1. In 1959 Nicolaides 4 extended his analysis of asymmetric missiles to include nonlinear rollorientation-dependent terms and thereby introduced the concepts of "spin lock-in" and "catastrophic yaw." Since then, spin lock-in has been studied by a number of authors.5-6The angular trim produced by a nonlinear static momenthas been treated by Kanno.7 The quasilinear analysis technique, which has been most successful in describing the angular motion of symmetric missiles,8-9 has recently been extended to the general angular motion of a slightly asymmetric missile. 10 The detailed nonlinear behavior near resonance has been discussed by Clare. 11 Finally, Nayfeh and Saric 12 have shownthat the resultsof References10-11 can be obtJined by the more sophisticated method of multiple scales.
2. (13) The approximate fonns of Egutions {12-13) are, of course, valid only when maH- is large.
3. l 2 Equations (16-17) shows that the third case is the only possibility and then only if the average of sin 1 is nonzero. A condition for generalized subhamonic response is, therefore,
4. , Equations (16-17) for zero damping nowprovide a condition for 'I' and a relation between the modal amplitudes