Build Your Own Model Hot-Air Balloon

Many of today’s very active balloonists, started off making their own model balloons. They are great advertising tools, can be engaging for education demonstrations and can even create wow-factor at night-glow events as they can dance tethered and shining in the dark.

‘A mini balloon, really is a delight, perfect for those that want to pilot a balloon but are not quite ready for the real thing….’

‘I like to fly my model as an education resource for school science days when children are studying flight. To see enchantment and wonder in their faces…’

Model balloons, really can be as simple or as accurate as you like - anything from a tissue-paper indoor model whose lift is provided by a fan-heater to an accurate to-scale model suitable for even the most exacting model enthusiast.  

We at Cameron Balloons hope you enjoy this step-by-step guide to building a mini-working hot-air balloon and actually we are hoping to over time to build a gallery of all those models built with a little help from Cameron Balloons.

Please read all these notes carefully before starting work on your Cameron Balloons model balloon envelope.

GENERAL OVERVIEW

These notes are to help you make a model Hot-Air Balloon Envelope suitable for radio-control one of two different volumes, either 50m3 or 80m3 using the same fabrics as their full-sized cousins. Expect to take about 25hours to build a model balloon from start to finish (and that is if you are used to ‘driving’ a sewing machine.)

However, if you would prefer a bit of help… At Cameron Balloons we can even pre-cut and add the build information onto fabric in colours of your choice so it is ready for you just to sew up – contact sales@cameronballoons.co.uk for a price and a delivery time.

Each model is made from 24 identical gore panels, a ring of alternating wide and narrow Nomex panels round the base, and a flat disc at the top.

GOOD LUCK! Let the adventure begin!

Order of construction
1) MAKE PAPER PATTERNS.
2) CUT OUT THE FABRIC FROM THE PAPER PATTERNS.
3) SEW THE ENVELOPE FABRIC TOGETHER.
4) MAKE THE WIRES AND SCOOP.

To Start: 
TOP TIP 1. – READ all the instructions first!
TOP TIP 2. – DECIDE what size model you are making and stick to instructions for that size throughout

1. MAKE PAPER PATTERNS

You will need the following to make the paper patterns for your model balloon

• A roll of paper
• A large setsquare. A large T-square is helpful when making the pattern
• 1m ruler or tape measure and long straight edge (a piece of straight timber for example)
• Pencil or ball-point pen
• String or thread
• Pair of scissors

The gore pattern is drawn out as in Fig 1 (click here to view)       (Click here to see Table 1 for dimensions)

To make a complete gore pattern you will need a length of paper to the following dimensions.

                For the 50 m3 envelope 6m long by a roll of paper minimum of 700mm wide

                For the 80 m3 envelope 7m long by a roll of paper minimum of 800mm wide

Stage 1: Draw a centre-line down the centre of the paper, then make a mark on the centre-line 50mm from one end of the roll of paper label this ‘Base’ just above the mark.

Stage 2: From this mark measure along the centre-line the 1st gore step length (see Fig.1   &   Table 1) and make a mark.

Stage 3: From the new mark measure along the centre-line the next gore step length (Table 1) and make a mark ‘BM’. Repeat for all the gore steps.

Stage 4: With the set square draw lines 900 out from both sides of the centre-line at each gore step mark, and extend these lines across the width of the paper.

Stage 5: Mark out the ½ Gore-width (click here to see Table 1) on each line on both sides of the centre-line.

Stage 6: Joint these marks together with a straight line between each mark to complete the balloon gore pattern.

Stage 7: Cut out the finished gore pattern. Then label the Top, Equator and add for ‘BM’ labels in the positions shown.

The Nomex paper patterns are drawn out as in Fig. 2 >> Click here       (CHECK Table 1 for dimensions).

To make the patterns for the Nomex panels NXA & NXB you will need two pieces of paper to the following dimensions -

                For the 50 m3 envelope 500mm long by a minimum of 300mm wide;
                For the 80 m3 envelope 600mm long by a minimum of 350mm wide.

Patterns for the Nomex panels NXA & NXB are marked out as follows

Stage1: Draw the panel centre-line down the middle of a piece of paper. Then make a mark on the centre-line 20mm from one end of the paper. Then from this mark measure along the centre-line the panel height (see Table 1) and make a second mark.

Stage 2: At both marks on the centre-line draw lines at 900 out from both sides of the centre-line, and extend these lines across the width of the paper.

Stage 3: Mark out the ½ Gore-width (see Table 1) on each line on both sides of the centre-line, and then join the marks together with a straight line.

Stage 4: Cut out the finished patterns and label the top of each pattern as shown.

 To make the top disc pattern you will need a piece of fabric to the following dimensions.

