Why is the exhaust nozzle of the March 16, 1926 rocket above the fuel tank? Early in Dr. Goddard's rocketry research, when he was working on solid fueled designs, he had the nozzle positioned at the bottom of the rocket, like today's rockets are. However, when he started working with liquid fueled rockets before the March 1926 flight, he put the nozzle above the fuel tanks, as you can see in the diagram. His reasoning was given in Section 2 of an August 1929 report to the Clark University trustees (the university helped support his early research): "Stability of flight is, incidentally, ensured from the facts that the nozzle is above the center of gravity of the rocket, as a whole, and that there is a comparatively large air resistance at the lower part of the rocket, as seen in Fig. 91 this is a photo of a rocket that is very similar to the one launched in March of 1926 ..." When the launches of March 16th and April 3rd did not exhibit stable flight paths, Dr. Goddard reverted to having the nozzle on the bottom of the rocket. The reason for this was to reduce the weight of the rocket so that less force would be needed to lift it. In the same report cited in the previous paragraph, Dr. Goddard wrote "Two final attempts at launching a rocket of this scale; he then went to one that was twenty times larger were made to secure greater lightness and greater lifting force. The change consisted in placing the combustion chamber and nozzle at the bottom of the rocket, as shown in Figs. 137 and 138 these are photos of Goddard standing next to a rocket with its nozzle at the bottom ... This plan was used in order to avoid the weight of the long asbestos-covered supply pipes for the liquid, and the two asbestos-covered braces the braces were added for the April 3rd flight , and also to avoid the downward force of the gases ejected from the nozzle on the asbestos-covered aluminum cone which protected the liquid oxygen tank from the flame. The weight was thus reduced to 5 1/4 lbs. from the 6 lbs. of the March 16th rocket ..."
Space/Science » in reply to re: Eighty years ago today...
the nozzle is above the fuel tanks