High Altitude Balloons

                                                                              

SSOK, Sky Science Over Kansas, launched it's first balloon on February 1, 1992 and since has flown and recovered over 20 payloads.

We have found, like other groups, that amateur radio and high altitude balloons form a great match for getting people of all ages and backgrounds interested in ham radio.

Our flights have ranged from simple cw transmitters carrying still cameras, as shown in the above picture, to live ATV, environmental data collection, and light weight big envelope types like the current payload below.

 

Current Payload

Current electronics block diagram.

Keeping things simple but reliable is the main focus.

Current payload less chute

Laminated construction keeps the electronics >20 C.

Enclosure

Basic foam cylinder before adding electronics

Fitting the electronics

The electronics are mounted on balsa wood rails for support while in the cylinder.

Electronics

Shown here is the emergency locator transmitter, MIM packet module, and the Alinco 300 MW transceiver.

Electronic, rear side

Shown is the battery pack, and GPS interface board, and the GPS engine.

Mechanical release system

A hobby servo, 2 meter receiver, and a tone decoder is a low power method of releasing the payload.

Inflation and launching

 

One of the major problems faced by launch crews is surface winds. Gusty surface winds can cause the balloon to come in contact with the ground or nearby objects and be punctured. So almost all balloon launches are prefaced with the caveat "dependant on surface winds we will launch". Winds in the calm range will ensure a smooth transition from inflation to release but it is not always calm on the launch day picked a week before.

I wanted to remove the stress of worrying about the surface winds, so I had to take that part of the equation out of the launch scenario.

A large mobile launching box was built to hold the balloon safe after being inflated in a large building. This box has one door and a hinged lid, and when opened creates an artificial calm area for the launch.

The enclosure is a 10'6" cube made of 2x4 framing and covered with light weight canvas. The inside is cardboard stapled to the framing with the staples covered with duct tape for protection. A grounding system that has contact with the balloon at all times is the only electrical part of this system ( we use hydrogen sometimes). 2 large steel forks are  underneath for attaching to the tractor's front end loader. A winch connected by pulleys opens the top.

This unit has been used several times in winds that would have caused concern with the old way      ( inflating in a building, opening the doors, and carrying the balloon out by hand).  The problems started at the door with wind eddy currents pushing and pulling the balloon.

I should be able to use this system in winds up to 30 mph. To date 10 to 20 mph winds has been no problem.

The following pictures describe the launch process from inflation to release.

Click on the thumbnail for a larger view.

 

Balance beam scale

Simple mechanism for getting accurate nozzle lift readings.

Scale

Accurate to within 1 gram.

Filling a 1200 gram balloon

Test balloon with helium 4.27.2004

Transport box

Allows launching in high surface winds.

Tie down

Eyelet will hold balloon in center of box.

Anchored

Balloon is centered in box.

Ready to move

Balloon is protected from damaging winds.

Getting a lift

Box is secured to front end loader for transport to launch site.

Load door opened

At the launch site with the door opened on the lee side. The payload is in the foreground.

Top being opened

The top section (lid) is rasied by a winch. Balloon is protected from wind.

Releasing step#1

Person on the side is controlling the balloon with an attached line.

Releasing step #2

Balloon is still not affected by surface winds.

Releasing step #3

Balloon at this point is just starting to be affected by the wind.

Up & away

Easy launch in 20 mph winds.

Data Stream Sample

The following data is from a bench test. Each line is sent every 10 seconds with the data line once a minute. GPS lines are the GGA & RMC.

WB0DRL-11>APRS: <<UI>>:
$GPGGA,033448.00,3849.5649,N,09746.7250,W,1,04,1.7,435.6,M,,M,,/GPS FIX
WB0DRL-11>APRS: <<UI>>:
$GPGGA,033456.00,3849.5649,N,09746.7254,W,1,04,1.7,435.6,M,,M,,/GPS FIX
WB0DRL-11>APRS: <<UI>>:
$GPGGA,033508.00,3849.5649,N,09746.7258,W,1,04,1.7,435.6,M,,M,,/GPS FIX
WB0DRL-11>APRS: <<UI>>:
$GPRMC,033518.00,A,3849.5649,N,09746.7261,W,0.1,216.6,200404,,/GPS FIX
WB0DRL-11>APRS: <<UI>>:
$GPGGA,033528.00,3849.5690,N,09746.7215,W,1,04,2.3,410.3,M,,M,,/GPS FIX
WB0DRL-11>APRS: <<UI>>:
$GPGGA,033536.00,3849.5687,N,09746.7218,W,1,04,2.3,412.1,M,,M,,/GPS FIX
WB0DRL-11>APRTLM: <<UI>>:
T#035,149,000,000,000,239,11111111, MIM v1.07

This last line is the telemetry, it is sent every minute. The T# is followed by a minute number with a max of 255 then starts over.  So this is the 35th minute since  power up. The 149 is the internal temperature and is calculated by xxxxxxxx.   The 000 are unused A/D channels. The 239 is battery voltage. ( BatV=A/D*.0392 ) in this case, 239*.0392=9.37 volts. The 1s are unused digital switch inputs and if low would return a 0.

 

Last up dated:  09/13/2005