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

2
votes
1answer
58 views

What is the Specific Fuel Consumption of CFM56-7B24/26/27 engines?

I think the title completely says what I need. I use FSX (Flight Simulator X) to simulate flights and while flying the B738 I saw that it consumes much more fuel than the estimated amount, which is ...
-1
votes
1answer
72 views

How is pressure kept nearly constant in jet engine burner? [duplicate]

How do engineers make sure the pressure doesn't rise, but velocity does. I have no idea how that can work, please help!
31
votes
7answers
9k views

Have there been any incidents caused by an inability to shut down an engine?

I read many items on the avherald.com site where it says "engine shut down during flight" or words to similar effect. I'm wondering if there are any instances where an engine could not be shut down ...
0
votes
0answers
77 views

How does a partially covered air intake affect the thrust of a propeller ?

does a partially covered air intake of a ducted propeller significantly affect its thrust? If so, will it be like 10 or rather 90 percent less thrust ? Thanks for your answers! Simon
16
votes
3answers
3k views

How much water is produced in jet exhaust?

If a jet has typical combustion efficiency, what equivilent amount of liquid water will be created per gallon of jet or kerosene fuel. An acceptable answer can be a ratio in weight or volume to the ...
0
votes
1answer
128 views

Could the reversers of a PW4000 on a 777 be deployed in-flight? [duplicate]

Could the thrust reversers accidentally be deployed during a flight? Here, I’m referring to the PW4000 series on a B777, where the engine is similar to the type involved in the crash of Lauda Air ...
0
votes
1answer
171 views

What is the cause of cracking and corrosion in Trent 1000 engines?

According to this description and this one of some Trent 1000 engine problems, there appears to be a problem with cracking/corrosion of the fan blades, but does anyone have any insight as to why this ...
1
vote
1answer
79 views

Could a kerosene fueled jet engine run on methanol without significant modifications? [duplicate]

Could a kerosene fueled jet engine run on methanol without sacrificing performance other than specific impulse? Would it require changes to the fuel injection/turbopump system? Would the combustor ...
0
votes
0answers
50 views

How does a mixer reduce noise in a turbofan engine?

I want to know how does a mixer reduce noise in a turbofan engine? How does its shape influence the flow and the acoustics of the output air generally?
1
vote
0answers
64 views

Do plug nozzles improve efficiency on lower throttle settings?

Plug nozzles are used to adjust for the overexpansion/underexpansion of the exhaust with altitude. Do they also adjust for overexpansion/underexpansion of the exhaust caused by lowered mass flow ...
6
votes
2answers
243 views

What exactly does the MB-326's 'relight' button do?

The following picture shows the engine throttle of an Aermacchi MB-326, which is powered by the Rolls-Royce Viper turbojet: (source - all photos © Drive&Fly Model Club) I wonder what exactly the ...
1
vote
1answer
172 views

What is the relationship between EGT, Fuel Flow, N1, N2 and Air Temperature?

I initially wanted some sample data for EGT, Fuel Flow, N1 and N2 to build a prognosis system that predicts engine failure (ECTM). I searched for some sample data online but got to know that there's ...
1
vote
0answers
44 views

Single Engine operation on Twin Engine aircraft [duplicate]

I recently came across ETOPS and I wanted to know: How does a twin-engined aircraft balance out the lack of thrust on one side in the event that one of the engines is non operational? Any ...
-1
votes
1answer
58 views

How does ice affect the combustion systems of jet and piston aircraft engines? [closed]

What are the effects of ice on a jet and piston aircraft engine? I've tried Google but I'm not satisfied with the results.
0
votes
2answers
313 views

Does Rolls Royce produce any engine that matches the capabilities of the GE9x?

Does Rolls Royce produce any engine that matches the capabilities of the GE9x? If not, does Rolls Royce have any public plans for such an engine in the future?
13
votes
1answer
2k views

What is this aircraft that has both piston and jet engines?

A friend sent me this picture of a trimotor aircraft with what looks like two radial engines and a jet in the middle. He didn't know what is was and neither do I. Anyone recognize it?
2
votes
2answers
238 views

Can current fighter jets perform a deadstick landing?

