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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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1answer
107 views

Is there any recorded instance of a passenger's hat or scarf being blown into an aircraft's engine?

Passengers climbing the stairs into an airliner are often subject to gusts of wind; I've had to hold onto my own scarf in the past. It doesn't seem beyond the bounds of probability that a passenger'...
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0answers
47 views

Leasing costs engines and aircraft dry lease [on hold]

What would be the cost of a 3 year operational lease for two Boeing 737-800ng aircraft? Will this include the engines? question 2. What would be the cost of leasing two cfm56-3c1 engines to have the ...
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0answers
83 views

Experimental 4 seats diesel airplane with or without parachute(BRS) [closed]

Anyone knows any experimental 4 or 2 seats diesel airplane with or without parachute(BRS), experimental/kit or homologated?
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2answers
103 views

Is it possible to develop a quadcopter with F35 VTOL-capable jet engines? [closed]

I have little knowledge about engineering so it might be a stupid question but... Is it possible to make a flying vehicle that looks like a quadcopter but uses maybe two jet engines that suck the air ...
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0answers
41 views

Oultlet vane guides

I have looked around the web and I could not fine this information. How many vanes are there for the CF6-80 and the CFM-56? Is the count dependant on anything particular, such as fan diameter?
6
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2answers
368 views

Does the person directing the plane to parking not risk getting ingested by a jet engine?

According to answers in this post, a jet engine can suck a human into its engines, even on idle power. Aircraft use their engines post landing taxi and into their parking space, and I notice people ...
1
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1answer
108 views

Which is better a push fan, a pull fan or both

intricate examination of modern by pass jet engines is despite where it is mounted, they use a pull fan configuration to generate thrust, which set up the most efficient, a pull fan or a combination ...
5
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4answers
280 views

What are the advantages/disadvantages of in-fuselage engines (eg most fighter jets) vs wing/fuselage mounted engines?

Most modern jet fighter designs incorporate their engine(s) within the fuselage, while most other medium/large aircraft mount them either under the wings or on the rear fuselage. What are the ...
4
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2answers
127 views

Jet engine throttle-down time

Apparently airline jet engines lose ~80% of their thrust within 1 second after fuel is cut. However this seems to conflict with long throttle-down times noted in another question. This lead to a ...
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3answers
92 views

How to apply the TO/GA time and EGT limits?

If there is a published 1) EGT limit and a 2) TO/GA time limit, which one should be applied when the EGT is well below the EGT limit and possibly even below the 'max continuous' EGT. Particularly with ...
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3answers
96 views

How does the power distribution change for a turbofan engine from being stationary to going at full speed?

I have found out that a turbofan engine of say an F-16 is producing zero power when stationary since $Power = Thrust × Velocity$. But assuming that the engine is producing the same thrust, it appears ...
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4answers
2k views

Are taller landing gear bad for aircraft, particulary large airliners?

Buiding larger engines for larger aircraft as opposed to smaller but many engines has proved to result in more fuel efficiency. Having established one of the main drawbacks or impediments to building ...
3
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1answer
278 views

Does the P&W F100 turbofan engine of the F-16 really produce this much power?

I've been trying to calculate the power a P&W F100 engine on a F-16 is producing using some of the available data on thrust and velocity and I ended up with a number that I want to confirm. Here's ...
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1answer
97 views

What type of engine is mounted on the Cessna Citation Hemisphere?

What type of engine is mounted on the Cessna Citation Hemisphere? Image Source That does not look like a high bypass turbo jet engine. If its not a high by pass turbo jet engine, and given a high ...
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2answers
4k views

What features enable the Su-25 Frogfoot to operate with such a wide variety of fuels?

It is widely attested* that the Su-25 Frogfoot's engines (the Turmansky R-95Sh and later the R-195) were designed to function using a wide variety of fuels, including diesel, gasoline, petrol, ...
5
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1answer
192 views

Is it safe to mix different types of fuels in a jet engine?

