8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 95 



must be loaded with a maximum amount of propellant and conse- 

 quently must Start with as small an acceleration as possible. At these 

 small initial velocities fixed air vanes, especially those of large size, 

 are worse than useless, as they increase the deviations due to the wind. 

 It should be remarked that fixed air vanes should preferably be small, 

 or dispensed with entirely, if automatic stabilization is employed, to 

 minimize air resistance. 



In order to make the construction of the rockets as rapid as pos- 

 sible, combustion chambers were used of the same size as those in 

 the work of 1930-32, together with the simplest means of supplying 

 pressure, namely, the use of a tank of compressed nitrogen gas on 

 the rocket. The rockets were, at the same time, made as nearly 

 streamline as possible without resorting to special means for forming 

 the jacket or casing. 



PENDULUM STABILIZER 



A pendulum stabilizer was used in the first of the new series of 

 flights to test the directing vanes, for the reason that such a stabilizer 

 could be more easily constructed and repaired than a gyroscope stabil- 

 izer, and would require very little adjustment. A pendulum stabilizer 

 could correct the flight for the first few hundred feet, where the 

 acceleration is small, but it would not be satisfactory where the ac- 

 celeration is large, since the axis of the pendulum extends in a direction 

 which is the resultant of the acceleration of the rocket and the 

 acceleration of gravity, and is therefore inclined from the vertical 

 as soon as the rocket ceases to move in a vertical direction. The 

 pendulum stabilizer, as was expected, gave an indication of operating 

 the vanes for the first few hundred feet, but not thereafter. The 

 rocket rose about 1,000 feet, continued in a horizontal direction for 

 a time, and finally landed 11,000 feet from the tower, traveling at 

 a velocity of over 700 miles per hour near the end of the period of 

 propulsion, as observed with the recording telescope. 



GYROSCOPE STABILIZER 



Inasmuch as control by a small gyroscope is the best as well as 

 the lightest means of operating the directing vanes, the action of 

 the gyroscope being independent of the direction and acceleration of 

 the rocket, a gyroscope having the necessary characteristics was 

 developed, after numerous tests. 



The gyroscope, shown in plate 8, figure i , was set to apply control- 

 ling force when the axis of the rocket deviated 10° or more from the 

 vertical. In the first flight of the present series of tests with gyro- 



