Tests were made in the NACA 8-foot high speed wind tunnel of a metal-covered, riveted, 'service' wing of average workmanship to determine the aerodynamic effects of the manufacturing irregularities incident to shop fabrication. The wing was of 5-foot chord and of NACA 23012 section and was tested in the low-lift range at speeds from 90 to 450 miles per hour corresponding to Reynolds numbers from 4,000,000 to 18,000,000. At a cruising condition the drag of the service wing was 46% higher than the drag of a smooth airfoil, whereas the drag of an accurately constructed airfoil having the same arrangement of 3/32-inch brazier-head rivets and lap joints showed a 29% increase. The difference, or 17% of the smooth-wing drag, is apparently the drag caused by the manufacturing irregularities: sheet waviness, departures from true profile, and imperfect laps. the service wing, for one condition at least, showed a drag increase due to compressibility at a lower air speed than did the more accurate airfoil.
The Effect of Surface Irregularities on Wing Drag. IV - Manufacturing Irregularities
1938-02-01
Miscellaneous
No indication
English
Effects of some common surface irregularities on wing drag
Engineering Index Backfile | 1939
|The effects of some common surface irregularities on wing drag
TIBKAT | 1939
|Drag of exposed fittings and surface irregularities
TIBKAT | 1928
|Drag of exposed fittings and surface irregularities on airplane fuselages
Engineering Index Backfile | 1928
|