1965 (2nd) New Dimensions in Space The Space Congress® Proceedings Technology Apr 5th, 8:00 AM Development of the Titan Stage III James G. Davis Martin Company Follow this and additional works at: https://commons.erau.edu/space-congress-proceedings Scholarly Commons Citation Davis, James G., "Development of the Titan Stage III" (1965). The Space Congress® Proceedings. 4. https://commons.erau.edu/space-congress-proceedings/proceedings-1965-2nd/session-7/4 This Event is brought to you for free and open access by the Conferences at Scholarly Commons. It has been accepted for inclusion in The Space Congress® Proceedings by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. DEVELOPMENT OF THE TITAN STAGE III James G. Davis Martin Company Canaveral Division Cocoa Beach, Florida Summary This paper presents the design and the field test program associ­ ated with the development of the propulsion module for the third stage of the Titan III Standard Space Launch Vehicle. The primary objective of this vehicle development is to provide a launch vehicle with the capability of performing a wide variety of space missions. The vehicle configuration(s) evolved to satisfy this objective consists of a modi­ fied Titan II equipped with a third stage designated as Configuration ftA M or Core, and the addition of two segmented solid propellant rocket motors, one on either side of the Core designated as Configuration ft C ff . The third stage of this vehicle is called the transtage. This stage is composed of two modules: the control module, which contains the guidance, flight controls, and attitude control subsystems} and the propulsion module which is identified as stage III. Stage III consists of a pressure-fed, re-startable, space propul­ sion system which utilizes storable hyper golic pr ope Hants. Pro pe Hants are contained in two titanium tanks which are secured to the vehicle airframe in a parallel arrangement. The engine assembly consists of dual thrust units which are individually gimbaled to provide vehicle attitude control during stage operation. Each thrust unit consists of an ablative cooled combustion chamber with a radiation cooled nozzle exit section. The pressurant is stored gaseous helium and propellant tank pressure is maintained by use of pressure switch controlled solenoid valves. The stage is designed to have a useful life in space of at least 6.5 hours. A review of the stage III design requirements, the mechanization used to fulfill these requirements, and the development test program used to verify the mechanization is presented. Stage III subsystem and design confirmation testing includes mockup and full scale (battleship) tests of the pressurization subsystem, model and full scale (battleship) test of the propellant subsystem, and captive tests using battleship tankage of the complete propulsion system. Stage design confirmation tests include a series of altitude simulation firings at the Arnold Engineering Development Center Rocket Test Facility and System Compati­ bility Firings at the Martin Denver Static Test Facility. The flight test program at the Eastern Test Range consists of several flAff configu­ ration launches from a reworked Titan I launch pad followed by lfC ff configuration launches from the Titan III Integrated Transfer and Launch (ITL) facility. In addition, the prelaunch and countdown preparations and utilization of checkout and flight test results in system design improvements are presented. 343 The Titan III Standard Space Launch Vehicle The Titan III or Program 62A-A is the U. S. Air Force's booster system for varied space projects. The intent of the program is to provide the Air Force and the country with a standardized (multiple payload capability with no modifications to the booster), economical, and reliable launch vehicle with mission flexibility. Payload capabi­ lity ranges from 5,000 to 25,000 pounds and mission capabilities in­ clude : 1. Low altitude elliptical orbits by direct injection 2. Low altitude circular orbits 3. Low altitude circular orbits with Hohmann transfer to another orbit 4. Synchronous orbit 5. Deep space trajectory to escape 6. Orbits with plane changes. Payload configurations may include: 1. Lifting body vehicles 2. Bulbous loads 3. Various payloads which can be enclosed in a ten foot diameter standard payload fairing. In order to provide this greater mission flexibility, the launch vehicle has been designed such that it can be flown in one of two configurations. These two configurations are Configuration "A" and Configuration'^ 11 . Figure 1 illustrates Configuration "C". Configuration "A" Configuration "A" or Core vehicle consists of a modified Titan II 1CEM, a new liquid propellant stage referred to as transtage, and a standard payload fairing. Modifications to stage I consist of structu­ ral strengthening, mounting provisions for two solid propellant rocket motors, and an engine altitude start capability. The stage II modifi­ cations include the shortening of the space between propellant tanks by increasing tank size and the addition of autogenous pre ssurization to the oxidizer tank. The transtage is composed of two modules: a propulsion module (Stage III),and a guidance and control module. The guidance and control module, located atop the propulsion module, contains the major elements of the flight control, electrical, instrumentation and guidance sub­ systems. This module also contains an attitude control propulsion system which is used for propellant settling prior to stage III engine starts and attitude control during transtage coast. The propulsion module contains two titanium propellant tai ks, two 8,000 pound-thrust, re-startable engines, and a helium gas pressurization system. The transtage is illustrated in Figure 2. 