Questions tagged [inlet]

Also known as intake, is an opening that feeds air to an engine, air conditioning system, oil cooler, etc.

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What is the tapered cone on the B747 CF6 engine inlet cowling?

B747 and B767s are supposed to be using exact same GE CF6 engine, and as such their components are interchangeable including inlet cowl as they show to be effective in the IPC. However some of the 747 ...
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2 votes
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What are these holes on the intake of Progress D-18T which are mounted on AN-225?

I was seeing a Progress D-18T of AN-225 and saw these holes on the intake of them. What are they for?
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3 votes
2 answers
967 views

What is a ram recovery point?

As aircraft speed increases, thrust tends to decrease somewhat; as the aircraft speed reaches a certain point, ram recovery compensates for the losses caused by the increases in speed. The inlet must ...
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4 votes
1 answer
241 views

Why is there an intake in front of the landing gear on this C-160?

I went to a aircraft museum and saw this C-160, it has intake in front of the landing gear which is now blocked with the orange thing as you can see below in the picture below. Why is there an intake ...
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15 votes
1 answer
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What are those half-vanes in the engine inlet of a 707-328?

I just saw this: Source They look like IGVs but I'm not sure. What could those be? Do you know the engine?
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Does an increase in Mach number lead to a decrease in Total Pressure Recovery (TPR) for supersonic inlets?

I am curious if the total pressure recover for supersonic inlets, in general, decrease for an increase in Mach number.
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9 votes
1 answer
502 views

What are these four tubes for in the intake for an Extra 300?

The fuel-injected engine has six cylinders, so it's not a "per-cylinder" thing nor is it related to a carburetor. P.S. That screen is the entirety of the air filter. Apparently it's meant ...
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3 answers
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Are there aircraft with multiple inlets for a turbojet engine?

Are there aerial vehicles which have multiple inlets with air ducts (shaped in S-forn) , which all lead the air to one single turbojet engine? I have not enough space to put just one inlet area on my ...
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1 vote
1 answer
238 views

What is a typical range of air temperature used for engine inlet cowl anti icing?

So i was searching the internet for engine inlet cowl anti icing and found that usually compressor bleed air is used to prevent the ice formation in several parts of the aircraft. I am mainly ...
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1 answer
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Why is an air intake located on the root of the tail on some aircraft?

There is a small air intake on the root of the tail of some aircraft, especially those with engines near the end of the aircraft. What is it and why is it located there?
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3 votes
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Why do the intake of some helicopters have a bump body?

Not all but the intake of many helicopters have a bump body. Why? e.g.
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0 votes
1 answer
391 views

How to find capture area of an engine inlet?

I tried to relate intake pressure recovery in terms which do not involve efficiency of an inlet and capture area, i was able to formulate pressure recovery without intake efficiency but now i need to ...
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What would an inlet look like on a hypersonic aircraft? Would it be fixed or movable?

What would an inlet look like on a hypersonic aircraft? Would it be rectangular or like a cone (assymetric). Would it move and if so how?
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4 votes
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What is the purpose of a movable inlet on a jet engine?

I was reading that aircraft like the F-15 and SR-71 have movable inlets. What's the purpose of this? I was also reading aircraft like the F-22 doesn't have a movable inlet. Why?
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4 votes
2 answers
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Do nose cones work well at high angles of attack?

On a lot of fighter jets, I see a heavily slanted intake, such as the F-15. I always thought this is to help ingest air at high angles of attack. However, what about something like the MiG-21? There'...
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Why are inlet vanes used instead of variable geometry inlets to prevent compressor surge/stall?

Jet engine core axial compressors (that of subsonic turbofans anyway) are designed to keep air flowing the right way at max RPM(or close to it). Below that, the airflow slows more and more, and ...
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2 votes
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How hot is supersonic intake air?

How hot is the air at the compressor inlet at supersonic speed? For instance the Concorde at mach 2.2 or other jet engines at even higher speeds.
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1 vote
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Why did the dividing wall separating the engine intakes of early twin-engine Westland Wessexes cause difficulties with intake anti-icing?

