Structural dynamic analysis of the X34 orbital vehicle engine

Preliminary dynamic analysis of the major subassemblies of the X34 upper stage orbital vehicle engine are incomplete. However, the analyses to date have provided the designers with important information. Modal analysis of the lox pump induccr blade shows that resonance can be avoided if the number of lox pump exit vanes is 12 or less. Analysis of the gas generator (gg) showed that the initial design of having the gg cantilevered off the turbopump turbine inlet produced high dynamic stresses due to random vibrations. A design change resulted in applying a support bracket from the free end of the gg to the chamber/nozzle assembly or the main injector. Additional analysis will be required to determine which component the bracket will be attached. Dynamic analysis such as these will continue to aid in the design of the X34 upper stage orbital vehicle engine. Introduction The X34 hypersonic suborbital reusable booster (HSRB) is a small (1000 LB class) launch system designed to achieve a $5M recurring cost per launch. The system is made up of four elements: The NASA 747 Shuttle Carrier Aircraft (SCA), the reusable booster vehicle that will be launched from the SCA, a expendable upper stage, and the ground and airborne support equipment. 1 *Aerospace Technologist, Structural Dynamics **Aerospace Technologist, Structural Dynamics; Member AIAA Copyright G 1996 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes. All other rights are reserved by the copyright owner. The HSRB will be flown to an altitude of 30,000 ft. and released from the Boeing 747 Shuttle Carrier Aircraft. The SCA performed a similar function during the Space Shuttle Orbiter Enterprise's reentry flight trials. The normal mission of the SCA is to ferry the orbiter between the Edwards California landing site and the Cape Kennedy Florida processing and launch facility. The Modified 747 will dive away from the HSRB which will fire its mainstage engines after the SCA has cleared the area. The booster then proceeds to one of several predefined orbits that varies by mission and payload requirements. Once the vehicle has reached its orbit, a clam-shell type hatch will open and the upper stage will be released. The HSRB will return to earth and land like an airplane on a runway. The upper stage consists of the payload, upper stage engine, and attachment hardware. The upper stage engine, which is the only non-reusable element, delivers the payload to its final orbit Orbital Sciences Corporation and Rockwell International formed a corporation called American Space Lines (ASL) to operate the launch vehicle. NASA is a partner in the X34 program and is tasked with the development of the upper stage engine called the orbital vehicle 1 (OV1). TheOVl is a Lox/Kerosene engine that will produce 24000 Ib. of thrust and at least 320 seconds of Isp. The gas-generator cycle engine consists of a single in-line turbopump, gas generator, main injector, combustion chamber nozzle combination, valves, lines, pneumatic and ignition systems. The design team divided the engine into four main areas: turbopump, combustion devices, lines and valves, and systems. The structural dynamic analysis team followed the same convention. This paper focuses on the dynamic analysis required to support the design of the O V1. The following sections discuss the approach taken