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Questions tagged [jet-engine]

Engines which propel aircraft via "jet propulsion", i.e. by expelling high-velocity gasses (usually primarily air) through propelling nozzles.

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3answers
741 views

Is it practical to integrate turbofan or ramjet engines into an airliner wing?

The de Havilland Comet had turbojet engines integrated into its wings, such that its nacelles were mostly flush with the wings like so: (wikimedia.org) I recognize that turbofan engines are ...
4
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1answer
2k views

How does the FADEC prevent compressor stall during rapidly increasing thrust demand?

My understanding is that if the demanded thrust is increased rapidly on a jet engine (for example going from nearly idle to TOGA during a go-around), the engine will likely experience a compressor ...
12
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1answer
276 views

Did some early jet engines catch on fire at higher power settings?

Recently I've being playing some IL-2 1946, and in this flight simulator jet engines had a strange problem where if I suddenly throttle up more than 60% the engines would catch on fire. Is this a real ...
13
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2answers
968 views

Why are the B-52 thrust levers advanced inside-out?

As I understand, the standard procedure for advancing the throttle (for take-off) is as follows: Advance throttle to desired engine input & output (N1 & N2) Release brakes Gradually increase ...
0
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2answers
215 views

Can heat from the engine inlet be used to produce thrust?

As the engine inlet temperature increases, Is more heat energy provided by air? if yes then can we utilize that heat energy to produce more thrust?
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1answer
67 views

What is the link OR difference between change in momentum & pressure difference?

I ask in regards to the the thrust formula, which includes change in momentum, as well as difference in pressure between inlet & outlet of the engine to calculate generated thrust; this implies ...
1
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1answer
512 views

Does an increase in inlet temperature affect fuel flow and power output?

The fuel flow rate decreases as the inlet temperature of the air entering the engine increases. Will the engine produce same amount of power as when the fuel flow was higher?
3
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1answer
603 views

Why does lower atmospheric pressure produce higher EPR (thrust)?

Recently, I read manual about engine, PW JT8D-217A/C, and there is a chart making me so confused. Manual show the reference table tells you what number, EPR, is normal in specific temperature and ...
3
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1answer
426 views

Is hypersonic flight possible with a Busemann's Biplane?

The modifications to the Busemann's Biplane design reported in this article have proven that it is possible to design a modified Busemann's Biplane wing design that actually produces lift at ...
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5answers
2k views

Is water a possible fuel for jet engines?

Jet engines can run on almost any fuel, and the operating temperatures of modern jet engines' hottest sections are anywhere between 3000 and 3150 degrees F (1648 and 1732 degrees Celsius). Does that ...
0
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1answer
298 views

Bypass ducts and spinning blades [duplicate]

I want to start out by saying these questions will make me look a fool but i simply haven't found answers for them anywhere so i'm hoping you could help me! What is the purpose of bypass ducts? If ...
5
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8answers
4k views

What would be the drawbacks of using a rotating engine as thrust reverser on airliners?

What are the drawbacks for having engines mounted on an aircraft such that their direction can be hydraulically controlled for best performance and efficiency? The idea would be to turn the engine 180 ...
5
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3answers
711 views

How much weight does a thrust reverser add?

How much weight does a thrust reverser add to an engine? Let's take the CFM Leap 1B as an example, which powers the new version of the Boeing 737. This engine can produce up to 130 kN of thrust for ...
17
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2answers
6k views

Where is the generator in a large turbofan of a commercial airliner?

So, where do you put the electrical generator? If it's gonna be coaxial, the only place is the rear (it will be burnt) or the front (it will get in the way of intake). If it's gonna be coupled to a ...
4
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2answers
598 views

Are there turbofan/turbojet analogues to a centrifugal-compressing jet engine?

Axial-compressor jet engines fall into two categories (and only two as far as I'm aware): turbofan and turbojet. I'm wondering if centrifugal-compressor jets also have such a distinction or something ...
8
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2answers
428 views

Will manually removing nicks from compressor blades significantly affect the operation of the compressor?

