are not always free.      
External Antenna Like a magmount on top of the vehicle for signal reception. Rick $0 Rick
Walkie Talkies For vehicle to vehicle communication during the chase.      
GPS To keep track of vehicle location in comparison to balloon. Also for plotting optimal route to balloon.      
Ham Radio Dedicated ham radio for receiving APRS packets directly from the balloon. Essential for tracking. Rick $0 Rick

Launch Sites

Potential launch sites go here. Good to have alternates in case weather conditions don't play well with our plans. Need to ensure the balloon will not land anywhere near large bodies of water, forrest, or mountains. We want to recover the payload after all.

Launch Procedure

Launch procedure goes here once we have everything else designed and built.

logging telemetry data to sd card

Additional Ideas

  1. Internal / External Temperature Sensors
  2. Logging telemetry data to SD card

-- RickO - 2011-10-12
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Topic revision: r7 - 20 Oct 2011, ClifCox

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