The Rolls-Royce1 Gnome-engined variants of the Westland Wessex helicopter family (i.e., the twin-engined versions)2 draw air for both engines from a common intake (having been designed prior to the ...
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Considering a piston engined aircraft, what resistance pressure would be generated within its engine bay against its cooling intake?

Consider a piston engine with all its coolers and components within an aircraft engine bay. To cool this engine, cooling intakes are positioned facing the direction of flight. Now, the condition at ...
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13 votes
1 answer
3k views

What are these small engine inlets on the Super Hornet?

Does anyone know what these two small variable inlets on top of the engines are used for on the Super Hornet? Source: navy.mil; cropped
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Which Inlet Barrier Filter (IBF) is used in Airbus H145?

Inlet barrier filter (IBF) is an optional equipment in H145 / MBB-BK 117 / EC145 helicopters, which company Inlet Barrier Filters are used on them Donaldson, Aerometals etc.. The H145 Helionix / ...
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17 votes
1 answer
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Why do the 737-100's JT8Ds, and no others, have suck-in doors?

Of the various use cases of the Pratt & Whitney JT8D (the most-produced low-bypass turbofan in history, and the second-most-produced turbofan of any description1), those installed on the 737-100 ...
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6 votes
2 answers
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What is the purpose of the vertical splitter and the NACA duct at the MQ-9 Reaper engine scoop?

The engine scoop/intake on the MQ-9 features a vertical splitter at the inlet face, as well as another smaller NACA duct on the top cowl surface just aft of the inlet lip. I am guessing the former ...
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11 votes
2 answers
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How can an F-22 Raptor reach supersonic speeds without having supersonic inlets?

The F-22 Raptor and some other jets do not have inlet spikes, yet they are able to achieve supersonic speeds. How is that possible?
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0 votes
1 answer
900 views

How do you design a NACA intake?

What are the construction guidelines to geometrically build a NACA intake (submerged intake) for aircrafts? The relationships between the aerodynamic performance parameters (ram recovery, drag, and ...
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4 votes
1 answer
322 views

How is the flow of air through a NACA submerged inlet determined?

This question pertains to the design and/or selection of NACA submerged inlets. I am trying to understand what kind of airflow would enter a NACA submerged inlet/scoop and am looking for a good ...
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Why is the intake of the 757 (RR) engine slanted? [duplicate]

I'm sitting looking at a 757 with Rolls-Royce engines and just noticed that the intake is slanted forward by 5-10 degrees. Anyone know why? (wikimedia.org)
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7 votes
2 answers
2k views

Why do the inlet cones on an SR-71 retract at higher speeds while the one on a MiG-21 extends at higher speeds?

As shown by this illustration in the SR-71 flight manual, its inlet cones (spikes) retract as its speed increases: (source) Meanwhile, the Wikipedia page for the MiG-21 describes the opposite ...
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19 votes
2 answers
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Why is the S-duct intake on the Tu-154 uniquely oblong?

Is there an advantage to the oval/elliptical shape of the Tu-154's S-duct intake? It appears to be taller and an overall different shape than the side-mounted cowlings. This doesn't appear to be a ...
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5 votes
1 answer
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Why does a subsonic nacelle inlet have a throat before the diverging section?

Aircraft propulsion 2nd edition by SAEED FAROKHI" p.340 Aircraft propulsion 2nd edition by SAEED FAROKHI" p.123 As we can see from the image, the nacelle slightly converges towards a throat, before ...
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13 votes
2 answers
2k views

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

I have long been wondering what is the official name of this little air intake tube located in front of the fan blades and its intended functions. I did search it on google but it was in vain. I guess ...
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2 answers
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In turbojet engines, does the fan play a key role in the air intake to the inlet? [closed]

In turbojet engines, does the fan play a key role in the air intake to the inlet?
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1 answer
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How is the F-22's nacelle/engine bay ventilated?

