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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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51
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2answers
204k views

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 ...
45
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3answers
17k views

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 ...
32
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14answers
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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) ...
30
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2answers
79k views

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?
26
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3answers
4k views

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 ...
26
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6answers
4k views

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?
26
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2answers
17k views

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?
25
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3answers
12k views

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 ...
24
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3answers
4k views

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 ...
24
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7answers
7k views

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 ...
24
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7answers
21k views

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
22
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3answers
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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 ...
22
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1answer
29k views

What are the differences between a helicopter engine (turboshaft) and an aircraft engine (turboprop)?

Given the fact that most helicopters nowadays use turbo shaft engines and many aeroplanes still use turboprop engines (which are essentially turbo shaft engines with a propeller), how do you ...
21
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2answers
4k views

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 ...
20
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4answers
4k views

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 ...
20
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3answers
5k views

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 ...
17
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7answers
37k views

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 ...
16
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1answer
2k views

How does a turboprop engine keep running during thrust reversal?

For thrust reversal after landing, a turboprop engine reverses blade pitch and blows air forward. But the engine itself requires air flow for the turbine. How can a turboprop engine keep running when ...
15
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3answers
5k views

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 ...
14
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3answers
48k views

What does feathering mean and how does it work technically?

Before I ask "What does Feathering mean when it comes to Jet/Propeller Engines" I have to say what I think I know: Feathering jet/prop engines mean achieving a sufficient turbine rotation speed at ...
14
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3answers
5k views

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 ...
13
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2answers
3k views

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 ...
13
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4answers
70k views

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 ...
12
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2answers
3k views

Can these vortices be dangerous?

There is a question related to this one right here but I'm more interested in the danger of those vortices. Are they very dangerous to cause a wake turbulence for the aircraft that comes behind this? ...
12
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5answers
4k views

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; ...
12
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2answers
3k views

Do turboprop and piston engines perform differently at higher altitudes?

When flying at higher altitudes, does it matter if you have a turboprop vs a piston engine driving a propeller?
12
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2answers
2k views

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 ...
11
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5answers
5k views

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 :)
11
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2answers
5k views

Why is the compressed air (from engine compressors) taken from High Pressure (HP) stage instead of Low Pressure (LP) stage?

An aircraft that uses Turbofan or Turboprop engines would be taking the compressed air from 3rd stage and 6th stage (varies) and supplying it to the Pressurisation and Air Conditioning Kit (PACK). ...
11
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2answers
3k views

What is this on the starboard engine of the Dash 8?

On the inside of the starboard engine of the Bombardier Dash 8 Q400 there is a small aerofoil shaped object* protruding from the casing. There also appears to be pipes protruding from the end of it. ...
11
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3answers
2k views

How is lift provided by a wing affected by propeller wake?

Does the lift of that section of the wing which is in the wake of the propeller increase (because the airspeed in that section is higher)? If yes, is this fact used actively to improve the lift ...
11
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1answer
989 views

On a larger airplane, how do they manage balance?

I have flown a bunch of times on a Bombardier Dash-8 Q400 on a couple of different airlines, and several times I have flown a shuttle flight that is basically empty. I have been instructed to change ...
10
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4answers
2k views

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?
9
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2answers
670 views

Why were turbojets the first kind of turbo-engines, instead of turboprops?

During WW2, the first jet engines appeared en mass in combat aircraft. Britain and Germany made the first ones. But why were turbojets first? Why not turboprops, which are easier since the turbo-...
9
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4answers
3k views

Where can I find detailed dimensions of an aircraft engine compressor blade?

I am currently working on the modeling of blade/casing interactions in aircraft engines. The work is carried out in partnership with a company, therefore, there is a limited amount of it that could be ...
9
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3answers
5k views

What happens when a turbo-prop is over-torqued?

What does one need to do when a turboprop engine gets over-torqued? I haven't over-torqued an engine before, but it seems it could happen inadvertently, say while doing a go-around. My questions ...
8
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1answer
447 views

Does the DC-3 have a prop sync?

I'd like to ask if the DC-3 has a prop sync. I found nothing about prop sync in the DC-3 operations manual, in the running specs, design features, or in the chapters about its engine and propeller. I'...
8
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1answer
1k views

How do intake deflectors work?

Some turboprop aircraft, for example DHC 6 Twin Otter have “intake deflectors” which should be engaged when taking off from or landing on unpaved surface to prevent foreign object damage. But how does ...
7
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5answers
857 views

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 ...
7
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1answer
477 views

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?
6
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1answer
16k views

Which are typical rpm values for aeronautical turbines?

I wonder which of these has higher or lower rotational speed: turboshaft turbofan turbojet turboprop Does anybody know the typical speeds for these kind of engines?
6
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1answer
582 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 ...
6
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1answer
2k views

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?
6
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1answer
3k views

What is the purpose of a reverse-flow orientation for turbo-prop aircraft?

If I decide to utilize a PT6 (ignoring for now the cornucopia of variants) as the turbine engine I will be using on my newly designed turbo-prop aircraft, do I then decide how I will orient the engine ...
5
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2answers
2k views

In turboprops, is there a mechanism to prevent the blades running in opposite direction?

Because, it might lead to reverse flow of air and could stall the plane. Is there some mechanism to prevent this? There was a crash in Ireland a few years ago, when the pilot of a small charter plane ...
5
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1answer
354 views

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 ...
5
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1answer
705 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?
5
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3answers
10k views

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 ...
5
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2answers
328 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 ...
5
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1answer
4k views

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, ...