                For the 50 m3 envelope 1300mm long by a minimum of 1300mm wide;
                For the 80 m3 envelope 1500mm long by a minimum of 1500mm wide.

The top disc pattern is marked out as follows -
a) Find the centre of the piece of paper

b) Using string or thread, draw a circle to the top disc radius. (The radius of a circle is the length of the line from the centre to any point on its edge)

c) Make twelve equally spaced marks round the circumference of the top disc.

d) Cut out the pattern

2) CUT OUT THE FABRIC FROM THE PAPER PATTERNS.

Remembering the old adage ‘Measure twice, cut once’ can save a lot of upset – please check your patterns carefully and cut fabric all from one side
(Using the shiny side on the outside will make it look really nice.)

Two types of fabric are used to make your model balloon envelope

Cameron Balloons Rip-stop nylon and Nomex, 12mm webbing tape, 2mm kevlar string and some Velcro or clips for the scoop. 

The NXA, NXB and Scoop panels are made from Nomex. All the other panels are made from rip-stop nylon.

Click here for Table 2 - Estimated Fabric usage

Cutting the NXA and NXB Nomex panels

Your envelope requires 12 NXA and 12 NXB panels cut from Nomex fabric.

Place each pattern on the fabric and draw round with thin lines in dressmaker’s chalk. Repeat for the number of panels required.

You will have to rotate and position the pattern carefully so as to cut all the panels from the amount of Nomex given in the table above.

You can rotate the patterns 1800 and nest up against the last marked panel so the both panels have a common edge.

When marking out is complete, cut off the panels with a sharp pair of scissors.

Mark the top edge of each cut panel with a small “T”

Cutting out the rip-stop panels

TOP TIP - Keep fabric on the roll until you are using it, to keep it flat for construction – much easier when trying to put patterns on it and although hard on the knees (wear kneepads) it is easier to prepare fabric on a clear, flat (non-carpeted) floor

Cutting method – stack cut up to six fabric layers into gores at a time. Perhaps consider making your first model a plain colour – which makes it easier to build and assemble as of course there will be less seams to sew and less extra measuring to do….

TOP TIP - It is MUCH easier and usually more accurate to do just one or two gores at a time if you want a really tidy accurate model.

Stage 1: Unroll the fabric and cut to length. Repeat a further five times. Then make a neat stack from the six lengths of fabric.

Stage 2: Place the pattern on top of the flat smooth fabric and pin in place.

TOP TIP - Make sure the pattern is pinned to all the layers.

Stage 3: Cut out the panels.

TOP TIP - It is easier if you use a very sharp pair of scissors and let the scissors run through the fabric rather than snipping. 
(You might want to practice on some scrap fabric first).

Stage 4: - Before unpinning the pattern make a small mark on each panel edge, at the equator and ‘BM’ positions. These balance marks will help when sewing the gores together. Also mark both the top of each cut panel with a small ‘T’ for Top.

TOP TIP – Keep all the marks small so they hide in the seam once assembled

Repeat the above so you have the 24 gores required for the model balloon envelope.

For the top disc - pin the pattern to a single layer of fabric and cut out. Then transfer the 12 small marks on the pattern to the fabric panel. After unpinning the pattern, make a chalk mark in the centre of the fabric panel. 

TOP TIP – Save large scrap pieces to practice, sewing, check tensions and stitch length on the sewing machine before starting to sew

3. SEWING THE ENVELOPE TOGETHER.

To sew the envelope together you will need a single needle lock-stitch sewing machine and a suitable nylon thread.

The stitch length should be set to between 5 to 8 stitches per 25mm (inch). You can stray outside these limits when sewing your model balloon envelope, but it won’t be as neat.

TOP TIP – use a piece of sacrificial scrap fabric to start each gore (which is trimmed off) so that the fabric start points do not bunch up with thread during the forward and back lock stitch sequence and gives you something to hold onto to help ‘pull’ the fabric through neatly.

The rip-stop fabric used for your model is coated on one side. It is this coating that makes the fabric airtight and keeps the air inside the envelope. It also affects the appearance of the fabric.

Before sewing your envelope it is important that you decide if the coating will be on the outside or the inside.

For most fabrics the coated side has a slight sheen to it, but for some colours it is difficult for the untrained eye to tell which is which.

Before you start sewing, for all the rip-stop panels clearly mark which side of the panel is the outside.
TOP TIP - It is also quicker, if you make sure you have filled an adequate number of sewing machine bobbins.

How to sew a seam    Click here to See Fig.3 - Seam Detail All the seams in this model envelope are sewn the same way.