If a current modern day fighter were to have a total engine failure over a suitable landing site or airport, can the pilot safely perform a dead stick landing? If so, are they routinely given training ...
6
votes
2answers
181 views

How do engine manufacturers derive varying amounts of thrust from a single engine model?

What changes do manufacturers make to an engine to vary the amount of thrust it produces for different applications? Take the GE CF34 for example where there is a 10780lb difference between the thrust ...
2
votes
1answer
49 views

How can you explicate the efficiency of a turbofan engine with Carnot's theorem?

From Carnot's theorem, we know that efficiency is $$ \eta = 1-\dfrac{T_c}{T_h}$$ where $T_c$ is the temperature of the cold reservoir and $T_h$ the temperature of the hot reservoir. But what do we ...
-1
votes
1answer
177 views

How much air does a GE90 ingest at sea level and at cruise level per meter?

I just wanted to know how much air PER METER a GE90 turbofan engine sucks in considering the same thrust output at different altitudes to better understand how the engine can travel further while ...
3
votes
2answers
112 views

Why do compressors constrict flow if this decreases pressure?

An axial compressor (and a ramjet intake, for that matter) is commonly depicted as decreasing the volume of air travelling through as we move closer to the combustion chamber. In axial compressors, ...
2
votes
1answer
180 views

Why are jet engine nacelles, used on the same plane, so different? [duplicate]

One thing that is plainly obvious about the design and configuration of jet airliners is how little they tend to differ. It's surprising then that even on the same airliner, you will see two quite ...
1
vote
1answer
126 views

Why are most turbofans tractors, but most propfans pushers?

Turbofans and propfans are, in concept, quite similar: both have a turbojet core, plus one or more additional turbine stages that drive a fan(s) which blows air around the core (this is known as ...
1
vote
1answer
133 views

What prevents DC-9 series aircraft from being reengined with more-efficient engines?

All DC-9s except for the MD-90\B717 series use old, inefficient Pratt & Whitney JT8D series low-bypass turbofan, even the best of which has a paltry 1.74:1 bypass ratio. We know that a DC-9 can ...
3
votes
3answers
142 views

How does the nozzle diameter affect the thrust of a ducted propeller?

I currently do some experiments with ducted propellers in which I try to figure out which effect a nozzle has on the thrust produced. My theory goes like this: If I reduce the exit diameter of the ...
5
votes
3answers
211 views

What is this tab above the DC-10's #2 engine? [duplicate]

What is this big rectangular tab (?) thingy extending backwards just above the DC-10's #2 engine? What does it do? (wikimedia.org, picture modified to point out the tab thingy)
0
votes
2answers
209 views

Could two GE9x engines power a 747? [duplicate]

These new GE9x engines are huge and extremely powerful, but could two of them power a B747–8? It is possible for some engines to power the original 741s but I am mainly interested in the B748.
4
votes
1answer
215 views

Is “laze” (lava + haze) as hazardous as volcanic ash to turbo engines?

Reading an article about Pahoa, I read that erupting Hawaiian volcanoes produce a combination of lava and haze - resulting in clouds that contain hydrochloric acid. Are these as dangerous as ...
1
vote
1answer
193 views

What happens during Engine Performance Restoration

What is the typical process during an Engine Performance Restoration? I am trying to find a resource that gives an overview of what happens but I have not been successful. Any help would be much ...
1
vote
4answers
181 views

How bad is the efficiency of jet engines under low loads?

VTOL operations need 4-5 times more thrust than a conventional take-off of an aircraft. If you don't want to install additional lift-engines into a hypothetical aircraft and use thrust vectoring to ...
0
votes
1answer
179 views

Why does an Exhaust Gas Temperature (EGT) gauge require a power source?

Why does the EGT gauge on jet engines require bus power if thermoelectric voltages generated by thermocouples are sufficient to move the needles?
-1
votes
3answers
236 views

Why should pilots keep the engines running so they are hot or warm immediately after landing?

Understandably, airliner pilots - particularly those operating in extremely cold climates and airports - should preheat the engine at idle for 3 minutes or more so they do not apply full thrust and ...
30
votes
7answers
19k views

Why don't 747s use unreliable, but cheap, jet engines instead?

