- Start a Construction Log Book
I use a FileMaker database. You can use a paper bound note book, Excel, Microsoft Access, or what ever you are comfortable with. The FAA requires the 51% rule for Amateur Built aircraft. Having a log book to show everything you have done is excellent proof that you did indeed do the construction yourself. It is a good idea to take pictures as you go too. Keeping a log book makes it easy to keep track of how much money and time you spend on the project. An electronic log book makes this even easier.
If you are new to sewing, practice sewing the French Felled Seam or Folded Fell Seam. Practice a LOT. Make sure that your sewing machine is adjusted to your fabric and thread. See http://www.apexballoons.com/tips/ for tips and instructions on how to do a proper seam.
- Determine Size of Balloon
Decide what size balloon you want to make. Also decide on number of gores. See Discussion on Balloon Size.
- Make the design, colors, etc
Do not get too complex (At least not on your first one) Use a paint program and play with colors. Inlaid designs are very difficult for the beginner. See discussion on Balloon Color.
- Calculate Panel Dimensions
See Discussion on Calculating Panel Dimensions. Figure out how many panels of each color you need. Order at least 15% more than you need, and if are buying seconds, buy 25% more.
- Buy Materials
Most places only sell by the roll. They often have different size rolls in stock. Ask what they have in stock and buy what fits your needs.
- Apply for N-Number
It is easier to apply for a special N-number than it is to get one 'assigned'
Send in Registration Application and Amateur Built Affidavit. Yes, do this early.
Amateur Built Ownership Affidvait
- Cut Panels
Advisable to cut all panels before starting to sew. See discussion on Cutting Fabric.
Consider cutting one or two extra panels for later repairs. This is more practical for balloons with only one or two colors. If you do decide to do this, make sure you order a little extra fabric.
- Sew Panels into Vertical Half Gores
Easy sewing, LOTS of short seams.
Make the seam so that it sheds water. This is so that when the balloon is upright, the lip faces down. Think of it this way, you don't want a ridge that collects dust. With the way most people sew the folded-feld seam, this means start at the bottom of the gore and work your way up.
- Sew Vertical Half Gores into Full Gores
Lots of LONG seams. This is the CURVED seam.
Make sure you start with FRESH FULL Bobbins each time. Unless you are making a really big balloon, a full bobbin should be enough to finish the entire seam. Changing bobbins mid-seam is a pain. It is doable, but avoid it if you can.
- Install Turning Vents
If you are going to make turning vents, do it here. Take 3 full vertical gores and sew them together. Then make the turning vents in this set of 3 gores. Then use this set of 3 gores as the beginning of the next step. See http://www.skychariot.com/vent.html for more detailed directions on how to make turning vents.
- Sew Full Gores together
Start at one side. Sew each gore onto the previous gore. If you have a pattern, make sure you get the gores in the correct order. The vertical load tape gets attached here. Using a Tape Foot is highly recommended but not required. Some people prefer to not use a tape foot. See picture of a tape foot below.
You need to put two layers of load tape for the bottom 18" to 24". You also need to have the same amount extra to sew back on the inside. This gives you two layers of load tape going thru the V-Ring, with 18" to 24" going back up inside.
- Sew in Temperature Wire Sleeve
Determine which gore you want the sleeve for the temperature wire. It is usually on one of the bottom-left gores, as you are looking up into the balloon when it is being cold inflated. When you get that seam finished, turn the balloon over and sew the sleeve onto the inside of the load tape. Don't forget this. Adding it later is VERY difficult. Instead of a sleeve, you can sew in tie straps. At every other horizontal seam, sew in a 12" piece of 3/4" or 1" piece of load tape. If you are going to use a wireless temperature sensor, you do not need to do this. But I recommend putting in the tie straps at minimum incase you ever change your mind.
To make the sleeve, take scraps (the longer the better) cut it 8" - 10" wide and sew them into a tube. You want to end up with a tube 4-6" wide. You want to have breaks in the sleeve at every 20" or less to make it easier to feed the wire.
- Sew Horizontal Load Tapes
If you are going to have any horizontal load tapes, attach them now, before the last seam is sewn. Horizontal load tapes are best sewn on top of a seam. Leave 18" overlap so that when the last seam is sewn you can come back and overlap the load tape on top of itself.
- Sew in Parachute Centering Line Attachments
With the envelope still open, go in and sew in attachment points at the second or third seam down from the parachute opening. These are best attached to the load tape at a seam intersection. This can be done after the envelope is closed up, but it is a little easier to do it before.
- Sew the Last Seam
This is actually a little easier than it sounds. Double check EVERYTHING before you start this step. There are many things that need to be done before you close up the envelope, many of them are MUCH MUCH easier with the balloon still able to be laid out flat.
Lay the balloon around the sewing machine, with the left edge to the left of the machine and the right edge of the balloon behind the machine.
- Finish any Horizontal Load Tapes
If you have any Horizontal load tapes, go back up the last seam and overlap them so they are continuous around the balloon.
- Attach V-Rings
Take the load tape, put a V-Ring on it, overlap it at least 18 inches inside the balloon. Then sew a second layer of load tape 18 - 24 inches overlapped on the inside and outside of the balloon. Sew back and forth over all of this at least 4 passes. Note: You are going through four layers of load tape and 4 layers of Nomex.
