MABEL-1

Michigan Area Balloon Experimental Launch 1

By Phil W8IC, Jeff N8QPJ, and Chris N8UDK

 

Project Overview - Phil W8IC

The conception of the MABEL-1 Balloon project occurred in January of 2000. The actual launch took place on November 5, 2000. In retrospect, the most difficult part of this project was in getting started. Ann, KT8F,and I are both avid fox hunters and had dreamed about doing a balloon launch for several months before the decision was made to try it. We decided to send one up, no matter what. A serious commitment had to be made to begin the project and see it through to the launch and recovery. A decision was made in the early days of the project to not seek outside funding. I hoped that our cost would not be more than a couple hundred dollars in non-recoverable supplies. A project of this size requires the help of many others. I began to contact other amateur radio operators that I believed might be interested. Soon an e-mail list was compiled, and new info was sent out every week or two as updates. Frank, N8BNA who maintains the SEMARA Club's web page <http://members.home.net/semara/> joined in and added these updates to their page. This allowed members new to the group to see what had already taken place in the construction and research.

Chris, N8UDK joined the group in February. He offered to send up several pieces of electronics that would add greatly to the audience appeal for the flight. The equipment included an ATV transmitter, camera and controller, along with a video overlay board. This came as a much needed boost at the time for the project. Chris also had the equipment and talent to program the various boards for the flight. Jeff, N8QPJ also joined the group at that time. He brought to the project knowledge of radio controlled aircraft construction and audio/video production and interfacing; as well as the necessary electronics expertise required to assemble all the various parts of the payload. Jeff had experience in installing video cameras on R/C airplanes and remote controlled model cars. Both Chris and Jeff promote amateur television. They are the founders of the Detroit Amateur Television Society. What better way is there to promote ATV than to launch a balloon that will send ATV at 90,000 feet! Throughout the winter and spring, many discussions took place between the various members. A set of general flight guidelines was eventually developed. The assembly of equipment began. The Internet was consulted for a parachute. I found a 72 inch chute at Priscilla's Parachutes Company in California < >. Next, I ordered a 1500 gram balloon from the Kaymont Company at <http://www.kaymont.com/pages/pilot_frmst.html>. Through the balloon mailing list at < >, I found a source for lithium batteries. I was able to buy two 15 ampere- hour battery packs for $25. Although the expiration date on my packs was 06/92, they worked great with plenty of power to spare.

Chris and Jeff were kept busy working on ideas for the inter connection of the various components as well as locating a GPS for supplying data to the video overlay board. Although the number of volunteers and interested parties grew larger, the great majority of the work was done by Chris, Jeff and me. This worked out well, as the extra manpower was needed most during the launch and recovery operations.

The pace of the project started to lose momentum around the end of May, and since the launch was still not close to being ready, I decided to suspend operations for the summer. Everyone enjoyed three months of summer, as well as a nice break from my updates.

September arrived and the project was started up once again. I felt that it was possible to launch before winter arrived. After checking with Chris and Jeff, a tentative date of November 4 was set. Our problem at the time was that the payload still had not been built. We also did not have a voice module or MIMMS Module or even a launch site.

I started investigating potential launch sites. Two sites were offered to us. Both were great. It was decided that the site farther to the west would be the safest to use due to the generally westerly winds. The location chosen was Bannister, Michigan, located about 30 miles northwest of Flint Michigan.

Arranging the launch site was one of my biggest concerns. Now I could move on to other jobs. While Jeff and Chris worked together on the payload and the internal components, I turned my attention to other tasks. First a balloon filling tube was fabricated. To construct the fill tube I started with a 1" by 12" long piece of electrical schedule 40 PVC conduit. I capped off the bottom end and installed a hook to measure the lift of the balloon as it was filling. The hose was attached by drilling a hole in the side of the conduit near the bottom. Into this hole I threaded a standard air hose fitting and sealed it with JB weld. Two radiator hose clamps were used to secure the balloon to the fill tube. Fortunately, I happened to have a regulator, otherwise I would have rented or borrowed one. A Helium tank has about 2500 pounds of pressure when full. I found that Helium was available at a local welding shop. A 244 cubic tank could be rented for $45.00 per month. It had to be returned empty according to the shop keeper, so I really wanted the launch to proceed. Next, I located the 50 pound rated string. This is the maximum strength allowed by the FAA between the balloon and parachute.

The month of October seemed to be the fastest month of my life. During that time, Jeff built the capsule including all the supports and partitions needed to keep the components separated. He also installed two of his cameras. A color camera was aimed at the horizon, and a high resolution black and white camera was pointed straight down to get a good view of the earth below. Chris purchased the MIMMS Module, UHF antenna and GPS. He already owned a supply of controller boards, as his company manufactures these boards and has supplied them to other balloon projects.< >. Chris was responsible for the programming of the MIMM'S Packet Module and main controller board. Jeff then built the voice module and had his Mom record the voice announcement.

