Questions tagged [turboprop]

A turboprop engine is a type of turbine engine which drives an aircraft propeller to produce thrust (as opposed to a jet engine, where the turbine exhaust provides thrust directly).

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1answer
624 views

Has a general aviation twin-engine turboprop with counter rotating propellors ever been built?

In my experience with general aviation twin-engine turboprops I've never heard of one with counter rotating propellors. I've never seen any data about an engine manufacturer building left-rotating ...
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1answer
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How do blade cuffs help cool the engine?

How does the blade cuff (a fairing of suitable airfoil shape used to cover the shanks of propeller blades in order to reduce the aerodynamic losses) help cool the engine?
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What does the condition lever in turboprops control?

Turbojet and turbofan engines have just one control lever that controls the thrust by setting the amount of fuel injected. But most turboprop aircraft have three levers. One adjusts the fuel flow, ...
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1answer
219 views

How heavy are turbofan and turboprop propeller blades?

How heavy are the blades from Turbofan (CFM56-5B, RRTrent800, PW4062A) and Turboprop (PW127M) engines? Is there a general appromixation like $$ m_\mathrm{Fan} = 0.1 \times m_\mathrm{Turbine} $$ ...
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Is a turboprop or a turbofan more eco-friendly?

If we compare them, which one wins? Why? And, what about CO2 emissions?
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What could cause lower torque than normal during cruise in a King Air 300?

At approx FL200 in our King Air 300 we experience a vibration and notice the torque drop for both engines. The torque stays about 10% lower than normal in cruise. The vibration is intermittent and ...
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1answer
712 views

Does the nose-up attitude of a jet make it more difficult to land than a turboprop?

Due to the more acute nose down attitude of a turboprop on approach, does this make it less difficult to control compared to the relatively high nose up attitude of a jet?
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How does the Pratt & Whitney Canada PT6 differ from other turboprop engines?

As far as I know, all turboprop engines have mechanical continuity between the engine and the propeller except for the Pratt & Whitney Canada PT6 family of engines. What is the correct term for ...
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Why is the generator turned back off for starting the second engine on a King Air?

The engine start procedure for the Beechcraft King Air B200 says (emphasis mine): Right Ignition and Engine Start Switch – ON [R FUEL PRESS] annunciator – OFF Right Condition Lever – LOW IDLE (...
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2answers
442 views

How do the compressor stages keep spinning after start in a free turbine?

In a ‘free’ (or uncoupled) turbine engine (specifically the Rolls Royce C20-250), what is spinning the compressor blades (N1) after start? It can’t be N2, because it’s a free turbine. I don’t think ...
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What are the major hazards in operating a PT6 Turbine Engine?

I am just in the process of doing a bit of study in the hope of doing my Basic Gas Turbine Endorsement in the next few months, and just wanted some feedback/comments/discussion on the major hazards ...
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738 views

How does propellers' pitch change during the use of reverse thrust in turboprop/propfan propelled planes?

Which way do proplellers turn during the use of reverse thrust in turboprop/propfan propelled planes: A) Do the leading and trailing edges of propellers remain the same or... B) Do the propellers ...
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What turbine blade alloy did the Jendrassik Cs-1 use?

Wikipedia says that the first turboprop aircraft engine was the Jendrassik Cs-1 invented in Hungary by György Jendrassik. It says it was supposed to run at 1000 hp but "combustion problems" limited ...
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Why is there still a preference for turboprop airliners over the new regional jets? [duplicate]

In the 1950s and in the early 1960s, jets were mostly available as fighter/military or big, long haul aircraft. Regional aviation was based primarily on piston aircraft that could operate in smaller ...
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1answer
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What happens when changing the throttle on a PT-6 engine?

Imagine a PT-6 in cruise flight. What would pushing the throttle forward for increased power show on the engine instruments? We know (I assume!) the prop RPM remains constant by varying the pitch, but ...
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Why does a turboprop lag?

Compared to a [modern] turbofan/turbojet, why is the throttle response slow in a turboprop? A constant speed propeller mounted on a piston engine responds much quicker. Is the underlying reason ...
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284 views

Do a turboprop’s compressor and turbine rotors windmill when the engine is shut down and feathered?

If a jet engine is shut down in flight, it continues to turn due to the aircraft’s forward motion forcing air through the engine, causing it to “windmill” in the airflow. Is this also true for ...
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What are the effects of an increase in altitude upon ESHP of a turboprop engine?

This is one of the questions in the ATP material: What effect will an increase in altitude have upon the available equivalent shaft horsepower (ESPH) of a turboprop engine? A) Lower air ...
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Where does fuel from the boost pumps go before engine start?

For example let’s take the PT6A-27. In every video related to engine start I see, the fuel boost pump is turned on, and then the fuel pressure goes up. Example: My ...
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1answer
327 views

How does the load transfer from a prop to the airframe?

I was just watching this video... Restoration and startup of a Wright 1820 Cyclone ...and it got me thinking: a propeller shoves back air, and this creates a forward force on the prop. The prop ...
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3answers
460 views

In a pusher configuration with turboprop(s), how is the superhot exhaust avoided?

I actually looked around for turboprops in a pusher configuration, and so far I only found one: P180 Avanti. You can see the propellers are behind the turbine, and in fact it looks like two exhaust ...
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1answer
824 views

Is there a modern single-seat turboprop?

There seem to be a number of tandem seat turboprop trainers like the PC-9/Texan and the Super Tucano. Are there any single-seat turboprops? I am asking about modern production planes.
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How much runway is needed for comfortable operations in a PC-9?

I am familiar with simple single engine props and twins and am thinking of moving up to turboprops like a Soccata TBM 700 or Pilatus PC-9. How much runway do aircraft like these need to operate ...
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1answer
179 views

What do these explanations for propellor RPM increases mean?

