Flutter

Flutter is a self-excited structural oscillation of the aircraft which derives its energy from the air mass in which it is flying. It must be shown by analysis? and tests where applicable, that the aircraft will be free from destructive flutter at speeds up to 1.2 times the design dive speed.

Divergence

Divergence, unlike flutter is dependent only on the flexibility of the structure rather than on the characteristic of the structural oscillations. The external air loads will cause a redistribution to occur which can reinforce the original loading. When a speed is reached in which the structure can no longer support this loading, divergence deflection will occur and the analysis must prevent this divergence.