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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Is it possible to find the actual dimensions of the Radial Drive Shaft and Bevel Gear of the CFM56-7B?
I am trying to draw to make a 3d model of the RDS in the CFM56-7B and I wasn't able to find the dimensions anywhere on the internet. And, what are the materials used to make them?
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What are the benefits of buried engines? [duplicate]
I recently came over the de Havilland Comet, and I found an interesting feature of the aircraft: it had four engines, and all of them seemed it be embedded inside the aircraft wings. I later research ...
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How much energy per second would a nuclear reactor need to power a fighter jet?
Fighter jets typically require high amounts of thrust compared to other aircraft. Lets take the F-22 for example, and lets assume the F-22 powered by a nuclear reactor and the F-22 powered by a ...
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What is the produced Drag by a Jet Engine on an airliner?
Are there certain estimation formulas to calculate the drag created by a Jet engine mounted above the fuselage, as shown?
Digital DATCOM seems not to estimate it.
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Why hasn't there been an alternative to jet engines yet?
Why do airlines and military jet aircraft still use jet engines after 85 years of the introduction of this technology?
Why hasn't there been a viable alternative to jet engines yet, even though this ...
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Why don't airliners use engines one behind another?
Why do airliners use the engines the way they currently do and not one behind another?? Would it not lead to better thrust and in case any one of the 2 engines placed together has to fail, the 2nd one ...
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What does the suffix "A“ mean on specific PW1100G(A) engines?
Some time ago I tried to find out what the difference between a PW1100G and a PW1100GA exactly is. I am asking this question here because there seems to be no information online that could be useful ...
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Name of this part of jet engine inlet
I can't find any name of it. I see it on some gas turbines but not all of them.
Edit: Found them, they are called struts.
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I'm having a hard time conceptualizing this statement from "The Jet Engine" by Rolls-Royce
This is taken from section 21 of Chapter 3, Compressors that discusses axial flow compressors in turbine jet engines.
The more the pressure ratio of a compressor is increased the more
difficult it ...
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Lightoff to speak about an engine start
Why is the term lightoff (or light-off) used to describe the moment an engine ignite/is started ? I'm wondering why the suffix 'off' is used in an 'ON' sense (start, ignition) ? Is there a ...
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Why cant all planes use the best engines like the GeNX or the Trent XWB?
Why do airline manufacturers not prefer using the best engines(max thrust: weight ratio and best efficiency) for their airplanes? Doesn't this just not lead to lower sales and losses for the company?
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How do tubojets compare to afterburning turbofans in terms of efficiency?
Turbojets used to be more common in the 40's and 50's but once jet engine design matured they pretty much went extinct in favor of the more efficient turbofan. I know one advantage of the turbojets is ...
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NASA's and Boeing truss-braced wing fuel savings breakdown
According to its Administrator Bill Nelson, NASA is working on a project with Boeing that will reduce single-isle aircraft fuel consumption by 30%. He described it as a higher and thinner wing and ...
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Is it a good idea to increase exhaust duct length?
I am a big newbie in aviation but still, I have a question:
Let's assume a civil aircraft (Boeing 737 or Airbus 320), flying with those impossible real life hypothesis:
the exact SAME turbofan are ...
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How did the engines on the ME-262 work? [duplicate]
I have been looking into the ME-262 jet engines recently but cannot quite understand how they worked and was wondering if anyone could explain it to me in a simplified way.
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Can jet engines stay running without electrical power?
A piston-engine aircraft will continue to run as long as its magnetos still work, even if there is zero electricity in the battery and the alternator is broken, because magnetos are independent of the ...
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Is the clamshell on the AN-72 what causes the Coanda effect?
The AN-72 uses the Coandă effect to improve lift and give it better STOL features.
In this image of an AN-72 (presumably on a takeoff roll) one can see a clam-shell bucket open at the top of the ...
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Why aren't all fighter jets' engine intakes on top instead of forward?
Reading the question and answer to How does the Yak-130 fly with blocked engine inlets, I am now wondering why it - or any fighter jet - has forward engine intakes at all? The top and accepted answer ...
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How does the Yak-130 fly with blocked engine inlets?
In this Yakovlev Yak-130 youtube video you can see at 2:45 where it closes the inlets(something I've never seen before, I've only seen the typical engine inlet covers) and then it does a perfect take ...
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Scared of flying in an Airbus A220
The A220 is exclusively powered by PW1500G geared turbofan engines, which have a history of reliability issues.
Multiple airlines grounded their entire A220 fleet amid engine concerns (A220 Engine ...
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How do after-burners work on jet planes?
I've always wondered this after getting introduced to fighter jets, the sheer concept of being able to create a larger "exhaust" out of a fighter jet and cause it to speed up has always just ...
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Exhaust temperature of CFM56 engines range (Nozzle downstream temp)?
EGT is available but not the temp of the exhaust nozzle in the CFM56 series.
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Function of the compressor in a gas turbine engine
I am trying to understand the importance of having compressed air in the combustion chamber of a gas turbine engine. As far as I understand it, the reasons are twofold.
Firstly, the compressor is ...
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What legacy turbojet would have detailed documentation and drawings available for free or cheap?
I am fascinated by the technology of jet engines. As a hobby, I might like to create a detailed animated 3D model of one (and publish it with a Creative Commons license). Obviously I am not going to ...
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Why are these characteristics of the FT-180 highlighted?
I have been checking the FT-180 engine used to establish speed record for remotely controlled aircraft (i.e. model airplanes). There are some specific features highlighted on the manufacturer site. I'...
