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I was just watching something the other day about how jet engines have gotten more efficient and powerful over the last 50 years where commercial airliners real
by mattbrewsbytes 1y ago
I was just watching something the other day about how jet engines have gotten more efficient and powerful over the last 50 years where commercial airliners really only need 2 engines. All 2 engine aircraft also have to be able to operate on 1 engine as well if there is a failure.
One has to wonder if this was a bird strike incident on both engines that maybe having 4 engines would have allowed the plane to circle back around.
- Ichthypresbyter 1y agoWhy would a flock of birds large enough to be ingested by both engines of a two-engined plane not also be large enough to be ingested by all four engines of a four-engined plane?
- Waterluvian 1y agoGood point. We should be discussing eight-engine planes.
- ivan_gammel 1y agoWe should be discussing no-engine planes, since they are obviously safer in such situations.
- FridayoLeary 1y agoLike the b 52 bomber. I always liked them. We could convert them for passenger flights. Airlines could develop luggage pods that hang from the wings and the planes support mid air refuelling so that could help with turnarounds. They also have tail guns for even more safety. Also huge bay doors which will make getting on and off the plane much faster.
- beAbU 1y agoMake the cabin a cartridge that clicks into the bottom. Give the cabin wheels and propulsion.
- grues-dinner 1y agoThunderbird 2 was always the best one. Even if those stubby forward-swept wings don't really seem like what you need for the normal mission profiles!
- HeyLaughingBoy 1y agoDoor to door international service. I like it.
- Integrape 1y ago¿Por qué no los ocho?
- mikeyouse 1y agoThis is where some of the E-Plane concepts really shine. Let's see a flock of birds take out every engine on this NASA demonstrator: https://sacd.larc.nasa.gov/asab/asab-projects-2/x57maxwell/ https://sacd.larc.nasa.gov/asab/asab-projects-2/x57maxwell/
- gardenhedge 1y agoWhat's with these comments
- moralestapia 1y ago>Why don’t all four tires on a car blow out at the same time?
- Ichthypresbyter 1y agoThey do if you drive over a stinger (or perhaps a sufficiently large number of nails or other sharp objects).
- aipatselarom 1y agoThey also do if you go around the car with a knife and you stab them. But it is somehow implied that the context of the comment is normal driving conditions. Perhaps that comment could be reworded like: >When driving on a highway, while not being pursued by the police, on planet Earth, with a road temperature below 200C, and not driving behind a van transporting nails with an open door that's dropping them on the road, why don’t all four tires on a car blow out at the same time? That way people could get a better sense of what it is about.
- bregma 1y agoThe kid would have to have a pretty large glass milk bottle hidden under his coat for that to happen.
- defrost 1y agoA multiple engine aircraft maintaining flight on a single engine is vastly different to the same craft being able to complete a take off when an engine fails mid process. Aircraft can land (in right circumstances) by gliding in sans power .. the same cannot be said for take offs.
- bartread 1y agoIf during your takeoff roll you lose one engine on a twin engine jet below speed V1[0], you reject the take-off. V1 is calculated for the aircraft such that above that speed you are able to safely take off and execute a go-around in order to land again on just that single engine. Aborting above V1 is heavily discouraged because usually there's a strong risk of running off the end of the runway. Of course, if you lose both engines above V1, you're really in trouble and left without much choice. But we don't know what happened with this flight so nothing I've said here should be taken as indicative of whatever went wrong in this case. It's purely information. [0] Which depends on many factors including the type of aircraft, loading, weather conditions, state of the runway surface - for example, wet, or iced - etc., and needs to be calculated afresh for every take off.
- wkat4242 1y agoYeah in some cases rejecting after V1 is a better choice. If you're going to impact something anyway you'll be doing it with a slower speed and no vertical component in that case. An airliner in the US did it and the pilot was praised for making that hard decision. Everyone walked I think. I forget which flight.
- AaronM 1y agoModern commercial aircraft is designed to operate on a single engine through all modes of flight. One a plane reaches v1 during takeoff, it can lose an engine and still takeoff. It an engine was lost before v1, the takeoff would be aborted. Here is an Airbus doing just that. https://youtu.be/5QMJ3_NiWbs?si=5nZ4yU7T7hsGSUu2 https://youtu.be/5QMJ3_NiWbs?si=5nZ4yU7T7hsGSUu2
- 1y ago
- ajross 1y agoI don't think there's ever been a double-bird-strike incident, though. And what dual engine failures I can think of are due to failure of a shared system (e.g. fuel exhaustion, c.f. Gimli Glider). [Edit: yeah, yeah, forgot the Tom Hanks movie, sue me. I do wish folks would respond to the much more important point below, which isn't invalidated by a single data point though.] Constructing solutions for multiple-mode failures like this is a bad engineering smell. Almost always the solution isn't actually helping anything, and often makes things worse in whatever metric you're looking at. In the example here, having four engines makes the chances of total thrust loss lower, but it doubles the chance of a single engine failure. And the literature is filled with incidents of theoretically-survivable single engine failures that led to hull loss as a proximate cause (generally by confusing or panicking the crew).