If you want to be neat about this, put the second layer of load tape UNDER the first layer, thus hiding the ends of the second piece of load tape. If you are going to do this, you have to know it before you begin sewing vertical load tapes because you have to leave the bottom 18 inches of the seam unsewn (Or you have to rip out the seam).
- Sew Bottom Girdle
Use either 1" Load Tape, 1 1/2" Load Tape or 2" Seat Belt Webbing to make the girdle. I like using seat belt webbing, but 1" load tape is sufficient. That is what Aerostar uses.
- Optional: Load Tape Protectors
I suggest putting a layer of Nomex over the load tape on the inside of the balloon. This protects the thread on the load tape. Make 6" wide strips of Nomex. Sew them on top of the load tape, with 1" folded under on each side, making a 4" wide strip over the top of the load tape. The dimensions given are just suggestions.
sSew Parachute Girdle
Use 1" Load Tape to make the girdle.
- Sew in Crown Ring
- Calculate the Diameter of the Parachute Opening
Measure the EXACT Circumference of parachute opening. This can be done by measuring the width of each gore, until you are sure they are approximately the same, and then multiple by the number of gores. Divide the circumference by PI (3.14159265) to get the DIAMETER. Divide this by 2 to get the RADIUS.
- Measure the crown ring
Measure the INSIDE diameter of your crown ring. Divide by 2 to get the radius.
- Calculate the length of the load tape
Subtract the radius of the inside of the crown ring from the radius of the parachute opening.
- Mark each load tape
Go to each load tape. Measure up from the parachute girdle to the dimension calculated above.
Mark there. Then mark another 24" up from that.
Cut the load tape at this second mark.
- Attach load tape to crown ring
Fold the load tape over the crown ring at the first mark. To make it look nice, fold the load tape from the outside to the inside. That way the end of the load tape will be hidden inside.
Use a safety pin to hold the load tape together
Do this for all load tapes
Spread the entire thing out to visually check to make sure it is correct.
Once you have double checked everything, go back and sew the load tapes. Do at least 4 passes on the load tape.
- Sew in Spider Web
If the balloon is larger than 77k, you should put in a spider web. Measure in about 1/3 from the outside of the parachute opening. Measure the distance to the exact center of the crown ring. This is the Radius at that point. Multiple by 2 * pi (3.14159265). This is the circumference at that point. Divide this by the number of gores. This give you the dimension between load tapes at that point Distance-D. Take a piece of load tape that is longer than this circumference. Mark it every Distance-D. Sew this circumferential band on the load tapes at the points marked above
- Make Parachute
ccCalculate Parachute Diameter
Using the parachute opening diameter determined above, calculate the diameter of the parachute. Make sure you have at least 12 - 18 inch overlap, on bigger balloons you might even consider going to 20 inches. NOTE: This is added onto the RADIUS, so the diameter is 24-36 inches larger than the opening.
- Parachute Design
The parachute can either be made by making pie-shaped gores, or simple horizontal panels making circle the diameter needed. If you are using the Smalley spread sheet, it will give you the dimensions needed all the way to the center.
- Parachute Artwork
Consider putting some sort of artwork on the parachute, at minimum a smiley face is nice.
- Centering Line Attachment Points
Attach the centering line attachment points to the parachute. Use 18 - 24 inch pieces of load tape, with the parachute sandwiched in between the load tape.
- Outer Load Tape
Sew a row of load tape all the way around the parachute. Put the load tape on the INSIDE of the parachute. This gives the parachute a smoother surface to seal against the inside of the balloon.
- Parachute Velcro on Parachute
Sew Velcro on top of each attachment point. Use 2" Velcro, 6" long.
- Parachute Velcro on Balloon
Install Velcro Parachute Holding tabs in balloon
Can't be done until parachute is finished to make sure they are in correct location
- Install Parachute Rigging
Install the Parachute by tying in the Centering lines. Attach the shroud lines then attach the Red Line and its pulleys
The parachute centering lines may take some adjusting.
- Make and Install Basket Cables
Use NICOPRESS fittings. Make sure you use the Go/No-Go gauge to test EVERY fitting, Alternatively, you can use cables from a dead balloon. IF the old balloon has the same number of gores and approximately the same mouth diameter. Using the cables from an old balloon, or using the cable dimensions from a known balloon design makes this a lot easier. See discussion on Basket Cables
- Make Skirt or Scoop
If you made the number of gores and width of the bottom of the balloon the same as an existing balloon design, you can use patterns from that same balloon. I like making the skirt or scoop out of Nomex. This is more expensive, but I feel it is worth it. I prefer a scoop. It takes less material, and helps on windy inflations and tethers.
- Test Inflation
Take it slow. Check everything, especially parachute centering lines.
Take lots of pictures!
- Write Manual
FAA requires a flight manual. Look at other balloon manuals. Keep it simple. Don't put in any undo restrictions. Make your options flexible. Remember: If it is in the manual, it is probably okay.
- FAA Paperwork
Fun! 8130-6, 8130-12
- FAA Inspection
DAR (Designated Airworthiness Representative) or FAA direct. Using a DAR is easier, but costs money (typical is $300 - $400). The FAA is free, but they aren't as flexible in time.
- Test Flights
FAA requires 10 hours of testing in a 25 mile radius of a given airport. They usually require at least the first flight to be solo. Sometimes they may require all 10 hours to be solo. This will vary by FISDO. If flying a balloon solo that is designed for more than one person, make sure you take extra ballast with you.
Take lots of pictures!!