L46 SMITHSONIAN CONTBIBTJTIONS TO KNOWLEDGE VOL. '27 



" underneath " launching apparatus, and everything was got ready for a flight. 

 On lighting (he burners, they failed to work properly, and, upon investigation, 

 il was found that the air valve controlling the air pressure on the gasoline 

 lank, was oul of order. While this was being repaired, the wind rapidly in- 

 creased in velocity and became very gusty, thus endangering the aerodrome, as 

 the wings were very liable to be broken by the wind suddenly veering more rap- 

 idly thati the house-boat could turn or the turn-table could be moved, and thus 

 striking the wings from the side and putting an enormous upward pressure on 

 them, owing to the fact that the diedral angle between them gave to each wing 

 an elevation of 7^ degrees from the horizontal. The aerodrome was accord- 

 ingly dismounted and everything kept in readiness for a trial, with the hope 

 that the wind would die down, or at least become steady, but it did not do so 

 until after dark. 



JULY 28 AEEODEOME No. () 



Aerodrome No. (>, equipped with " single-tier " wings and Penaud tail, was 

 launched from the " underneath " launching apparatus. There was a dead 

 calm, the river not showing a ripple; the wind vane pointed to the northeast, 

 lull as the tide was low and the boat was aground, the launching track was point- 

 ing due south. At 7 a.m. the burners were lighted, and SO seconds were con- 

 sumed in raising a steam pressure of 120 pounds. Everything worked perfectly; 

 the uprights on the car, which initially support the aerodrome and upon its be- 

 ing released are instantaneously pulled down by rubber springs, as well as the 

 disappearing part of the track, acted without the slightest hitch. Immediately 

 upon leaving the launching apparatus, the aerodrome depressed its bow to an 

 angle of between ."> and 4 degrees and made a direct line for the water. At 

 this angle it struck just on the opposite side of the channel, about 300 feet from 

 the house boat, and while several minor parts, such as guy-posts, were injured 

 no damage of importance was done. Owing to (he difficulty of getting through 

 the marsh and recovering Aerodrome No. 0, it was found impossible to make 

 another trial with No. 5 before the wind had increased to a prohibitive veloc- 

 ity. The path of this flight is shown by the dotted line in Plate .'!(i. The data 

 on setting of wings, tail, etc., are given on Data Sheet No. 9. 



The last previous trial of Aerodrome No. fi was made on .lime 2.'!, ami the 

 balancing at that time was evidently correct for the settings of the tail which 

 were then used. The Penaud tail then had an elevation of 7! degrees, and the 

 coefficient of elasticity was such that 1 L'40 grammes were required at the center 

 of the tail to deflect it to the horizontal. In the trial above recorded, on July 

 28, the adjustments of the wings were practically what they were on dune 23, 

 the CG being moved forward 1 centimetre, but the Penaud tail had an elevation 

 of something less than 5 degrees, and the coefficient of elasticity was such that 



