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22 Cards in this Set
- Front
- Back
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Describe the relationship between thrust and power.
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P=TV/325
They are directly related. |
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Define thrust required and power required.
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Tr=the amount of thrust that is required to overcome drag.
Pr=the amount of power that is required to produce thrust required. |
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Describe how thrust required and power required vary with velocity.
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As velocity increases, Tr decreases until L/Dmax, then Tr increases.
As velocity increases, Pr decreases until MinPr, then it increases before L/Dmax |
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State the location of L/DMAX on the thrust required and power required curves.
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Tr: L/Dmax=MinTr
Pr: L/Dmax=right of the MinPr |
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Define thrust available and power available.
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Ta: the amount of thrust that the airplane's engines actually produce at a given throttle setting, velocity, and density.
Pa: the amount of power that the airplane's engines actually produce at a given throttle setting, velocity, and density. |
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Describe the effects of throttle setting, velocity, and density on thrust available and power available for a turbojet engine.
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Ta: Throttle setting has constant thrust with increase in Velocity. Ta decreases with density.
Pa: Full throttle=Max Pa Increase in velocity=Pa increases Decrease in Density=decrease in Pa |
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Describe the effects of PCL setting, velocity, and density on thrust available and power available for a turboprop engine.
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Ta: Max PCL= Max Ta
Increase Velocity=decrease in Ta Decrease Density=Decrease in Ta Pa: Max PCL=Max Pa Increase in velocity=initial increase in Pa but then decreases due to a decrease in Ta Decrease in density=Pa decreases |
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Define thrust horsepower.
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Thrust horsepower: propeller output, or the power that is converted to usable thrust by the propeller.
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Define shaft horsepower.
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Shaft horsepower: Engine output
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Define propeller efficiency.
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The ability of the propeller to turn engine output into thrust.
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State the relationship between thrust horsepower, shaft horsepower, and propeller efficiency.
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THP=(SHP)(p.e.)
THP is always less than SHP due to friction and drag but are directly related. |
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State the flat rated shaft horsepower and the Navy limited shaft horsepower of
the T-34C PT6A-25 engine. |
Flat rated: 550 SHP
Navy Limit: 425 SHP |
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State the instrument indications for the flat rated shaft horsepower and the Navy
limited shaft horsepower of the T-34C PT6A-25 engine. |
*
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Define thrust excess and power excess.
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Te: occurs if thrust available is greater than thrust required at a particular velocity.
Pe: calculated in a similar manner as Te. |
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State the effects of a thrust excess or a power excess.
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Positive Te causes an acceleration, a climb, or both, depending on the AOA.
Positive Pe causes an acceleration, a climb, or both. |
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State the conditions necessary to achieve the maximum thrust excess and
maximum power excess for a turbojet and a turboprop airplane. |
Prop: Te occurs at a velocity less than L/Dmax
Jet: Te occurs at L/Dmax Prop: Pe occurs at L/Dmax Jet: Pe occurs at a velocity greater than L/D max. |
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Describe the effects of changes in weight on thrust required, power required,
thrust available, and power available. |
Increase weight:
-Increase Thrust Required -Increase Power Required -No changes on Thrust Available -No changes on Power Available |
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Describe the effects of changes in weight on maximum thrust excess and
maximum power excess, and on the airspeeds necessary to achieve maximum thrust excess and maximum power excess. |
Max Te=decrease
Max Pe=decrease Airspeed increase |
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Describe the effects of changes in altitude on thrust required, power required,
thrust available, and power available. |
Increase Altitude:
-No Increase in Thrust Req. -Increase Power Req. -Decrease Thrust Available -Decrease Power Available |
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Describe the effects of changes in altitude on maximum thrust excess and
maximum power excess, and on the airspeeds necessary to achieve maximum thrust excess and maximum power excess. |
Max Te=decrease
Max Pe=decrease Airspeed increase |
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Describe the effects of changes in configuration on thrust required, power
required, thrust available, and power available. |
Increase drag configuration:
-Increase Tr -Increase Pr -No change in Ta -No change in Pa |
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Describe the effects of changes in configuration on maximum thrust excess and
maximum power excess, and on the airspeeds necessary to achieve maximum thrust excess and maximum power excess. |
Increase in Drag configuration:
-Decrease in Te -Decrease in Pe Airspeeds decrease to achieve max Te and max Pe |
