Computer Systems

The Flight computer system has not changed since HAPB-1. It is consists of a Primary Flight System (PFS), a Secondary Flight Computer (SFC), and a telemetry system. Each system handles different responsibilities.

JPEG versions of the schematic and layout. Schematic, PCB Layout, Front Image , Back Image
ExpressPCB versions of the schematic and layout. Schematic, PCB Layout

Primary Flight Computer (PFC)

The PFC is a Parallax BS2px and is still responsible for reading and recording latitude, longitude, time, altitude, internal capsule temperature, external capsule temperature, and taking still pictures. Additional responsibilities include managing memory storage, relay controls, and audible signals. Text Version Stamp Version

The program flow worked out really well during the maiden voyage so I decided not to change anything in the PFC.

Secondary Flight Computer (SFC)

The SFC is a Parallax BS2p24 and along with its previous duties of controlling the LCD, activating external lights when below 1000 meters, and providing visual indication that the PFC is working I added video control functions. During this mission, the SFC will trigger a digital video camera containing a 2 gigabit SD card. This will provide ~ 1h45m of video, which is not enough time to cover the entire flight. I decided that I would record while the capsule was below 2000 meters then have the SFC turn the camera off. It will then turn the camera back on when it reaches an altitude of 20,000 meters and leave it on until it drops below that altitude. At the point, the camera will be turned off again until it is below 2000 meters. I figured this would provide me the most interesting aspects of flight. Text Version Stamp Version

Parallax software is available on the Parallax download page.

Telemetry System

As with my previous flight, the indicator and display systems are used during testing, pre-launch, and post-launch activities. Tracking the payload throughout the flight is done via the onboard telemetry system and the vehicle tracking system. All in-flight data and photographs will be stored within the payload until recovery of the capsule. I redesigned the telemetry electronics to incorporate its own voltage regulator. The Open Tracker will be powered directly from the batteries, while the GPS and DJ-S11 will be regulated to 5v DC.

As before, I will be using my laptop PC connected to a Kenwood D700 dual band radio with built in TNC used in conjunction with UIView-32 and Precision Map along with my trucks GPS system and mapping software. This time I will be able to track my position with respect to the balloons position simultaneously during the recovery process. This should make things a little easier and more interesting. Like you do not already have enough to do during the chase.

JPEG versions of the schematic and layout. Schematic, PCB Layout, Front Image, Back Image
ExpressPCB versions of the schematic and layout. Schematic PCB Layout

Power System

This is the biggest change for the system. The PFC and SFC will be completely solar powered. Each PowerFilm has a operating voltage and current of 7.2 v DC and 200ma in direct sunlight. I connected all the panels in series and configured them in 2 rows. This will provide more surface area facing the sun at any given time and since the HAC is circular, the voltage and current should remain constant during the flight. There is a 4" gap in each row to allow for the cameras so I staggered the solar panels in each row to maximize the coverage. I need 230 ma to run the PFC and SFC. I still have testing to do and things might change before the flight but that is what experimentation is all about.

The OpenTracker and the Garmin GPS-18 worked really well during the first flight so I decided to continue with that setup with a minor change. For this mission I will not use solar power on the telementry system itself. Instead I have elected to use 6 x 1.5V batteries to power the APRS, the DJ-S11, and the GPS. In addition, each camera has its own power supply. The previous flight had 9vDC for the Open Tracker, primary and secondary regulated 5vDC for the GPS powered from 2 sets of 9vDC battery packs, and the radio was powered by the a seperate 4.5vDC power source. Basically I have reduced the system to 6 batteries as compared to the 21 batteries I had from the first flight.

Housing Assembly and Capsule (HAC)

The housing assembly and capsule are combined in this flight. Two rows of solar panels wrap the outside of the HAC. It is modular and assembled from the bottom up. Each section makes up the assembly. It is divided into 4 sections consisting of an impact chamber, instrumentation platform, avionics compartment, and a telemetry compartment. Structural Blueprints I used Expanded PVC Plastic sheets that I obtained from Budget Robotics again for this flight. The two primary compartment (telemetry and avionics) uses a custom insulation ring made from Great Stuff.

