4
Propulsion and Power

OVERVIEW

Power and propulsion are a concatenation of two very different technical areas. Power relates to onboard auxiliary electrical power systems of aircraft, including storage and distribution. Propulsion in the context of the current ONR program applies to gas turbine engine technology for naval vehicle applications such as missiles and manned and unmanned rotary- and fixed-wing aircraft. The only technical connection between the two is that the propulsion engines mechanically drive the electrical generators in most air vehicles.

Table 4.1 shows the ONR budget projection for the ATP propulsion and power programs, including planned transition to FNCs.

TABLE 4.1 ONR 351 Aircraft Technology Program Budget for Propulsion and Power Through FY02 (millions of dollars)

 

FY99

FY00

FY01

FY02

6.2

Propulsion

4.0

4.9

4.6

0.0

6.2

UAV propulsion (AO FNC)

0.0

0.0

0.0

1.4

6.2

Turbine improvement/IHPTET (TOCR FNC)

0.0

0.0

0.0

0.0

6.3

IHPTET

6.9

7.2

7.8

0.0

6.3

UAV propulsion (AO FNC)

0.0

0.0

0.0

1.5

6.3

Turbine improvement/IHPTET (TOCR FNC)

0.0

0.0

0.0

9.6

6.2

Thermal management

0.2

0.0

0.0

0.0

6.2

Power

0.5

0.5

0.1

0.1

6.2

AC power (TOCR FNC)

0.0

0.0

0.0

0.0

6.3

AC power (TOCR FNC)

0.0

0.0

0.0

0.9

 

Total

11.6

12.6

12.4

13.5

Note: See Appendix C for definitions of acronyms used.



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2001 Assessment of the Office of Naval Research’s Aircraft Technology Program 4 Propulsion and Power OVERVIEW Power and propulsion are a concatenation of two very different technical areas. Power relates to onboard auxiliary electrical power systems of aircraft, including storage and distribution. Propulsion in the context of the current ONR program applies to gas turbine engine technology for naval vehicle applications such as missiles and manned and unmanned rotary- and fixed-wing aircraft. The only technical connection between the two is that the propulsion engines mechanically drive the electrical generators in most air vehicles. Table 4.1 shows the ONR budget projection for the ATP propulsion and power programs, including planned transition to FNCs. TABLE 4.1 ONR 351 Aircraft Technology Program Budget for Propulsion and Power Through FY02 (millions of dollars)   FY99 FY00 FY01 FY02 6.2 Propulsion 4.0 4.9 4.6 0.0 6.2 UAV propulsion (AO FNC) 0.0 0.0 0.0 1.4 6.2 Turbine improvement/IHPTET (TOCR FNC) 0.0 0.0 0.0 0.0 6.3 IHPTET 6.9 7.2 7.8 0.0 6.3 UAV propulsion (AO FNC) 0.0 0.0 0.0 1.5 6.3 Turbine improvement/IHPTET (TOCR FNC) 0.0 0.0 0.0 9.6 6.2 Thermal management 0.2 0.0 0.0 0.0 6.2 Power 0.5 0.5 0.1 0.1 6.2 AC power (TOCR FNC) 0.0 0.0 0.0 0.0 6.3 AC power (TOCR FNC) 0.0 0.0 0.0 0.9   Total 11.6 12.6 12.4 13.5 Note: See Appendix C for definitions of acronyms used.

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2001 Assessment of the Office of Naval Research’s Aircraft Technology Program PROGRAMS REVIEWED Propulsion Findings The ONR Code 351 propulsion program consists entirely of a Navy portion of the Integrated High Performance Turbine Engine Technology (IHPTET) program. This is a highly integrated, cross-Service 6.2–6.3 program very tightly coordinated from the Office of the Under Secretary of Defense (OUSD), with additional participation by NASA. IHPTET encompasses all of the Department of Defense’s (DOD’s) turbine engine research investment. The Navy is a junior partner in this endeavor, contributing about 10 percent of the funding. In business for more than a decade, the program has clear, ambitious, quantitative goals for improving overall gas turbine performance and life-cycle costs. Systems analysis is used to relate air vehicle goals to specific engine types and component technologies. The program is a mix of mid-term and long-term technologies and runs the gamut from materials, to mechanical components, to aerothermal designs, to controls and diagnostics. Much of the technology is generic in that it may be applicable to new centerline engines and as well as to major upgrades of legacy designs in a wide variety of engine sizes and applications. Industrial cost sharing is an important part of the program, so the military and industry work closely in setting the targets and selecting the technologies. Most of the IHPTET funding goes to industry, and it now accounts for the majority of the basic and applied research funding for gas turbine technology in the United States. Thus, industry is very interested in generic, multiple-use technologies applicable to a wide set of turbine engine applications, both military and civil. Only the Navy funds the 6.2 technology projects, while the funding of the 6.3 demonstration cores and engines is shared with the other services. Nine 6.2-funded projects include advanced materials (ceramic matrix vanes, tiled turbine blades), combustors (active combustor control, integrated-shortened combustors), integrated prognostics and health management, improved bearings (rolling contact bearings, magnetic bearings), and improved mechanical analysis (blade vibration code verification, crack growth models). Insufficient information was presented to the committee to permit detailed assessment of each effort. Since these Navy projects represent only a small fraction of the overall IHPTET 6.2 funding, a review of them in isolation runs the risk of being out of context. Regardless, these are all mainline, long-term gas turbine research topics done by creditable organizations. These efforts represent a reasonable research investment for the Navy. However, they are in no way Navy-specific and most do not fall into the category of D&I. None represent new ideas, but rather are part of the stepwise, long-term progression needed to develop new technology to the point that it can be adopted by gas turbine engine development programs with acceptable levels of technical risk. (Magnetic bearings, for example, represent a concept that has existed for several decades and has been demonstrated in an engine core as part of the IHPTET program. However, there is still considerable 6.2-and 6.3-level research needed on magnetic bearings before they can be a viable design option for an engine development program.) With one exception, there are no naval-unique basic gas turbine technologies. Specific naval applications may have unique requirements (e.g., those associated with carrier operations and the marine environment), but these are accommodated in engine development through design and validation testing. The exception is short takeoff and vertical landing (STOVL) and vertical takeoff and landing