Hypothetically, if: one got stuck somewhere at a remote airport the jet aircraft or airliner they are flying had a 1/3 tank full of the proper jet A1 fuel there was a tanker at the airport with 1/3 ...
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2answers
121 views

How long are the nacelle strakes on a GE-90?

For my school project, I'm doing something where I create a nacelle strake on a model plane and I want to make it to scale. Could you please let me know the dimensions of a nacelle strake? I would ...
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1answer
79 views

What are the major causes of flameout, excluding ingestion of foreign objects?

What are the most frequent causes of flameout, excluding ingestion of foreign objects and other sudden forms of damage to the engine? I'm limiting this to modern turbojet and turbofan engines with a ...
0
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1answer
101 views

Any unique characteristics to identify aircraft engine? [closed]

I love to find out the engine manufacturer and make, used in all of the aircraft I fly. Can anyone provide hints on how to identify an engine uniquely? The CFM56 on a Boeing 737NG is easy. It has a ...
18
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3answers
10k views

Why would a jet engine that runs at temps excess of 2000°C burn when it crashes?

Airline engines are designed to work at very high temperatures. Yet, when a plane crashes they're burnt (see below). Is it something in their design? (bostonherald.com)
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2answers
1k 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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0answers
132 views

Does any modern jet engine have blow-in doors, if not, why?

Are the blow-in doors concept on some engines like the JT3D used on modern jet engines, or not? If they are unusual, please explain why?
3
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2answers
257 views

What is that extended nacelle feature on the Honda HA-420 HondaJet?

Here is a picture of the Honda HA-420 HondaJet with strange extended engine housings. Why are they required? What are they for? I am not asking about the red covers, but the white engine housing ...
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2answers
155 views

Why Engine Exhaust Nozzle can not be totally buried in aircraft fuselage? [closed]

Why The CD nozzles of the fighter aircraft are always outside the fuselage, Why the whole engine is not buried in the fuselage?? If engine shroud also can be made variable area and varies with CD ...
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2answers
66 views

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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1answer
138 views

Are turbofans compensated for gyro effect?

In a multi-spool design is the gyro effect canceled or mitigated by having the two or more spools spinning in different directions?
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1answer
253 views

Why B-52 was not re-engined as a more efficient 4-engine? [duplicate]

Why B-52 was not re-engined as a more efficient (also for maintenance) 4-engine but is still an 8-engine aircraft? In history, almost all others models were re-engined with new engines also quite ...
4
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1answer
255 views

How difficult is it to design a high bypass turbofan given a military derived core?

Suppose one of the big-threes is given a military low-bypass turbofan core, how difficult would it be to produce a design centered around this core that matches the competitive performance of a ...
3
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1answer
164 views

Can a turbofan engine have less noise so that it doesn't disturb our ears?

A few years back I have seen that Pratt and Whitney 's Geared Turbofan Engine(GTF) has reduced it's noise levels to about 50%. But recently I was having a discussion with a friend and he told me that ...
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3answers
228 views

Is there a practical carbon-free jet fuel?

For example, when I want to use a small turbojet or low bypass turbofan as both the APU and bleed air supplier for blown flaps, ailerons, elevators, (like the ShinMaywa US-2 amphibious plane) and ...
17
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2answers
1k views

What is that CFM56 with a toothed exhaust on an A321?

I stumbled upon a wikimedia picture and I saw something that I have not seen before: a CFM56 with a toothed engine exhaust. Can someone explain to me what engine variant that is? Source Author: ...
2
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1answer
123 views

What is the aircraft in the 'Be Altitude' album cover?

In 1972, the Staple Singers released the "Be Altitude" album, which has them posing in a jet engine's intake. My question is what aircraft does that engine belong to? And why would someone let them ...
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2answers
834 views

Are centrifugal turbojets easier to make than axial ones?

Looking at the history of jet engines, I noticed that the British first made centrifugal-types, but the Germans went straight into axial-types. Which type is easier, if any? By that I mean, which ...
4
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2answers
180 views

What are the issues involved in converting a quadjet into a twinjet?

