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November 12, 2008

Ten Times Improvement in Affordable Jet Engine Capability by 2017


GE90 engine is an example of improving engine affordability and with better performance

Phase 2 and 3 of the Versatile Affordable Advanced Turbine Engines (VAATE) program are being funded. The VAATE program is structured in three phases to achieve 4X performance/cost by 2009, 6X performance/cost by 2013 and 10X performance/cost by 2017.

The Adaptive Versatile Engine Technology (ADVENT) program is a 5-year project that aims to produce a revolution in jet engine design. Project ADVENT is a actually the flagship effort under the Versatile, Affordable Advanced Turbine Engines Program, or VAATE.

A single contractor will be selected in 2009 to carry out the Phase 2 effort. This phase covers work from engine-detailed design through Technology Readiness Level 6, which signifies it is ready for a full-up, operational test in a relevant engine environment. Engine demonstrator testing would occur in 2012.


By 2017 the military user will realize a factor of ten (“10X”) improvement in turbine engine-based propulsion system affordable capability. “Affordable capability” is defined as the ratio of propulsion system capability to cost. “Capability” in this context measures technical performance parameters including thrust, weight, and fuel consumption. “Cost” quantifies the total cost of ownership, and includes development, procurement, and life cycle maintenance cost. These improvements are to be realized relative to a baseline representative of year-2000 state-of-the-art systems.


Examples of goal factors for the large turbofan/turbojet class include:
• 200% increase in engine thrust-to-weight ratio (a key jet engine design parameter)
• 25% reduction in engine fuel consumption (and thus fuel cost)
• 60% reduction in engine development, procurement, and life cycle maintenance cost




Followup to the Integrated High Performance Turbine Engine Technology (IHPTET) programme

The IHPTET programme was completed in 2005, it demonstrated a 100 per cent increase in the thrust-to-weight ratio of turbofan engines relative to their counterparts of a generation ago. It showed that a 35 per cent decrease in production and maintenance costs is achievable in today's manufactured products. The results have been fed into many contemporary engine projects. The completion of IHPTET Phase I in 1991 -- after it had successfully demonstrated a 31 per cent improvement in combat engine thrust-to-weight ratios -- led, for example, to the supercruise capability of the F-22.


VAATE Focus Areas

The four VAATE Focus Areas are: (1) Versatile Core, (2) Intelligent Engine, (3) Durability and (4) engine-airframe integration.

The Versatile Core Focus Area concerns the most fundamental part of a gas turbine propulsion system, the engine “core.” Within the core, engine pressure, temperature, and rotational speed reach maximum value, as do the resultant thermodynamic and structural design requirements. The core is the heaviest, most complex, and highest cost component of the propulsion system and thus a component where technology advancement has great payoff. In addition to fuel consumption, thrust, and emissions improvements, Versatile Core technologies will reduce engine cost by allowing engines optimized for different applications to be built around identical core hardware. In one scenario, the engines for a large subsonic transport aircraft would have significant parts commonality with that for a high-performance supersonic fighter, thereby spreading nonrecurring costs over a larger customer base. Such explicit emphasis on dual-use capability will increase competitiveness of U.S. products in the demanding civil market.

The Intelligent Engine Focus Area concerns achieving the maximum utility from the engine through improved engine control systems, advanced prognostics and health maintenance, and integration of the engine, airframe, and power management subsystems. Advanced engine architectures utilizing pulse detonation combustion or hybrid gas turbine/fuel cell concepts will also be examined. By focusing on the Intelligent Engine area, VAATE allows capture of benefits that can be realized only through air vehicle system-level optimization of propulsion and power architectures and hardware.

The Durability Focus Area concerns reducing engine maintenance and part replacement costs by doubling component life while providing a significant increase in hot-time capability. Durability improvements are pervasive and not only benefit future systems, but also can often be retrofitted into legacy aircraft engines. An additional aim of this Focus Area is to prevent component failures, increase engine life and reliability, enhance reparability, and improve system readiness.

Engine-airframe integration technologies are key in attaining the significant cost and weight reductions required in order to achieve the VAATE tenfold goal.

Whereas IHPTET focused on bottom-up component technologies for engine performance improvement, VAATE will prioritize investments by emphasizing a top-down, air vehicle system-level approach.


Specific power and specific fuel consumption are, in general, improved by increasing pressure ratios and turbine inlet temperatures. As stronger, lighter-weight materials become available and more precise temperature measurement and control become possible through developing pyrometry, electrical controls and turbine cooling technology), increased pressures and temperatures are forecast.

Desired Results

Future scenarios envision a responsive, lethal, survivable force involving diverse platform requirements such as global strike, uninhabited air vehicles, advanced stealth combat, high Mach cruise, low-cost access to space, and Vertical/Short Take Off and Landing (V/STOL). VAATE will provide these systems with multiple benefits, including increased range, decreased logistics footprint, increased readiness, improved noise, emissions, and observability (stealth), and high speed endurance. For a future U.S. Air Force structure, specific benefits of VAATE-class technology (over that of a year-2000 state-of-the-art baseline engine) include: a 100% improvement in range for a manned fighter; a 200% improvement in range-payload per unit cost for a global reach transport; and a staggering $200+B reduction in life cycle cost for the entire future force structure.

Many mission requirements of these future weapon systems simply cannot be achieved without propulsion advancements. For example, a responsive strike aircraft should have twice the range at half the aircraft unit cost of current systems. Certain Unmanned Combat Air Vehicle (UCAV) concepts require 2.5 times the mission radius or 3 times the mission persistence (loiter time) of today’s manned vehicles. For access to space, a fuel-efficient, on-demand turbine engine accelerator up to a speed of Mach 4+ is required. Such capability does not exist today. For multi-role mobility, a future aircraft must be capable of Short Take-Off Vertical Landing (STOVL) with a 2-to-4 times mission radius increase over today’s conventional take-off aircraft.


FURTHER READING
Improving the Efficiency of Engines for Large Nonfighter Aircraft (2007)

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