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Beginner's Guide to Propulsion
Maximum Flight Time - Worksheet
- The Maximum Flight Time for an aircraft depends on the
specific fuel consumption, net thrust, and the
mass of the fuel load. If all other
factors for the following aircrafts remain the same, which of the
2 aircraft has the longer maximum flight time? Place an
"X" on the correct line.
AIRCRAFT A - The throttle setting is 58%
AIRCRAFT B - The throttle setting is 75%
AIRCRAFT A - The engine is producing
1500 pounds of thrust _______
AIRCRAFT B - The engine is producing
2000 pounds of thrust ________
AIRCRAFT A - has a turbojet engine with
an afterburner ________
AIRCRAFT B - has a plain turbojet engine
AIRCRAFT A - has a turboprop engine
AIRCRAFT B - has a rocket engine
AIRCRAFT A - has a L/D (lift to drag
ratio) of .5 __________
AIRCRAFT B - has a L/D (lift to drag
ratio) of .8 __________
AIRCRAFT A - has a fuel mass flow rate
of 2500 lbm/hr_________
AIRCRAFT B - has a fuel mass flow rate
of 3500 lbm/hr__________
Note: Please show the formula you are using as well as
- For a given mission, the required flight time could replace
the maximum flight time in the required equation. This idea may be
needed to solve the following:
A. For mission I, we need 4500 pounds of thrust for 3
hours. If the Thrust Specific Fuel Consumption is .8, how much
fuel is needed for this mission?
B. For the second mission, the engines are being fed from a
fuel tank that delivers 3200 pounds mass per hour. If the aircraft
is producing 2500 pounds of thrust, what is the TSFC?
C. If the aircraft can carry 20,000 pounds mass of fuel
plus the amount needed for takeoff and landing, what is the limit
for the time the mission can take?
D. The aircraft plans to maintain a cruise speed of 120
mph. What is the aircraft's maximum range?
E. The aircraft was forced to land unexpectedly. At that
time, there were only 15,000 pounds mass of fuel in excess of that
needed for takeoff and landing. All other conditions remain the
same. If the final destination of the mission is 630 miles away,
what cruise speed should be maintained?