Question about turbo props

[v1valarob]

Below the gate: PL = blade angle CL= fuel

Above the gate: PL = fuel CL = Blade angle.

I <3 Beta

 

[CutEmUp]

Torque is not power. Torque is the force applied to the propeller shaft (often expressed in lbft, Nm, or % for operational use in some aircraft). Depending on prop RPM the power generated is significantly different for the same torque value. 2230lbft@2000rpm=850hp, but 2230lbft@1700rpm=720hp

 

[mesaba13]

If your going to split hairs on me torque as it relates to turboprops, is the tendency for a shaft to rotate about a specific axis. This is measured on some aircraft by the actual amount of deflection or twist of the shaft that occurs under load and displayed as a % of maximum.

Obviously torque is not the same unit of measure as power just as EPR is not a measure of power but a ratio or pressures. As I said in my previous post torque % is what is primarily used in the Saab to set a desired amount of power (100% torque is about 100% power).

 

[IBNAV8R]

Torque is not power. Torque is the force applied to the propeller shaft (often expressed in lbft, Nm, or % for operational use in some aircraft). Depending on prop RPM the power generated is significantly different for the same torque value. 2230lbft@2000rpm=850hp, but 2230lbft@1700rpm=720hp

Torque IS power in the purest sense. Assuming a prop could even turn with zero torque it would be incapable of producing any force without a torsional load. Pick an engine. zero torque = zero power = zero thrust.

In every turboprop I have flown, torque is the PRIMARY measurement of power. Of course, I've never flown a turboprop with a fixed pitch prop. (pitch-locked notwithstanding). While most piston aircraft and jets don't measure torque, it is nonetheless there and part of the power/thrust equation.

Now, I have heard of some aircraft capable of flight without torsional force from the powerplant. They're called gliders (and balloons)

 

[Quimby]

Chicks dig beta.

 

[zasca]

PDT had a chick dig the good vibes on a dash so much her mother threaten to sue the airline... true story

 

[IBNAV8R]

niiice.

 

[CutEmUp]

If your going to split hairs on me torque as it relates to turboprops, is the tendency for a shaft to rotate about a specific axis. This is measured on some aircraft by the actual amount of deflection or twist of the shaft that occurs under load and displayed as a % of maximum.

Obviously torque is not the same unit of measure as power just as EPR is not a measure of power but a ratio or pressures. As I said in my previous post torque % is what is primarily used in the Saab to set a desired amount of power (100% torque is about 100% power).

Is 100% torque=100% power @ 50% RPM?...No.

 

[CutEmUp]

Torque IS power in the purest sense. Assuming a prop could even turn with zero torque it would be incapable of producing any force without a torsional load. Pick an engine. zero torque = zero power = zero thrust.

In every turboprop I have flown, torque is the PRIMARY measurement of power. Of course, I've never flown a turboprop with a fixed pitch prop. (pitch-locked notwithstanding). While most piston aircraft and jets don't measure torque, it is nonetheless there and part of the power/thrust equation.

Now, I have heard of some aircraft capable of flight without torsional force from the powerplant. They're called gliders (and balloons)

0 torque = 0 power...wrong. If you have 0 power then you will have 0 torque, but this equation is not symmetric. How much power is being applied to a shaft if has 1000Nm of torque on it at 0 RPM?...0. Back to statics and dynamics class.

 

[mesaba13]

Send out an emergency alert to all turboprop operators:

"Do not look up % torque on the manufacture charts to determine takeoff power setting. A genius pilot on FI has pointed out that we have been doing it wrong all these years. In the future the operator needs to convert the appropriate % torque values to equivalent Horsepower (or watts) and utilize that for all operations. Horsepower gauges are in the process of being installed in all aircraft. Per ICAO requirements Watts will eventually be the official power setting used."

ex: "Set 2400 horsepower" or "Set 36000 Watts"