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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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87 views

Difference between engine rev up and run-up

Explain please the difference between these jet engine terms: rev up run up Obviously they are completely different procedures. The reason I ask this question is because I'm not a native speaker ...
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0answers
32 views

What is a jet engine tolerance for a bird strike? [duplicate]

Similar questions have been asked ; a partial answer is in 14 CFR part 33-76, stating 16 small birds ( 85 g) must be tolerated . But what other qualification tests are there ; for medium and large ...
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222 views
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Does the auto thrust at takeoff compensate for asymmetric engine characteristics?

When a percentage thrust has been determined for take off the auto thrust system (Airbus) or the auto throttle (Boeing) will send the data to the engines FADECs to provide the required thrust. When ...
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2answers
126 views

Would a long pole help stablize a jet pack?

Jet packs are classically worn like a book-bag on the back. Would it be more stable if the exhaust ports were separated? Would the jet pack be easier to control if the turbines were at the ends of a ...
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1answer
212 views

Is it normal for a Boeing 757 engine to bounce under its fairing?

Earlier this week I was on a 757 flight from SFO to JFK and the right engine was bouncing under the fairing under mild turbulence, and really moving 2+ cm under moderate turbulence. Is that in any way ...
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1answer
168 views

How (often) are jet engines cleaned?

In the on-board magazine of my today's flight, there was a report on how fuel efficient the airline flies. They accomplish this by new scitimar winglets, daily optimized route planning, and regular ...
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2answers
120 views

What is the difference between an engine “shut down”, “cut-off” and “cut down”?

Explain please for non-native speakers the difference between these engine (jet or piston) terms: shut down cut-off cut down I'm studying at a civil aviation university to become a pilot and a ...
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2answers
113 views

Is it possible to overheat or damage the engine on an F-16?

The MiG-25 can supposedly damage its engines by commanding too much thrust and gaining too much speed. Somewhere around mach 3 damage to the engines is likely, I believe. What about the F-16? What ...
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4answers
3k views

Why do airplanes use an axial flow jet engine instead of a more compact centrifugal jet engine?

Axial flow jet engines take up a lot of space. Centrifugal jet engines create high pressure. Can you create a centrifugal air pump that pushes as much air as a axial jet engine. Centrifugal air ...
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3answers
4k views

Would jet fuel for an F-16 or F-35 be producible during WW2?

I understand that different types of engines use different types of fuel, and as the description of the [jet] tag says, turboprops and jet engines use different types of fuel. So if – like in the ...
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2answers
276 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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1answer
186 views

Are turbine and compressor blades and vanes cast or forged?

I was wondering how blades and vanes are typically made in commercial jet engines. Would you typically use investment casting to make compressor blades or just in the turbine section to accommodate ...
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0answers
113 views

Why use turbofan engines for high altitude flight?

I noticed that a lot of high altitude aircraft have turbofans for engines. So I researched and figured out that turboprop engines are more efficient. But most high altitude aircraft like the Global ...
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0answers
72 views

Can a protective mesh protect engines from bird strikes? [duplicate]

Can a protective mesh be installed on the front of the engines to stop birds from entering the engine and causing damage?
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2answers
8k views

Has a commercial or military jet bi-plane ever been manufactured?

Are there any, or have there ever been any commercial/military jet bi-planes? What would be some of the major advantages vs disadvantages if one was built? Electric radio controlled ducted fan model. ...
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1answer
179 views

How did this Vampire's takeoff damage the runway so much?

This appears to be real, but, what's the cause? Aircraft is a DeHavilland Vampire on takeoff from a small airfield, but the runway's surface disintegrates from jet blast Full file at https://i.imgur....
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1answer
114 views

How heavy are turbofan and turboprop propeller blades?

How heavy are the blades from Turbofan (CFM56-5B, RRTrent800, PW4062A) and Turboprop (PW127M) engines? Is there a general appromixation like $$ m_\mathrm{Fan} = 0.1 \times m_\mathrm{Turbine} $$ ...
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1answer
192 views

Why does the DC-8-70 have the same MTOW as the DC-8-60, despite its more powerful engines?

The DC-8-70 is a more-or-less straight reengine of the DC-8-601, replacing the obsolete JT3D-3B low-bypass turbofans of the DC-8-60 with the CFM56-2C1 high-bypass turbofan. According to Wikipedia, ...
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2answers
180 views

How to measure thrust produced from combustion chamber of Gas Turbine Engine?

I'm conduction a scale model experiment of thrust production in combustion chamber by using different types of fuel source. Comparing the thrust produced by using hydrogen gas, kerosene and petrol. ...
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1answer
133 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
43 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?
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2answers
436 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 ...
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1answer
118 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 ...
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4answers
301 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 ...
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2answers
135 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
104 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
107 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 ...
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1answer
339 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
107 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, ...
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1answer
213 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
128 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
114 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 ...
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1answer
118 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 ...
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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
142 views

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

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?
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2answers
272 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
171 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
71 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
143 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
309 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 ...
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1answer
265 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 ...
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1answer
173 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
241 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 ...
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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: ...
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1answer
137 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
882 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 ...
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2answers
201 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 ...