NO. 3 LANGLEY MEMOIB ON MECHANICAL FLIGHT HI 



clutch D. While the clutch I) is rigid])- attached to G to prevenl transverse 

 movement, it is hinged to the latter at 3 so thai it can fold in a Longitudinal di- 

 rection. Screwed to the clutch I) is a narrow plate 4, which, when the clutch is 

 closed, is behind the lug 5, thus preventing any turning about the hinge 3. 



But when the arms of G and the jaws of the clamp are thrown out by the 

 depression of F, the plate 4 is moved out from behind the lug 5 and the clamp 

 is free to fold to the front. The strut, hinged at G, is under a constant tension 

 from the spring 7 to fold up, and is prevented from doing so only by the connec- 

 tions 8, by which it is held down until the release of the plate 4 from behind the 

 lug 5, when the spring snaps them instantly up and out of the way. 



As the struts BB have no fixed connection with the aerodrome, they are re- 

 leased by the relaxation in the rigidity of the other connections and are thrown 

 up by their spring 9 and held in that position by the clip 10 catching beneath the 

 upper cross-piece. 



The power for the propulsion of the car is obtained by means of from one 

 to nine helical springs working under tension, and multiplying their own mo- 

 tion four times by means of a movable two-sheave pulley, as shown in the 

 drawing. 



Description of Aerodrome No. 5 



When the details of the aerodrome, whose description is to follow, are con- 

 sidered from the standpoint of the engineer accustomed to make every pro- 

 vision against breakage and accident and to allow an ample factor of safety in 

 every part, they will be found far too weak to stand the stresses that were put 

 upon them. But it must be remembered that in designing this machine, all 

 precedent had to be laid aside and new rules, adapted to the new conditions, ap- 

 plied. It was absolutely necessary, in order to insure success, that the weight 

 should be cut down to the lowest possible point, and when this was reached it 

 was found that the factor of safety had been almost entirely done away with, 

 and that the stresses applied and the strength of material were almost equal. 



The same observation holds true of the boilers, aeolipile, and engines, when 

 regarded from the point of view of the economical generation and use of steam. 

 It was fully recognized that the waste of heat in the coil boilers was excessive, 

 but as it was necessary that there should be an exceedingly rapid generation of 

 steam with a small heating surface, this was regarded as inevitable. 



In the engine the three points aimed at in the design were lightness, strength 

 and power, but lightness above all, and necessarily in a degree which long- 

 seemed incompatible with strength. No attempt was made to secure the re- 

 quirements of modern steam-engine construction, either in the distribution of the 

 steam or the protection of the cylinder against the radiation of heat by a suitable 

 jacketing. The very narrow limits of weight permissible required that the bar- 



