Application of the Ram Jet to Vertical Ascent

Citation

Rowney, James Victor (1950) Application of the Ram Jet to Vertical Ascent. Engineer's thesis, California Institute of Technology. doi:10.7907/DRA1-DS60. https://resolver.caltech.edu/CaltechETD:etd-02112009-094718

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The purpose of this paper is to investigate the applicability of the ramjet to replace the first step of a two-step or multi-step rocket, with the hope of increasing the efficiency and performance of vertical ascent missiles of the present day. The ramjet is considered as a booster motor to boost the primary missile through the atmosphere. It is to be discarded from the primary missile after reaching its maximum velocity. To boost the ramjet to operating speed the second stage rocket must be operated for the first few seconds as a ducted rocket. General ramjet performance is calculated graphically by using a step-by-step integration process to solve the differential equation of motion. The resulting flight velocity, fuel consumption per initial weight, and altitude are presented graphically in terms of time after launching the ramjet. It is assumed throughout the problem that gravity is constant and that the altitude necessary to start the ramjet is negligible. The acceleration of the missile is limited to 25 g's. Important results present in this paper are: The most important factor that limits the performance of the ramjet is the air density ratio. The greatest increase in second-step launching altitude, by improved thrust and drag coefficients and increased ramjet cross-section area, is achieved at low ramjet launching velocities. The performance of the ramjet missile operating at a specific fuel consumption of .0007 [...] shows a marked increase of efficiency over a missile using a higher fuel consumption value. Missiles using a lower specific fuel consumption value, of the same order as the increased value, show negligible improvement in efficiency. When ramjet performance is compared to rocket performance; specifically, maximum velocity, altitude of maximum speed and altitude attained, the ramjet missile will burn only one third of the fuel required by a two-step rocket. Conversely, for the same fuel consumed, the ramjet missile will attain 65% more altitude than the two-step rocket.

Thesis Files