NO. 3 LANGtiBY MEMOIE ON MECHANICAL FLIGHT 231 



ing the large aerodrome from the top of the house-boat. He apparently re 

 alized as well as anyone, that in many respects the making of the tesl from 

 the top of the house-boat had many serious drawbacks, but he emphasized and 

 impressed on the writer the importance of following as far as possible in the 

 construction and test of the large machine, the plans which had brought suc- 

 cess with the models. Believing, however, that there was probably a better 

 method of launching the aerodrome than from the top of the houseboat, and 

 that it would be well to prepare before hand as far as possible for following 

 some other plan of launching immediately after a first successful test had been 

 obtained from the top of the boat, Mr. Langley had constructed some flouts 

 which were arranged to be attached to the launching car of the quarter-size 

 model so that the car could be converted into a catamaran raft. It was not be- 

 lieved that this crude arrangement would suffice for a complete launching appa- 

 ratus, since the power of the aerodrome propellers would not be great enough 

 to force the raft through the water at a sufficiently high speed; still it was 

 thought that by having the launching car arranged in this way the model might 

 be allowed to drive the raft rapidly through the water and thus give some idea 

 as to what would be necessary, in a more complete launching apparatus, to ob- 

 viate the danger of the drag of the raft causing the model to plunge over head- 

 long into the water. The launching car with these floats attached to it, and 

 with the quarter-size model mounted on the car, is clearly shown in Plates 73 

 and 74. 



While the results obtained with superposed wings in the tests of models 

 Nos. 5 and 6 in the summer of 1899 indicated that the " single-tier " surfaces 

 were much more efficient, still, as has been already stated, the great advantages 

 of the superposed surfaces, so far as strength of construction is concerned, was 

 fully realized at all times. As a result of these tests it was decided to use 

 the " single-tier " surfaces in the first test of the large machine in order to in- 

 sure as far as possible the best conditions. However, it was from the begin- 

 ning planned to construct superposed surfaces for use in the later tests of 

 the large machine; and, in order to obtain more reliable data on such surfaces 

 than had been obtained in the tests of the models in the summer of 1899, a 

 set of superposed surfaces for the quarter-size model were constructed during 

 the winter of 1900-1901. The quarter-size model, equipped with these surfaces, 

 is shown in Plates 75 and 70, where the model is seen mounted on its launch- 

 ing car, which is attached to the floats heretofore referred to. It was originally 

 planned not to employ guy-posts when using the superposed surfaces, but after 

 the latter had been constructed and attached to the frame, it was found that 

 they would have to be made with rigid joints instead of hinged joints if the 

 guy-posts were omitted. As the hinged joints, however, were already made. 

 and permitted the surfaces to be folded up so as to occupy a much smaller 