How is the aircraft skin around the engine bay in the F-22 cooled? As in the F-35, there are scoops below the wings, which provide ram air around the engine bay, but you don't see any scoop around in ...
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0 votes
2 answers
186 views

How do engines cope with various intake airflow speeds?

On a recent trip out of Washington Dulles to San Francisco, our B777 met with 200+ mph headwinds (as per the passenger entertainment system) at 35,000 ft for the first half of the route, before ...
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4 votes
1 answer
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Do ramjets use variable geometry supersonic inlets?

Ramjets are very often portrayed as super simple, I've read on few occasions that the only moving parts in a ramjet are the fuel pumps. However, turbojets operating at similiar speeds (mach 2 - mach 3)...
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1 vote
0 answers
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How much lift can be generated by the intake lip of a duct?

How to calculate the extra lift gained by the intake lip of a duct? Aside from improving efficiency by preventing tip vortices, if a duct has a bell-shaped intake, this lip around the edge creates ...
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3 votes
4 answers
2k views

What drives the shape of an engine's intake on a fighter jet?

Rectangular intakes have more corners which might increase subsonic pressure losses and would weigh larger than a pitot (Semi-circular) type intake. Are the designer drivers solely based on supersonic ...
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28 votes
6 answers
7k views

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

I think I read once that they served to cool the on-board computer systems, but I'm not sure.
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6 votes
1 answer
264 views

How come diverterless supersonic inlets haven't been discovered much earlier?

DSI's seem like such an absolutely elegant solution to a problem that has, so far, been solved in a truly overly complicated way. So, if I'm not missing out on some important small speck of knowledge ...
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25 votes
3 answers
7k views

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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5 votes
2 answers
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How does a subsonic jet engine intake design ensure correct air intake?

I think I understand that inlets are there to slow down the airflow and increase the pressure to stop the compressors stalling?. If this is the case, I don't understand how the nacelle or intake ...
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2 votes
1 answer
786 views

What technical problems stopped scramjets from being used on hypersonic aircraft?

I have been researching hypersonic aircraft and scramjet engines after running a few calculations looking at ramjet/rocket hybrids for making single stage to orbit vehicles. After doing the analysis ...
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4 votes
0 answers
216 views

What different intake designs are there, and what are their pros and cons?

I noticed that over the years (on fighter jets specifically) there have been many different methods of directing air into the engines. Primarily, the nose-intake, side intake, and underbody intakes ...
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6 votes
1 answer
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How is the jet engine inlet danger area affected when airborne?

Boeing published engine hazard areas as shown below: I am curious as to how the danger area is affected when the aircraft is in flight as the jet engine is still vulnerable to foreign object damage. ...
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12 votes
1 answer
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What is the difference between side-by-side vs under-cockpit engine intakes?

What is the main difference between these two engine configurations? What are the differences between planes that have the intakes below the cockpit as compared to those who have them on the sides? ...
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11 votes
2 answers
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What is the function of the holes in splitter plates?

Do the holes in splitter plates reduce the boundary layer, or do they serve a different function such as acoustic/vibration damping? Many splitter plates have a series of holes drilled into the ...
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17 votes
2 answers
5k views

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

Look at the photo below. As you can see the intake isn't attached to the fuselage. Why? Other examples include the F-16, F-22, and F/A-18 Hornet. (F/A-18E Super Hornet Walk Around)
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1 vote
0 answers
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Why does intake of turbofan engine have angle of attack? [duplicate]

As you can see the title of the question, intake of turbofan engine has an angle of attack. why? see:
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10 votes
1 answer
5k views

Is the nose cone of the MiG-21 adjustable in-flight?

In some of the photos I saw of the MiG-21, the nose cone was extended and in others it was shortened. So, is the nose cone of the MiG-21 adjustable in-flight to allow for increased/decreased air flow? ...
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3 votes
1 answer
232 views

Does intake mass-flow rate vary linear proportional with turbine fan speed?

Is jet turbine intake mass-flow rate linear proportional with its fan speed (N1)?
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