- changoplatanero 1y ago> I don't think there's ever been a double-bird-strike incident, though There was this very famous double bird strike https://en.m.wikipedia.org/wiki/US_Airways_Flight_1549 https://en.m.wikipedia.org/wiki/US_Airways_Flight_1549
- whycome 1y agoHudson/Sully was dual engine bird strike no?
- fabian2k 1y agohttps://en.wikipedia.org/wiki/US_Airways_Flight_1549 https://en.wikipedia.org/wiki/US_Airways_Flight_1549 There certainly have been bird strikes that disabled all engines.
- GeertJohan 1y ago> I don't think there's ever been a double-bird-strike incident, though. The most well known double-bird-strike incident is probably the one where Sully landed a plane on the Hudson River. https://en.wikipedia.org/wiki/US_Airways_Flight_1549#Takeoff_and_bird_strike https://en.wikipedia.org/wiki/US_Airways_Flight_1549#Takeoff... -edit: ok, everyone had the same thought, haha -
- deleted 1y ago
- snickerbockers 1y agoBut does that rule apply during liftoff or only when it's in-flight? Based on the map it probably never got that much altitude, as it barely traveled 2*length_of_runway, and that's including the runway itself.
- JumpCrisscross 1y ago> does that rule apply during liftoff or only when it's in-flight? Any time after it’s too late to abort takeoff. Pilots should be able to “regain full control of the aeroplane without attaining a dangerous flight condition in the event of a sudden and complete failure of the critical engine…at each take-off flap setting at the lowest speed recommended for initial steady climb with all engines operating after takeoff…” [1]. [1] https://www.easa.europa.eu/en/downloads/136694/en https://www.easa.europa.eu/en/downloads/136694/en 25.143(b)(1)
- chromehearts 1y agoThe full length was used https://www.flightradar24.com/blog/live/air-india-boeing-787-8-crashes-on-takeoff-in-ahmedabad/ https://www.flightradar24.com/blog/live/air-india-boeing-787...
- moralestapia 1y agoYour comment does not deserve to be downvoted, there is absolutely nothing wrong with it.
- klausa 1y agoIt's baseless speculation by someone who doesn't have any relevant expertise, based purely on conjecture not any facts around the accident. It's _exactly_ the kind of comment that deserves to be downvoted here.
- aipatselarom 1y agoThe guy's just asking if four engines instead of two would have made a difference? It's curiosity, it's learning, it's looking for an explanation. That's exactly the kind of comment that deserves to be here. >[...] who doesn't have any relevant expertise, Is that a requirement to comment on this thread? Do you fulfill that requirement you brought in?
- klausa 1y agoMaybe I'm overly strictly pattern-matching on the type of people that tend to use the phrase "one has to wonder"; but I don't think that's usually uttered from place of learning and exploration. If I'm wrong, then apologies to the OP.
- aipatselarom 1y agoDo you have relevant expertise in this topic?
- klausa 1y agoOn the topic of dudes online speculating wildly? Yes, I've been on this website quite a long time, unfortunately.
- 1y ago
- fredoralive 1y agoIn the 1980s a British Airways 747 flew through volcanic ash and lost all four engines. So just having more engines may not always be the solution, as in suitably unlikely circumstances you can still lose all of them. (In that case they were at cruising altitude, so had time to handle the situation and relight the engines).
- arethuza 1y ago"Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress." https://en.wikipedia.org/wiki/British_Airways_Flight_009 https://en.wikipedia.org/wiki/British_Airways_Flight_009
- ho_schi 1y agoIt depends on the situation. Redundancy and additional power increase margins. More for the sake of more isn't necessary helping. https://www.youtube.com/watch?v=z_ewa7R20MA https://www.youtube.com/watch?v=z_ewa7R20MA Lufthansa 747-8 after engine failure: *We're not an emergency.* It depends on what is causing the failure and how situation evolves. Let us take British Airways Flight 009 as example, the wiki says that all engines failed, all engines were restarted and engine number 2 surged again and was finally shut down. So even this awkward situation was relaxed a bit by the additional safety margin. Most airlines avoid nowadays the invest into maintenance of four engines airliners. Others have prefer the additional transport capacity and margins. Lufthansa has it's own maintenance branch "Lufthansa Technik" and doesn't need to handle extra costs. Emirates needs the huge capacities of the A380. PS: The 747 can and does - if necessary - ferry flights without passengers and only three engines. Not possible with twin engine planes.
- wkat4242 1y ago> Emirates needs the huge capacities of the A380. I think it's more that they needed the prestige of having the biggest planes, offering a whole bedroom with shower etc. It goes well with their ultra luxury image. If it's just about seats that can fly smaller ones with the benefit that they can operate more frequently and thus attract more transit passengers looking for a good connection. That's their main market. An A380 is quite a hassle because most airports can't even handle one.