Why does the Va on light aircraft increase with an increase in weight?
Va has to do with momentum.
I'm not sure it has anything to do with momentum.
Va is the manoevering speed. Below this speed, any full, abrupt movement of a single control will not result in damage to the aircraft. This is because, below this speed, a full abrupt movement of a control will instead result in an accelerated stall before the structural load limit is reached.
Stall speed increases with weight - at heavier weights, the aircraft stalls at a higher speed. So, at heavier weights, the aircraft will also enter an accelerated stall at higher speeds than it would do at lower weights, hence Va is higher.
FFF
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