Windsock

I first began to realize that there was more to picking a launch site than finding good ground cover in July of ’93. I was crewing for my brother Jim at the Great Texas Balloon Race in Longview, Texas. Jim had been a pilot for seven years and he had done most of his flying for recreation and at weekend "competitive" events.

Don’t get me wrong, I never thought that picking a launch site was a completely random event (although sometimes it did appear that way) but I did believe that planning was pretty much limited to seeing if you could launch a small helium balloon that would eventually head in the general direction of the target area. After all, I thought, no pilot wanted to be completely embarrassed by drifting directly away from the target right after a launch.

Those magnificent men/women and their flying machines
The morning of the first event was much as I imagined. The pilots were hanging out together, catching up on old acquaintances and telling ballooning stories (which were amazingly like fishing stories). It seemed as though they were all good, close friends. This was, of course, until they were dismissed to begin the first task. I had crewed for my brother before but never in a competitive event. This was different. A noticeable tension immediately filled the air and a mad scramble ensued. I guess this was understandable. After all, there was big money on the line (actually on a pole) and you can’t underestimate a pilot’s pride. This had turned to war.

Some groups did seem to know what they were doing; the rest appeared to just follow them. Now I’m still not sure why the speeding laws don’t apply to balloonists and their crews but if they did, the City of Longview could have filled their monthly ticket quota on that day alone. Strategy sessions started playing out. The leaders tried to evade the followers, friendly chatter turned to hushed murmurs, and asking another pilot what they thought about a particular site would be a little like Lincoln asking Booth if box 7 in Ford’s Theater had a good view of the stage.

The most closely guarded secrets seemed to be embedded in the computer screens and printouts that were found in several chase vehicles. I asked Jim what was so interesting on those computers and he explained that although the upper wind conditions had been given at the pilot meeting earlier that morning, the winds can change significantly shortly after sunrise. These pilots were getting up-to-the-minute winds aloft conditions at different sites by tracking intermediate pibal movements using a compass, clinometer and specialized computer software. He explained that this information is current, very accurate and can be an invaluable aid when choosing a launch site for a task.

Now this was a great idea. I had been a computer engineer for over 10 years and I was fascinated with the idea of a computer analyzing the upper wind conditions. I knew that a computer would not help regulate the flow of propane to the burners or improve a pilot’s arm or timing during a baggy drop, but it was clear that the proper use of this technology could significantly improve a pilot’s odds by aiding with the proper selection of a launch site.

... and the Kitchen Sink
I asked Jim why he didn’t have a system like this. He said that he had come close to buying one but the current systems had too many shortcomings. He said that the software was very expensive and by the time you buy a laptop computer you were already out several thousand dollars. Add a battery powered printer and you had better win more than a few events to justify the cost. Even if you "borrowed" a laptop computer from the office or home, you still had to drag a rather delicate piece of equipment back and forth between the office and an often rugged field environment. If the computer is damaged or stolen in the field, there goes three weeks of work, your client database, your checkbook and your last year’s income tax (maybe not such a bad idea after all).

Personal computers could also be overly complicated for a single task. Why do you need to bring your kids with you just so they can fix the autoexec.bat file when things go wrong? And, he added, keep in mind that laptops use rechargeable batteries which, like camcorders, seem to have problems in direct proportion to the importance of the event.

"What was really needed", he explained, "was a unit that was so small that it could be carried with you in flight. It should fit in the palm of your hand or in your shirt pocket and it should be small enough that one person could take the pibal measurements and enter them without additional help. It should cost a few hundred dollars, not a few thousand dollars, so even the recreational pilots can justify the cost." He added, "One of the real advantages to having a system like this is being able to get current wind speed and direction, which is as beneficial to the purely recreation or corporate pilots as it is to the competitors. Make it simple so that you do not need to be computer literate to use it, and make it so that a set of regular batteries will power it for a whole season." Oh sure, I thought to myself, and you probably want it to drive your chase vehicle and pack your balloon when you’re done. I was familiar with most all available computer technologies and the thought of putting a pibal tracking system in the palm of your hand intrigued me enough to start my quest for the perfect pibal tracking system.

