NO. 3 LTQUID-PROPELLANT ROCKET— GODDARD 5 



The combustion chamber finally decided upon for use in flights 

 was 5I inches in diameter and weighed 5 pounds. The maximum lift 

 obtained was 289 pounds, and the period of combustion usually ex- 

 ceeded 20 seconds. The lifting force was found to be very steady, 

 the variation of lift being within 5 percent. 



The masses of liquids used during the lifting period were the 

 quantities most difficult to determine. Using the largest likely value 

 of the total mass of liquids ejected and the integral of the lift-time 

 curve obtained mechanically, the velocity of the ejected gases was 

 estimated to be over 5,000 feet per second. This gave for the mechani- 

 cal horsepower of the jet 1,030 hp., and the horsepower per pound 

 of the combustion chamber, considered as a rocket motor, 206 hp. 

 It was found possible to use the chambers repeatedly. 



The results of this part of the development were very important, 

 for a rocket to reach great heights can obviously not be made unless 

 a combustion chamber, or rocket motor, can be constructed that is 

 both extremely light and can be used without danger of burning 

 through or exploding. 



FLIGHTS DURING THE PERIOD 1930-32 



The first flight obtained during this period was on December 30, 

 1930, with a rocket 11 feet long, weighing 33.5 pounds. The height 

 obtained was 2,000 feet, and the maximum speed was about 500 

 miles per hour. A gas pressure tank was used on the rocket to force 

 the liquid oxygen and the gasoline into the combustion chamber. 



In further flights pressure was obtained by gas pressure on the 

 rocket, and also by pumping liquid nitrogen through a vaporizer, the 

 latter means first being employed in a flight on April 19, 1932. 



In order to avoid accident, a remote control system was constructed 

 in September 1931, whereby the operator and observers could be 

 stationed 1,000 feet from the tower, and the rocket fired and released 

 at will from this point. This arrangement has proved very satisfac- 

 tory. Plate 5, figure 2 shows the cable being unwound between the 

 tower and the 1,000-foot shelter, the latter being seen in the distance, 

 and plate 6, figure i shows the control keys being operated at the 

 shelter, which is provided with sand bags on the roof as protection 

 against possible accident. Plate 5, figure 2 shows also the level and 

 open nature of the country. 



One observer was stationed 3,000 feet from the tower, in the rear 

 of the 1,000-foot shelter, with a recording telescope (pi. 6, fig. 2) . Two 

 pencils attached to this telescope gave a record of the altitude and 

 azimuth, respectively, of the rocket, the records being made on a paper 



