Rather than invest large sums of money into the development of clean-sheet airframe designs, in recent years OEMs have elected to redesign, improve and re-engine already successful airframes for the next generation of aircraft. In many of these cases, the engine accounts for a significant proportion of the efficiency savings.
Innovation in the aero engine industry is a constant process to stay one step ahead of the competition. Take the Rolls-Royce Trent 1000 for example. It competes against the GEnx on the Boeing 787 platform. Six years after entering service in 2011, Rolls-Royce developed an improved model, the Trent 1000-TEN, with more than 70 percent of parts either new or changed from the initial models. The Trent 1000-TEN contained technology through research attained from the Advance3 program and its sister engine, the Trent XWB.
There are myriad factors that an engine OEM has to consider when designing and manufacturing an engine. The OEM must ensure the operating and maintenance costs remain low, and reliability is high as these are key considerations for an operator during engine selection. The OEM must also comply with emissions and environmental regulations. These factors are largely tied to the propulsive and thermal efficiencies of an engine. In a nutshell, the goal is to develop an engine with as great a propulsive efficiency — that of the fan system, and thermal efficiency, that of the core — as possible.
Achieving these gains is proving increasingly difficult, particularly with current engine architecture, as much of the improvements are incremental rather than offering a step-change in efficiency. Advanced material development is costly and bypass ratios can only increase so much before size and weight become prohibitive and negate any perceived gain. However, could a demonstrator developed 40 years ago provide the answer?
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