Rising and drooping R-curves

Data from the literature are re-analysed to show that a drooping R-curve is consistent with an analysis based on internal energy. A rising R-curve exists for small amounts of growth, or if the whole curve is based on external work rate rather than internal energy rate. The criteria for rising or drooping can be related to the value of omega through omega > f( eta ) for a rising curve, rather than just the J-controlled condition of omega large. The particular definition of an R-curve, the three-parameter technique (TPT) proposed by Garwood et al. , is related to the steady state condition of Rice, Drugan and Sham, with good agreement for the data considered. 12 ref.--AA