I've recently found a channel on Youtube where a jet engine technician goes into great detail about the work he does on maintaining and repairing jet engines In this particular video (and also an ...
5
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2answers
529 views

What is the operating temperature of a turbo bypass engine, and how is it kept at that temperature?

What is the operating temperature of a turbo bypass engine? If advancements were made to materials through material science for the internal components would increasing the operating temperature ...
5
votes
1answer
842 views

What fraction of air intake becomes bleed air in airliner engines?

Gas turbines typically bleed air from the late compressor stages. Some of this air bypasses the combustion chamber and is expanded through the turbine to prevent the blades from becoming too hot. I ...
4
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1answer
699 views

What is the longevity and replacement schedule for turbine engine blades?

I'm trying to understand how frequently hot section turbine engine blades are changed out. Is this a calculation based on flight hours, material, engine size or maybe something else? Apologies if ...
7
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3answers
1k views

Can a jet engine benefit from nitrous oxide boost?

I just read this wiki article again about the GM-1 boost system. This was used in Nazi planes during WW2. It injected Nitrous Oxide (N2O) into the supercharger of the piston engine. The idea was to ...
1
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1answer
188 views

Viability of Magnetically started engines [closed]

I am working on a school project of mine which involved testing the viability of a magnetically started jet engine. By magnetically started, I mean that there are magnets which accelerate the main ...
5
votes
1answer
445 views

How do the engines of a multi-engine airplane shut down after fuel starvation?

If a multi-engine aircraft runs out of fuel, can the engines flame out at different times due to fuel inequality between the tanks, or do they both die at the same time because fuel is constantly ...
7
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2answers
3k views

How common is engine failure?

What are the failure rates for piston, turbine, and jet engines? (If more subdivisions of "engine" are necessary to make the data useful, please point them out).
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2answers
4k views

Why do jet engine fan blades have a twisted shape?

is this a good answer. the blades rotate, the tip moves faster than the hub. So to make the blades efficient, the blades are usually twisted. The angle of attack of the blades at the tip is lower than ...
6
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1answer
245 views

Since when are ground-based starting devices no longer in common use? Are there any jetliners flying that would still require them?

Nothing is written in Wikipedia on how the engines of the De Havilland Comet or other similar airliners were started. However, it seems that aircraft of this generation could not start the engines ...
5
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3answers
989 views

Which engine(s) do airliners taxi with? [duplicate]

I have read that pilots only taxi on 1 engine to save fuel. Which engine does a twin engine jet such as a 737, 777, a320 or similar use to taxi? Left or right, or does it vary by pilot or some other ...
8
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3answers
3k views

Why weren't the Airbus A330 engines designed with a system to stop their fans?

Why wasn't the Airbus A330 designed to stop its fans (with some kind of 'handbrake')? To clarify, I am specifically talking about the aircraft that flew Air Asia flight D7237. During the flight the ...
2
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2answers
306 views

Could an airliner get better fuel efficiency at higher altitude? [duplicate]

By higher I mean like 60k feet instead of 30k. Seems like the rate limiting step is engine performance at 60k feet. Are people working engines that can operate at higher altitudes? How close are we ...
2
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1answer
243 views

What is the equivalent of Hobbs and Tach in a Jet or Turbine Aircraft?

As a piston pilot I am only familiar with tracking hours for my pilot log book and maintenance log book using the Hobbs and Tach times. Can someone tell me what the equivalent is for a Turbine and ...
19
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5answers
3k views

What does the area around the fan blades in the engine nacelle contain?

I was intrigued to find this picture below. There was so much space around the engine. So what is inside of that extra space? Or is it just a hollow casing? Image Source Details about the picture as ...
3
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0answers
86 views

Why aren't plane engines mounted closer to each other or closer to the fuselage to reduce extra forces on the wings? [duplicate]

Why aren't plane engines mounted closer to each other or closer to the fuselage to reduce extra forces on the wings?
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0answers
137 views

Why is EGT decreasing on a jet engine when the generators cut in?

