Comment on "Prediction of Range and Endurance of Jet Aircraft at Constant Altitude"

Abstract

I his Engineering Note, Professor Bert has made an error in calculating the value of the coefficient a1 in Eq. (13), The value of al should be 6.160xlO~ 8 lb-s/ft instead of 0.6160X 10~ lb-s/ft. Therefore his conclusions concerning an optimum velocity are incorrect. In fact, starting from Eq. (12) and using simple calculus we can obtain an expression for the optimum velocity (Kopt) which maximizes the value of the specific range ( R s ) :