As you are probably all aware already, the fewer engines you have, the better your fuel efficiency; that’s why the airlines are selling off their (quadjet) 747s and buying (twinjet) 777s, why they’ve ...
3
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2answers
170 views

Why aren’t any JP-1-type (extreme-narrow-cut) fuels in use today?

JP-1 was the first U.S. military standard jet fuel (hence the 1 in the designation), with its specifications issued in 1944; it was an extremely narrow-cut, high-alkane kerosene, not far from what ...
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0answers
68 views

What is the minimum size of a ramjet?

Having recently learned that 155 mm ramjet artillery shells are now a thing, I wonder how much ramjet engines can be miniaturized. Could we see ramjet tank shells? Man-portable recoilless guns? ...
2
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2answers
206 views

How do bearings in a jet engine keep water out when it's been cleaned?

When a jet engine is running, it's generally immune to any liquid in the incoming air as the liquid would have been evaporated in the compressor. However, when the engine is being cleaned for carbon ...
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1answer
156 views

Who should design the nozzle of jet engines on aircraft?

There is a question in my mind that which company should design the nozzle of jet engine - the aircraft designer or the engine designer? If you watch this documentary: BBC Documentary Rolls Royce ...
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1answer
142 views

Why does the Convair 990 produce this howling sound during landing?

Watching this video of a landing Convair 990, one can hear a whooshing howl at about 0:11-0:12, as it flares just prior to touchdown (not to be confused with the run-of-the-mill howling that you can ...
26
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4answers
13k views

Why didn’t the Captain of Cathay Pacific flight 780 shut down engine 1 and land with a more reasonable speed?

In the approach phase, engine 1 of Cathay Pacific flight 780 got stuck at about 70% N1 and it forced the crew to do an overspeed landing (230knots). Why didn't they shut it off by turning the fuel ...
5
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1answer
421 views

Why Western fighters' afterburner glow is reddish orange while Eastern Bloc fighters' is blue?

Recalling what little physics I know, this could be explained by two factors: The blue color is given by the characteristic EM radiation of C-H bond breaking, C- and H- radicals forming and ...
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1answer
148 views

What percentage or airplanes have engines [closed]

I heard that some airplanes don't have engines. how many airplanes in the world have engines?
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1answer
150 views

Increase to Flight idle during start-up?

Ground idle takes about 5% of the total rpm, flight idle takes about 85% of the total rpm. Why is so much of the engine power wasted before it gets to flight idle?
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4answers
245 views

How is vertical speed managed in Airliners? [duplicate]

When an Airplane starts to take off, the Horizontal velocity would generate it the necessary lift, and then Airplane pitches up to further increase the lift. As the Airplane is climbing up, the net ...
3
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3answers
121 views

Would there be a purpose for a set of compressors in an electric turbo fan?

This is actually a two part question. Would there be a purpose to a compressor in an electric turbofan where there is no need for a combustion chamber, and if not, is there then a purpose for a bypass ...
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2answers
113 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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5answers
3k views

Why didn't Boeing or Douglas make a jet airliner before the British DH Comet?

I was looking at the history of commercial aircraft and was wondering why UK-based De Havilland was the first to produce a jet powered airliner (the DH 106 Comet) when the US had a much bigger civil ...
3
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1answer
191 views

What is the purpose of the pressure relief door fitted on the PW1127G-JM engines of the A320NEO?

Hey guys many times during my exterior walkaround I noticed on the A320NEOs that they have this pressure relief door and our SOP for the exterior walkaround states to check that this door is closed. ...
2
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1answer
148 views

Why is there a minimum altitude for at least some high-speed jet engine restarts?

While reading this other question about envelope constraints for jet-engine restarts, I noticed something odd in the graph provided (of the relight envelope for the Honeywell HTF7000 medium-bypass ...
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3answers
193 views

What are the advantages of using a ramjet in an air-to-surface missile?

Which are the advantages of using a ramjet compared to a rocket engine in an air-to-surface missile? I suppose the cost rises a lot, so why do some countries use ramjets as a way of propelling ASM ...