FreeSpace reaches 18 miles up!
Author: T.J. Bordelon (KI5CZ), President of  FreeSpace. 8/31/98

Photo taken from RadioFlier-1 at 94,000 feet above Barstow, CA)
For more photos, visit the >>>Photo Gallery<<< BE PATIENT, there are many pictures

It was around September of 1997 that I decided to start trying to reach in the direction of achieving the highest altitude I could with my own hands. Almost one year later I reached halfway into space and took a look around with FreeSpace’s first launch of RadioFlier.

This project turned out to be a smashing success in just about every way. We retrieved stunning pictures, great video, and detailed telemetry. How did we do it? Read on!

Weather balloons reach altitudes higher than you might think. It isn’t uncommon for some of these huge balloons to achieve 100,000 feet. This altitude might be meaningless to you, so let’s put it into perspective. This altitude is about 20 miles up, or about halfway to the US defined space border of 51 miles up. Passenger jets rarely fly over 40,000 feet.

At this extreme altitude the sky is black and you can see the curvature of the earth. Clouds appear way below you and can’t even make out buildings on the ground. You’re 2/3 of the way through the stratosphere where temperatures are boiling in the sun and freezing in the shade. As if that weren’t enough, you’re above 99% of the density of the earth’s atmosphere—Almost a perfect vacuum! Heat doesn’t dissipate via convection currents at these low pressures, so it tends to build up on whatever is producing it.

Sounds pretty hostile to me too! After doing my initial research and coming up with these facts, I wanted to launch a tank! I thought that my electronics and batteries would explode at altitude, that my heatsinks would overheat, and that my package would freeze due to the -50 F temperatures on the way up.

And so I set off building my tank. When I finished, I had an aluminum box with an ATV transmitter, a VHF transceiver, a modem, a computer, a pressure sensor, two temperature sensors, GPS, and a power supply all crammed in there. Basically you just had to apply power and some antennas , slide the entire thing into a pressure-sealed container and off you went. Boy, did I overdo it.

SO… I was ready to launch, right? WRONG! I had so many problems with this package. The modem would flake out and needed to be readjusted every other day. When my package transmitted, I would get weird voltages in my sensors that would screw up my readings. The list went on and on. I could solve all these problems, but it was already 8 months into this project and I was still building the payload I thought would take me a month to build. The reason? I built everything from scratch, therefore I had to debug everything.

If there was one thing I learned from that, it was the fact that you should buy before you build. Everything I had built could have been bought for a fraction of the cost that I built it for. For example, the 1200 bps modem I built cost me $5 and over 100 hours of frustration trying to tune it to work right. The off-the-shelf alternative was a Packet modem for $100. Unless I like getting paid $1 an hour, it just wasn’t worth it.

Something else that lead me to rethink my design was my discovery of other balloon groups doing exactly what I set out to do—launch a weather balloon with radio gear on board for control and tracking. These guys were using all off-the-shelf components like handheld radios, Packet modems, GPS boards, and the like and putting them all into a Styrofoam container wrapped in aluminized mylar. No worries about pressure at all! And the best part was that their stuff was working. Looking into what these guys were doing lead to a complete redesign of my project and also saved me a lot of headaches.

Unfortunately most of these balloon groups fail to mention the technical details of the gear they send up. This missing information was what I had to figure out with my own research. It’s hard to feel sure about something you’ve never done before, especially when it’s next to impossible to reproduce the conditions it will be operating under on the ground. How could you ever be sure the thing will work? How can you let a $1500 balloon go and not be sure of that? It was hard.

Before I let my project go, I tried as much as I could to test it on the ground. I decided to trust that the package would be fine with the insulating materials the other groups were using—but I didn’t know what they used for their antenna systems. How far away could they stay in contact with the balloon? This was something I could test on the ground. To do this, I placed the package high on a mountain top and did some range testing with different antennas.

What did I find out? Use high frequencies so your antennas don’t have to be huge. Also, use circular polarization on the package so your signal won’t flutter with package spin, and will reflect more to reach farther away.

Within a few months of my redesign, I was finished with my package and was ready to launch. I used all off the shelf components and kept the complexity to a minimum. This turned out to be the key to the project’s success!

"Avionics"

• 68HC11E9 computer
• Motorola Oncore GPS module
• Kantronics 1200bps packet modem
• 35mm camera
• Audio buzzer
• Yeasu 5 watt 440mhz handheld radio feeding an Eggbeater antenna
• Alinco 1/3 watt 144 mhz beacon feeding a horizontal whip antenna
• Lithium battery providing 12 volts @ 16 amp/hrs
• Camcorder
• Emergency cutdown system (Detaches balloon from payload)
• 144 mhz horizontal whip antenna

Physical package

• Square Styrofoam cooler covered with aluminized mylar (Space blanket available at camping stores)
• Two masts off the sides of the cooler supporting the gps and telemetry antennas
• Lots of hot glue (For mounting things inside) and transparent tape (to tape on the mylar)
• Parachute
• 1200 gram Kaymont weather balloon
• Helium ( ~200 cubic feet for lifting 11.5 lbs + 1 LB lift)

On the ground

• 440 Mhz yagi antenna (6 element, 8.6 db gain)
• Kantronics 1200 bps TNC
• Pentium laptop computer
• Custom software giving balloon position, ground position, easy entry of commands for balloon to carry out, and logging of all data.

