Questions tagged [turboshaft]

A type of turbine engine that does not (directly) propel an aircraft, but, rather, provides power for other systems.

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Why does the torque curve of free shaft gas turbines keep gradually dropping as RPMs increase?

When i look at the output shaft torque curve of a free shaft gas turbine i can see that they are almost like an electric motor. It makes peak torque at very low rpm and then torque keeps gradually ...
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6 votes
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How exactly is the free shaft part of a gas turbines controlled?

As you can see in the picture, the free turbine still gets the same exhaust gas that the main turbine gets. How can it exactly spin freely from the main turbine? How can the free shaft even stay ...
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There is any example/studies/concepts on really short blade jet turbines/turboshafts? [closed]

Well, from the little I know, I think the reason jet turbines can't go that fast is because the tip of the blades would reach supersonic speeds and starting to generate too much drag. However, if, for ...
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How are compressor disks connected to the shaft?

I am trying to learn how compressor disks and shaft are connected each other. I don't have any idea about the terminology so I couldn't find anything useful. Here is a section view of a sample and I ...
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Can coaxial rotors be mounted on a piston engine like the Lycoming O-320?

What are the drawbacks of this compared to coaxial configuration with a turboshaft engine?
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Why does a turbine helicopter need to spin a tail rotor?

Should not the exhaust of the turbine supply enough byproduct to deflect and maintain yaw with a simple deflector (i.e. rudder/stabs)?
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Do the Mt. Everest rescue helicopters have modified engines to operate at high altitudes?

There are so many climbers on Mt. Everest today that there is now a helicopter rescue service there. They operate rescue up to 21,000 + ft. Because this is essentially stationary service it seems that ...
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5 votes
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Does a turboshaft's exhaust provide any thrust?

See the below figure. Does the exhaust gas coming out through the nozzle have any force? If the exhaust gas has force then how is it controlled by the helicopter?
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Can a gas turbine be able to switch from torque to thrust?

Can a turbine engine be switched from providing torque (like a helicopter) to the rotor to transfer power to provide exhaust thrust (like a jet plane)? Related: BV-347 upgrade this way?
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Is the combustion process in turbofans and turboshafts different?

According to a journal paper, for a Gnome turboshaft engine, fuel-air equivalence ratio decreases as power output increases. However, for a CFM56 turbofan engine, the opposite trend is true, and ...
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why are turboprop/turboshaft engines rated only in horsepower and never in ft-lbs of torque like diesel engines or electric motors?

I realize torque and horsepower are essentially the same measurement since horsepower is simply torque over time. But I'm curious as to why diesel engines or electric motors always provide torque ...
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Do Military Turboshaft engines have a distinctly different sound from Civilian ones?

I live in India, and near an airbase so there are a moderate amount of helicopters flying overhead. My friend claims that he can distinguish between a civilian helicopter or a military one based on ...
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Benefit of a deswirl vane for a turboshaft helicopter engine

I am trying to understand the benefit of deswirl vanes on a turboshaft helicopter engine. For these type of engines, the kinetic energy of the exhaust stream is essentially wasted energy. Also, ...
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Where should I find a Pratt & Whitney Canada PT6 operator's manual?

I'm studying the PT6 in detail but the infos I get around the web are sometimes lacking in depth of informations. I'm pretty much interested in the power curve vs RPM of this engine. Where should I be ...
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Why is the first turbine in a turboprop (or turboshaft) connected to the compressor?

Typically the first turbine after the combustion chamber drives the compressor as shown in this picture. (wikimedia.org) This first turbine spins the fastest and harvests the most energy from the ...
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Are there helicopters with vertically mounted turbines?

On the helicopter representation in this answer, the turbine is horizontal, with gear required to drive the vertical-axis propeller. Are there helicopters where the turbine is vertical and directly ...
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Why does it take so much fuel to start a jet engine?

I just watched an Abrams tank documentary and it said something like it takes "1 liter of fuel for every mile but 39 liters for a startup." Is it true of turbine engines in general that they need a ...
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