I made up a simple horizontal dipole for 2 meters which was attached to a Radio Shack HTX 202 with one watt output. This transmitter would beacon on 144.34, the national ATV simplex frequency. The voice announcement would alert any listeners that live ATV was being transmitted from a high altitude balloon on 439.250 mhz. The beacon transmission would include a packet GPS burst, and CW telemetry as well as the voice announcement. The beacon transmissions alternated between the HTX 202 and a 300 milliwatt Alinco credit card HT with built in antenna. This provided a chance to see what the difference would be between a 1 watt transmitter with a horizontal dipole and a 300 mw with built-in 4 inch vertical. Jeff fitted the lithium battery packs into the bottom of the capsule. The other equipment was arranged above them. Testing of the electronics in the payload was accomplished by using the second set of batteries. The batteries measured full strength after a four hour test.

Two trips were made to the launch area in order to check out the sites and find repeaters for communications between all the search teams. I compiled a list of frequencies and sent it to all in the group. Floyd, W8RO volunteered to run a 40 meter net along with VHF operations during launch and recovery.

It seemed important to have the flight show up on the APRS system, so two digi stations were set up. These stations were used to digi the 144.34 signal to the APRS system on 144.39 mhz. The first digi station was located in my van at the launch site. A temporary 25 foot high vertical fed with 50 watts was used. The second digi station was at my home in Warren, Michigan. I planned to disassemble the portable set-up at the launch site after the balloon was a few thousand feet high. The Warren location would digi from that point on.

Our flight was exempt from the FAA regulations because the payload was under 6 pounds and none of the surfaces were over 3 ounces per square inch. Even so, it was decided, for safety's sake, to file a "Notice To Airmen" with the FAA. I contacted the FAA by calling 1-800-WXBRIEF. The information they wanted included: time and date of launch, location of the launch, projected maximum altitude, projected landing site and time of landing, and distance to any major airport. I think the info requested may vary with the FAA person contacted. I filed my report three days in advance, but had to cancel and reschedule the flight due to high winds. The flight was rescheduled for the next day, November 5, 2000. I believe you must launch within one half hour of when the flight is scheduled to go, or call to cancel or modify your notice.

National Weather Service data and two computer programs are very valuable at this point. "Liftwin" is a program used to determine the ascent rate, approximate burst altitude, and approximate time until burst. It is available at http://www.geocities.com/capecanaveral/3161/hablic.htm. "Balltrak" is available at http://www.eoss.org/wbaltrak/ This program will take data from the Internet that has been gathered from NWS weather balloon radio sondes and then uses this data to make predictions for the flight of a balloon. It will demonstrate on a Street Atlas map such as SA5 the track the balloon is predicted to take.

 

Payload Construction - Jeff N8QPJ

Payload Box Construction:

I had three weeks to design and build a box that would carry all the equipment that was needed for this project. The box had to protect the equipment from the harsh environment of near space, survive the impact of landing, stand out in thick woods so it could be found and while doing all the above continue sending video and telemetry for nearly four hours and weight less than six pounds. Having no payload box building experience and unable to find much info on the Internet about the subject. I thought about it for a few days and came up with a design. Let the building begin!

The Inner Shell:

The material chosen to use in the construction of the box was Sturdy Board. Sturdy Board is 3/16” thick lightweight foam board. It is made of two pieces of card stock with foam between them. The foam board is easy to work with and very light. I assembled all the equipment that had to go in the box so I could come up with the dimensions the box had to be. The inside dimensions of the box are 8” W X 8” D X 9” H. The box is divided into upper and lower compartments by a removable shelf. I strengthened the bottom of the box by gluing another layer of Sturdy Board to the inside bottom. The box was held together with hot melt glue and epoxy.  To provide attachment points to tie the box to the parachute, two 3/16 inch dowels were used.  The dowels ran through the box and stuck out 2.5 inches on either side.  To prevent the dowels from tearing the Sturdy Board, 1/8 inch light plywood pieces were epoxyed on the inside and outside of the box where the dowels passed through the box.  The windows for the cameras were made from 1/8 inch Plexi-Glass glued in flush with the outside of the box.

The Outer Shell:

The outer shell consists of 1 inch polystyrene foam epoxyed to the outside of the box on the four sides, bottom and 1/3 of the top.  Bright orange model aircraft Ultracote was ironed on the polystyrene to add strength and visibility.  The top cover was made of Sturdy Board and polystyrene and also covered with the Ultracote.  Just before launch the top cover was hot melt glued on and orange electrical tape was used to seal the seams.

