EXPERIMENTS WITH THE LANGLEY AERODROME. 117 



of ^Ir. jMaiily. These engines were to he of nearly douhlc the power 

 first estimated and' of little more weight, hut this increased power and 

 the strain caused hv it demanded a renewal of the frame as First huilt. 

 in a stronger and consecpiently in a heavier form, and the following 

 sixteen months were spent in such a reconstruction simultaneously 

 with the work on the engines. 



The flying weight of the machine complete, with that of the 

 aeronaut, was 8;W pounds: its sustaining surface, 1,040 square feet. 

 It therefore was ])i-ovided with slightly greater sustaining surface 

 and materially gi-eatci- relative horsepower than the model subse- 

 quently descriljed which flew successfully. The brake horsepower 

 of the engine was Oii ; the engine itself, without cooling water, or 

 fuel, weighed approximately 1 kilogram to the horsepower. The en- 

 tire power plant, including cooling water, carburetor, l)attery, etc.. 

 weighed materially less than 5 pounds to the horsepower. Engines 

 for both the large machine and the quarter-size model Avere completed 

 before the close of 1901, and they were immediately put in their 

 respective frames and tests of them and their power-transmission 

 appliances were begun. 



It is well here to call attention to the fact that although an engine 

 may develop sufficient i)ower for the allotted weight, yet it is not at 

 all certain that it will be suitable for use on a machine Avhich is 

 necessarily as light as one for traversing the air. for it would l)e 

 impossible to use, for instance, a single cylinder gasoline engine in a 

 flying machine unless it had connected to it j^rohibitively heavy fly- 

 wheels. These facts being recognized, the engines built in the Smith- 

 sonian shops were provided w^ith five cylinders, and it was found 

 upon test that the turning efl'ect received from them was most uniform, 

 and that, by suital)le l)alancing of rotating and reciprocating parts, 

 tliey could be made to Avork so that there was j^ractically no vibration, 

 even when used in the very light frames of the aerodromes. 



The engine is not all the ai)paratus connected with the development 

 and delivery of poAver, for obviously there must be shafts, l)earings, 

 and in the present case there were also gears; and all of these parts 

 nnist necessarily be phenomenally light, while all of the materials 

 must be capable of withstanding repeated and constant sti-ains far 

 bej'ond their elastic limit. It is also evident to anyone having famil- 

 iarity with such constructions that it is most difficult to keep the 

 various bearings, shafts, gears, etc., in ])i-o])cr alignment without 

 adding excessiA'e Aveight, and also that Avhen these various parts once 

 get out of alignment when sul)ject to strain, tlie disasters Avhich are 

 caused render them unfit for further use. 



The engines themseh^es Avere successfully compIet(Ml before the close 

 of 1901, and were of much more poAver than those oi-iginally designeri: 

 but nearly a year and a half had been spent not only in their comple- 