344 Configuration "C" Configuration TT C !! consists of Configuration "A" plus two identical ten foot diameter, 1,000,000 pound-thrust solid propellant rocket motors (stage 0) attached in parallel to stage I of the core vehicle. Transtage The key to the Titan III mission flexibility is the transtage. By coasting and restarting techniques, the following maneuvers may be per­ formed: 1. Orbital altitude change 2. Orbital plane change 3. Circularization of orbit 4. Precision escape trajectory. The propulsion systems which provide these capabilities consist of an attitude control system and the main stage III propulsion system. Both systems utilize nitrogen titroxide oxidizer, and a blend of unsym- metrical demethylhydrazine and hydrazine fuel. Attitude Control System The attitude control system provides impulse for bottoming the propellants in the main transtage tanks, and provides pitch, yaw, and roll control impulse for the transtage and payload. The system is a pressure-fed, storable, hypergolic, liquid-propeHants, pulse width modulated rocket engine control system. The system is subdivided into packages, namely, the pneumatic, ordnance, regulator, safety, and engine modules plus propellant tanks, lines, and burst disc assemblies. Reference Figure 3. Gaseous nitrogen is stored at a pressure of 3100 +_ 100 psig in a spherical pressurant tank. The tank is made of titanium and has a nominal capacity of 3.55 pounds of GN2» Included in the pneumatic module is a manual fill valve. The ordnance package which isolates the high pressure nitrogen from the entire system until the launch countdown consists of a squib fired two-way isolation valve plus a squib fired three-way valve. The three-way valve is part of the redundant regulator system and is only fired upon overpressurization in the primary regulator system. Components included in the regulator package are the primary regu­ lator, secondary regulator, two ground test ports, and two filters. Pressurant upon release by the isolation valve flows through a two micron nominal and ten micron absolute filter into the regulator. The regulator is an all stainless steel regulator with a capacity up to 12 scfm while maintaining a regulated pressure of 290 ^ 10 psig at inlet pressures varying from 3100 to 500 psig. Ground test valves are in­ stalled in the module for ground checkout of the regulators before the isolation (start) valve is actuated. If overpressurization occurs, the over pressure switch trips when 345 ^ 10 psia is reached, which in turn actuates the three-way valve, bringing the standby regulator into opera­ tion, and isolates the primary regulator from the system. 345 A filter, two check valves, two relief valves, and two ground checkout valves are incorporated into the safety module. The function of the check valves is to prevent any propellant or propellant vapors from leaking back into the pneumatic module. The relief valves are sized to relieve maximum flow (12 scfm) of the regulator and will re­ lieve at 370 psig and reseat at 355 psig. Checkout valves are used for checkout and during cleaning and filling procedures. Propellant tanks, one oxidizer and one fuel, are made from 6066 aluminum and have capacities of 73.64 pounds of oxidizer and 47.26 pounds of fuel at 130° F. The volume of the tanks are 1515 in.3 in­ cluding 10.23 in.^ and 20.86 in.3 ullage for fuel and oxidizer respec­ tively. The tanks are designed for a 98% expulsion efficiency. Teflon bladders are used to give positive expulsion under zero "g" conditions. The oxidizer tank has two 0.007 inch baldders and the fuel tank has tbree .004 inch baldders. The bladder life is 20 cycles minimum. The attitude control system utilizes four engine modules. Two of the modules (pitch) contain a 45 pound thrust chamber. The other two modules (roll - yaw) each contain two 25 pound thrust chambers and one 45 pound thrust chamber. The chambers are made of 90° oriented astro- lite ablative material with an external glass wrap and a non-ablating silicon carbide throat insert. The rocket engine modules incorporate burst diaphragms upstream of the propellant valves. The diaphragms rupture when the isolation valve is actuated. The rocket engine assem­ blies utilize a splash plate injector and the nozzles have a 60 to 1 expansion ratio.