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2001 Assessment of the Office of Naval Research’s Aircraft Technology Program (VTOL). The Air Force has no current interest in STOVL and VTOL technologies, while the Army’s interest is confined to rotorcraft. While many STOVL technologies are often considered part of the airframe rather than the propulsion systems, there are some gas turbine technologies (vectoring nozzles, short-life lift engines, enhanced emergency power-boost, and so on) that are of interest only to the Navy. Recommendations Currently, the Navy 6.2 propulsion program is focused on technologies appropriate to large manned aircraft. The committee recommends that the propulsion program devote more attention to areas unique to the Navy and Marine Corps, such as short takeoff and vertical landing (STOVL) and vertical takeoff and landing (VTOL), even at the expense of the more generic gas turbine technologies currently being pursued. In addition, given the marked shift in emphasis to small UAVs/UCAVs and the need for extended-range munitions, the committee recommends that ONR consider reallocating the investment portfolio between large and small gas turbine engines. There is no balance between 6.1, 6.2, and 6.3 in propulsion since both the IHPTET program and the Navy have no direct 6.1 funding supporting gas turbine technology development. ONR ceded responsibility for 6.1 basic research to the Air Force and the Army about a decade ago. The IHPTET program never had a 6.1 component, which is perhaps its major weakness given the ambition of its technical goals. Power This technical area focuses on onboard auxiliary power systems for aircraft, including generation, storage, and distribution. Technology and performance improvements in this area are important to all military and civil aircraft. The problems for naval aircraft seem to be like those for all aircraft and vehicle systems. The national investment in this area, as reported by the Code 351 briefing, is broadly distributed among industry and government agencies. There are no novel or unique approaches being pursued by the ONR Code 351 program that will pace or focus the larger national efforts. Multifunction Power Controller Findings The objectives and approach for this program area are reasonable and straightforward. Innovation is low and not unique from an S&T perspective. The solutions being developed are not unique to Navy applications. Recommendations ONR should assess the potential benefits of this program in the light of other high-priority, underfunded needs. Unless a critical capability will not be achieved from investments by industry and other agencies, it should terminate the work and invest in more pressing aircraft technology needs.

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2001 Assessment of the Office of Naval Research’s Aircraft Technology Program Smart Wire Findings This technology has the potential for significant payoff for most aircraft applications. The Navy has unique and difficult maintenance, environmental, and operational conditions that demand enhanced diagnostics and detection of anomalies in onboard electrical systems. This area has received considerable attention because of the problem of aging civil aircraft. Recommendations ONR should ensure that the program takes full advantage of other relevant work and focuses on the problems unique to naval aviation. It should move the technology to demonstration as rapidly as possible and transfer implementation to the program managers (aviation) in charge of the impacted aircraft maintenance and upgrade. Only two projects were briefed as part of the review. However, based on the information provided, the committee believes that the power program has marginal impact on high-priority and naval-unique aircraft technologies and recommends that it be critically assessed against other high-priority demands on resources. The quality of the work is satisfactory, but most of the gains for the Navy in this area will come from industry and other agency investments. Suggested Topic in Propulsion and Power for the Future ATP The committee recognizes that the Navy and Marine Corps may wish to employ small/medium size UAVs for long-endurance intelligence, surveillance, and reconnaissance missions at low and medium altitudes in operations from both ship and shore bases. To power such air vehicles, compact, fuel-efficient, ship-compatible engines would be required. Accordingly, the committee recommends that ONR explore and develop as necessary under S&T funding the technologies that will enable the design and manufacture under program funding of fuel-efficient UAV engines suitable for long-endurance flight at low and medium altitudes.