Searching for Hardware
I knew the math was fairly basic and involved some trigonometry and vector arithmetic. Add some graphics functions for output and I estimated that a basic wind analysis software would compile to less than 15K bytes of software code in memory. It was quickly becoming apparent that Jim was right-personal computers with their megabytes of memory, multiple disk drives, power hungry microprocessors and complex operating systems were definite overkill for this task.

The search was on for a smaller, less expensive and easier to use solution. My first thoughts focused immediately on personal digital assistants (PDAs for short). These were the new keyless handheld computer systems in to which you entered data using a pen-like device. Although it would be great fun to experiment with these new gadgets, I found that they were still relatively expensive (around $700), were difficult to program and their handwriting recognition systems were prone to errors.

The search moved to "palmtop" computers. These are ultra-miniature computers with very tiny computer keyboards. They store data and programs using non-volatile memory instead of disk drives and, since they are IBM compatible computers, they would be much easier to program than PDAs. The major problems with palmtop computers were that they were still relatively expensive (around $500 for a basic system) and would preclude the pilots with vertically challenged fingers.

Finally, my search focused on the new wave of programmable calculators. Although these machines are marketed as advanced graphics "calculators", they are actually sophisticated handheld computers with non-volatile memory, alpha-numeric keyboards, and LCD screens capable of full screen graphics operations. Best of all they were inexpensive. For around $100 I could get a machine that had 32 KBytes of memory, perfect for pibal tracking software.

After researching the different calculators available, one stood out as clearly superior, the Hewlett Packard 48G. The 48G is rugged, easy to use, and measures only 3" x 7" x 1". It can operate for over a year on standard AAA batteries and has an infrared communication port for wireless communication to the optional battery- powered printer. The built in RS-232 port can provide a link to an external peripheral (such as a GPS) so future applications can provide pre-flight or in-flight consultation and analysis. This was indeed the perfect solution. As a bonus, the 48G has a big brother called the 48GX which comes with 128 KBytes of memory and is expandable via plug in memory cards. This version would allow for a wide range of future ballooning applications in a single unit.

Windsock Software
The 48G features an object oriented programming language with built-in vector, timing and graphics operations which simplified the programming task and minimized the memory requirements. By calculating and saving the pibal’s position in four dimensional space at each sample interval, the average relative wind direction and speed could be determined at each height using basic math functions. The software, which we called Windsock, came to life as we continued to add feature after feature.

As a tribute to those who paid attention to their metric lessons in school, Windsock supports distance units in both U.S. customary and metric units and can display speed units in knots, mph or kph. Since all fields are not created equal, we added support for variable field elevation and magnetic declination parameters. Jim said he wanted to know the wind conditions at height intervals (for example every 200 ft), so we made the pibal sample period fully programmable using either time intervals or pibal height intervals. Wind directions can be displayed as either winds to or winds from and a fully scaleable graphical display of the pibal’s ground track can serve an invaluable aid in viewing the relative wind conditions at a glance. We also added a file system so that the current wind conditions could be saved and recalled for comparison or conversion to a different unit base or wind perspective.

Of course, full calculator functionality is standard with the 48G. Other useful features include full unit conversion, a distance calculator, calendar, time of day clock and even an alarm clock (so Jim wouldn’t miss those early morning pilots’ meetings). Now if we can just calculate the trajectory of a baggy thrown at an angle of 15 degrees from 250 feet ...

The basic Windsock pibal tracking system sells for $295 plus shipping and handling. Printers, clinometers, pibals and cases are available separately. For more information contact Bob Summersett at:

Custom Craft, Inc.
9110 Scottish Pastures Cove
Austin, TX 78750
(512) 219-1989 Phone
(512) 219-8491 Fax