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Fucknag posted:They are, relatively. It's called the TF-39, they produce less than half the thrust of a GE90, and have a lower bypass ratio (8:1 vs 10:1 for the GE90) so the fan is smaller relative to the core. 747s use the similar CF-6, look at the GE90 test 747 to see the size difference: So why doesn't Boeing outfit two of those on the 747 and call it a day? Aren't they more efficient than its current engines?
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May 22, 2013 17:58
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OptimusMatrix posted:So why doesn't Boeing outfit two of those on the 747 and call it a day? Aren't they more efficient than its current engines? Because a lot of 747 customers buy it because it is 4 engined.
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May 22, 2013 18:08
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OptimusMatrix posted:So why doesn't Boeing outfit two of those on the 747 and call it a day? Aren't they more efficient than its current engines? To throw things out there; for one thing 744 and 767s share engines, 748 and 787 share engines. The engines would probably need to be on different pylon locations for weight distribution. The new plane would be subject to ETOPS.
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May 22, 2013 18:08
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hobbesmaster posted:To throw things out there; for one thing 744 and 767s share engines, 748 and 787 share engines. The engines would probably need to be on different pylon locations for weight distribution. The new plane would be subject to ETOPS. Yeah ETOPS would be the big issue here, plus that big an engineering change would probably mean a new type certificate, which means they might as well engineer a new plane. It'll be cool, they'll call it the 777. ETOPS, by the way is the requirements for 2 Engined planes to be certified for inter-continental flights. It stands for Engine Turns or People Swim. It allows for a 120 minute diversion time. Wikipedia, which never lies, posted:On December 12, 2011, Boeing received type-design approval from the U.S. Federal Aviation Administration (FAA) for up to 330-minute extended operations for its 777 fleet. This certification applies to the 777-200LR, 777-300ER, 777F and 777-200ER equipped with GE engines.[7] Jonny Nox fucked around with this message at 18:54 on May 22, 2013 |
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May 22, 2013 18:52
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Why Boeing can't stick two GE90s on a 747 and call it a day: Airliners have to be certified to lose an engine on takeoff and continue to climb. A 747-400 has four engines rated at 60,000 lbs of thrust give or take. If it loses an engine on takeoff, it still has 180,000 lbs of thrust. The highest rated GE90 makes 115,000 lbs of thrust. With only two, if one were lost, the plane would only have... You see why this doesn't work. The GE90 would have to be half again more powerful. You can also see why twins are way overpowered for climb as compared to an equivalently sized quad. Incidentally, the 777-9X will practically be a direct replacement for the 747-400, so there you go.
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May 22, 2013 19:17
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Jonny Nox posted:ETOPS, by the way is the requirements for 2 Engined planes to be certified for inter-continental flights. It stands for Engine Turns or People Swim. It allows for a 120 minute diversion time. The triple is up to 330 minutes ETOPS now for some operators, which is pretty nuts.
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May 22, 2013 19:35
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GE likes to add the "one GE90 can power a 747 in cruise!" everywhere. No poo poo, TO/GA power is what matters.
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May 22, 2013 20:13
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Understeer posted:Why Boeing can't stick two GE90s on a 747 and call it a day: Tri-GE90 747's 
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May 22, 2013 21:39
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Bugsmasher posted:So there is most definitely at C-5 here at Calgary right now (apparently due to a fuel leak in the cargo hold): There was some idle chat about the C-5 at the office this morning; my first statement was, "I'll bet it's here because it's broken." If there's one thing you can put your faith in, it's a C-5 breaking down. Blistex posted:Tri-GE90 747's Something like this then?  Yes, that's a real concept, by the way.
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May 22, 2013 22:01
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MrChips posted:There was some idle chat about the C-5 at the office this morning; my first statement was, "I'll bet it's here because it's broken." If there's one thing you can put your faith in, it's a C-5 breaking down. Except the engine on top would be goddamn near the width of the fuselage and incredibly impractical...Photoshop time! movax fucked around with this message at 22:06 on May 22, 2013 |
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May 22, 2013 22:03
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In a parallel universe where ETOPS isn't a thing the trijet 747 is probably the backbone of international fleets.
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May 22, 2013 22:12
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MrChips posted:There was some idle chat about the C-5 at the office this morning; my first statement was, "I'll bet it's here because it's broken." If there's one thing you can put your faith in, it's a C-5 breaking down. What does it mean when you see four C-5s at an airforce base, and three of them are up on jacks? It means the tool shop ran out of jacks.
