Pilot Balloon Launch
From OakenWiki
- This document was used to help organize some of the information we had gathered while doiing BYU-Idaho's first balloon launch, Thor 1. This document was originally created in July 2005. It is intended to help the beginner - it is not all inclusive. An all inclusive faq is at the Balloon FAQ
Contents |
[edit] Essential Components
[edit] Balloon
Balloons are described in terms of their weight. Balloons are a one-time use component. A 350g balloon costs about $20. Balloon sizes come in 350, 600, 800, 1200.
Considerations
- Maximum volume
- Helium (gas) required
- EOSS says we should add about 6 ounces to 1 lb of extra lift. The manner in which the balloon is filled is as follows:
- Get a helium tank from the school. Cost of a K size tank is $50. We will not need all the gas in this tank.
- Get some PVC pipe and a tube that will connect the balloon to the regulator on the tank. Connect the pipe to the tube, and then connect the tube to the regulator. The tube should be big enough so that the balloon fits snuggly around it (EOSS recommends a tube with about a 2 inch diameter). The tube should have a hook on it for attaching the dummy weight below.
- Get a scale. Place the balloon, payload, parachute, and cables (eg everything that will go up) on one side. Add an extra 6 ounces to 1 lb. of weight. On the other side, fill a milk jug up with water until the scale balances.
- Lay the balloon flat, preferably in an enclosed area to protect it from wind. Wind will toss the balloon around and might cause it to pop.
- Attach the dummy weight to the balloon.
- Fill the balloon until it just barely lifts the dummy weight off the ground.
- EOSS also recommends using gloves and laying a tarp down under the balloon during the filling process.
Supplier list
- Kaymont
Phone: 1-800-644-6459; Note they are in the eastern timezone, so you must call before 3. - Kaysam?
[edit] Batteries
Walmart sells e2 Energizer lithium AA batteries. These offer 2900mAh at 1.5 volts each. This may be a good solution. S&G sells D cells that reportedly cost only $15 per 10 cells. Each cell carries 3 volts. The S & G cells are used, so it seems like a risky move to use them.
Note that at 50,000 feet we approach temperatures around -60 degrees centigrade. Alkaline batteries's electro-chemical reaction will cease at that temperature; once the batteries return to proper temperature, they will work again. Practically, therefore, you are left with only one option: Lithium (not lithium ion) batteries.
What about solar cells or fuel cells?
[edit] Making a power Budget
Every launch should include a power budget. The power budget is calculated by finding the amount of current required for each component. Some components, such as transmitters, will draw two different levels of current: one when it is transmitting, one while it is idling. What you want is the average.
For example, suppose the Pocket Tracker draws 26 ma when transmitting, and only 9 when idling. Further assume that transmits take 1 second, and the rest of the time is, of course, non-transmit time. The the average, per minute, (is 26*1 + 9*59)/60 = 9.28 ma / min. , or about 560 ma per hour. Of course these numbers are fictional, mind you! But the calculations should work.
Suppliers
- WalMart
- S & G Electronics
618 S. 62nd St.
Philadelphia, PA 19143
Phone (voice): 215 474-7663- The cells by S&G deliver over 6000mAh each.
[edit] Gas
The BYU Idaho supplies department offers K size tanks for $52. They will supply the regulator. These supplies can be obtained with only one days notice. Praxair was recommended by April Christensen.
April Christensen says 2 K or 1 T size tank will fill a 1200g balloon. It would be good to be able to calculate how much helium will be needed to produce the lift we need, which will likely be somewhere in the order of 0.77 lbs (350g balloon) + 1lb (parachute) + 3lb (payload) + 1 lb (packaging, cables, all else) = 5.77, or approx 6 lbs. They say 1 cubic foot of helium lifts 28.2 g. Using this as a guide lets us get an idea of how much helium we need to purchase. The amount of lift needed is:
<math>\frac{n}{0.06294}</math>
Most K tanks hold over 200 cubic feet of gas. On launch date, we will be more concerned with getting enough gas to lift our total balloon + stuff weight, plus 6 ounces to a pound for lift.
