>This does not seem to be dimensionally correct. > >In english units D is in lbs., V is in ft/sec, W/L is in lb/ft^2, and rho >(density) is in slugs/ft^3 (gotta love those english density units!). >Converting from density to weight (density * g ) gives the left side in lbs and the >right side in lbs/ft^2. > >I believe the missing term is the average chord (Cavg^2).
I have to admit that I am not well versed in English units (and probably will never be), but here is the dimensionality check in SI units for you: D(N) = [ W(N)/L(m) ]^2 / [Pi*q(kg/m*s^2)], (note, that W = m*g (N = kg*m/s^2)), therefore for the units: N = [N^2/m^2]/[kg/m*s^2] = N^2*s^2/kg*m = N^2/N = N So nothing is missing, there is no average chord there. Actually I just tried the same check in English units and it all works out the same: lb = [lb^2/ft^2]/[slug/ft*s^2] = lb^2*s^2/slug*ft = lb^2/lb = lb You did not need to convert mass density into weight density. I stand by my previous statement: that total induced drag does not depend on the AR for a fixed span (which is aero 101 really). And I just learned something about English units! Best regards, Oleg. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
