Engineering topics

Grimes, D. W.

Publications and source records attributed to Grimes, D. W..

7 records

NASA NTRS1982

The Delta improved second stage - First flight results

On July 16, 1982 the successful launch of the Landsat-D spacecraft marked a significant step in the evolutionary growth of the Delta launch vehicle. This growth is related to the development of the Improved Second Stage (ISS). The second utilization of the ISS occurred August 26, 1982 with the successful launch of the Canadian Telesat-F communications satellite. Used in conjunction with the PAM third stage, this spacecraft was placed in a geosynchronous transfer orbit with extremely high accuracy. The various steps in the 22-year history of the Delta launch vehicle are briefly examined. In mid-1979 it became apparent that the expendable-to-Shuttle transition time would increase over that previously planned. In connection with this development, it was decided to design the ISS. Attention is given to design details, a system description, the development schedule, aspects of performance capability, first flight results, and future performance improvements.

Grimes, D. W.↗

NASA NTRS1982

Delta mission planning in the Shuttle transition era

Delta mission planning is aimed at providing Shuttle transition era user support which is flexible, dependable, and reliable. The flexibility of support is being enhanced by the development of a new Delta vehicle model, the 3920, capable of providing backup compatible performance for Shuttle SSUS-D (solid spinning upper stage) users. Reliable interfaces, flexible scheduling policies, and new launch facilities will help satisfy increased user demand.

Grimes, D. W.↗

NASA NTRS1982

Delta capability for launch of communications satellites

The evolution of capabilities and the current performance levels of the Delta launch vehicle are outlined. The first payload was the Echo I passive communications satellite, weighing 179 lb, and placed in GEO in 1960. Emphasis since then has been to use off-the-shelf hardware where feasible. The latest version in the 3924 first stage, 3920 second stage, and Pam D apogee kick motor third stage. The Delta is presently equipped to place 2800 lb in GEO, as was proven with the 2717 lb Anik-D1 satellite. The GEO payload placement performance matches the Shuttle's, and work is therefore under way to enhance the Delta performance to handle more massive payloads. Installation of the Castor-IV solid motor separation system, thereby saving mass by utilizing compressed nitrogen, rather than mechanical thrusters to remove the strap-on boosters, is indicated, together with use of a higher performance propellant and a wider nose fairing.

Grimes, D. W.↗

NASA NTRS1982

Future capabilities of the Delta launch vehicle

Design features and payload delivery capabilities of the Delta 3920 launch vehicle are presented. The 3920 is the 14th iteration in a series that was first launched in 1960 and has in recent years surpassed a 97 percent success rate. Capacity is 2800 lb to GEO. The second stage has a propellant capacity of 13,244 lb and a specific impulse of 319.2 sec and produces 9443 lb thrust. The first mission is the Landsat-D satellite and 27 more launches are scheduled through 1985, some associated with different upper stage configurations. The 3924 configuration delivers payload to GEO at a cost of $7500/lb. A fairing has been designed to provide back-up for Shuttle payloads, although the larger size reduces the GEO payload to 2715 lb. Performance enhancements may, however, be gained through pneumatic thrusters for the Castor IV engine separation, higher Castor IV thrust levels, increased booster thrust, and a cryogenic second stage.

Grimes, D. W.↗

NASA NTRS1981

Delta's role in reaching the fourth environment

The Delta launch vehicle has played a significant role in spaceand airborne studies since its first launch in 1960, and a high volume period of service is planned for the 1980s. The historical role played by Delta in launching satellites from 1960 to the present is discussed, and vehicle modifications made during this period are summarized. It is shown that out of 154 launches, 143 proved successful for an overall reliability of 93%. The forecasted launch schedule through 1985 is also presented. Various modifications are now under way to provide spacecraft interchangeability with the Shuttle: a Payload Assist Module (PAM) is proposed to provide an orderly transition from the Delta expendable vehicle to the Shuttle reusable vehicle; the new Delta 3920 Improved Second Stage is the result of a need for improved Delta performance to meet 3910 payload capabilities; the firing sequence of the solid rocket motors was altered from five at liftoff and four during ascent to a sequence of six and three, thereby increasing spacecraft weight in geosynchronous transfer orbit. Potential future improvements discussed include the Delta 4920, 9-ft-diam fairing, booster engine performance, PAM solid motor performance, a universal second stage, a hydrogen-oxygen second stage, and large strap-on solids.

Grimes, D. W.↗

NASA NTRS1973

The Atmosphere Explorer spacecraft system.

Brief description of the design goals, spacecraft, data system, and data analysis concept for the Atmosphere Explorer (AE) mission. The AE mission is shown to have been conceived and to be implemented for making possible a variety of studies of the lower thermosphere. The spacecraft support system, including an onboard propulsion system, will enable investigations to be carried out deep in the thermosphere and at all points of aeronomic significance about the earth.

Spencer, N. W.↗

NASA NTRS1973

The growing importance of costs and ways to maintain cost control on a large program in today's competitive environment

Discussion of management techniques that make it possible to overcome inflationary and developmental cost rises while holding schedule and performance fixed in scientific space programs. The techniques reviewed pertain to high personnel motivation, continual review of contract rigidity for de facto modification by senior judgment, standardization vs design innovation, cooperative customer/contractor goal orientation vs task orientation, and deep real-time management visibility.

Newman, J. J.↗