Future Aerospace Ground Test Facility Requirements for the Arnold Engineering Development Center (1992)

As discussed in Chapter 2, the Arnold Engineering Development Center represents a financial investment of approximately $3.64 billion, with 87 percent devoted to technical facilities (see Appendix B ) assembled during its 40-year history to match the needs of Air Force testing over a broad range of speed and altitude. Virtually all of the major facilities are subject to improvement and modernization (I&M) as part of a policy program that extends from component replacement for age to facility modifications that provide major technology upgrades to achieve advanced systems. Primarily these are in the area of wind tunnels, rocket and turbine engine test cells, environmental space chambers, and sensor system laboratories. For example, the 1987 modification to the 16T facility improved that wind tunnel's flow quality in Mach number uniformity for aerodynamic testing. Without the upgrade, the attainable aerodynamic accuracy may have been unacceptable for the development of several strategic and tactical systems.

The estimate of lifetime value for a facility is complicated by issues such as the demand for use, replacement versus maintenance costs, and its ready availability as a unique resource. Thus, it is generally inappropriate to assign a finite life span. Most important, systematic modifications are essential to keep the center current with the requirements for new testing capabilities, the ever-increasing detail and kinds of data that are requested, and complex simulation scaling of advanced model configurations.

Appreciable changes in testing capability require the installation of either new or upgraded system components, and upgrades are the frequent choice as the mechanism to introduce major new initiatives. However, significant upgrades require special program funds, and the Center's annual budgeting for generic improvements and modernization has shown marked decreases--down from $13 million 8 years ago to a recent $3 million expenditure level. In contrast, a substantial facility upgrade--for example, conversion of a rocket test stand to alternate fuel operations or addition of a clean air supply at higher temperatures and Mach numbers for hypersonic testing--typically involves expenditures on the order of $50 million to several hundred million.

A sense of the adjustment dynamics as they have taken place at AEDC is shown in Table 6-1. Only approximately 17 percent of the 53 facilities have become available in the last two decades. However, upgrades ranging from the near-replacement level to substantial modifications

have contributed to the pool of active (55 percent) and stand-by (32 percent) equipment, the latter classified according to an estimate of the 3- to 6-month preparation time necessary to bring them into full operation. The relatively small number that have been closed (13 percent) are still provided minimal maintenance to avoid deterioration and are retained because it is less expensive than to remove them. Closures accompanied by complete removal are very infrequent. The decision that leads to specific facility closure is a complex one involving many factors that are in constant flux. This issue is best addressed by the LRPT planning process discussed in Chapter 2.

Since stand-by status follows from infrequent requests for use, the evolutionary response is to adapt stand-by equipment to parallel the requirements for Air Force system testing. Upgrades then satisfy the users' needs and simultaneously modernize facilities to provide consistency at least with those systems that are under development. However, it is extremely important that the upgrade policy also reach beyond the technology of current system needs and support the requirements that are foreseen for systems still in the concept stage and even beyond.

The distinction between current and future needs is relevant for all simulators but has been especially evident in the hypersonics area. The National Aero-Space Plane (NASP) project has identified stand-by equipment that is potentially of use after completion of projected modifications, but for a wide portion of the required flight envelope, advanced facilities have not received timely attention. Effectively, there is excess capacity relative to demand in both flow and space testing, but at the same time, facilities are not necessarily available for all requirements. It is not clear that the excess capacity results solely from a mismatch with current development needs, as opposed to the mismatch with demand that results from advanced and unique facilities being either available or unavailable. Upgrade planning should take into account the potential contributions and gains from each component of need as well as the time constraints for the possible applications.

There is an awareness of a number of missing elements in lagging areas of testing capabilities. Some typical concerns are those involving hypersonics for higher Mach numbers (higher than 8 approximately); propulsion unit testing with alternate fuel; and control of inlet flow fields, cryogenic fuel systems, transient and dynamic influences. Funded upgrade projects have lagged behind the number of identifiable advances that require unique facilities, and in most cases, some background study of facility characteristics and the degree of achievable simulation must be completed as well.

The diminished I&M funds, the evolutionary match of upgrades to immediate testing needs, and the Center's identification of major advances that await approval for completion of upgrade tasks, all reflect difficulties that AEDC will face when attempting to satisfy future requests. Projected systems requirements are sufficiently fuzzy to justify meeting upgrade improvements as rapidly as possible once they are recognized.

The committee recommends that planning and funding policy should be committed to eliminating the backlog of approved facility upgrade projects. Modest funds also should be allocated for research into advanced facility concepts. ¹