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May 22, 2013 22:20
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And seriously people; ETOPS prevents twin 747's? It's like this thread has warped to GBS or something. Changing the wing structure to mount a twin, changing the structural dynamics and tuning the harmonics of the structure to mount 2 really big lumps of metal instead of 4 normal-big lumps of metal, then redesigning the high-lift devices and control surfaces for the different air flow is what prevents a 747 twin. Johnny Nox wins an e-cookie for being the only sensible person. movax posted:Except the engine on top would be goddamn near the width of the fuselage and incredibly impractical...Photoshop time! Not really. If you need 3 60klb engines for takeoff on a normal 747, then replacing with 2 GE-115's would mean that in the event of engine out you would only need another 60klb or so, so the tail mounted engine could be a standard CF6. Nobody ever said the engines had to be the same! vvv... my point exactly. ETOPS doesn't apply to trijets and isn't the thing that prevents them from making a come-back Captain Postal fucked around with this message at 22:51 on May 22, 2013 |
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May 22, 2013 22:23
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Captain Postal posted:ETOPS won't stop a trijet from becoming the backbone of a fleet. T means "twin" The economics of trijets in an ETOPS world means there's no reason to spend the extra fixed costs on a trijet.
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May 22, 2013 22:29
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Captain Postal posted:ETOPS won't stop a trijet from becoming the backbone of a fleet. T means "twin" No poo poo; trijets were everywhere when the minimum allowed over water was 3 engines. With ETOPS twins are everywhere but the heaviest of the heavy routes where economics let the 747 and A380 show up. If single engine airliners showed up tomorrowoand were allowed over water in a decade only FedEx would fly twins.
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May 22, 2013 22:36
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Captain Postal posted:ETOPS doesn't apply to trijets and isn't the thing that prevents them from making a come-back uhhhhhhh
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May 22, 2013 22:45
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Captain Postal posted:ETOPS won't stop a trijet from becoming the backbone of a fleet. T means "twin" The point isn't that ETOPS outlaws trijets or 747s, it's that ETOPS lets twinjets replace them.
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May 22, 2013 22:46
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NightGyr posted:The point isn't that ETOPS outlaws trijets or 747s, it's that ETOPS lets twinjets replace them. re-read. Makes more sense now. Please carry on.
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May 22, 2013 22:49
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Why not put 4 GE90s on a 747?
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May 23, 2013 01:51
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drgitlin posted:Why not put 4 GE90s on a 747? Be pretty good for pure speed and GTOW (and aerobatics  ), but I imagine the thrust and improved fuel consumption would be outweighed by having 4 of them. It would probably drain the tanks faster and thus reduce range, which is a no-go on a long-range hauler.
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May 23, 2013 02:34
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Triton had it's first flight today. http://www.popsci.com/technology/article/2013-05/navys-mq-4c-triton-long-range-maritime-spy-drone-completes-its-first-flight https://www.youtube.com/watch?v=hEuCWJ2qAQY
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May 23, 2013 03:10
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Just looking at the design of the Triton in the youtube preview pic - is the head shape and engine placement designed like that to act as a lifting body?
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May 23, 2013 05:06
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Gorilla Salad posted:Just looking at the design of the Triton in the youtube preview pic - is the head shape and engine placement designed like that to act as a lifting body? Maybe a bit? Apparently they improved on the Global Hawk design for increase aerodynamics and more efficient engine design. Given that it's based on the Global Hawk with about 10 years more tweaking/development I wouldn't doubt it. The main reason the head is that bulbous is comms equipment. I also know nothing about aero.
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May 23, 2013 05:16
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Gorilla Salad posted:Just looking at the design of the Triton in the youtube preview pic - is the head shape and engine placement designed like that to act as a lifting body? Not as far as I know, just an aerodynamic shape to hold a gigantic satellite antenna.
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May 23, 2013 05:16
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Bugsmasher posted:
I've been looking at this for ages and can't work out what it is. Am I right in thinking it's some kind of UH-60 derivative? I'm not sure which specific one it is though. Some kind of extended range deal?
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May 23, 2013 12:02
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Vitamins posted:I've been looking at this for ages and can't work out what it is. Am I right in thinking it's some kind of UH-60 derivative? I'm not sure which specific one it is though. Some kind of extended range deal? Just a regular UH-60 with wings and extended range tanks. They're modular, can be installed and removed at will. Also; snow skis.
