Question about turbo props

[no1pilot2000]

I was in a Dash8 the other day and noticed levers to the right of the throttles, also with a numers also on them. I was told that they are called condition levers. What are condition levers and how do they work? Also, what is torque as it applies to turbo prop aircraft?

Thank you

 

[Nevets]

Condition levers control fuel metering. High idle, low idle, and cut off. For many aircraft, operationally, they are just a fuel cut off lever. That's how you would introduce fuel during start and shut down the engine. Torque is a measurement of power/thrust. It's the amount of force applied to the power section/RGB.

 

[mesaba13]

Torque is used as a primary power setting and conditional levers generally control Prop RPM (oil controlled system). If the CL are set and you increase the power lever position, more fuel is added and in order for the prop RPM to stay constant the blade angle has to take a bigger bite and thus torque is increased. The condition lever also has feather, reverse, and is also used to introduce fuel to the engine during start, and shut fuel off to the engine.

 

[no1pilot2000]

Interesting. Thanks for the infomation.

 

[zasca]

Condition levers do not have reverse...

First job, introduction of fuel for start.
Second job, control Prop RPM and blade angle in the forward range.

The power levers control reverse blade pitch angle and rpm.

 

[kmox29]

Wait a minute...someone asked a question and factual responses were posted without insulting the original poster? I thought I logged into FlightInfo!

Happy new year everyone. I hope the regional industry rights itself without too much chaos. :beer:

 

[AntiJedi]

The power levers control reverse blade pitch angle and rpm.

As well as Beta mode on the ground.

 

[Kaman]

On some airplanes like the Q-400 the "condition levers" are really not even levers, but electrical switches that talk to the FADEC and PEC via the Engine Control panel. It wasn't really necessary to have the levers, except for single-type certification.

 

[mesaba13]

Sorry my bad! Been a little too long away from the Saab. CL do not in fact control reverse or Beta.

 

[kmox29]

Sorry my bad! Been a little too long away from the Saab. CL do not in fact control reverse or Beta.

Once you autocoarsen, you never go back.

 

[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"