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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91 views

How to choose engine type for a MALE Unmanned aerial system?

I want to choose an engine type for a Medium-Altitude, Long-Endurance (MALE) drone which should survey permanently an area (500km*500km) located 800km from departure base. Given the following ...
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Would blade-less (Dyson style) jet engines work? [duplicate]

Is it possible to design an aircraft with blade-less (same concept as Dyson) design to generate thrust? What are some of the key benefits, drawbacks and examples of attempts (if any) at this kind of ...
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Why do white marks on the spinners in front of engines have different patterns? Not Yellow? Omitted for some models?

In aeroailas' answer I understand that the cones in front of the props/fans are called spinners. In Farhan's answer I understand that the ehite marks painted onto the spinners act less as scarecrows ...
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Mass flow rate for jet engine combustion [duplicate]

Want to know about the mass flow rate in typical turbofan engine combustion chamber
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1answer
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Thrust varaition of a Turbofan engine with altitude and mach number [duplicate]

my classmates and I are trying to find a mathematical model for a low bypass turbofan engine, we ended up finding a model given by Snorri on "General Aviation Aircraft Design", but the ...
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What are these holes on the intake of Progress D-18T which are mounted on AN-225?

I was seeing a Progress D-18T of AN-225 and saw these holes on the intake of them. What are they for?
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2answers
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Airflow through axial flow compressor

So I'm reading the Gas Turbine Engine Fundamental, and suddenly come across the airflow passes through one axial compressor stage. I wonder why the Resultant Rotor Inlet Velocity is pointing downward,...
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2answers
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Do jet nozzles reset after the engine is off for a while?

I have seen jet engines with nozzles being able to dilate to adjust for throttle and things of the sort, but the question I have is, if the engine is turned off, does the nozzle "reset" to a ...
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What inspired the unique design of the F-105 Thunderchief intakes?

The horizontally forward-swept intakes of the Republic F-105 Thunderchief is not a design emulated in other production aircraft of the time, or I think at any time. If viewed as a more typical intake ...
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113 views

What’s the NCVA at the end of the F135 engine?

What’s NCVA at the end of the F135 engine? And what does it do?
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60 views

What is the speed the fan blade would go if it would separate from the shaft with the engine at full throttle?

I'm making a simulation of a blade separating from the shaft to test the case of the engine, but i don't know what speed should i put on the blade to go outwards the case, anyone has any idea how to ...
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Is this image of Compressor aerodynamics correct?

Image Source: Air Gas Turbine Technology by Treager, Chapter 5 The rotation direction of rotor shown seems opposite. If it is correct, these are the questions I would like to ask: Why the Y vector is ...
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Why do the replacements for craft like the C2 Greyhound and E2 Hawkeye still use turboprops?

These two airplanes are some of the classics in naval history, but replacements for them exist. When taking a look at them, they do have some improvements, but I still have one question. Why do they ...
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1answer
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How to determine the length of the CD nozzle?

I am designing a convergent nozzle as well as a CD(Converging-Diverging) nozzle. How do I find out the length of those nozzles? If the throat of the CD nozzle has 0 length then what should be the the ...
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Why pressure and temperature decreases along the length of a convergent nozzle?

I know that the pressure and temperature follows stagnation relations of pressure and temperature as well as area mach relation inside a convergent nozzle along the length. And according to that ...
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Why does a rocket engine increase power with speed if the burn rate is constant?

A rocket produces constant thrust with speed, and that means increasing power with speed. Where does this increase in power come from if the fuel burn rate is constant? How can we explain this in the ...
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What type of bearings are used to support the shafts in jet engines? [duplicate]

I would like to know which types of bearings are commonly used to support the shafts in jet engines and why. I also read something about hydrodynamic bearings, how common are they?
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Can anyone help identify this turbine blade?

At the local army/navy surplus store and found this in a "junk" box. Got it for $1. Would live to know what airframe this came off of. Im new to this so compressor blade? Compressor turbine? ...
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Does the nacelle strut experience reaction forces due to lift, drag, thrust, weight of engine during cruise flight?

Cruise flight indicates that total lift and weight of aircraft cancel and thrust forces generated cancels with total drag forces. However, I am looking closely at the nacelle instead of the whole ...
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How do jet engines cool the gas in the combustion zone?

The adiabatic flame temperature of kerosene in air is 2093 C (source). Modern jet engines have a turbine inlet temperature (TIT) of 1700 to 1800 C. This is the max acceptable temperature before the ...
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What does "military band" mean in this chart?

I'm reading the manual of J79 engine, and I just saw this chart: Does anybody know what "military band" means?
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1answer
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Why does J79 have speed more than 100%? [duplicate]

In the maintenence manual of J79 saw this table: As you can see, there is speed more than 100% and it looks that the engine can handle it. Can't it? One more thing, days ago, watched this movie: ...
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How does a jet engine burn fuel when it is not on an afterburner?

I understand the idea behind afterburner as fuel is added to the exhaust to increase the mass and expansion of gasses to increase the thrust, and that explains (in very obvious way) how the fuel is ...
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What does "time at temperature" mean in the maintenance manual of the J79 engine?

I was reading the maintenance manual of the General Electric J79 and saw these two charts: and What does "time at temperature" mean?
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Why are jet engines still so noisy?

In general, jet engines on passenger aircraft make so much noise that in a long-duration flight it becomes really tiresome and uncomfortable. Nowadays, technology is much more advanced than before. ...
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Can you have a Hybrid Turboprop-Jet engine?

