Reducing the cost of placing payloads in orbit depends greatly on reducing the weight & improving the performance of the launch vehicles including the Space Shuttle launch vehicle so that greater payloads may be carried. Improvement of the launch vehicle rocket motors is key to achieving the goal of greater payloads in orbit @ reduced cost. The rocket motor design can be made more efficient by increasing the engine mixture ratio. Ideally, the design should strive to approach the stoichiometric mixture ratio of eight. A necessary concommitant development would be to improve the means of attitude control by using rocket exhaust diversion vanes in lieu of swivelling the entire rocket motor. This paper presents an advanced performance rocket motor concept for the launch vehicles including the Space Shuttle vehicle, & a rocket exhaust diversion system for achieving attitude control. NOMENCLATURE A = Area, square inches or feet CT = Thrust coefficient, n.d. HP = Horsepower, 550 foot-pounds per second h = Altitude, feet P = Pressure, pounds per square inch T = Temperature, Degrees Farenheit, or Rankine T = Thrust, pounds t = time, seconds Q = Flow, Cubic feet per second V = Velocity, Feet per second *copyright D.L Jensen, AIAA publisher by permission. # Member AIAA DISCUSSION The present state of the art in liquid (hydrogen / oxygen ) propulsion is @ a mixture ratio of six to one. The Space Shuttle vehicle rocket engines, for instance, expel thousands of pounds of uncombined hydrogen because they operate @ a mixture ratio of six to one. The resulting loss of energy is 15,000+ calories of heat energy lost per pound of unused hydrogen. Another way to look at it is that the same amount of energy is released by combining only 173 thousand pounds of hydrogen with oxygen @ a mixture ratio of 8 to 1; as is obtained using 230 thousand pounds of hydrogen @ a mixture ratio of 6 to 1 as the Space Shuttle now does! The lesser fuel weight, 57 thousand pounds, could be replaced by about 25 thousand pounds of payload. It would seem most appropriate therefore to perform research & development towards achieving more efficient rocket engines which operate at mixture ratios approaching 8, so that all or most of the energy available is obtained from the combustion of oxygen & hydrogen. The work necessary to accomplish this requires development of materials & techniques associated with the temperatures & operating pressures which are the likely consequence of combining oxygen & hydrogen @ mixture ratios approaching 8. The present Shuttle-Orbiter main engines provide for "staged" burning. There are pre-burner turbo-pump combinations before final combining in the combustion chamber. The steam generated in the pre-burners is also used in a so called "boot strap" operation to power the turbines which pump the propellants. A more (c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. advanced engine could extend this concept by incorporating multiple pre-burner turbopump combinations which could successively combine more hydrogen until the final burning in the combustion chamber results in the combining of hydrogen & oxygen at the ultimate ratio of 8 to 1. A conceptual drawing of such a three combustion stage rocket motor is shown in Figure 1. Figure 1. Advanced Rocket Motor Design These engines can be less expensive & simpler to build because they will have fixed nozzles rather than swivelled engines as are now commonly used. The heat shield design will also be simplified because it will not have to accomodate engine movement. The design shown has a mass flow rate of 900 pounds per second; 100 pounds of liquid hydrogen, & 800 pounds of liquid oxygen. The nominal chamber pressure is about 3000 pounds per square inch @ a temperature of about 5700 degrees Rankine.For an expansion ratio around Staged CombustioaRocket Motor I .ox ii SsiiL ( -—rr >-m_*f v»^pLv<-