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CanadaFair
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737max: why not raked wingtips?

Sat Jun 24, 2017 9:57 pm

Did Boeing consider adding raked wingtips to MAX like on Navy 738s?
 
chiki
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Re: 737max: why not raked wingtips?

Sat Jun 24, 2017 10:01 pm

I think they did not want the Max to fly low and slow like the P8 but high and fast
 
mjoelnir
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Re: 737max: why not raked wingtips?

Sat Jun 24, 2017 11:06 pm

The 737MAX have to fit the gates. The maximum span for a code c gate is less than 36m or less than 118 feet. The wingspan of a 737MAX with split scimitar winglets is 35.9 m, the P8 has a wingspan of 37.64 m or more than 123 feet, to much for the corresponding code c gate.
 
MesserJ
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Re: 737max: why not raked wingtips?

Sat Jun 24, 2017 11:07 pm

I think gate space is a big reason why they aren't using raked wingtips on passenger 737s. The raked wingtips increase the wingspan by 10 feet, which makes it exceed or close to exceeding the maximum allowable wingspan for gate infrastructure designed for the 737's class.
Last edited by MesserJ on Sat Jun 24, 2017 11:08 pm, edited 1 time in total.
 
Newbiepilot
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Re: 737max: why not raked wingtips?

Sat Jun 24, 2017 11:37 pm

chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I heard a rumor that the winglets on the 737NG were not capable of operating at low altitudes continuously in icing conditions that a P8A is expected to fly in. That is why they went to raked wingtip since gate dimension constraints isn't the biggest problem whereas that is a huge factor with the 737 MAX.
 
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RL777
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Re: 737max: why not raked wingtips?

Sat Jun 24, 2017 11:53 pm

Gate space
 
BoeingGuy
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 12:02 am

chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I don't follow. Does that mean the 787, 777-300ER, 777-200LR, 747-8 and 767-400 fly low and slow too?
 
AA737-823
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 12:20 am

Newbiepilot wrote:
chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I heard a rumor that the winglets on the 737NG were not capable of operating at low altitudes continuously in icing conditions that a P8A is expected to fly in. That is why they went to raked wingtip since gate dimension constraints isn't the biggest problem whereas that is a huge factor with the 737 MAX.


I'm not so sure about that for the following reason:
While it's true that the leading edge of the winglet is NOT thermally de/anti-iced, which would/does result in the accretion of icy building, the same is true of the outboard section of the leading edge of the 737NG wing.
That is, slats numbers 1 and 8 are NOT heated when wing anti-ice is turned on- only 2, 3, 4, 5, 6, and 7 are.
So, I don't think that the winglets would drive a restriction, if part of the wing is just the same.
 
chiki
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 5:06 am

BoeingGuy wrote:
chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I don't follow. Does that mean the 787, 777-300ER, 777-200LR, 747-8 and 767-400 fly low and slow too?

see article below

http://www.ainonline.com/aviation-news/ ... -its-wings

According to Boeing, the wingtips–not offered to commercial customers because of the additional length they add to the wingspan–give about the same level of performance as the winglet-equipped airplane. The wing also includes additional de-icing equipment. To accommodate the new design and the four under-wing weapons pylons, each of which has a 3,000-pound weight limit, the internal wing structure has been specially strengthened. The aircraft is expected to easily meet the Navy requirement for 2.2-g sustained flight, along with certification for operations down to 200 feet.
 
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LAX772LR
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 7:01 am

BoeingGuy wrote:
chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I don't follow. Does that mean the 787, 777-300ER, 777-200LR, 747-8 and 767-400 fly low and slow too?

The rakes ENABLE the aircraft to fly the lower, slower, more ice-prone missions more efficiently, they don't restrict it to that.
I myself, suspect a more prosaic motive... ~Thranduil
 
rbavfan
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 8:39 am

Newbiepilot wrote:
chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I heard a rumor that the winglets on the 737NG were not capable of operating at low altitudes continuously in icing conditions that a P8A is expected to fly in. That is why they went to raked wingtip since gate dimension constraints isn't the biggest problem whereas that is a huge factor with the 737 MAX.


They went to the raked wingtips because the navy does not neet to meet the gate space. The main differences are around 5% fuel savings vs 7-8% & crosswinds are worse for winglets.
 
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VirginFlyer
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 8:54 pm

mjoelnir wrote:
The 737MAX have to fit the gates. The maximum span for a code c gate is less than 36m or less than 118 feet. The wingspan of a 737MAX with split scimitar winglets is 35.9 m, the P8 has a wingspan of 37.64 m or more than 123 feet, to much for the corresponding code c gate.