I'm a neophyte who was reading a little bit about jet engines, and the economics behind them. In particular, I was curious about what makes jet engines so expensive compared to piston engines. A ...
0
votes
0answers
30 views

What is a Compressor Stall and what is the main cause of it? [duplicate]

What is compressor stall when does it happen and what is the main cause of it is it dangerous ?
1
vote
3answers
305 views

What are the consequences of throttling up past 100% of N1?

The B737 is probably my favorite aircraft and I'm always sure to never throttle past 100% of N1. I was told the aircraft is pretty much totaled if you take N1 past 100% but you can eke out that extra ...
9
votes
2answers
2k views

Which jet engines have the highest thermal efficiency?

Some automakers (Mercedes-Benz, Toyota) have recently been making news about the improved thermal efficiency of their engines, stating that they reached the 50% mark. I was wondering if it was the ...
7
votes
1answer
296 views

Are engine casings expected to contain turbofan blade fragments?

On Southwest 1380, initial indications are that a fragment of the engine blade pierced the engine casing, which then hit the airplane window (or perhaps a part of the casing did). According to the BBC,...
2
votes
2answers
174 views

What were the make and model of the engine that failed in flight Southwest 1380?

Regarding the tragedy of Southwest 1380 flight on 2018-04-17 involving an engine failure, what company manufactured that engine, and what engine model/type was it?
8
votes
2answers
248 views

What is purpose of engine pylon airfoils on the Hondajet HA-420?

The engine pylons on the Hondajet are aerodynamically shaped so as to provide a lift force laterally and outwardly. Engine pylon as viewed from rear Engine pylon as viewed from front Are these for ...
1
vote
1answer
362 views

What are the advantages of 3 spool over 2 spool turbofan engines? [duplicate]

What are the advantages of 3 spool over 2 spool turbofan engines?
34
votes
1answer
7k views

What exactly happened in this bird strike incident?

This Boeing 737 was hit by a bird and continued all the way to its final destination, from Prague to Las Palmas. What actually happened here? Was the incident considered a bird strike or an engine ...
1
vote
1answer
66 views

What are “referred” speeds and “referred TET”?

i'm currently reading the Rolls Royce publication The Jet Engine. It makes reference to "referred speed", "referred TET" and "referred mass flow". Referred speed seems to be defined as N/sqrt(T). I ...
2
votes
3answers
296 views

What does RPM mean in a propellor aircraft, compared to a jet aircraft? [closed]

What is the practical significance of speed RPM in a propeller aircraft for a pilot? I am not able to correlate it with RPM in jet engines?
8
votes
1answer
369 views

How an Engine thrust changes with airspeed? Why?

I'm interested in how the thrust of a turbofan engine is affected at higher airspeeds (TAS). I know (I believed) that engine thrust(at constant N1) was relatively constant like in the following graph (...
0
votes
0answers
74 views

What is the inner diameter of the nozzle cone on the Trent 1000 engine?

Since the nozzle diameter shown is 63 inches, so what is the diameter of the one inside that circle? Need it for my project to find the actual size of nozzle
1
vote
0answers
83 views

What could cause an engine shutdown on a Q400 with CDS codes 732, 907, 915 and 938?

A Bombardier Q400 displays error code 938 on the Central Diagnostics System(CDS), which is attributed to turbomachinery chip detector. An examination shows debris in the detector hitch which is ...
5
votes
3answers
3k views

Why don't most military transports use modern commercial engines?

Why don't most military transports use modern commercial engines? More specifically planes like C-17, the Antonov's use older less powerful engines while modern efficient and powerful engines are ...
0
votes
1answer
260 views

How are jet engine RPM cycles used to monitor LCF life?

Can someone please define what are N1 and N2 throttle cycles? These are used to keep track of the accumulated low cycle fatigue (LCF) life of rotating components. But I cannot find an exact definition ...
24
votes
6answers
13k views

Are German, Japanese, and Chinese companies not able to build aircraft jet engines on their own?

As far as I know, only 4 countries can build aircraft jet engines on their own: USA {GE, P&W} Russia {Klimov, NPO Saturn} France {Safran} UK {Rolls-Royce} All other countries use jet engines ...
3
votes
1answer
576 views

What is so special about new Russian jet engine called PD-14?

I think PD-14 engine is being promoted by Russians as something extraordinary. What is so special about PD-14 that the West doesn't have? Can you explain this in layman's terms?