Launch day

Unlike other balloon groups, our balloon launch team had a total of three people. Myself, my girlfriend Christy, and my boss at work, J.Walt. At 3:30am, we headed to our launch location from our office in Burbank. Around 6:00am, we arrived at our launch site in Barstow.

After 2 hours setup, we called the FAA and let them know about our launch. Surprisingly, they said "Well… OK." (We filed no paperwork and called at the last minute) At 8:00 am we let our balloon go and watch it go up about 10 feet and come right back down. We didn’t fill it enough! Our first filling attempt was with a mismeasured weight attached to the balloon as ballest. On our second attempt, we used the actual package as the ballest with a 1 lb weight on top. This gave us 1 pound of positive lift and away our balloon went!

The entire trip up went flawlessly. I remained on the ground pointing my antenna in the direction of the balloon. Telemetry went back and forth the entire time with no missed data. Watching the GPS data coming back from the balloon was so exciting. Every 10,000 feet was another success in itself. We launched a heavy payload (11.5 lbs) so we figured we would only reach 70k feet or so. We were so wrong.

During the flight up, we all agreed not to abort unless absolutely necessary. We decided to deal with the package where it landed and not to abort prematurely. With all the restricted areas in the Mojave desert, it’s hard not to get trigger happy with the cutdown button.

When the balloon reached 25 miles away, it started coming right back to us.. But then started drifting more north. J.Walt was staring right at the balloon with his naked eye when it popped at it’s max altitude of 94,000 feet. At that altitude, the balloon had to be huge in order to be that visible from the ground.

The next part of this story is amazing. I watched as the balloon descended rapidly on my laptop. 10k, 8k, 3k, "GPS Timeout; Boot successful; Enter command>". The package hit the ground so hard it rebooted, yet somehow we still had a link! We were probably line of sight as we could see most of Barstow from our high vantage point. Mission successful—We had only to get the package. We all hoped farmer Ned wasn’t probing it with his pitchfork. "What the hell’s this thaang? Martha! Come see! We’ve got another UFO!".

We drove about 10 miles north and I heard a strong signal from the package’s 5 watt radio—It was sending out beeps just waiting for us to find it. We had to drive on very sandy dirt roads for a few miles. We ended up in the middle of nowhere. There was absolutely no sign of civilization anywhere. J.Walt said that we should be within one mile of the package, yet the 5 watt tracking signal was not to be heard.

We assumed the batteries died, so I got out the 2 meter yagi and did a sweep of the area. To my surprise, there it was! The faint crackle of the 2 meter beacon! We followed that bearing to the beeping box. Thank goodness for that backup beacon.

The box was so hot inside, we couldn’t handle the radios. All the hot glue had turned molten. No wonder the 5 watt radio quit! It was in thermal shutdown because our box was acting like a solar oven, cooking the equipment inside. As a matter of fact, it was so hot that anything placed in the sun for 10 seconds would be too hot to touch. The LCD screen on my handheld radio and watch were black from the heat. I would have never guessed heat would be a problem. Despite the unforgiving sun, everything was OK, and the film turned out great.

One weird thing we noticed is that the cutdown mechanism didn’t release the balloon from the package. Further examination yeilded the answer: Estes model rocket engines don’t ignite at 100,000 feet! Our crude yet effective cutdown mechanism was a simple model rocket engine that would ignite and burn through straps worked fine on the ground. The rarified atmosphere apparently didn’t allow whatever reaction needed to take place in order to fire that engine. Funny, as I thought those engines had oxygen in their fuel. I’ll have to do more research on this one.

Even though the parachute didn’t fully open, the payload touched down at about 20mph and was completely intact! 

What did I learn?

So much. For starters, I learned to keep things as simple as possible, and stick to your goal. It's easy to deviate and get caught up on small details. I also gained some confidence in the field of transmitter hunting. My choice gear for doing this has to be a yagi. Sure you can get all those fancy DF units that do dopler and whatnot, but I was amazed at how cheap and easy my yagi was. Of course, it does help to have an analog signal strength meter.

And of course,I haven't forgotten all the cool data we retrieved from the launch. We weren't super scientific about how much we filled the balloon, but we believe we had somewhere around 1 pound positive lift. Here's Time Vs. Altitude:

And where did it go? Here's a plot of the balloon's location. It went about 25 miles northeast of us (the starting point is at the bottom), almost going into restricted airspace. It came back to within 8 miles of us and landed about 13 miles north of us.

I was also curious about how fast the package was descending, so I plotted this graph. I averaged the samples over a few minutes to get data that made a bit more sense. You can see the slope of the graph above varies wildly. It went up at about 8-10 miles per hour, and peaked briefly at 60 miles per hour on descent. The package slowed to under 20 mph before touching down and rebooting. Ok, so maybe it slammed down.

So this concludes RadioFlier-1, a complete success! I appreciate you taking the time to look at our first project, and hope it was informative for you. 73's from KI5CZ

-Tj