Recovery, Rocket Building

Creating sleeves for the Shock-Cord

I wanted to protect the shock-cords from the brutal heat of the ejection charge. I knew I can purchase nomex variants, but I didn’t have any place I could purchase them easily and I thought I’d try my chances and make something that might provide them “some” protection at minimal cost.

The solution needs to provide some protection for a few flights. It doesn’t need to be so strong it will last 20 flights. i.e. something modest is satisfactory.

Materials

I did some research on materials and it seems that:-

  • Wool is not flammable
  • Cotton is probably not too bad a material at resisting fire.
  • There are some Polyesters that are impregnated with some compounds that make them inflammable.

I ended up finding a material that is a blend of Wool and Polyester – not perfect, but something that could provide some protection over 2 or 3 flights before requiring replacement.

Creating the sleeve

It was quite a simple process, however I thought it would be important to show some photos below of what I did.

 

Fabric is roughly cut out.
Fabric is roughly cut out.
Pinned the fabric length wise.
Pinned the fabric length wise.
Comparing pinned fabric with shock-cord to make sure the shock-cord will fit inside it.
Comparing pinned fabric with shock-cord to make sure the shock-cord will fit inside it.
Sewing the sleeve with my sewing machine, using the pins as a guide and removing them as I approach them.
Sewing the sleeve with my sewing machine, using the pins as a guide and removing them as I approach them.
Finished sewing sleeve.
Finished sewing sleeve.
Trimmed the sewn sleeve - make it look neat.
Trimmed the sewn sleeve – make it look neat.
Shock-cord in sleeve.
Shock-cord in sleeve.
Shock-Cord bowline knot around the Quicklink.
Shock-Cord bowline knot around the Quicklink.
Sleeve fits snugly around the whole bowline knot. Later on, I use zip-ties to hold it in place and reduce chance of hot gases going up length of sleeve.
Sleeve fits snugly around the whole bowline knot. Later on, I use zip-ties to hold it in place and reduce chance of hot gases going up length of sleeve.

How does it fair?

The result of two ejection tests. This sleeve needs to be replaced.
The result of two ejection tests. This sleeve needs to be replaced.

 

Cut open of sleeve shows interior is fairly untouched. The Shock-Cord looks like it is relatively good health
Cut open of sleeve shows interior is fairly untouched. The Shock-Cord looks like it is relatively good health