Figure 3. Mean ± SD speed specific drag, as calculated based on the different methods. kp: passive drag coefficient; ka_{PL =} active drag coefficient, as determined by means of the “planimetric method”; ka_{ST =} active drag coefficient, as determined by means of the “residual thrust method”; ka_STfit = active drag coefficient, as determined by means of the “residual thrust method” (model fitting). Individual values are reported in Table 2.