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Post by BearClause on Dec 6, 2018 16:04:23 GMT -5
Here's a new one. A 737 landing in Burbank apparently skidded off the runway in heavy rain, but was snagged by an arrestor system that was installed.
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Post by mikegarrison on Dec 6, 2018 16:14:58 GMT -5
Here's a new one. A 737 landing in Burbank apparently skidded off the runway in heavy rain, but was snagged by an arrestor system that was installed. AKA in the racing world, a "gravel trap". (Not exactly the same, really, but similar in purpose. EMAS gravel trap )
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Post by BearClause on Dec 6, 2018 21:58:57 GMT -5
Here's a new one. A 737 landing in Burbank apparently skidded off the runway in heavy rain, but was snagged by an arrestor system that was installed. AKA in the racing world, a "gravel trap". (Not exactly the same, really, but similar in purpose. EMAS gravel trap ) Sounds almost like a runway truck ramp, although most also use an incline as well as gravel. Still - I found video that shows it often stops a truck cold before it gets to the incline.
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Post by ironhammer on Dec 6, 2018 22:05:47 GMT -5
So someone tell me, why have geared turbofans so far been applied in the relatively smaller engines with lower thrust ratings like Lycoming ALF 502 or Garrett TFE731? Correct me if I am wrong, but the biggest geared turbofan is the PW1000G, but that only applies to narrow bodies like A320neo. But what about those big engines with high thrust ratings? Like the PW4000/GE9X/RR Trent type of engines? Why no gear turbofan for those class of engines?
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Post by mikegarrison on Dec 7, 2018 2:55:01 GMT -5
So someone tell me, why have geared turbofans so far been applied in the relatively smaller engines with lower thrust ratings like Lycoming ALF 502 or Garrett TFE731? Correct me if I am wrong, but the biggest geared turbofan is the PW1000G, but that only applies to narrow bodies like A320neo. But what about those big engines with high thrust ratings? Like the PW4000/GE9X/RR Trent type of engines? Why no gear turbofan for those class of engines? Don't know for sure, but there could be lots of reasons. Gears to handle 100,000 lb of thrust may be just not practical. Or making the fans any bigger may not be practical.
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Post by ironhammer on Dec 7, 2018 10:54:32 GMT -5
So someone tell me, why have geared turbofans so far been applied in the relatively smaller engines with lower thrust ratings like Lycoming ALF 502 or Garrett TFE731? Correct me if I am wrong, but the biggest geared turbofan is the PW1000G, but that only applies to narrow bodies like A320neo. But what about those big engines with high thrust ratings? Like the PW4000/GE9X/RR Trent type of engines? Why no gear turbofan for those class of engines? Don't know for sure, but there could be lots of reasons. Gears to handle 100,000 lb of thrust may be just not practical. Or making the fans any bigger may not be practical. That makes sense.
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Post by BearClause on Dec 7, 2018 15:19:32 GMT -5
So someone tell me, why have geared turbofans so far been applied in the relatively smaller engines with lower thrust ratings like Lycoming ALF 502 or Garrett TFE731? Correct me if I am wrong, but the biggest geared turbofan is the PW1000G, but that only applies to narrow bodies like A320neo. But what about those big engines with high thrust ratings? Like the PW4000/GE9X/RR Trent type of engines? Why no gear turbofan for those class of engines? My understanding is that the current offering is just the first step. Obviously it can be a game changer once it works reliably, but there seem to be a lot of teething pains. I thought they were late on their initial deliveries, and they've been suffering from some early failures in production engines. If Pratt can figure this out and then apply the same technology to larger engines, they could take up a huge portion of the market, when right now they're reliant on military sales. And it could even be used in military applications. Still - I'm not sure exactly how this works since they're not exactly drop-in replacements. I thought that Pratt decided against competing for some planes like the 787. It's going to be a while before they'll have anything in that size.
