PICO Prep & Launch

PICO Balloon Preparation and Launch Routine

Disclaimer: These suggestions are not the only methods that will work.


1.  Chinese Party Balloon, 90 cm diameter.

2.  Zach Tek, 20 meter transmitter.

3.  AWG 30 gauge magnet wire 1/2 wave dipole antenna.

4.  Kaplan tape or TYVEX house tape.

5.  Miscellaneous weights used for testing. Coins, washers, fishing weights.

6.  Precision gram scale.

7.  6 pound test braided fishing line.

8.  99.9% pure helium.  (“Party” balloon gas can be troublesome.)

9.  Controlled volume and pressure pre-streacher for pre-launch conditioning. (Option)

Transmitter/Solar Panel Tests:

1.  Attach panels and antenna to the transmitter board.

2.  Assuming the transmitter has been properly configured as per the maker’s instructions, you can probably test a VHF system by simply suspending it in an open area where the sun is shining.  The radio would wake up and start transmitting when it has a proper GPS fix.  If a HF system, the antenna is 1/2 wave of 20 meters so, for testing,  it has the upper element attached to a high point and the lower element attached to another high point or sloping down to a near-ground point.  Let the transmitter(s) operate for an hour or so.

3.  Verify that the transmitter is working by observing on board LEDs and listening to your receiver tuned to the correct frequency and by watching the WSPR and APRS websites to confirm that the signal is being received by the tracking systems.

4.  Roll each element of the 20 meter dipole onto 1/2 of a toilet paper roll core.  This allows easy transport of the system without bothersome tangles, etc.  VHF antennas, due to their size, are easier to manage.

Inflation Steps:

1.  Pre-streach the balloon envelope to 4 - 4.5 kPa.  (Optional)

2.  Prepare two simulators for testing.  Weigh every part of the payload including the transmitter, solar panels, wire, string, ribbon and all fittings like rings & swivels.  This will probably be between 12 and 18 grams.  Collect weights equal to this amount and place them in a zip-loc bag.  Include the bag weight, hollow tube weight and the weight of  any fastener clips in the total.

3.  Construct a similar simulator for the desired “free lift” weight.  It probably will be between 5 - 6 grams for a Chinese Party Balloon.

4.  Insert a hollow tube into the balloon inlet.  Tape the balloon around the tube.

5.  Slowly introduce helium into the hollow tube keeping the inside end pointed to the center of the balloon.  As the balloon fills it will start to float up from the resting surface.  At this point clip both simulator weight bags to the inlet of the balloon.  Continue introducing helium until the balloon floats in a neutral condition, neither rising or sinking.

6.  Remove the “free lift” simulator and the balloon should start to rise.  Place the balloon/simulator package near the floor and release it.  Determine the acceleration rate (change in distance / change in time) by timing the rise to about waist high.  If the time is 1 - 1.5 seconds that means the acceleration rate is approximately 1.5 m/s/s.  If the rate is faster than that you might consider letting some helium out of the balloon and if it is slower you might want to introduce more helium. This is not a very accurate way to determine actual acceleration but it gives a pretty good idea of the helium content.  


7.  Remove the payload simulator and the hollow tube.  Give the balloon a couple of quick shots of helium for good measure.  Fold and seal the inlet and apply kapton tape or TYVEX tape to the folded area.  Punch a small hole about 3mm from the bottom edge of the fold.  Your swivel hook can be inserted here or you can use a small ring, etc.  Apply a layer of tape around the final assembly.  (There are other techniques that work here.  Some use strong ribbons looped through the folds and offer an attachment point below the edge.) With the attachment point secure you are ready to launch.  The payload should be really close to the simulator weight and the balloon should try to rise.  If it does not you will have to repeat these steps starting with #5.

8. The balloon envelope may appear to not have enough helium and look to be not  inflated sufficiently.  As it rises, however, the volume of the gas will expand and the envelope will stretch to its limit.  

Launch Criteria:

1.  Weather conditions should be favorable with very low, calm winds and few clouds.  Early morning seems to work best in most areas.

2.  Transport the tested transmitter and balloon to the launch area.  It should be located away from power lines and buildings.  

3.  For an HF transmitter the antenna must be kept free from snags and trees.  A large, grassy field works well.  A 3 person team makes the launch easy to manage.  Person #1 holds the transmitter and Person #2 unrolls the upper dipole element to where Person #3 is standing with the balloon.  Person #2 snaps the upper dipole into the attachment point of the balloon and the upper element is kept elevated at all times.  Person #2 walks back to Person #1 and unrolls the lower element of the dipole in the opposite direction from Person #3.  Now the antenna is fully extended and has never touched the ground.  Person #3 releases the balloon with the attached upper dipole element.  The balloon rises toward the person holding the transmitter in the center.  When it is above the center, Person #1 releases the transmitter and the balloon/transmitter rises above the last person holding the lower element of the dipole.  When the whole assembly is above the last person the lower element is released and the balloon floats to the sky.

4.  For VHF the release process is easier due to the antenna configuration.  One person can probably manage it entirely.

5.  A properly filled the balloon will disappear from sight quickly.  If the sunlight is sufficient the transmitter location signals will begin to be received by the networks.