How to build:
A Hot Air Balloon Envelope
© 2007-2013 Keith Sproul
!!!! DISCLAIMER !!!!
Materials
and ideas listed here are in part unproven and may be hazardous to use
in the construction and operation of experimental hot air balloons.
Building and flying experimental aircraft involves significant risk and
may lead to serious injury or death. Always obtain professional advice
when building or flying human-carrying aircraft!
This web
site will explain how to build a modern hot air balloon. It will show a
few different ways on how to do things, but it will not show all
options. The intent of this is website to help somebody just starting by
putting everything you need to know in one place. The information
needed to make a balloon has been out there on the Internet, but the
problem has been that it hasn't been easy to find. When you did find it,
you couldn't find everything in one place, and you had to guess at some
pieces of information. This website will have all the information
needed to make a modern hot air balloon envelope. This is an ongoing
project, and I welcome input, comments, and additions. The website is
copyright by Keith Sproul. The information is public and may be
distributed as anyone sees fit. If you redistribute this information,
please provide links back to this website.
I -HIGHLY- recommend reading the balloon design directions at http://www.xlta.org/plans/index.html
There
is lots of useful information there. The main difference between that
website and this on is that the XLTA website has the design for a 54k /
16 gore envelope only. This site uses the Smalley Spread sheet and has
the calculations so you can create any size envelope with any number of
gores. You can use this to make a radio controlled balloon with a volume
of less than 3,000 cu ft up to any size you want.
If you have comments, additions or corrections, please send them to me at ksproul@skychariot.com
Making
a balloon is not as difficult as it sounds. Making a home-built
airplane, even from a kit can take 3,000 hours. With the modern
quick-build kits, that can drop down to 1,000 to 1,500 hours or so, but
you pay extra for the quick-build kit. Making an airplane from plans can
take 5,000 hours.
Making a balloon can take anywhere from 150 to
300 hours. This is approximately 1/10 the amount of time it takes to
make an airplane.
Sproul Construction Times
| Picture | Registration | Year Made | Size | Gores | Time | Comments |
|---|
 | N-48KX | 2003 | 48,000 cu ft | 16 | 7 Weeks
175 hours | First Balloon
Turning Vents |
 | N-73KX | 2004 | 73,000 cu ft | 24 | 5 months
250 hours | Pattern took more time
Turning Vents |
 | N-72KX | 2004 | ~90,000 cu ft | 3 sides
48 panels | 5 Months
150 hours | Tetrahedron |
 | N-9713T | 2006 | ~60,000 cu ft | 3 sides
42 panels | 4 months
130 hours | Tetrahedron |
 | N-72KX | 2010 | ~90,000 cu ft | 3 sides
48 panels | 16 months
210 hours | Tetrahedron
Inlaid Stars were troublesome |
 | N-73KX | -- | 73,000 cu ft | 16 | Future Rebuild of N-73KX | For Aurora basket
or 2 place Chair |
| | N-50FR | -- | 50,000 cu ft | 16 | May 2012
Fabric Purchased | Special Shape / Appendages
For SkyChariot |
| | N-105BR | -- | 105,000 cu ft | 24 | May 2012
Fabric Purchased | Special Shape / Appendages |
Before you start, answer the following questions:
- Why do you want to make a balloon?
- What do you want to do with the balloon once it is done?
- How many people do you want to carry?
- What size of balloon do you want to make?
- How much time can you put into the project each week / month?
- Do you have space to dedicate to this project?
Or do you have to get it out and put it away each time you want to work on it?
|
Design Discussion
The
information presented here will primarily discuss how to make
horizontal-cut hot air balloon. This design we will use is what is known
as the SMALLEY SPREAD SHEET. This is a spread sheet that will
give you the dimensions you need to make a balloon. The Smalley spread
sheet can be used for both vertical cut gores and horizontal cut gores.