The impact chamber is exactly what it sounds like. It is the bottom 2 inches of the HAC consisting of a 1" insulation plate and a 1" x 2" insulation ring. The theory behind the chamber is that during the landing the ring will compress and absorb most of the force on impact. The 4-40 screws holding the chamber to the rest of the HAC use thru holes into the avionics compartment and are allowed to slide up into that compartment. The shape of the chamber is maintained by the insulation. The ring will be replaced after each flight. Structural Blueprints

I added a new switch and 2 DB9 connectors to the instrumentation platform. As with my previous flight this is where all my bells and whistles are located for easy access. It contains the toggle switches, LCD, and light indicators. The new switch activates the telemetry equipment and the DB9's give me easy access to the computers. In addition, it has my contact information in case someone else finds it before I do. Panel Image It is covered by a insulation ring and insulation plate. The ring ensures the switches and buttons are not depressed during close-out procedures. Movie – Instrumentation Panel (7 megs), Structural Blueprints

Additional Images - Top, Profile1, Profile2, Profile3, Profile4

The Avionics compartment contains the PFC and SFC. Structural Blueprints  

The telemetry compartment holds the APRS unit, a modified DL-11 hand held radio, and power supply. I am using the same antenna that I used on HAPB-1, a 2-meter dipole made from coax cable. Structural Blueprints

System Testing

Early experiments showed promising, however, after the HAC was assembled only a few attempts were needed to show that additional solar panel(s) will be needed.

An additional panel was installed on the top of the HAC to provide the necessary current supply when only one side panel was facing the sun. The sun was 20 degrees above the horizon with a thin layer of broken up cirrostratus clouds. During the testing I kept the LCD running which requires 60ma of current. The power system appears to working properly now. I figure I must have been early close on my original power calculations because now I have excess power for running the LCD which I did not include in my original power calculations.

I have finished my testing and everything appears to be working. I recently purchased a 2 Gig SD card and it turns out that my video camera can now run for 3.4 hours at 640x480 or 4.5 hours at 320x 240. In both cases the video time is longer then the mission duration. It is amazing, just a year ago 2 GB SD card was selling for over $200 and now you can buy one for less then $20. Technology, you gotta love it. I decided to not use the computer controll for the video camera and I disabled the servo and commented out the procedure that turns the recording on and off. KISS is always best.

Launch & Recovery(October 27, 2007)

It was a perfect day for launching. Visibility was 15 miles with no clouds in the sky. We watched HAPB-2 burst at 89,391, very cool BTW, and was able to visually track her part of the way down. She landed next to an electric fence ~ 1000 feet from a dirt road. It was funny to watch the cows grazing all around the payload.

I did get a few good images from the film camera during the ascent phase, however, the video camera settings got changed when I had to make some last minute adjustments to the payload which resulted in no video. My wife captured some good video and images of the launch and recovery and my friend Paul shot some good video of the chase.

Pictures: Predicted Path, Actual Path, Pre-Post Launch Pics, In Flight Pics

Video Clips: Launch (10.4MB), Chase (2.1MB), Locating (7.3MB), Cow Washers (5.7MB), Recovery (23.2MB), Inspection (12.5MB)


Damage Assessment

The capsule suffered a fair amount of damage. From the looks of the balloon train the latex balloon was wrapped up with the parachute causing a faster then anticipated descent. This in turn caused enough damage to the payload to make it unusable for another flight without doing some major repairs. During the preflight launch I had to reopen the capsule to reseat a connector. My hand could barely fit in the same cutout I made which resulted in my hand inadvertently changing the video camera from video to still pictures. The secondary computer was not setup for that function – thus no video. I plan to redesign the capsule again making it lighter and a little more modular with easier access to components. The design phase is the half the fun for me anyway so I don’t mind creating a new capsule.

The solar panels did a great job and I plan to continue to use them for future launches but I will increase the number of the panels. Early morning light caused us to delay the launch until the sun was about ~15 degrees above the horizon. HAPB-3 is going to get underway after the holidays.

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