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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Turboprop vs Turbofan: How to compare Specific Fuel Consumption

I understand that Turboprop engines have a lower Specific Fuel Consumption (SFC) than Turbofan engines, on average. I want to see this for myself by analysis, ideally by comparing values of SFC for ...
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Why are there no large turboprop passenger airliners? [duplicate]

If turboprop engines are more efficient than turbofan/jet engines at lower speeds, and have a lower specific fuel consumption, why are there no large passenger airliners that utilize the turboprop ...
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Is a turbocharged piston aircraft the same thing as turboprop?

Simple question, and I've always assumed that they are the same thing, but I'd like feedback from someone who knows more than me :)
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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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Would jet fuel for an F-16 or F-35 be producible during WW2?

I understand that different types of engines use different types of fuel, and as the description of the [jet] tag says, turboprops and jet engines use different types of fuel. So if – like in the ...
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What is the purpose of having contra-rotating props on an aircraft?

Why do planes, like the famous XF-11 and the Tu-95, have contra-rotating props? What is their purpose? Image credit: Mike Freer / Touchdown-Aviation / Wikimedia
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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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Why are propeller engines uncommon on airliners?

My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range. I assume that turboprop engines are more fuel ...
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How does turbine efficiency compare with internal combustion engines if all the turbine power is converted to mechanical energy?

It is widely know that early turbojets guzzled fuel and created thrust simply by spewing accelerated matter out the back. Modern jets have come a long way in earning a better reputation with ...
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What is the difference between a turbofan and a turboprop engine?

I'm not an aircraft expert and I just realized that there are two different terms - turbofan and turboprop. I always had them combined in my head as a term for a large jet engine (like you would see ...
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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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Why can't turbojets or turbofans be overtemped or overtorqued the way turboprops can?

Turboprops that aren't FADEC controlled can be overtorqued or overtemped if the power lever is moved too far forward yet I have never heard of a jet that can't be "firewalled", FADEC or not. Why is ...
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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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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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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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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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Which engine is more efficient between turboprop vs jet?

Are turboprops really more efficient than jets? If yes, does that mean that airlines who use jets sacrifice fuel for faster flights?
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Did the XF-84H Thunderscreech really cause “900 sonic booms per minute”?

The Republic XF-84H, known as the "Thunderscreech" was an experimental version of the F-84F Thunderstreak. It was intended to be a supersonic turboprop fighter. Even at idle, the prop tips rotated at ...
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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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Why don't small planes use turbine (turboprop) engines?

Turboprop engines are more fuel efficient1, lighter for the same power, mechanically simpler and consequently more reliable. They are also slightly easier to operate (no need to fiddle with mixture) ...
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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 is “Hotel Mode” on a turboprop engine?

I have heard that some aircraft that do not have an APU can run an engine in "Hotel Mode". What is hotel mode? Are there any advantages to having it instead of an APU?
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Which engine type requires the shortest take-off run: a turboprop or a turbofan?

If two fixed-wing aircraft almost identical except for the engines, one turbofan and one turboprop, which one would need less runway to take off?
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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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Why is the Tu-95 so efficient despite having propellers that spin faster than the speed of sound?

I've ready many, many times that propellers are not efficient near the speed of sound because it's so hard to get a tip-speed above Mach 1. Then I came across this: It's the Tu-95 "Bear", a ...
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Why do we refer to “power” for turboprop engines and “thrust” for turbojet/fan engines?

In jet engines, I read that thrust is related to the fuel flow rate, whereas in turboprop engines power produced is related to the fuel flow rate. What is the reason and brief math behind this?
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Why is the bypass ratio of a turboprop higher than turbofan?

Whenever, I come across turboprop, the author always mentions that they have higher bypass ratio than turbofan but no one explains the reason for this. So, is the bypass ratio higher due to higher ...
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Why aren't there any widebody propliners for the high-density short-haul markets?

Jetliners come in both narrowbody (one aisle) and widebody (two or more aisles) versions, but all propliners, to the best of my knowledge, are narrowbody aircraft. Now, granted, one of the big ...
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How to compare turboprop engines and with which values?

I have found this website that lists a lot of turboprop engines. I would like to compare them with as few values as possible. As an example, there are tons of different values that describe a jet ...
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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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Why would a turboprop rev down just before going full throttle during takeoff?

The only turbprop I've travelled is the ATR 72. I've noticed that the props' rev go down (for like a second, the sound also goes down) just before engaging full throttle in order to takeoff. I've ...
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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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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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Is it incorrect to refer to a C-130 as a jet?

In this article by CNN, the C-130 involved in the unfortunate crash in Savannah, GA is referred to as a "jet." Is this considered proper usage? I'm not looking for public opinion here but official ...
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What is the fastest single-engine civil turboprop aircraft with cabin seating?

I was having a discussion with some friends about general aviation aircraft with cabin-class seating. We were discussing cruise speeds and there were some "shop talk opinions" flying around about what ...
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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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Why the lack of faster piston-powered planes?

There aren't very many fast piston airplanes in production. By "fast" I mean, if you look back in the early to mid 20th century, before turbines won out, there were lots of piston airplanes in ...
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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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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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Why are turboprop intakes placed below the propeller?

On many turboprop aircraft, such as the A400M and the ATR 72, it seems that the air intake tends to be placed below the propeller (images: Wikipedia): source source Given that mounting the intake ...
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How long does it take for a propeller engine to spool-up?

To build further upon the question Why does a turboprop lag?, the following: Assuming a propeller engine is running in idle and the throttle lever is switched to full thrust instantaneously at t = 0 ...
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Is it possible to drive a prop directly from a jet engine without a gearbox?

I'm studying turbojets, turbofans, and turboprops. I can see that, for the latter engine configuration, a gearbox is necessary so that the propeller rotates at a lower velocity than the main ...
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Why would some flights use props instead of jets?

Two years ago I flew from Tel Aviv, Israel to Tromso, Norway via Riga and Oslo. The Tel Aviv-Riga leg was flown in an A320, and the Riga-Oslo and Oslo-Tromso legs were flown in prop planes, Fokker ...
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Is the Progress D-27 really a propfan?

On WikiPedia, the Progress D-27 is described as a propfan engine and the airplane it powers, the Antonov An-70, is described as propfan-powered. This Air&Space magazine article contradicts that; ...
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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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What prevents miltiary jets and turbo-props from being refitted with a turbofan?

What prevents military jets and turbo-props (such as P-3 Orion) from being refitted with a high bypass turbofan?
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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 does an aircraft as big as the Airbus A400M use turboprops?

Why is it that a plane as big as the C-17 (the A400M is slightly smaller though) use turboprops instead of turbofans? Both aircraft seem to have the same purpose and are both capable of landing at ...
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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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Given the same engine, why install a gearbox on a turboprop but not on a turbofan?

I am reading the book Mechanics and Thermodynamics of Propulsion, by Hill and Peterson. I found out this image while reading the chapter 5, "Thermodynamics of Aircraft Engines": Why would there be a ...