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Post by ironhammer on Dec 7, 2018 21:26:41 GMT -5
So someone tell me, why have geared turbofans so far been applied in the relatively smaller engines with lower thrust ratings like Lycoming ALF 502 or Garrett TFE731? Correct me if I am wrong, but the biggest geared turbofan is the PW1000G, but that only applies to narrow bodies like A320neo. But what about those big engines with high thrust ratings? Like the PW4000/GE9X/RR Trent type of engines? Why no gear turbofan for those class of engines? My understanding is that the current offering is just the first step. Obviously it can be a game changer once it works reliably, but there seem to be a lot of teething pains. I thought they were late on their initial deliveries, and they've been suffering from some early failures in production engines. If Pratt can figure this out and then apply the same technology to larger engines, they could take up a huge portion of the market, when right now they're reliant on military sales. And it could even be used in military applications. Still - I'm not sure exactly how this works since they're not exactly drop-in replacements. I thought that Pratt decided against competing for some planes like the 787. It's going to be a while before they'll have anything in that size. Well, there are always going to be teething issues with any new advances in technology. Arguably geared turbofans is the next big leap, you first got turbojets, then low-bypass turbofans followed by high-bypass turbofans and now geared turbofans.
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Post by BearClause on Dec 8, 2018 2:04:20 GMT -5
My understanding is that the current offering is just the first step. Obviously it can be a game changer once it works reliably, but there seem to be a lot of teething pains. I thought they were late on their initial deliveries, and they've been suffering from some early failures in production engines. If Pratt can figure this out and then apply the same technology to larger engines, they could take up a huge portion of the market, when right now they're reliant on military sales. And it could even be used in military applications. Still - I'm not sure exactly how this works since they're not exactly drop-in replacements. I thought that Pratt decided against competing for some planes like the 787. It's going to be a while before they'll have anything in that size. Well, there is always going to be teething issues with any new advances in technology. Arguably geared turbofans is the next big leap, you first got turbojets, then low-bypass turbofans followed by high-bypass turbofans and now geared turbofans. Right now they don't seem to be that reliable, but as you noted it's teething pains. Nobody else is in production for anything the size of Pratt's PurePower or larger. Rolls is working on it. They say they're targeting 2025 for production. But I thought Rolls pretty much gave up on engines in the 737/A320 class. www.rolls-royce.com/media/our-stories/innovation/2016/advance-and-ultrafan.aspx
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Post by ironhammer on Dec 8, 2018 7:14:01 GMT -5
Well, there is always going to be teething issues with any new advances in technology. Arguably geared turbofans is the next big leap, you first got turbojets, then low-bypass turbofans followed by high-bypass turbofans and now geared turbofans. Right now they don't seem to be that reliable, but as you noted it's teething pains. Nobody else is in production for anything the size of Pratt's PurePower or larger. Rolls is working on it. They say they're targeting 2025 for production. But I thought Rolls pretty much gave up on engines in the 737/A320 class.
I guess they changed their minds then. I suppose RR has done their profit/loss projection and figured there can be money made in the narrow-body market.
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Post by ironhammer on Dec 8, 2018 14:27:29 GMT -5
And another thing, correct me if I am wrong, but I notice Boeing use vortex generators on the wings for almost all their jet airliner models except the 747. Why is that?
While Airbus do not have them on the wings of their aircraft models except the A300 I believe. I think the generators can be added to the underside of the wing for the A320 as an aftermarket modification, but does not come as standard.
I know vortex generators are used to improve airflow and enhance aerodynamic performance of the wing. So why do Boeing have it and not Airbus?
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Post by mikegarrison on Dec 8, 2018 16:16:04 GMT -5
Vortex generators tend to be added to a surface after testing shows that they would help. Nobody just puts them on by default.
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Post by BearClause on Dec 8, 2018 18:07:06 GMT -5
Right now they don't seem to be that reliable, but as you noted it's teething pains. Nobody else is in production for anything the size of Pratt's PurePower or larger. Rolls is working on it. They say they're targeting 2025 for production. But I thought Rolls pretty much gave up on engines in the 737/A320 class.
I guess they changed their minds then. I suppose RR has done their profit/loss projection and figured there can be money made in the narrow-body market. I don't believe these geared turbofans they're working on are for the narrow-body market. I was just thinking that Rolls is working on something that isn't specifically going to be competing with PurePower. It's a variation on the Trent XWB, which only powers the A350 now.
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Post by ironhammer on Dec 8, 2018 21:16:21 GMT -5
Vortex generators tend to be added to a surface after testing shows that they would help. Nobody just puts them on by default. I didn't said they were put there on default, did I? But the question remains, why not on Airbus wings? And on Boeing wings?
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Post by BearClause on Jan 23, 2019 14:02:53 GMT -5
So, I've been reading about the 777x. What's with the folding wings? I've never heard of any used on commercial aircraft. Mostly it seems to have been for naval aircraft that need to deal with tight storage spaces.
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