(You can also use the gore dimensions from the Areostar manual for the
S49A, S50A, S51A, S52A, S53A, S55A, S57A, S60A, S71A, S77A and S81A
envelope patterns.) Making a horizontal cut gore balloon requires more
cutting and more sewing. But, the cutting is MUCH easier, takes less
space, and produces a stronger balloon. If you make a balloon with
vertical cut gores, you need a hallway 10 feet wide and as long as your
gores (80 - 100 feet). Since must of us don't have access to that, it is
impractical to make balloons that way. In addition, by making a
horizontal cut balloon, you get seams every five feet. These seams act
as rip stops, and also as horizontal load tapes. With a vertical cut
balloon, you have to add horizontal load tapes. With a horizontal cut
balloon, you either don't need any horizontal load tapes at all, or
maybe only one or two. In a horizontal cut balloon, All panels will be
cut with straight edges, simplifying cutting and sewing.
| # of People | Size Cu Ft | Diameter Ft | Height Ft | Aprox Weight |
|---|
| 1 | 31,000 | 40 | 40 | < 100 lbs |
| 1-2 | 50,000 | 50 | 50 | |
| 2-3 | 77,000 | 55 | | |
| 3-4 | 90,000 | 57 | | |
| 4-5 | 105,000 | 60 | | 200 lbs |
| Pros & Cons of Experimental vs Commercial |
|---|
| Pros | Cons |
|---|
| Less Expensive than buying new | Can't fly Commercial |
| You can do your own inspections and repairs | |
| | |
Tools that you need
|
|---|
| Cutting Table | 6' x 10' or longer ideal | Pool table or Ping-Pong table will do
Put MDF (Medium Density Fiber board) on top for cutting surface. Also nice to have rotary cutting mats, but they are expensive |
Rotory Cutter
or good scissors | | Available at your local sewing store. |
| Double Needle Sewing Machine | Singer 112w140
Singer 112w116
Singer 212w140
Brother
Consew
Juki
Pfaff | 3/8" needle spacing is preferred. You can change the spacing of a machine for less than $100
EBay is a good place to look
A puller is nice, but not needed. Pullers are also hard to find
Do NOT get a walking foot sewing machine |
| Seam Folder | | Tennessee Attachments
I highly recommend a seam folder. You need to get one designed specifically for your fabric and seam size. |
| Metal Rulers | 4 ft
6 ft
12 ft (or length of table) | Ace Hardware Home Depot Lowe's
12 ft is just a straight edge, and does not need to be a ruler
A pieces of 2" aluminum angle works well |
| Spring Clamps | | Ace Hardware Home Depot Lowe's |
| Marking Pencils | Sharpies
White Fabric Pencils | Various colors of Sharpe's Especially Silver for dark fabrics |
| Masking Tape | 2" wide Normal Masking Tape | Ace Hardware Home Depot Lowe's
Buy the Contractors pack (10 rolls in a package). Don't get the Blue stuff, also don't get the tape marked as "LOW TACK". |
Materials that you need
|
| Material | Quantity | Source / Comments |
| Nylon | 500 - 1000 yards | www.westmarkcorp.com
www.noahlamport.com |
| Load Tape | 500 - 1000 yards | www.ballyribbon.com
kwwebbing.com
www.pamnarrowfabrics.com
tnwebbing.com |
| Nomex | 20 - 40 yards | Tex Sales, Montreal, Canada (Was Difco Performance Products)
www.noahlamport.com
www.davisinteriors.com |
| Crown Ring | 1 (4" - 11" Metal Ring) | From an old balloon |
| V-Rings | 1 per gore | From an old balloon or
Forgecraft (Part # 54A90B2)
www.dj-associates.com |
Quick-Links /
Rapide Links | 1 per gore | www.dj-associates.com |
Hook & Loop Fastners
(Velcro) | 2" wide for Parachute
6" - 8" per gore | Get the sew-on kind, NOT the stick-on kind |
| Pulley(s) | 1 or 2 for Parachute
1 for each turning vent | From an old balloon |
Caribiners
or A-Blocks | 4 | From an old Balloon
http://www.stumpfballoons.com/carabine.htm
Many other sources |
1/8" or 3/32" Aircraft Cable
7/19 Galvanized | 10-15' per gore | Aircraft Spruce and many other sources |
| Cable Thimbles | 1 per gore | Aircraft Spruce and many other sources |
| Nicopress Fittings | 1 1/2 per gore | Aircraft Spruce and many other sources |
Red Line
Vent Lines | | From an old balloon or
-GOOD- polyester braided rope NON-stretchy |
| Thread | Polyester Bonded
Size 69 or Size 92
Left Twist
3 1 lb cones/spools | Do
not use Nylon. Polyester is much better. Make sure it is bonded. You
will need three cones of thread, one for each needle and one for the
bobbins. |
Steps to make a Horizontal Cut Smalley Design Hot Air Balloon Envelope
- 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.