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May 23, 2013 12:07
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MrYenko posted:Just a regular UH-60 with wings and extended range tanks. They're modular, can be installed and removed at will. Ah thanks a lot! I had no idea they were modular like that, I thought they just built them to different specs. It's a very pretty chopper 
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May 23, 2013 12:10
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Can a coffee mug be AI?
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May 23, 2013 17:55
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New Stupid Boeing idea: 737, F414 engines. Only so that we can have the captain come on the intercom and say: "Ladies and Gentlemen this is the captain, in a few seconds we are going to be engaging the afterburners for takeoff, please make sure your seats are in the upright position, and you're holding on tight"
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May 23, 2013 19:05
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Jonny Nox posted:New Stupid Boeing idea: You could even pod them up like the old 737-200! I miss those old 737s, they had some absolutely unmistakable characteristics, chief among them the sounds they made. The JT8D makes a very distinct whine at idle; the kind of noise you would expect a jet engine to make, unlike the hissing wall of noise the CFM makes. Even better was the roaring crackle they'd make as they made their way down the runway, billowing smoke the whole way. I guess I could consider myself fortunate, as we still get a smattering of 737 "Jurassic" traffic here at YYC, but nothing like it was 10 years ago when Westjet still had dozens of them.
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May 23, 2013 20:17
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MrChips posted:I guess I could consider myself fortunate, as we still get a smattering of 737 "Jurassic" traffic here at YYC, but nothing like it was 10 years ago when Westjet still had dozens of them. The northern airlines still use them, like First Air, Canadian North, and Air North, but holy poo poo they are loud, like cover your ears when they taxi by loud.
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May 23, 2013 20:38
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Good. Jets should be loud n smokey. 
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May 23, 2013 21:46
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holocaust bloopers posted:Good. Jets should be loud n smokey. What?
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May 23, 2013 22:46
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Sorry you're going to have to speak up a bitD C posted:The northern airlines still use them, like First Air, Canadian North, and Air North, but holy poo poo they are loud, like cover your ears when they taxi by loud. We get Canadian North here (they mostly fly workforce charters out of YYC) and the occasional Air North 737-200 (though most of their flights these days are with 737-400s), but it's a far cry from ten years ago. My favourite of all the loud old jets would have to be the Fokker F28s that Canadian North used to fly here. Seriously, tbose things were louder than a CF-18 on takeoff. Can't tell you how many times I went racing out of the hangar to see the fighter jet takeoff only to be disappointed by one of those little Fokkers.
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May 23, 2013 23:40
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Gorilla Salad posted:Just looking at the design of the Triton in the youtube preview pic - is the head shape and engine placement designed like that to act as a lifting body? The head shape is dictated by the needs of the satellite antenna. I think the dorsal intake is just a passing nod to controlling radar cross-section.
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May 24, 2013 01:02
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MrChips posted:There was some idle chat about the C-5 at the office this morning; my first statement was, "I'll bet it's here because it's broken." If there's one thing you can put your faith in, it's a C-5 breaking down. When the C-5's were here at Stewart ANG with the 105th Airlift, we had one drop an engine onto the neighborhood below. How that loving happened boggles my mind to this day. Stewart was the main maintenance hub for them 
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May 24, 2013 01:12
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VikingSkull posted:When the C-5's were here at Stewart ANG with the 105th Airlift, we had one drop an engine onto the neighborhood below. DC-10s have precisely three engine attachment bolts per engine, where it attaches to the spar structure, IIRC. A failure of any one of the three would probably result in separation. They're incredibly strong, and incredibly rigorously tested parts, but, like anything man-made, failures happen. I've heard 777s have one, gently caress-off huge, titanium engine mount bolt. I've not seen one first-hand to confirm, though. Of course, heres a Kalitta 747 with all the mounting bolts still attached to the spar. Proof that poo poo happens.   Yes, that is part of the casing, still attached to the spar. MrYenko fucked around with this message at 01:27 on May 24, 2013 |
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May 24, 2013 01:24
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VikingSkull posted:When the C-5's were here at Stewart ANG with the 105th Airlift, we had one drop an engine onto the neighborhood below. I suppose that's why MIL spec has to be so stringent, to compensate for the monkeys wrenching on them.
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May 24, 2013 01:28
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lol engine jettison. That's gotta be alarming to the crew when poo poo's all happy happy then it's like, "Yo engine 3 dropped off. Literally, it is no longer with us."
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May 24, 2013 01:31
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holocaust bloopers posted:lol engine jettison. Today, we find out what aileron trim is for!
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May 24, 2013 01:34
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