The need for a broad, design-oriented view of engine dynamics is illustrated by four incidents where “today’s science” missed mechanisms critical in the high-bypass turbofan. In missing the significance of Rankine’s 1869 observation of the destabilizing/stabilizing mechanism in line shafts, experts for over 88 years have discounted the action of drive torque on turbomachine whirl. As a consequence, a vital lesson in the Lockheed Electra crashes of 1959–1960 was missed. The suspected Electra propeller-nacelle whirl is examined to create a simple & realistic analytical model showing how coupling between forward and backward whirl in the whole power plant, including associated propeller flexing, poses potential whirl amplification/modulation by torque loading. The model illustrates mechanisms essential to the cited new, physics-based, design analysis of vibrations in a whole engine via distinct waves. The prevailing presumption that an interlocked shroud inevitably produces friction damping is contradicted by a 1989 airline crash investigation.

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