Initiating combustion of altitude control rocket engines in a precombustion chamber of ductile material reduces high pressure surges generated by hypergolic propellants. Two-step bipropellant valve concepts control initial propellant flow into precombustion chamber and subsequent full flow into main chamber

Capps, J. E.

Ferguson, R. E.

Pohl, H. O.

English

NASA Technical Reports Server

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August 1969	 Brief 69-10280 
.
NASA TECH BRIEF 
--
 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Informatiow, Springfield, Virginia 22151. 
Two-Step Rocket Engine Bipropellant Valve Concept 
The problem: 
Attitude control rocket engines which utilize hyper-
golicpropellants tend to generate high pressure surges 
or spikes in the combustion chamber at the instant 
combustion is initiated. These surges are detrimental 
to chamber structural integrity where non-ductile 
refractory materials are used. 
The solution: 
It has been found that the high pressure spikes in the 
primary chamber can be reduced by initiating combus-
tion in a precombustion chamber that is isolated from 
the primary combustion chamber and is constructed 
of a ductile material. Various two-step bipropellant 
valve concepts exist which could control the initial 
propellant flow into the precombustion chamber and 
the subsequent full propellant flow into the main
chamber for full thrust. The example below describes 
a toraue motor valve conceDt. 
How it's done: 
Fuel and oxidizer enter their manifold chambers at 
a predetermined pressure; for initial combustion con-
ditions, a low propellant mode is maintained by dis-
placing the flapper buttons from the orifice leading to 
the precombustion chamber. This action is achieved by 
energizing the field coils which produces an electro-
magnetic flux across the air gap. A bending moment 
is thus created on the torque arms causing rotation of 
the flapper stems which in turn, controls the flapper 
buttons. The amount of current through the field 
coils determines the angular position of the flapper 
stein. At a predetermined high current level, the check 
continued overleaf) 
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valves are opened by the stems and maximum com-
bustion conditions are achieved by the propellant flow 
being conducted to the manifold rings in addition to 
the continued flow to the precombustion chamber. The 
two distinct thrust levels allow the momentary estab-
lishment of stable combustion conditions within the 
main combustion chamber prior to the introduction of 
maximum propellant flow, and in this way eliminates 
the primary chamber pressure spike condition. This 
technique also may be used where two discrete thrust 
levels are desired and the high thrust level is approxi-
mately one order of magnitude greater than the low 
thrust level. 
Notes: 
I. A solenoid-controlled valve system applicable to 
rocket and internal combustion engines has been 
designed to prevent high pressure surges on start-
up. This control system is in the conceptual stage 
only; no model or prototype has been built. It may 
be of interest to the aircraft, hydraulics, and pneu-
matics industries.
2. No further documentation is available. Inquiries 
may be directed to: 
Technology Utilization Officer 
Manned Spacecraft Center 
Houston, Texas 77058 
Reference: B69-10280 
Patent stattus: 
This invention is owned by NASA, and a patent 
application has been filed. Royalty-free, non-exclusive
licenses for its commercial use will be granted by
NASA. Inquiries concerning license rights should be
made to NASA, Code GP, Washington, D.C. 20546. 
Source: J. E. Capps, H. 0. Pohl, and R. E. Ferguson 
Manned Spacecraft Center
(MSC-1095 I) 
I 
Brief 69-10280	 Category 05


Two-step rocket engine bipropellant valve concept

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