Hydrodynamic And Aerodynamic Tests Of Models Of Flying Boat Hulls Designed For Low Aerodynamic Drag

N.A.C.A. models 74, 74-A, and 75 were tested in the N.A.C.A. tank to determine their hydrodynamic properties and in the N.A.C.A. 20-foot wind tunnel to determine their aerodynamic properties. The forms of these models were derived from that of a solid of revolution having a lowe air drag, and the departures from the form of this low-drag body were the minimum considered to give satisfactory take-off performance. Model 74 has a rounded bottom with flared chines, a transverse step wit ha small fairing aft of it, and a pointed afterbody. Model 74-A has the same forme except for the removal of the fairing aft of the step. Model 75 has a pointed step and a horizontal afterbody derived from the form of the N.A.C.A. model 35 series.

Includes the Committee's Technical reports no. 1-1058, reprinted in v. 1-37.

Deflections and all internal forces have been calculated for concentrated static loads. Vibration modes are also presented. The effects of neglecting shearing strains in the ribs and spars and also of assuming the ribs to be rigid have been investigated by modifying the electric circuits to correspond to these simplifications.