OBSERVATION OF NOVEMBER 20, 1891. | ||||||||
| OBSERVER, S.P.L. | LOCALITY, UPPER HALL, SMITHSONIAN BUILDING. | |||||||
| No. 30. Single wings. |
No. 31. Superposed wings. | |||||||
|---|---|---|---|---|---|---|---|---|
| CPm | 1516.5 | cm. | ||||||
| CG1 | 1515 | 1517 | cm. | |||||
| CFw | 1528 | cm. | ||||||
| Length (without fender) | 120 | cm. = | 3.94 | ft. | 120 | cm. = | 3.94 | ft. |
| Width over wing tips | 120 | cm. = | 3.94 | ft. | 120 | cm. = | 3.94 | ft. |
| Weight of rubber (72 grammes in each tube) | 144 | gr. = | 0.32 | lbs. | 144 | gr. = | 0.32 | lbs. |
| Total flying weight (including tail) | 432 | gr. = | 0.95 | lbs. | 506 | gr. = | 1.11 | lbs. |
| Turns of rubber | 30 | 30 | ||||||
| Diameter of propellers | 37 | cm. = | 1.21 | ft. | 37 | cm. = | 1.21 | ft. |
| Width of propellers | 7 | cm. = | 0.23 | ft. | 7 | cm. = | 0.23 | ft. |
| Pitch of propellers | 50 | cm. = | 1.64 | ft. | 50 | cm. = | 1.64 | ft. |
| Area of wings (each 992 sq.cm.) | 1984 | sq.cm.= | 2.13 | sq.ft. | Each pair 1984 sq.cm.= 2.13 sq.ft. Total 3968 sq.cm.= 4.26 sq.ft. | |||
| Area of tail | 373 | sq.cm.= | 0.40 | sq.ft. | 373 | sq.cm.= | 0.40 | sq.ft. |
Area of wings and tail in No. 30, 2357 sq. cm. = 2.53 sq. ft. 2.53 sq. ft. ÷ .95 = 2.7. Therefore, there are 2.7 or nearly 3 square feet of sustaining area to the pound. | ||||||||
Langley Memoir on Mechanical Flight, Parts I and II / Smithsonian Contributions to Knowledge, Volume 27 Number 3, Publication 1948, 1911
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About This Book
The memoir chronicles systematic experimental work toward powered, heavier-than-air flight, presenting a chronological account of small flying models, aerodynamic tests with a whirling table, development of lightweight steam engines and launch apparatus. It explains why laboratory measurements differ from free-flight conditions, analyzes equilibrium and center-of-pressure issues, and records iterative trial-and-error design of wings, propellers, and supporting structures. Part of the text compiles detailed test data, field trial reports, and engineering challenges encountered during attempts to achieve sustained, controllable mechanical flight, with editorial additions completing later sections of the experimental record.