Range Flashcards
Range is defined as
Distance covered on the available fuel
Specific range is the ratio between
True air speed and rate of fuel consumption
SAR
Specific Air Range:
TAS/Fuel Flow
Or
TAS —————————- SFC X (Thrust Required)
SGR
GS/Fuel flOW
Fuel Flow vs thrust
Higher thrust = more fuel flow (Jet)
Higher power = more fuel flow (Propeller)
Specific Fuel Consumption in a jet and propeller aircraft
Fuel flow per unit of thrust in a jet
Fuel flow per unit of power in a propeller aircraft
SFC is lowest when
Air temperature is low engine running as design RPM 90-95%
Best range cruise speed for a jet is
1.32VMD
Best range cruise speed for a propeller aircraft is
VMD
Optimum altitude
Best range
2000ft deviation = 1% change in consumption
8,000ft deviation = 10% change in consumption
Wind Vs Range
Does not affect SAR
SGR
Tailwind - Slightly slower than 1.32MD
Headwind - Slightly faster than 1.32MD - flying faster to compensate for wind
Long range cruise speed
Flying faster than 1.32MD MMR speed to complete more flights
MLRC = Long range cruise speed
SR long range = 0.99 x SR max range
4% faster than MMR
SFC Consumption Formula
Fuel Flow/Thrust