7 No. 30 Straight horizontal flight; time three and three-fifth seconds, when rubber ran down; distance 13 metres. 8 No. 30 Straight flight as before; time two and four-fifth seconds; distance 13 metres. 9 No. 30 With a curved wing in the same position as the flat wing had previously occupied, model flew up and struck the ceiling (nearly 30 feet high), turning to right, with a flight whose curtate length was 10 metres. 10 No. 30 Wing having been carried back 5 centimetres, model still flew up, but not so high, and still turned to the right. 11 No. 30 Wings carried back 5 centimetres more; model still flew high; time two and two-fifths seconds; distance 13 metres. 12 No. 30 Wings carried back 4 centimetres more; model still flew high during a flight of 13 metres. -------+----------+--------------------------------------------------- The observations now ceased, owing to the breaking up of the model. The objects of these experiments, as of every other, were to find the practical conditions of equilibrium and of horizontal flight, and to compare the calculated with the observed positions of the center of pressure. They enable us to make a comparison of the performances given by earlier ones with a light rubber motor, with the relatively heavy motors used to-day, as well as a comparison of single flat, single curved, and superposed flat wings. The average time of the running down of the rubber in flight was something like three seconds, while the average time of its running down when standing still was but one and a half seconds. It might have been expected from theory that it would take longer to run down when stationary, than in flight, and this was one of the many anomalies observed, whose explanation was found later in the inevitable defects of such apparatus. The immediate inferences from the day’s work were: 1. That the calculated position of the ‹CP› at rest, as related to the ‹CG›, is trustworthy only in the case of the plane wing. 2. The formula altogether failed with the curved wing, for which the ‹CP› had to be carried indefinitely further backward. On comparing the previous flights of November 14, with these, it seems that with the old rubber motor of 35 grammes and 50 turns, the single wing, either plane or curved, is altogether inferior to the double wing; while with the increased motor power of this day, the single wing, whether plane or curved, seems to be as good as the double wing. It also seems that the curved wing was rather more efficient than the plane one.