- Practice
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 from Noah Lamport, 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
http://registry.faa.gov/aircraftinquiry/aircraft_inquiry.aspx
http://aircraft.faa.gov/e.gov/NN/reserve.aspx
It is easier to apply for a special N-number than it is to get one 'assigned'
- Registration
Send in Registration Application and Amateur Built Affidavit. Yes, do this early.
- 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 when all done, sew this set of 3 gores into the rest of the
balloon. 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.
- 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 ever 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.
- Sew 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
- Calculate 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.
See http://www.skychariot.com/BalloonParachutes.html
- 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!!
|
Discussion of Steps
- Balloon Size
Balloon Size depends on a lot of things. How many people do you want to
fly? How big you are? What type of temperatures do you fly in? If the
balloon is too small, you will easily overheat it. If it is too big, it
can be hard to bring down. Yes, this sounds hard to belive, but it is
true. Also, if the balloon is too big, you will be under-pressurized.
This will allow the balloon to cave in on the sides if you go thru bad
wind-shears. I like to fly balloons cool, so I usually make them a
little bigger than needed, but you don't want them too big.
You also
need to decide on the number of gores. For smaller balloons, 16 gores
is usually enough. If you are making a balloon larger than 77k, you
should consider 24 gores. The more gores, the smoother / rounder the
balloon. Less gores make the balloon more bulbous.
- Balloon Color / Pattern
KISS
Keep It Simple Stupid. Especially on your first balloon. Having
different panels different colors is very easy. Inlaid designs are
difficult and not recommended for the beginner.
- Calculating Panel Dimensions
Calculating
the actual dimensions of the panels can be one of the hardest steps in
this project. The Smalley Spread Sheet itself only gives the dimensions
for a vertical cut balloon. If you are not comfortable with simple
algebra, this step can be very daunting.
- Determine the width of your fabric.
Nomex
is normally 60" wide. The 1.3 oz Silicone that many of us uses is
normally 65" wide. Other types of Nylon are often 60". If you are lucky,
all of your rolls of fabric are the exact same width. If not, you will
have to cut the fabric to the same width (except for the Nomex, we will
treat that separately). You can have different panel heights in your
balloon, but this gets confusing and is not recomended. Any panel will
have to be the height of the width of the narrowest color in that
panel.
- Determine the width of the bottom panel
This
should be made the same as a known balloon design so you can use
cables, skirts, and scoops from that balloon design. For example, for
the Aerostar S55A (77K), S57A (90K), and S60A (105K) This bottom
dimension is 11.70 inches and for the Aurora S53A (69K) and S49A (54K) the dimension is 16.25 inches.
The Smalley Spread sheet, or the Aerostar panel dimensions give you
fabric widths at different station points along the gore length, but
never in the exact place that you need the dimension. So you have to
interpolate between the given widths to get the needed widths. This can
be done using on-line interpolation tools.
For example http://www.ajdesigner.com/phpinterpolation/linear_interpolation_equation.php.
The version of the Smallley Spread Sheet that I give out has this
interpolation calculation in the spread sheet. You still have to type
in the numbers to get the dimensions you need for your balloon size. If
you are having problems with this, let me know and I will be happy to
do a set of dimensions for you.
- Calculate the dimensions of the rest of the panels
Using
the width of your fabric, go up the gore and find your next cut point.
Use the interpolation, calculate the width at that point. Then go back
down 2.25 inches (this is TWICE the overlap dimension of
1.125 inches) and interpolate again. The interpolation calculations in
my spread sheet do both of these at the same time. This saves on
typing.
