CPC F02C 7/32 (2013.01) [F01D 15/10 (2013.01); F05D 2220/50 (2013.01); F05D 2220/7642 (2013.01); F05D 2260/4023 (2013.01); F05D 2260/4031 (2013.01); F05D 2270/02 (2013.01)] | 15 Claims |
1. An aircraft power system comprising:
an auxiliary power unit (APU) configured to output a first APU rotational power during a first condition and a second APU rotational power during a second condition different from the first condition;
a transmission unit configured to receive the first APU rotational output power from the APU, the transmission unit configured to output a transmission rotational power based on the first APU rotational output power and to output the transmission rotational power based on the second APU rotational output power;
a drive shaft rotatably coupled between the APU and the transmission unit, wherein the APU drives the drive shaft to rotate at a first rotational speed so as to deliver the first APU rotational output power and to rotate at a second rotational speed so as to deliver the second APU rotational output power; and
a generator configured to receive the transmission rotational power and to produce an alternating current (AC) voltage having a target frequency based on the transmission rotational power, wherein the first condition is a first altitude range at which the APU drives the drive shaft at a first speed of about 21,630 rotations per minute (RPM) and the second condition is a second altitude range at which the APU drives the APU drive shaft at a second speed falling within a second speed range which ranges from about 24,030 RPM.
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