For the calculation of the climbing speeds of aeroplanes several methods are in use, which, as is well known, do not yield quite accurate results when applied to machines with great climbing capacities, and give rise to inaccuracies which become of greater importance with increasing climbing capacity of the plane. The climbing speed, up to the present, has not been great in respect to the forward speed used when climbing, so that for the calculation of the climbing speeds the method fairly generally used and described in the “Handbook of Instructions for Airplane Designers, ”from the U.S. Army Air Service, could be used without serious objections. It has, however, been found desirable to look for a better method for calculating the climbing speeds, owing to increasing engine powers accompanied by decreasing drag coefficients of the aeroplanes, as well as to the introduction of variable pitch airscrews.