Performance II Flashcards
What is the basic definition of mechanical power? What are the BG units?
Energy per unit time. In the BG system, it ft*lb/s.
If the thrust required is known, how can be the power required be calculated?
By multiplying the thrust required by the velocity.
The power required is inversely porportional to _____.
(CL)^(3/2) / CD
The point on the velocity vs power required curve that represents the minimum thrust required is also where ______.
L/D is maximum
Define Shaft Brake Power (SBP).
The power delivered by the engine’s crankshaft to the propeller.
Is all of the SBP available for thrust? Explain.
No, a significant portion of the power is lost through the mechanism of converting the power to thrust (the prop).
Engine power is usually expressed in ______.
shaft brake horsepower
In general, how does a jet-reaction engine create its thrust?
The combustion & heating of an incoming stream of air and exhausting it at high velocities through a nozzle.
The max flight velocity for either a jet or prop-driven aircraft lies at the intersection of _____.
The power required and power available curves.
True or False
For steady, unaccelerated, climbing flight, the lift is less than the weight.
True
True or False
For steady, unaccelerated, climbing flight (SUCF), where the climb angle is small, the power required is not influenced by weight.
True
True or False
Total Drag is smaller for climbing flight than level flight.
True
Slide 29
True or False
For steady, climbing flight, L is smaller therefore the induced drag is larger.
False, the induced drag is smaller when lift decreases.
True or False
Excess power can vary with velocity.
True
Note: Excess Power = V*(T–D). This is not the same as specific excess power which is defined as the weight normalized excess power.
The max rate of climb for SUCF is given at ______.
The maximum specific excess power.