 The Lower Compartment:

The lower compartment is subdivided into several smaller compartments to accommodate the equipment and to keep the pieces secure.  The compartments were made by cutting pieces of Sturdy Board and hot melt gluing the pieces to the bottom and sides of the box.  The below list is the equipment that is in the lower compartment.

The Upper Compartment:

The upper compartment consists of the removable shelf and two smaller fixed shelves on the wall of the box.  The removable shelf is held in by two screws and a groove.  The below list is the equipment that is in the upper compartment.

Outside the Box:

Five items were mounted outside the box.  The piezo beeper, outside temperature sensor, Amateur Television antenna, cut-down device and 2 meter dipole antenna.  The piezo beeper is held in place with coax seal and has a quick disconnect so it can be turned off.  The temperature sensor is mounted in the polystyrene and epoxyed in place.  The Amateur Television antenna is held in place with wire ties. The coax for the antenna is run through a hole in the bottom of the box and the hole was sealed with coax seal.  The cut-down device was attached to the string for the balloon and had two wires running through a hole in the top of the box.  The 2 meter dipole antenna was attached to a 3/32 inch wood dowel with wire ties. The 3/32 inch dowel was epoxyed to the two 3/16 inch dowels that were used to attach the parachute.

 

Payload Electronics Construction - Chris N8UDK

Forward:

MABEL-1 had all the elements I look for in a project. First, it was fun! Why spend a huge chunk of time (and possibly money) if something isn't? Second, it promoted several hobbies: amateur radio, ballooning, and space science. Everyone evolved, from the foxhunters to the videographers, could find something they could relate to. This “combining of hobbies” is a great way to get new people into ham radio! And the third ingredient for a great project was the educational value. I believe we all learned from the experience. What more could you ask for in a project?

Overview:

The major design objectives for the MABEL-1 payload:

There were several obstacles in designing the electronics for MABEL-1. I can only begin to appreciate the knowledge and skills of people who build real payloads for a living. For us the major obstacles were payload weight, power consumption, and temperature.

At the heart of the electronics is the flight computer, which consists of a single micro controller chip, called the PIC16F84 (no big surprise.) The PIC controlled the keying of the two 2-meter radios, switched the two on-board cameras, triggered the DVR message, triggered the APRS packet data, and generated CW inside/outside temperatures with battery voltage. The PIC also controlled a larger audio beeper on the outside of the payload.

The supporting on-board hardware:

The temperatures are acquired through two Dallas DS1620 IC’s. The battery pack voltage is acquired through a Linear LTC1298 IC. The APRS packet is received on the ground and converted to real-time positional information (displayable on a map). The 1 watt PC Electronics TXA5-RC ATV transmitter is on 439.25 MHz (cable channel 60).

Operation:

The “flight computer” (PIC) performs a majority of the on-board functions. The only independent processing is performed by the OSD-GPS board which overlays GPS information on top of the video cameras. The flight performed the following tasks:

During accent:

  1. Switch to down pointing camera for 40 seconds
  2. Switch to horizon pointing camera for 20 seconds
  3. Repeat

During decent:

  1. Switch to down pointing camera for 20 seconds
  2. Outside beeper on
  3. Switch to horizon pointing camera for 10 seconds
  4. Outside beeper off
  5. Repeat

During entire flight:

  1. Key 1-watt radio
  2. Transmit APRS packet
  3. Transmit inside temperature in CW
  4. Transmit outside temperature in CW
  5. Transmit APRS packet
  6. Un-key 1-watt radio
  7. Key 300 mw radio
  8. Transmit APRS packet
  9. Transmit inside temperature in CW
  10. Transmit outside temperature in CW
  11. Transmit APRS packet
  12. Un-key 300 mw radio
  13. Key 1-watt radio
  14. Transmit APRS packet
  15. Transmit DVR voice message
  16. Transmit battery voltage in CW
  17. Transmit APRS packet
  18. Un-key 1-watt radio
  19. Key 300 mw radio
  20. Transmit APRS packet
  21. Transmit DVR voice message
  22. Transmit battery voltage in CW
  23. Transmit APRS packet
  24. Un-key 300 mw radio
  25. Repeat

Conclusion:

The hard work on the payload helped make MABEL-1 a success. We met all our design objectives. The video from the balloon was spectacular. The FM beacons were heard in over six states and Canada. WE GOT THE PAYLOAD BACK. Everyone seemed to have a good time.

A few future enhancements for the MABEL project are adding more cameras with higher resolution, a “defrosting” device for the camera windows, and DVR telemetry (e.g. a voice stating “MABEL altitude is 83,000 feet).

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