47 votes

Can these vortices be dangerous?

While @Peter Kämpf 's answer is great and sufficient to answer the question, I would like to add a clarification (which should be a posted as a comment, but is too long for this format). In the image ...
mins's user avatar
  • 73k
46 votes
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Would jet fuel for an F-16 or F-35 be producible during WW2?

Jet fuel is mostly kerosene, with some aromatic hydrocarbons mixed in for stability, temperature range and the like. You could probably run military jets on pure kerosene if they were magically ...
GdD's user avatar
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41 votes
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How does gas turbine efficiency compare with supercharged piston engines?

The most efficient IC engines are large Diesels. At the extreme end are ship engines with better than 50% thermal efficiency resulting in a specific fuel consumption of only 0.260 lbs/hp/hour or 158 g/...
Peter Kämpf's user avatar
41 votes

Is a turbocharged piston aircraft the same thing as turboprop?

They are both internal combustion engines that have a turbine in their exhaust that is used to power a compressor to pressurize the air before it is used for combustion. In the turboprop, the turbine ...
smithkm's user avatar
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40 votes
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Why do aircraft with turboprop engine have black painted anti-icing system?

These are rubber boot deicing systems. When ice forms on the leading edge of a wing, pressurized air is used to inflate the boot so the ice will pop off. Normally, this inflation is not permanent but ...
Peter Kämpf's user avatar
37 votes
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Why would a turboprop rev down just before going full throttle during takeoff?

Because the pilot is taxiing the airplane with the props in the beta range (turboprops turn into landsharks if you don’t do this and you end up really riding the brakes to keep the speed down), then ...
Romeo_4808N's user avatar
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35 votes
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Why do we refer to "power" for turboprop engines and "thrust" for turbojet/fan engines?

Ultimately what you want from all three types of engines is quantification of thrust available to push an airplane through the sky. The turbofan/jet engines are self contained and produce thrust ...
Pilothead's user avatar
  • 20.1k
34 votes

Why are turboprop intakes placed below the propeller?

Inertial separators are augmented by gravity when located under the engine. It is easier to discharge ingested ice and debris downward, rather than some other direction, so that is where they go if ...
Pilothead's user avatar
  • 20.1k
32 votes

Why would a turboprop rev down just before going full throttle during takeoff?

It's because he was taxiing in DISC (discing, or flat pitch making the prop like a big disc), which is in the ground beta range, then coming out of it. Beta range is a mode where propeller blade ...
John K's user avatar
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31 votes
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Why are propellers de-iced before the engines are started, and does ice on the fuselage affect the flight characteristics of the plane?

The props are done before starting because you need to make sure the blades and spinners are fully cleaned off while they are stationary. Otherwise, they'd vibrate like hell when starting and shed ...
John K's user avatar
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26 votes
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Why do propellors have white markings on their tips?

It is so you will see a circle when they are turning. Without contrasting bright tips turning propellers are invisible, and pose a grave risk for someone who is deaf, wearing heavy hearing protection,...
Michael Hall's user avatar
26 votes
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What is this indication on most turboprops?

This is the propeller synchronization (usually just called "prop sync") indicator, or "synchroscope." It rotates one way or the other to show the change in phase alignment of each ...
TypeIA's user avatar
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24 votes

Why do we refer to "power" for turboprop engines and "thrust" for turbojet/fan engines?

Jet engines directly produce thrust by exhausting gas (and in a modern turbo fan also moving a lot of air around them), so fuel flow rate is directly related to the thrust that is generated. In a ...
Dave's user avatar
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24 votes
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Why have propeller engines never been mounted on the tail in production transport aircraft?

There are two really big issues with tail mounted powerplants with propellers; weight distribution and Foreign Object Damage. Tail mounted engines move the empty C of G aft. This forces you to put ...
John K's user avatar
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24 votes
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What does the small needle + scale on this turboprop's N1 gauges indicate?

It duplicates the percent graduations in the large dial but at a finer resolution, with one percent increments. It's just to make the individual percent graduations easier to discern at a glance ...
John K's user avatar
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23 votes
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Why the lack of faster piston-powered planes?

The power requirement of an airplane grows with the cube of speed. When you fly fast with an airplane which needs to comply with a set minimum speed imposed by regulations, your drag coefficient is ...
Peter Kämpf's user avatar
23 votes

Is a turbocharged piston aircraft the same thing as turboprop?

No, a turboprop is more like a jet engine with a propeller in the front instead of a fan: Source: Wikimedia In its simplest form a turboprop consists of an intake, compressor, combustor, turbine, ...
Ron Beyer's user avatar
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22 votes
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Is it possible to drive a prop directly from a jet engine without a gearbox?

As a side comment, there is a type of engine researched in the 80's/90's, but never marketed, where an unducted fan is driven directly by the turbine shaft without a gearbox: The propfan. It's close ...
mins's user avatar
  • 73k
22 votes

How are turboprops and other propeller planes pressurized?

Turboprops are actually turbine engines. They can produce bleed air just like turbine engines (e.g. turbofan). The bleed air can be used directly to pressurize the cabin, or it can drive another turbo ...
bogl's user avatar
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21 votes
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Can these vortices be dangerous?

No. The wing does a great job in straightening the propeller swirl, but adds its own vortex. Wake turbulence is dominated by the flow field around the wing.
Peter Kämpf's user avatar
21 votes

Which engine is more financially economical to operate, a turboprop or gasoline engine?

Piston engines are significantly less expensive to operate, as long as the aircraft's performance and reliability requirements can be satisfied by a piston engine. It's not just the fuel, it's the ...
Therac's user avatar
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19 votes
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How are turboprops and other propeller planes pressurized?

A turboprop plane can be pressurized in the same way a turbofan plane can: via bleed air from the compressor stage of the turbine engine. A turboprop and turbofan are not that different actually. You ...
Bianfable's user avatar
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18 votes
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What is this on the starboard engine of the Dash 8?

It is the engine drain mast. From the Dash 8 Series 400 airport planning document - Chapter 2, Page 40: Dash 8 engine drain; image from Dash 8 Series 400 airport planning document Basically, the ...
aeroalias's user avatar
  • 100k
18 votes

Why do aircraft with turboprop engine have black painted anti-icing system?

They're not painted black, but a rubber (hence black) device called a de-icing boot. Upon entering icing conditions, the system once activated will repeatedly inflate and deflate the rubber boots. ...
Sanchises's user avatar
  • 13.3k
18 votes
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What is the danger in the over-use of reverse thrust during ground operations when operating a turboprop powerplant?

One concern is Foreign Object Damage (FOD). More reverse thrust means more dirt is thrown into the air, which can then be ingested by the engine: Damage to turboprop engines is not as common as in ...
Bianfable's user avatar
  • 55.9k
18 votes

What is the danger in the over-use of reverse thrust during ground operations when operating a turboprop powerplant?

We used lots of reverse thrust in the C-130; it was normal to go to full reverse on landing, and also to use some reverse thrust in order to back the plane into or out of parking spots. The two common ...
Ralph J's user avatar
  • 51.4k
17 votes

Why do turboprops not have a thrust value in the specifications?

Because the turbofan's thrust value is derived from the integrated fan unit that is part of the engine. It's all an integrated product of the engine manufacturer. A turboprop's thrust making ...
John K's user avatar
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