Complex sentence: A number of changes were made to the prototype during testing, primarily the addition of supporting steel beams to improve and strengthen the suspension of the tank, which increased the weight to, which was the maximum weight that could be carried by a Hamilcar glider.
Split into simpler sentences: A number of changes were made to the prototype during testing. The main change was the addition of supporting steel beams to improve and strengthen the suspension of the tank, which increased the weight to, the maximum weight that could be carried by a Hamilcar glider.