IMPORTANT NOTE – this is NOT how to sew a man-carrying hot-air balloon – this model seam is NOT strong enough.

a) Lie two panels on top of each other with the outside of the fabric facing each other.

b) Sew together with a row of stitching, reverse back 2 or 3 stitches at each end to ‘lock’ off the sewing. Ideally you should sew 7 to 8 mm from the edge of the fabric.

TOP TIP - If you feel you can’t sew a constant 7 to 8mm from the fabric edge, then, use the edge of the sewing machine foot as a guide or stick a piece of tape with a felt tip line onto the sewing machine in the right place to use as a guide.

The easiest way to sew up the envelope together is as follows.
1) Sew the correct Nomex panel to the bottom of each of the complete envelope gores.

2) Sew the gores together in the correct order. (That is; make sure you alternate between NXA & NXB gores). Remember to use the ‘BM’ balance marks as a guide to make sure the panels are fed equally through the sewing machine. You will be making the Cameron Balloons model balloon inside out – this is ok!

3) Top disc, before pinning into place for sewing this to the envelope sew a small 12mm webbing loop for a crownline to the centre of the outside of the disc. Sew in the pinned top disc matching up the small balance marks as you go around to keep it tidy.

4) At the bottom of the Nomex turnover the fabric and sew a 5mm hem.

5) Add 12 wire attachment loops to the bottom of the model. Each loop is a 2cm length of 12mm webbing folded over and sewn to the bottom of the envelope as in Fig.4 - Click here. If you feel confident enough it is possible to add these loops when sewing the hem at the bottom of the Nomex panels.

6) You now have a complete model balloon envelope, which is inside out. Turn in the right way and add the flying wires.

4) MAKE THE WIRES AND SCOOP

Click here to see Fig.4 - Rigging Wire Loops

Rigging wires - Make the rigging wires for your model balloon envelope from 2mm kevlar string. All the wires are the same length and the finished wire length is dependent on the dimensions of your burner frame. Click here to view Table 4 - Rigging Wire Lengths

Scoop design and patterning - The scoop pattern is drawn out as follows (Click here to refer to Fig. 5)

To make the pattern for a scoop for your envelope you will need the following
          a) A piece of paper at least 1000mm by 1500mm
          b) A Large setsquare. A large T-square is also helpful when making the pattern
          c) 1m ruler or (tape measure and straight edge)
          d) Pencil or ball-point pen
          e) String or thread
          f) Pair of scissors
Before you can mark out the scoop pattern measure and note down the following -
          i) Length of the longest side of the model basket’s burner frame (BL)
          ii) The finished length of the rigging wires (W)
          iii) The distance between rigging wires round the base of the model balloon envelope (X)

 Following Fig.5 >>>

Stage A) Find the middle of the long edge of the paper and mark a centre-line across the width of the paper. Then make a mark on the centre line 50mm from one edge.

Stage B) At this mark on the centre-line draw lines at 900 out from both sides of the centre-line. The length of these lines is equal to half the dimension (BL). Label this line “BL” Then draw two lines parallel to the centre-line on either side of the centre-line; the offset from the centre-line is half dimension (X).

Stage C) Draw two arcs of radius dimension (W) as shown in fig 5.

Stage D) On both sides strike two arcs distance (X).

Stage E) Joint up the all the intersections with straight lines.

Stage F) Add a 7mm seam allowance all round.

Complete the scoop by sewing a 7mm hem around all sides. Add suitable clips or Velcro loops to the bottom two corners. Then sew the top edge to the base of the envelope. Make certain the scoop is outside the flying wires and Ta Dah! You are finished!!!!

(But, if it all got a bit tricky or you get a bit stuck - we have a few in-house model-balloon enthusiasts that would be very happy to give advice and support too. Contact via enquiries@cameronballoons.co.uk

Lastly now you are finished… may we be the first to congratulate you!

Please send to us here at Cameron Balloons a photograph of you, smiling, with your inflated model hot-air balloon. enquiries@cameronballoons.co.uk

What to do and where next… There are lots of events in the UK and Europe where model balloons attend – everything from balloon events to charity events, fun days to school education days – so really, have lots of fun and get flying!

Other useful sources of information
www.bbac.org – to contact Model Balloonists at The British Balloon & Airship Club email miniballoons@bbac.org

Here is a link to the guidance associated with the operation of model aircraft from the UK Civil Aviation Authority >>> https://www.caa.co.uk/Consumers/Unmanned-aircraft/Model-aircraft/

Some mini burner and basket kits can be found here http://www.modellballoneboelling.de/hier-geht-s-zum-shop/k%C3%B6rbe-und-korbteile/

Thank you & happy flying from all of us at Cameron Balloons Ltd.