1. An apparatus comprising: a gas turbine engine operation module structured to receive a requested engine configuration from a pilot and control variable mechanical features of the gas turbine engine to achieve the requested engine configuration, the gas turbine engine operation module structured to provide a plurality of candidate operation modes to the pilot that include: a nominal operation mode in which SFC is non-optimal in favor of rapid thrust response; an optimum SFC mode in which a cooling feature is in a minimum cooling setting; a bolster thrust operation mode in which the gas turbine engine is configured to produce a spoiled thrust through a variable mechanical feature that can be quickly reconfigured to produce a non-spoiled thrust; a flow holding operation mode in which fan speed is held and flow through an internal duct remains substantially constant while the gas turbine engine produces varying thrust levels through a configuration of variable mechanical features; and a power off-take mode in which engine is placed in a state that accommodates a heavy increase in demanded power without destabilizing the engine.