Often people ask if a balloon "will be able to hold" all the helium you give it. Note that there is a 12 lb. restriction - our payloa's total weight must be less than or equal to 12 lbs. Let's assume we have a 12 pounder. We really want it to rise fast, so we give it two whole extra pounds of lift. Using the above calculation, we get
<math>\frac{n}{0.06294} = \frac{14}{0.06294} \approx 350 cu ft.</math>
Wow, lots of helium! but yes, all the balloons we use will hold that.
Suppliers
- Praxair (208-356-0028)
- Gary Romrell
BYU-Idaho Stock Control Specialist
(208)496-2325
ROMRELLG@BYUI.EDU
[edit] Parachute
It cannot be stressed that the parachute is a single point of failure. So wisdom must guide the purchase of a parachute.
Suppliers
- RocketMan - April Christensen and others have recommended the rocket man. The R7C should left 3.5 to 8 lbs fall at a rate of 15 to 20 feet per second.
[edit] Cabling
April Christensen recommends Dacron heavy duty fishing line. This can probably had in a reel of 300 ft. for $15 (note this is more than will likely be needed for the first launch).
[edit] Payload
The payload will, in its most basic form, contain the following:
- Transmitter
- GPS unit
- Batteries
- Antenna
- Connective Cabling
The GPS unit, transmitter, and battery should all be kept inside a styrafoam container. This will provide padding to protect it from impact. The antenna should be firmly secured - it should not be allowed to flop! The payload box should have a “HARMLESS AMATEUR RADIO TRANSMITTER” note attached to it, which will have a return to address of BYU-Idaho, and a phone number/email address, and maybe a little detail about what the package is used for. It should also have either either a Buzzer or Strobe light or both to aid in recovery. Also, it must have a return to address, in case it is lost!
NOTE on redundency The following is taken from the EOSS balloon faq. REDUNDANCY! Live by that word! Have at least two transmitters. Each transmitter should have its own, totally separate power supply. If your package isn't transmitting when it lands, you aren't going to find it. One transmitter can be a milliwatt rig running from a 9 volt battery. Hint: you can buy oscillator modules from Digi-Key for a few bucks each that have frequencies in various HF ham bands. They run on five volts and draw next to no power.
[edit] Essential Milestones
Before a launch, the following should be done:
- Obtain all the essential components above
- Order balloon, parachute,
- Buy batteries
- Cabling
- Build or buy structure.
- Test the components above
- Start testing about a month before launch - This ensures time to be thourough.
- Test GPS/transmitter –
- Distance (taker up to R-Mountain)
- Temperature
- Duration (we should see if it can last at least 6 hours – we might need a redundant set of batteries)
- Obtain a licensed FCC operator for the transmitter
- Pick a launch location. The launch location should have a wind barrier of some sorts.
A couple days before the launch date:
- Project the landing destination of the balloon using Balloon Trak.
- Notify the FAA/local airport/Scroll of our launch
- Obtain a tarp, gloves, gas for filling the balloon
- On the day of the launch
- Test the transmitter
- Obtain two teams to track the balloon
- Make sure all teams can communicate via cell phones
- Make sure all teams have enough gas to drive for a couple hours.
[edit] Contacts
- April Christenson
- NASA Idaho Space Grant Consortium
- aprilm@uidaho.edu
- 208-885-4934
- April has contacts with NASA and is working on getting funding for the RISE (Research Involving Student engineers and educators)
- project at several universities in Idaho. She has corresponded with TVNSP. She also made several recommendations on the cabling,
- helium, and FCC licensing issues.
- Tony - N7MTZ
- HiValue Radio Inc. - Simplifying APRS (r)
- n7mtz@sunvalley.net
- Main contact for questions about the Pocket Tracker transmitter. Has good knowledge of antennas and radio. Tony has worked with
- the folks at TVNSP.
- Michael Zürch
- dg1cmz@freenet.de
- Lives in germany. Has headed at least one successful balloon project, and has been involved in several others. Made several
- recommendations for possible hardware solutions. Very willing to give advice.
- Stephanie Steele
- kc7dba@spamcop.net
- President of the Treasure Valley Near Space Project. TVNSP.org. TVNSP has helped with several high altitude balloon projects.
- Edge of Space
- www.eoss.org
- This has been one of the main sites for documentation relating to high altitude balloon project logistics. The
- EOSS balloon faq has been the main reference which we have based the project off of.
