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

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45 views

Does the stator blade angle changes? Why?

I have read that when jets are on the ground their compression ratio changes. With this change the stator compressor's blade angle changes. Is this true?
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0answers
77 views

What happened with the Boeing PETA Pulse Jet Engines

The boeing engines created a buzz when they were announced back in 2011, and were said to be proprietary technology. It created a buzz about easing VTOL concepts and more, but where does the project ...
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2answers
54 views

How does fuel flow and altitude affect the compression ratio of jets?

Does the compression ratio of jet engines change with altitude and/or with the rate of fuel flow?
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0answers
38 views

what is the impingement location of Streamwise vortices?

When I was reading an article about scalloped and lobed mixers in turbofan engines nozzle, I faced with this sentence that was comparing lobed and scalloped cases: "impingement location for the ...
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1answer
56 views

Wind correction on downwind during circling

A timing must be started when flying abeam the threshold on a circling approach. The FCTM of the B777/787 mentions 35 seconds and the SOPs of the Embraer 190 30 seconds. Do they need to be corrected ...
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1answer
145 views

What are the Boeing 777 thrust calculations? [closed]

Can someone show typical calculations for a Boeing 777 jet engine for the following criteria: Take off thrust of the engine at 170 mph take off speed and 45 degrees F Cruising thrust required at 500 ...
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0answers
66 views

What‘s the diameter of the engines of the Airbus E-Fan?

does somebody know the diameter of the E-Fan‘s engines ? To me the look like around 80cm or what do you think ? Also, with more and wider blades and 60 kW motors instead of 30 couldn‘t they get much ...
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1answer
67 views

Hydro-pneumatic fuel controls and hydro-mechanical fuel controls

What are the advantages and disadvantages of the hydro-pneumatic controls against the hydro-mechanical controls?
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2answers
80 views

How can I determine specific heats of gases for turbojet engine calculations?

I'm in a combustion lab and we are performing experiments on a turbojet engine. However, I am having some trouble calculating the exit velocity and compressor/turbine powers of the engine. Consider ...
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0answers
68 views

What are the air mass flow rate and fan pressure ratio of the Trent XWB?

I have some basic questions regarding the Trent XWB: What's the air mass flow rate (or its range) of the Trent XWB engine? Is all of the air mass flow of the engine produced only by the 118" diameter ...
1
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1answer
310 views

How much fuel does an airliner consume during passenger boarding?

As I understand, sometimes APU is running during the passenger boarding. How much fuel do the APU consume during this process? Of course, it must depend on the total boarding time, so I think it ...
3
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2answers
152 views

Could compressor stalls be caused by air in supercritical conditions?

It is likely that in compressors of jet engines appear conditions that cause the intaken air to become supercritical, cf Is the air in a jet engine supercritical? . Is it possible that ...
5
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2answers
269 views

Is the air in a jet engine supercritical?

Nitrogen has a critical point of 126.2 K and 3.4 MPa (34 bar). Air contains 75 % of nitrogen For example, nitrogen has a critical point of 126.2 K (−147 °C) and 3.4 MPa (34 bar). source : https://...
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1answer
151 views

How much thrust could a 400 mm EDF produce?

there's a 195mm EDF from Schübeler that produces 25 kg of thrust at a peak power consumption of 15 kW: https://www.schuebeler-jets.de/de/produkte/hst Now, my question is: How much thrust could you ...
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1answer
138 views

How do you maximize an electric engines thrust?

I‘ve been recently looking for answers to this question on the internet but the jungle of propellers, fans and electric motors didn‘t quite get me an anwer. How would I have to design an electric ...
2
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1answer
145 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 ...
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1answer
83 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!
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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 ...
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0answers
83 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
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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
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1answer
136 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
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1answer
264 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
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1answer
89 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 ...
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0answers
56 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?
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0answers
65 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
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2answers
251 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 ...
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1answer
224 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 ...
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0answers
45 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 ...
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1answer
62 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.
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2answers
424 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
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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
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2answers
460 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
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2answers
186 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 ...
3
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1answer
95 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 ...
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1answer
263 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
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2answers
145 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
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1answer
206 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 ...
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1answer
147 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 ...
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1answer
145 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
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3answers
208 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
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3answers
216 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)
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2answers
298 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
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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 ...
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1answer
279 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
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4answers
186 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
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1answer
238 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?
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3answers
247 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 ...
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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 ...
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0answers
31 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 ?
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3answers
326 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 ...