Is the EGT decrease related to the generators cutting on or is it related to the fact that the fan is now providing enough ventilation air for the engine?
12
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1answer
764 views

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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0answers
87 views

What are the differences between the proportional flow control FCU and pressure control FCU?

what are the basic differences between the proportional flow control FCU and pressure control FCU? ( FCU : fuel control unit )
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2answers
187 views

Does the compressor stationary vane have stagger angle?

Does the compressor stationary vane have stagger angle? ( stagger angle is the angle between chord of the blade or vane with engine's longitudinal axis )
4
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2answers
184 views

In what direction(s) is any debris typically ejected from a jet engine in the case of failure during flight?

Has there been evidence of ejected material striking the fuselage or other parts of an aircraft forward of the engine itself? Which of the various forces acting on rotor blades dominates the ...
7
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5answers
2k views

Can a human be blown away by jet engines of an A380?

Can a human be blown away by jet engines of an A380 at full throttle? If so what is the largest object that it can blow away and cause significant damage? Can it blow away another parked Airbus A380 ...
11
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5answers
6k views

Is it possible to upgrade a Boeing 747-8 and Airbus A380's engines for greater speed?

Is it possible to upgrade the Boeing 747-8 and Airbus A380's engines (upgrading to a newer engines) for greater speed, if the engines were more efficient and used less fuel at higher speeds relative ...
4
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2answers
390 views

How do aircraft engine manufacturers achieve a higher bypass ratio while still meeting the thrust requirements for a given aircraft?

I understand that a higher bypass ratio leads to greater efficiency as less air moves through the core, and therefore less fuel is burned. However, how is the thrust requirement for the same aircraft ...
7
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1answer
398 views

Is this an accurate depiction of the internal shape of a turbofan engine?

This image (so commonly used here that the first image reference for it that pops up in a Google search for "jet engine diagram" points back to ASE!) From Wikipedia Shows the housing of the actual "...
10
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1answer
2k views

What causes the distinct sounds of a jet engine?

I live a few miles from a major airport (BOS), under the path that a lot of airplanes use to depart. The planes are somewhat low over my house -- high enough that it's not deafening, but low enough ...
5
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1answer
658 views

Which type of jet leaves black trail at cruising altitude?

I was recently travelling to Morocco, and as I was sitting by the window, at some point mid-flight I noticed another jet travelling in opposite direction at our altitude. The reason I noticed it ...
7
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3answers
1k views

How is a turbine engine rotated for starting and inspections?

I'm doing an assignment for my Level 3 Aeronautical Engineering course and stumbled on this question and I can't seem to answer it (we have had no teacher for 4 months and therefore we have to learn ...
4
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4answers
832 views

Is it possible (not practical) to create a liquid nitrogen jet?

Would it be possible (though not practical) to create a jet that runs on liquid nitrogen that is heated, creating the expansion effect? I believe nitrogen takes up 674 (about) times as much space in ...
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1answer
308 views

Why does gas turbine engine have pressure oil supply tube and the scavenge oil tube?

What is the function of pressure oil supply line tube and the scavenge oil tube on turbo shaft engine?
5
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2answers
358 views

What fuels can turbofans burn?

I know that Jet-A is the fuel most often used for turbofans, but is there something else that these engines can burn? (ethanol, LPG, methane, butane, 100LL, etc.) Basically, can a turbofan burn ...
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2answers
773 views

I don't quite understand the bypass air [duplicate]

I am writing an essay on how a jet engine works, so I need specific answers on this. What percent of the air that is sucked into the engine is bypass air? I have heard that bypass air provides about ...
0
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0answers
79 views

Are there any performance details available for the D8 Double Bubble engines?

For the D8 Double Bubble, what are the thrust requirements for the engines? Has it been stated what the estimated max thrust will be for each engine? Source: sputniknews.com
4
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2answers
837 views

What equation describes the relation between engine thrust and EPR?

What is the formula for engine thrust as a function function of engine pressure ratio (EPR)? If the EPR is lower than 1, is the engine producing thrust? For example during descent, when the engines ...
26
votes
7answers
5k views

Why bother having different engine options on one aircraft?

When an airline purchases a new passenger jet, they often have a choice of engines (from different manufacturers). Why is this? I would expect that one of the engine options is "best" and that all ...