Necessary conditions for sustained reentry roll resonance

Using the method of near-identity transformations, we study a model of reentry roll resonance, a situation encountered when an almost axially symmetric vehicle reenters the earth’s atmosphere. This method allows us to extend previous results for the case of sustained resonance, when roll buildup occurs. In particular, we give necessary conditions (in terms of the slowly varying pitch or yaw frequency) both for entrainment to sustained resonance and for sustained resonance to continue and discuss their implications. In addition, we make a conjecture concerning sufficient conditions for sustained resonance.