Fuselage-drag Tests in the Variable-density Wind Tunnel

Fuselage-drag Tests in the Variable-density Wind Tunnel
Author: Ira H. A. Abbott
Publisher:
Total Pages: 576
Release: 1937
Genre: Aeronautics
ISBN:
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Results are presented on drag tests of six bodies of revolution with systematically varying shapes and with a fineness ratio of 5. The formes were derived from source-sink distributions, and formulas are presented for the calculation of the pressure distributions of the forms. The tests were made in the N.A.C.A. variable-density tunnel over a range of values of Reynolds number from about 1,500,000 to 25,000,000. The results show that the bodies with the sharper noses and tails have the lowest drag coefficients are based on the two-thirds power of the volume. The data show the most important single characteristic of the body form to be the tail angle, which must be fine to obtain low drag.

Hydrodynamic and Aerodynamic Tests of Models of Flying-boat Hulls Designed for Low Aerodynamic Drag

Hydrodynamic and Aerodynamic Tests of Models of Flying-boat Hulls Designed for Low Aerodynamic Drag
Author: Starr Truscott
Publisher:
Total Pages: 586
Release: 1938
Genre: Drag (Aerodynamics)
ISBN:
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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.