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Why are there (almost) no civilian single engine jet aircraft?
I have been looking at various engine configuration in jet powered aircraft. Most have 2 jet engines mounted either side of the fuselage, there are trijet models (e.g. B-727, MD-11) there are also 4-...
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How would you know the difference between a compressor stall and a surge based on indications in the cockpit?
I understand the difference between a compressor stall and surge.
Stall: One or two blade stages exceed the critical AoA, the airflow is turbulent, and the smooth airflow through the compressor is ...
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why you have to open 6 bypass valves in the J 58 engine?
I've noticed that the bypass valves in J-58 are opened after M=1.6. I don't understand why and what are the differences between the J-58 and a normal turbojet that reeaches more than M=1.6.
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What are the air source settings for on the F-16?
As part of the start up sequence for the F-16, the "air source knob is set to NORM", according to this source:
https://theaviationgeekclub.com/heres-why-starting-the-engine-on-an-f-16-viper-...
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Does the other engine have to go through extra checks when one engine fails
Many times I read articles on sites like aviaton herald about engine shutdown in fight because of some problem. It's given the problematic engine will be repaired.
Question is about other working ...
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Why no CFM-56 for the E3?
Why did the USAF not upgrade the E3 from TF33 engines to the CFM-56 like they did the KC135? From the Wikipedia page on the E3, the latter variants sold overseas had the CFM-56 from the factory and ...
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Why aren't ducted rotors used in gas turbines?
I am wondering why (for what I know) no gas turbine employs ducted enclosures for blade arrays on rotor stages.
I tried to search the internet for resources but I couldn't find anything related (so I'...
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Why do only turboprops have ground/flight idle selections?
Why is it that only turboprops have a pilot controlled flight/ground idle and not jets?
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How do engine doors work?
"Doors" here refers to something in or around the engine that can close or open, stopping or allowing the flow of air (or some other gas).
I've heard of such things in a few engines. GE9X ...
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Why do the engine of MiG-31 spit out flame when going for afterburner?
I was seeing this image. Always we can see an abnormal flame spit out of the engine when the pilot goes for afterburner. Why?
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Decreasing Area of Axial Compressor
in axial compressor, why the area is decreasing until it reaches the combustor?
and if the answer because of the pressure is inversely proportional to the volume. that's happened when the temperature ...
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Could a jet engine theoretically ingest not only oxidizer but fuel (on planets like jupiter)
Jet engines work by ingesting oxygen from the air and combusting it with an onboard fuel source like kerosene. But, on planets like Jupiter, with an abundance of hydrogen, would it be possible to ...
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How does momentum thrust mechanically act on combustion chambers and nozzles in a jet propulsion?
I'm asking this question since I can't intuitively understand how the acceleration of mass flow and therefore the increase of its momentum can actually mechanically act on the combustion chamber ...
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The phase having the hightest TIT for a flight mission
I have a query concerning the turbine inlet temperature (TIT) in the context of various flight mission phases. Specifically, I'm trying to ascertain at which phase the gas turbine reaches the highest ...
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Does the obstruction in a propeller duct increase exhaust pressure or decrease pressure/increase speed?
I came up with this question when looking through the answer for this question, which states that a convergent duct(obstruction) compresses the exhaust so that its pressure matches the ambient ...
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Why does thrust differ in different reference frames?
If a jet engine flies with 4 m/s in the air and we want to calculate thrust for two different reference frames, can we prove that the calculated thrust for both reference frames are equal to each ...
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What causes subtle cyclical changes in engine volume at cruise?
A few years back, while trying to snooze on a Jet2 flight up at cruising altitude, my semi-attention wandered to the droning of the engine. I realised there was a very subtle effect of its intensity ...
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Why do we take into consideration holes for pressure thrust in jet engine calculations?
In many sources related to jet engine thrust calculations such as https://www.jet-x.org/a8.html ,
pressure thrust of a module such as combustion chamber, nozzle or compressor, is calculated by front ...
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How can flow in the compressor of a jet engine go back to the inlet?
In aerodynamic lessons and books about jet engines, it is always said that there is a risk that air flow in the combustion chamber or compressor can go back to reverse direction, towards the inlet if ...
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Is diying a strong jet engine possible wih basic tools
Is it possible to manufacture a jet engine that provides 500 newtons of thrust with relatively primitive tools like a lathe or so , if someone did something similar can you provide me with the ...
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Why do we consider that air comes into jet engine?
While calculating air pressure and temperature during cruise of jet engines, we consider that air comes into the jet engine inlet with our flight velocity.
But why? In fact, air stops stagnant in ...
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What's the reason behind the 787 and 777's "thicker" engine nacelle?
If you look at images of the 777 and 787 engines (both RR & GE), such as these pics
https://upload.wikimedia.org/wikipedia/commons/thumb/e/e4/B787-2139.jpg/220px-B787-2139.jpg
https://www....
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How can over-expanded flow go out of nozzle when it has less pressure than ambient pressure?
We know that over expansion in flow means that nozzle exit pressure of flow is lower than ambient pressure at specific altitude. It gets narrower while exiting nozzle causing loss in efficiency.
My ...
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What increases the rotational velocity of air in an axial flow compressor?
In an axial flow compressor as used in modern jet engines, the goal of a compressor rotor is to increase the angular momentum of the air by imparting an increase in swirl velocity. (Note: the goal of ...
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Do compressors and turbines in jet engines end with rotor or stator?
I am trying to understand compressor and turbine design principle based on stators and rotors.
I know that turbines and compressors both have a rotating and fixed section that constitute a stage.
For ...
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