Finishing the Envelope

In this picture I am soldering in the temperature sensor that came from my old balloon. The sensor is hooked to Teflon covered wires. The Teflon coating is necessary as it will withstand 300 degree temperatures without melting.

Don't use normal wire!

Here I am sewing the pyrometer wire between the load tape and the balloon fabric. My old balloon used a separate sheath of fabric to enclose the wire. I thought I would be clever and put it under the load tape. In retrospect, I don't recommend my method. It makes sewing to that load tape too difficult.

Make sure to twist the wire before sewing it into the balloon. Otherwise there will be too much electrical loss and your temperature readings will be incorrect.

The moment you dream about for a long time--sewing the envelope together into a circle!

Actually this picture is of sewing the two big sections into one piece, but it looks just like sewing the envelope into a circle.

I have an entire run of fabric from the top to the bottom of the balloon (the bottom you can see is about to be sewn) underneath the arm of the machine. Sounds impossible, but as you can see it isn't that bad.

The hardest part is keeping the balloon from becoming a knot!

Here I have set several fans up to blow into the top of the envelope. (The fans are actually running, I'm just using a fast shutter speed.) I did this not just because it was fun, but because it helped me keep track of things when I tied the top of the balloon into the envelope.