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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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How are off-wing jet engines transported?

One of the optional services in Rolls-Royce TotalCare is "Engine Transportation" This service includes routine transportation of engines between the customer’s main base (or designated station) and ...
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What is the future of manufacturer independent jet engine maintenance repair and overhaul (MRO) services?

I have noticed that Air France KLM offer a Maintenence (MRO) service for aircraft and jet engines. This sounds like a potentially big threat to engine manufacturers like Rolls Royce who makes around ...
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How much would it cost for a large airline to switch engine manufacturer for their planes?

I am trying to understand how much of a hassle and cost it would be for a large civil airline, who already had lots of installed Rolls Royce engines on its fleet, to switch over to GE engines on new ...
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Why is engine No.2 started first, instead of No.1?

I realized that some Boeing manuals recommend that the engine number 2 must be started first, is there any special reason for this?
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What is the buzzing noise generated by the engines in this 777 takeoff video?

I've flown a few times in my life, both in economy and executive class. Every time I fly in executive, during takeoff, there is a different noise from the engines. In economy class (behind the engines)...
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Why is a higher bypass ratio more efficient at lower speeds?

Why is it that a larger volume of air moving slower is a more efficient means of propulsion than a smaller volume of air moving faster? (This is true up to a given speed, obviously, as supersonic ...
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Why are the Boeing 737 nacelles odd shaped?

Why is a Boeing 737 NG engine not completely round in shape? It seems to be flat at the bottom and round at the top and sides. Earlier Boeing 737 versions (100 and 200) seem to have a more rounded ...
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Why do the engines seem to power down and then back up after take-off?

What is the phenomenon on a commercial airliner (say, a 737-800) where shortly after takeoff and before we reach 10,000 feet the engines feel like they slow down dramatically or even power off ...
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Why do jet engines sometimes spit out flames after ingesting birds?

After seeing this video of a 757's engine catching fire because of a bird, I wonder: What happens to the engine? Why does it periodically exhaust fire? Is this some safety feature?
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What is this molten metal coming from the engine of an Avro RJ 100? [closed]

Yesterday I flew in an Swiss Avro RJ100. As soon as we landed I was shocked to see some sort of molten metal which was incandescent and glowing red dripping down from the vent as indicated in the ...
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What is this flange on the engine?

Flying home from the Denver ComiCon, on a 737, I saw an angled flange on the engine. Could you describe its purpose? Photos by CGCampbell licensed CC0
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Do aircraft engine intakes require air filters?

I see helicopters which have air filters in their engine intakes, but jet fighters and commercial turbojet airliners don't seem to have any filters in their air intakes. Isn't it true that even tiny ...
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What is the difference between a turbofan and a turboprop engine?

I'm not an aircraft expert and I just realized that there are two different terms - turbofan and turboprop. I always had them combined in my head as a term for a large jet engine (like you would see ...
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How does thrust reversal work on a jet engine, and when should it be used?

A two part question this time, though they are closely related enough that I figured I'd knock them out all at once. I figure the first question probably informs the second question anyway. Firstly, ...
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How do you start a jet engine if the start valve is stuck closed?

I was recently on a flight aboard an Airbus A380 where the flight was delayed 2 hours. The reason was claimed to be a start valve fault on engine #4, where it was stuck closed. According to the ...
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Can aircraft other than rockets go to space?

I always wondered if it was possible for planes and other aircraft to leave the Earth's atmosphere. Normal commercial transport airplanes can fly pretty high, but then they need air to get the speed ...
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How often does fan blade out happen?

Jet engines are designed to contain a fan blade failure, and the engines and airplanes are designed with this type of failure in mind. This is more critical in the modern high-bypass designs with ...
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2answers
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Which engines are Jet-A used in?

Is Jet-A used in turbojets or is it just used in turbofans, turboprops, and the SMA SR305-230 for Cessna?
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How do jet engines work?

I was doing research about jet engines, and they seem really difficult to fully understand. So, can anyone explain it in a simple way? An afterburner glows on an F-15 Eagle engine, source: Wikimedia. ...
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How do aircraft keep fuel from freezing while in flight?

On aircraft which fly above 30,000 feet, the temperature can often can get to temperatures below Jet-A's freezing point. For example: at 36,000 feet the standard outside air temperature is -56.5°C (-...
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What defines a cycle on a jet engine?

Is there a legal definition of a "cycle" on a jet engine? We must log the cycles, and some maintenance is determined by cycles. From my understanding, this is partially because of the thermal ...
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How are turbine engines started?

What happens to a turbine engine from the time that a start is initiated until stable idle is achieved? What can go wrong?
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1answer
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How can a passenger tell if a flame-out / engine failure has occurred?

Reading this page, a retired American Airlines pilot quotes: We tell passengers what they need to know. We don’t tell them things that are going to scare the pants off them. So you’ll never hear me ...
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Which engine is more efficient between turboprop vs jet?

Are turboprops really more efficient than jets? If yes, does that mean that airlines who use jets sacrifice fuel for faster flights?
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Where can I find detailed dimensions of an aircraft engine compressor blade?

I am currently working on the modeling of blade/casing interactions in aircraft engines. The work is carried out in partnership with a company, therefore, there is a limited amount of it that could be ...
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Why do jet engines get better fuel efficiency at high altitudes?

I'm told that this is true, but I can't imagine why. It seems like the fact that there is less air would make the engines less efficient... But that probably just shows how little I know about jet ...
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1answer
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Why do DC-9 and MD-82 have engines that are slightly angled upwards?

As per subject, I see that the above mentioned aircraft and some others that have engines mounted on the rear of the fuselage, have the engine intakes tilted slightly upwards. Why has this solution ...
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How does the mounting location of a jet engine affect aircraft performance?

Different jet airplanes mount the engines in different ways. For example: Under the wing To the fuselage How does the engine location affect aircraft performance? Is one better than the other?
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Why are propeller airplanes still made?

Airplanes with propellers were invented a long time ago. After that, jet engines came into existence. My question is: why do we still have propeller engines? The reasons I can think of are: They are ...
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Do fighter jets have a traditional inverted fuel system?

Common solutions for aerobatic piston singles is to have either header tanks (for wing tanks, as I understand it) or flop tubes (for fuselage tanks). Do fuel systems in a fighter jet work on the same ...
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3answers
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Why are propeller engines uncommon on airliners?

My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range. I assume that turboprop engines are more fuel ...
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Why do turbine engines take so long to spool up?

Piston engines reach full rpm within a second or two, but turbines take much longer. Why is that?
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Do turbine engines on multi-engine aircraft rotate in opposite directions to offset torque?

I'm not an aviator, I guess I'd call myself an enthusiast. I'm also a physics nut. I've always wondered about this but I equally worried my question posed to a commercial airline crew would land me in ...