To start things off I am writing this to gain information for vehicles in a story, so I am more so looking for theoretical possibilities, unless there are real world examples. The background and my ...
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214 views

Why aren't air turborockets used in military fighters?

Why aren't air turborocket engines used in jet fighters? Few Third World countries have the capability to manufacture high quality turbine blades. Thus, why not use air turborocket engines for the ...
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What exactly is the pressure thrust component and why does it exist?

I'm teaching PowerPlants on a ATPL theory course and honestly have some trouble wrapping my head around this one: Most literature describes the term "pressure thrust" – as opposed to "...
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Why in a CFM56-3 is vibration measured in displacement for N1 and in velocity for N2?

N1 is measured in mils (thousandth of an inch) and N2 is measured in IPS (inches per second). Why are different methods used?
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What does a High Pressure Turbine Clearance Control do?

In CFM56, I read that it is supposed to increase HPT performance but I don't know how it does that.
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Are turbine blisks common in jet engines?

This comes from a slightly related question about blisks. A blisk is a single component shaped like a disc with blades on it. This can be for compressors or turbines. I want to ask about the turbine ...
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Why is turbine inlet temperature called "TET"?

I assume that at some point giggling engineering students caused their instructor to change "turbine inlet temperature" from TIT to TET, but I wonder if anyone knows the real reason and ...
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Do jet fighters use Turbojet engines, and do cargo/passenger aircraft use Turbofan engines? [duplicate]

I have a feeling that Turbofan engines are used in jet fighters and Turbojet engines are used in cargo or passenger aircraft. Is my perception correct? Do jet fighters use Turbojet engines? Do cargo/...
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How does bypass air work?

As far as I’m aware, high-bypass engines have far higher fuel efficiency than low-bypass engines, and as a result the effective specific impulse of the engine is increased. What I’m trying to figure ...
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What is the highest operational ceiling for a nuclear scramjet?

A similar question is: What is the highest operational ceiling for an air-breathing jet engine? The answers point to scramjets. Cited reports focus on combustion kinetics. The Wikipedia Scramjet page: ...
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1answer
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How do variable bleed valves prevent surge?

All I know is that the valves open at low speed or when decelerating, and close at high speed or when accelerating. How do they prevent the compressor from stall or surge?
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Aircraft engine communication with satellite

Do pilots get an audible indication when the engines are communicating with the manufacturer whilst in flight. Do these "pings" or "hanshakes" begin on start up and are they always ...
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What is the principle behind flight of airplanes? [duplicate]

What is the principle behind flight of airplanes? Need a simple answer for grade 7 student. Thank you
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Need help with calculation of engine airflow and jet velocity and efficiency

This is an image of a set of questions that are relevant to an Airbus A380 type of aircraft (4 engines): As the answers are incorrect, I'd like to understand how these need to be calculated. Q1) I ...
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1answer
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What is this sound for when starting the engine of an F-15?

If I remember correctly, to start up old fighters such as F-4s, you need an ASU but it looks new fighters do not need an ASU. Today, I was watching this video. It's a so cool video to know how new ...
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What are those half-vanes in the engine inlet of a 707-328?

I just saw this: Source They look like IGVs but I'm not sure. What could those be? Do you know the engine?
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In a jet engine, what is the significance of the stagnation pressure/temperature?

I'm reading a paper on jet engines that repeatedly mentions the stagnation pressure and temperature. What does this mean? Is it the point where the jet engine stalls in performance/efficiency/thrust, ...
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What is that to and fro moving thing?

This video by AgentJayZ is the maintenance and repair of AI-25 turbofan. What is that thing moving due to applying certain pressure to that pipe? Can anyone describe its purpose and how it works?
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Overheating (fire thrown out of the nozzle) [closed]

At first I copied https://www.jetcat.de/en/productdetails/produkte/jetcat/produkte/hobby/Engines/P160_rxi_b Where I manufactured and installed all the parts and they are very similar to the original ...
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How are Fan pressure of and Static pressure in the turbofan engine related?

If the fan air is ducted to the rear, the total fan pressure must be higher than the static gas pressure in the primary engine's exhaust, or air will not flow. By the same token, the static fan ...
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why are modern rotor airfoils placed and set up in a compressor at a higher angle of incidence?

why is it that in modern compressors in gas turbine engines like the J79 the rotor blades are set up at a higher angle of incidence (more aligned to the axial axis) compared to older engines. I also ...
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1answer
106 views

Why is it that low fuel gauge is one indication of a compressor stall?

I am reading from my gas turbine engine class notes that apparently, one indication of compressor stall (besides the banging sounds, torque gauge low, N1 low, ITT gauge up, etc) is the fuel levels ...
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How are compressor disks connected to the shaft?

I am trying to learn how compressor disks and shaft are connected each other. I don't have any idea about the terminology so I couldn't find anything useful. Here is a section view of a sample and I ...
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1answer
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Can liquid hydrogen be pumped directly into a jet engine without a heat exchanger? Is it burned as a gas or a liquid in the combustion chamber? [closed]

This NASA research paper on H2 engines includes a diagram of Wesley Kuhrt's 1956 design for a hydrogen-fuelled engine, which has no heat exchanger: (Image by United Technologies Corporation, via NASA....
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Why is a combustor in a gas turbine engine asymmetric?

As the above question stated, the upper and lower section of the combustor isn't same. Is there any reason behind it? Due to which the cooling of the combustor is also different in the upper and lower ...

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