I have read in a book that if the engine RPM increases while descending, the probable causes are: Engine transfer bearing leaking excessively Excessive friction in blade bearings I am not able to ...
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How does this fuel pump work?

This question is about the fuel pump controlled by the hydro-mechanical fuel control unit. This is part of a fuel system for a turboprop engine, described on this page which actually comes from a ...
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459 views

Is turboshaft fuel efficiency affected by N2 loading?

When using a free power turbine turboshaft, does fuel burn get affected by N2 loading? I am asking as I want to in the future bench test a turboshaft for fuel burn, but I don't know if the loading ...
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1answer
321 views

How does the GE H75 eliminate the need for hot section inspections?

Operators of the Pratt & Whitney Canada PT6 will be familiar with the need for hot section inspections half way to TBO. General Electric is touting the lack of hot section inspection requirements ...
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1answer
801 views

Is the Cirrus SR22T a turbo-prop? Or does in just have a turbocharger?

Is the Cirrus SR22T a turbo-prop? Or does in just have a turbocharger like in a car?
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1answer
3k views

What is autofeather for?

What is autofeather and when is it used?
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Turboprop vs turbofan (in regional aircraft)

I'm trying to figure out WHY turboprops are more efficient at lower altitudes and airspeed, while turbofans are better at faster speeds and higher altitude. Simplistically, my explanation is the ...
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1answer
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FADEC or EEC for PT6-42A…is it feasible?

In a response to a You-tube clip showcasing Piper's M600 single turbo prop, a viewer dismissed it as an inferior engine compared to a GE (probably an H-80 series) due to lack of FADEC or Electronic ...
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536 views

Has the Beechcraft company considered building a single-engine turboprop?

I was passing a stack of magazines at a friend's office and I could have sworn I saw a cover article about a single-engine King Air. I went looking for that article and haven't been able to find it, ...
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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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why some airplanes have their exhaust gases vectored above the wing?

I was looking at images of the SkyCourier shown below and i have noticed the asymmetrical exhaust pipes in both engines (one pointing up and one is straight), doing my research on the internet, i ...
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1answer
4k views

How does a turboprop engine work? [duplicate]

I don't understand how it works, can someone provide me with details?
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What could cause an engine shutdown on a Q400 with CDS codes 732, 907, 915 and 938?

A Bombardier Q400 displays error code 938 on the Central Diagnostics System(CDS), which is attributed to turbomachinery chip detector. An examination shows debris in the detector hitch which is ...
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1answer
594 views

What is NH overspeed test and how it is preformed on DHC Q400 aircraft?

In the Aeroplane Operating Manual of DHC Q400 aircraft it is written that, at the time of normal engine shutdown, the engine system tests the NH overspeed circuitry by using it to shutdown the engine. ...
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1answer
314 views

For how long can a single-engine turboprop safely run the engine at idle?

Can a single engine turboprop (such as a Piper Meridian or TBM) allow idling long enough to drop off a passenger or package without shutting down the engine? If so, would the prop be feathered but ...
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1answer
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How to calculate the thrust of a piston or turboprop engine? [duplicate]

This spawns from a related question. Propeller-drive engines (piston/turboprops) seem to always list their output in horsepower or kilowatts, which are units of power. I want to know the engine's ...
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1answer
181 views

Can turboprops use a recuperator?

A recuperator is a device which extracts heat from the exhaust of a turbine and transfers it to the front air. This heats the air, which means the turbine uses less fuel to heat the combustion chamber ...
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1answer
2k views

Are turboprops less safe then jets?

On a recent trip to an airport, I noticed a large number of Bombardier Dash 8s. I wanted to know - are turboprops less safe than traditional jets like the 737 or A320? For instance, I would imagine ...
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1answer
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What happens when a propeller is placed in beta while feathered?

Could someone explain beta range to me? What happens when we set the throttle control lever to the beta range (reverse thrust) while the propeller blades are in the feathered position? Will the ...
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1answer
147 views

How big is the TP400-D6 turboprop installed on the A400M?

I am trying to re-create the A400M TP400-D6 engine in CAD, mainly the nacelle and propeller, yet I can't find any detailed dimensions for it. Europrop specifies a 0.92m diameter for the TP400-D6, so ...
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1answer
217 views

Could low pressure compressor blades be made of aluminum?

With the compressor blades on a gas turbine, could the low pressure blades be made of aluminum, or would it be catastrophic? Edit: Like the 6061 alloy.
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0answers
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Why use turbofan engines for high altitude flight?

I noticed that a lot of high altitude aircraft have turbofans for engines. So I researched and figured out that turboprop engines are more efficient. But most high altitude aircraft like the Global ...
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0answers
39 views

turboprop thrust relative to the jet's propulsion [duplicate]

What is the thrust ratio in a turboprop between propeller and its jet exhaust, and is the jet exhaust necessary for flight? Once the turbines are spinning, it seems the exhaust is waste product. This ...
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1answer
198 views

PT-6 Starting problems - PT6A - 67B, installed on a PC12

we are having trouble starting our PC12. After introducing fuel at stabilized 13% ng, the engine spools up very slowly - it takes forever to get through 20, 30, 40%ng. We've had several hung starts, ...
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3answers
155 views

Why do turbofans go faster than turboprops? [duplicate]

Can someone explain why turboprops are less effective in terms of thrust than turbofans? But at the same time, why turboprops burn less fuel? For example, the Bombardier Q400/De Havilland Dash 8 has a ...
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3answers
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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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1answer
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What is the highest service ceiling for turboprop airplane like a Cessna 425? [closed]

What is the highest service ceiling turboprop airplane, that is fairly small, like maximum of 8 seats, and fairly cheap as well, not going over a million dollars. I looked at Cessna 425, and this ...