Making tube sleeves

Goat glider design requires local increase of tube wall thickness in highly loaded areas, for example wing strut attachment points. This is achieved by inserting a shorter tube, the so called ‘sleeve’, into the main tube. To be able to carry loads from the main tube the outer surface of the sleeve should have a tight fit with the inner surface of the main tube. However the standard imperial 6061T6 tubes do not provide such option. For this reason it is necessary to increase the O.D. of the sleeve to get the right fit. For EC Goat we make the sleeves following way:

1.Cutting the necessary length of the sleeve from a tube with the closest size

2.Main tube I.D. minus sleeve O.D. divided by 2 gives us the required increase of sleeve wall thickness

3.Cutting a piece of glass fiber cloth and preparing an epoxy resin


4.Applying the resin on the fiber cloth and wrapping it around the sleeve tube. Number of wraps depends on required increase of wall thickness. Generally it is the required increase divided by fiber cloth thickness.


5.Sliding the ‘wet’ sleeve into the main tube.

IMG_20160513_203857836 IMG_20160513_203930780

Sometimes the sleeve has to be located deeper into the main tube. In such cases the sleeve is cured first and only then inserted into the main tube in a ‘dry’ condition. A little sanding may be required to get the correct fit.