- Cutting Table
The
biggest space you will need is a cutting table. If you have a Pool Table
or a Ping Pong Table you have all the space you need. Ideally, a table
6' by 12' (or longer) works great for cutting. Use MDF (Medium Density
Fiberboard) and make a table top to go on top of your pool table or
ping-pong table. Make sure your table top is perfectly square, you will
be using it as your measurement references for all cutting.
- Cutting Fabric
Most types of Nylon have a 'top side' and a 'bottom side' to the
fabric. Most fabrics also have a slight difference in color depending on
which side is out. So, you need to cut half of the panels so that you
get left side and half so you have a right side. You can do this by
cutting half 'face up' and half 'face down'. Also, it is HIGHLY
advisable to mark each and every panel with what panel # it is and note
somehow that what side of the fabric is 'top'. If you write small at
the edge of the fabric, it will be sewn into a seam and never seen. I
recommend picking a place on the panel, and writing in the same place on
every panel. For example, I write on the straight edge on the bottom of
the panel. For example, in the drawing below, I write where the '+'
is. By writing in the same place on every panel, you don't have to go
searching for the label, you know exactly where it is. For dark colors,
use Silver Sharpe's. Write small, less then 3/4" on the edge of the
panel.
The easiest way to cut fabric is to use a rotary cutter
(looks like a pizza cutter). But the that requires getting cutting mats
to put on top of the cutting table. This is expensive. Another good
choice is the electric rotary cutters. They do not require cutting mats.
They can easily go thru 24 layers of fabric.
The spread sheet gives you top and bottom dimensions for each panel. Lets call those W-Top and W-Bot. W-Top W-Bot
|-------------/-------+
|------------/--------|
|-----------/---------|
|----------/----------|
|---------/-----------|
|--------/------------|
+-------/-------------|
W-Bot W-Top
I
lay down a layer of fabric, tape it down with 2" Masking Tape and then
add another layer, and another, and another. Typically, I cut between 8
and 12 layers at a time. 12 is about maximum. The other limit is how
many layers you can get taped down and keep them straight. The silicone
nylon is slippery and since the tape does not stick well, it is hard to
keep taped down well.
By cutting this way, you get two panels per layer of fabric. It speeds up cutting and reduces waste.
If
you have a longer cutting table, you can even save more time by cutting
more than one panel/pair at a time. This saves on time because it takes
about the same amount of time to lay out the fabric, no matter what the
length, and it saves on waste because you have the same amount of waste
per layer if you are cutting one panel/pair or two panel/pairs. W-Top1 W-Bot1 W-Top2 W-Bot2
|-------------/-------|-------------/-------|
|------------/--------|------------/--------|
|-----------/---------|-----------/---------|
|----------/----------|----------/----------|
|---------/-----------|---------/-----------|
|--------/------------|--------/------------|
|-------/-------------|-------/-------------|
W-Bot1 W-Top1 W-Bot2 W-Top2
W-Top1 W-Bot1 W-Top2 W-Bot2 W-Top3 W-Bot3
|-------------/-------|-------------/-------|-------------/-------|
|------------/--------|------------/--------|------------/--------|
|-----------/---------|-----------/---------|-----------/---------|
|----------/----------|----------/----------|----------/----------|
|---------/-----------|---------/-----------|---------/-----------|
|--------/------------|--------/------------|--------/------------|
|-------/-------------|-------/-------------|-------/-------------|
W-Bot1 W-Top1 W-Bot2 W-Top2 W-Bot3 W-Top3
- Basket Cables
If
you use the mouth dimension of an existing balloon, you can use the
cable dimensions from that balloon, or better yet, get cables from a
dead balloon. If you are making a 16 gore balloon, use the dimensions
from an Aerostar Aurora, S49A / S-53A which are both 16 gore balloons
with the same bottom dimensions. If you are making a 24 gore balloon use
the dimensions of the Aeristar S-55A / S-57A / S60A which are all 24
gores balloons with the same bottom dimensions. Cameron / Lindstrand or
other brand dimensions and cables will work just as well.
To make
this work, the dimension of the bottom of the gore has to match the
balloon you are copying the cables from. See discussion about Calculating Panel Dimensions.
|
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