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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
  • 20k
29 votes

What is this F-18 Hornet "air intake" for?

It's for keeping the boundary layer flow from entering the intake, it's called a splitter plate. I think it's done to prevent turbulence inside the turbine (prevent compressor stall) and to make sure ...
Francis L.'s user avatar
  • 2,524
28 votes
Accepted

What are those half-vanes in the engine inlet of a 707-328?

You have a very interesting find there! It is in fact not an engine from a B707, but a Kuznetsov NK-8 from Russia. It was used in Ilyushin Il-62 and Tupolev Tu-154 aircraft. As for the intermediate ...
Jpe61's user avatar
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25 votes
Accepted

If the intake of a running jet engine is blocked for some short duration what would be the sequence of events following it?

This explanation is for a subsonic aircraft, a similar process occurs at higher speeds. Causes A bird, an object or ice can disturb the flow of air entering the engine. Another source of compressor ...
mins's user avatar
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23 votes
Accepted

What are these small engine inlets on the Super Hornet?

These are the auxiliary air inlets for the ECS (Environmental Control System): (image source) They provide air to the primary heat exchanger (A18), which is then exhausted via the ram air exhaust (...
Bianfable's user avatar
  • 55.4k
16 votes

What is the difference between side-by-side vs under-cockpit engine intakes?

I wouldn't call the Su-27 small, but that is another issue. The main difference is the wing planform. The Su-27 wing is optimised to work over all angles of attack up to 120° with very little pitch ...
Peter Kämpf's user avatar
15 votes
Accepted

What is this tube in a jet engine's air intake?

That's the EPR inlet pressure sensor (there's another one located aft of the engine in the exhaust). EPR = Engine Pressure Ratio, one way to measure thrust. (source) See also: What is the ...
Karl Stephen's user avatar
13 votes

What is this F-18 Hornet "air intake" for?

EDIT: I'd just finished writing out my own answer when I stumbled across this answer to a different question, which nevertheless explains the function of the small intake in greater detail. I've ...
Cooper's user avatar
  • 2,375
13 votes

Why is the S-duct intake on the Tu-154 uniquely oblong?

This doesn't fully answer the question, but the B727-100 also had an oval engine intake. AIRLINERS magazine Sept/Oct 99 edition: "The oval shape inlet on the 727-100 series was changed to a ...
Mike Sowsun's user avatar
  • 37.7k
10 votes

If the intake of a running jet engine is blocked for some short duration what would be the sequence of events following it?

The compressor would stall. This will cause a sudden rise in turbine temperature, which could damage the turbine(s). In the end, with no air intake, the flame will die out and the engine would stop.
TulaSan's user avatar
  • 111
9 votes
Accepted

How is the jet engine inlet danger area affected when airborne?

Let's assume the A320 is powered by V2500 engines, one of the options for it. This engine has an air mass flow of 355 kg/s. At sea level, air density is 1.225kg per cubic m. Hence, 355 kg/s = 355/1....
Penguin's user avatar
  • 4,493
9 votes
Accepted

Why is the inlet cone on some subsonic engines conical (sharp)?

This is not an inlet cone as found on supersonic aircraft engines. This is a spinner used on subsonic turbofan engines, both the rounded and pointed one. Older engines used rounded ones; the JT8D in ...
Pilothead's user avatar
  • 20k
8 votes
Accepted

What is the function of the holes in splitter plates?

Do the holes in splitter plates reduce the boundary layer? Yes. Suction is applied to remove the slow-moving layer of air close to the surface, so the air entering the intake has as uniform a speed ...
Peter Kämpf's user avatar
8 votes
Accepted

How does a long inlet affect a jet engine's performance?

Long, winding intake ducts can increase the drag on the airflow moving through them, reducing the amount of air which the engine can ingest as opposed to a traditional diffuser design on a nacelle. ...
Romeo_4808N's user avatar
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8 votes
Accepted

Which supersonic airplanes use Pitot Air intakes?

A pitot intake will decelerate supersonic flow in one single, straight shock, while a ramp or cone intake will do this in several oblique shocks. It takes its name from the pitot tube, which in turn ...
Peter Kämpf's user avatar
8 votes

How can an F-22 Raptor reach supersonic speeds without having supersonic inlets?

The jet uses a fixed, rhombohedral shaped jet intake combined with a serpentine intake duct. It allows for speeds just north of Mach 2 without the need for a variable geometry inlet to prevent ...
Romeo_4808N's user avatar
  • 73.5k
7 votes
Accepted

What type of supersonic intake does the Dassault Rafale fighter jet have?

It is a pitot intake, and the round shape makes the intake tube lighter. It is a pressure vessel, after all, because the intake converts flow speed into pressure and slows the flow of air to the ...
Peter Kämpf's user avatar
7 votes

What type of supersonic intake does the Dassault Rafale fighter jet have?

The semi-ventral pitot air intakes is a compromise between Ventral and Side Mounting where the intakes and their ducts are placed on the lower corner of the fuselage. In order to prevent interaction ...
DSarkar's user avatar
  • 3,610
7 votes

What is this F-18 Hornet "air intake" for?

The intake is for the primary heat exchanger. secondary is on the other side, Same location. The ambient air flows across a large rectangular heat exchanger. Basically a air to air radiator for the ...
Shawn's user avatar
  • 71
7 votes
Accepted

Why do the intake of some helicopters have a bump body?

I don't know of the Apache, but the Russian helicopters have a dust separator there. This link shows how the dust protection system works on the Mi-17. The Mi-28 and Ka-52 have the same engines, so ...
Efe Ballı's user avatar
  • 1,179
6 votes

Why are the intakes of some fighters not attached to the fuselage?

The problem which this gap is solving has to do with boundary layer air as @ymb1 suggested but performance is not the only complication. Boundary layer is not only slower, in some regimes of flight ...
Anbu Agarwal's user avatar
6 votes

Why are turboprop intakes placed below the propeller?

I believe the main reason is simply mechanical practicalities. The bulk of the engine core is mounted overlapping the structural members of the wing, either below or above the wing spars. The ...
Robert Jenkins's user avatar
6 votes

What is the purpose of the vertical splitter and the NACA duct at the MQ-9 Reaper engine scoop?

Went to do some research after @niels nielsen's answer; the engine being used on the MQ-9 is the Honeywell TPE331-10. As Niels has rightly pointed out, the turboprop engine has its inlet facing the ...
tacitrb's user avatar
  • 141
6 votes

What is the purpose of a movable inlet on a jet engine?

Jet engines require the air that flows into them to be subsonic. Supersonic air hitting the front fan would cause shockwaves inside the engine, with undesirable results. So the job of the intake on a ...
Hobbes's user avatar
  • 10.2k
6 votes
Accepted

Why should the dust protection on the Mi-17 helicopter not be used above 3000m?

Anything that blocks or restricts flow to the engines will hamper performance. At low altitude, the aircraft has sufficient performance margin that this is acceptable. However, engine performance ...
Rob McDonald's user avatar
  • 9,181

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