A minor correction: the split scimitar winglet is an aftermarket modification for the 737-700/-800/-900 offered by Aviation Partners Boeing. Among the modifications are a new scimitar-shaped tip to the standard blended winglet, and the addition of a strake attached to the underside of the winglet. The strake has a smaller root chord than the blended winglet.



The Advanced Technology Winglet, developed by Boeing, is the standard winglet fitted to the 737 MAX. See http://boeing.mediaroom.com/2012-05-02- ... MAX#Closed and http://www.boeing.com/commercial/737max ... -winglets/ for more details. The winglet features two elements, one angled upwards and the other angled downwards. The two elements have the same root chord, and appear more as an interested unit rather than a strake attached to a winglet. The upper element doesn't appear to have the same degree of blending as the previous blended winglet found on the 737NG (and its derivative the Split Scimitar winglet)



V/F
It is not for him to pride himself who loveth his own country, but rather for him who loveth the whole world. The earth is but one country, and mankind its citizens. —Bahá'u'lláh
 
BoeingGuy
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Re: 737max: why not raked wingtips?

Sun Jun 25, 2017 9:33 pm

LAX772LR wrote:
BoeingGuy wrote:
chiki wrote:
I think they did not want the Max to fly low and slow like the P8 but high and fast


I don't follow. Does that mean the 787, 777-300ER, 777-200LR, 747-8 and 767-400 fly low and slow too?

The rakes ENABLE the aircraft to fly the lower, slower, more ice-prone missions more efficiently, they don't restrict it to that.


I'm fully aware of that. I was responding to the first poster's comment a bit sarcastically.
 
tjh8402
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Re: 737max: why not raked wingtips?

Mon Jun 26, 2017 12:45 am

The P-8s are not intended for low and slow. They are designed for operating their missions at high altitudes. That's a main reason they lack a MAD. They are also planned to be equipped with torpedos that can be launched from 30,000 ft and higher.

https://www.flightglobal.com/news/artic ... on-435653/

Despite the company’s marketing, the navy’s ASW community were already eager to dispense with such laborious low-altitude operations, Rossi says. Indeed, the navy deleted the magnetic anomaly detector from the P-8A configuration, the only sensor that demands the aircraft fly at low altitudes.

“If it’s not something that drives you to low altitude, I’m not sure why you would go there,” Rossi says.

The P-8A has “no problem with low-altitude,” Rossi says. But the navy prefers to operate the aircraft at higher altitudes, where crews are less fatigues and can take full advantage of the Poseidon’s sensor suite, including a multi-mode radar, electro-optical/infrared camera and a multi-static active coherent acoustic system.


I had heard a while ago that raked wing tips do better over long cruises (hence their application on LH frames and the endurance focused P-8), whereas the winglets styles do better in climb and therefore the shorter flights typical of the 737. There's also the issue raised in the article already posted: raked wing tips cause increased wingspan which affects gate space.
 
BoeingGuy
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Re: 737max: why not raked wingtips?

Mon Jun 26, 2017 1:27 am

tjh8402 wrote:
The P-8s are not intended for low and slow. They are designed for operating their missions at high altitudes. That's a main reason they lack a MAD. They are also planned to be equipped with torpedos that can be launched from 30,000 ft and higher.

https://www.flightglobal.com/news/artic ... on-435653/

Despite the company’s marketing, the navy’s ASW community were already eager to dispense with such laborious low-altitude operations, Rossi says. Indeed, the navy deleted the magnetic anomaly detector from the P-8A configuration, the only sensor that demands the aircraft fly at low altitudes.

“If it’s not something that drives you to low altitude, I’m not sure why you would go there,” Rossi says.

The P-8A has “no problem with low-altitude,” Rossi says. But the navy prefers to operate the aircraft at higher altitudes, where crews are less fatigues and can take full advantage of the Poseidon’s sensor suite, including a multi-mode radar, electro-optical/infrared camera and a multi-static active coherent acoustic system.


I had heard a while ago that raked wing tips do better over long cruises (hence their application on LH frames and the endurance focused P-8), whereas the winglets styles do better in climb and therefore the shorter flights typical of the 737. There's also the issue raised in the article already posted: raked wing tips cause increased wingspan which affects gate space.


What's a MAD? I personally work with the Boeing P-8 Chief Pilot (who also supports the KC-46 program) and I have no idea what a MAD is. Makes me suspect no-one else knows what it is either.
 
ha763
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Re: 737max: why not raked wingtips?

Mon Jun 26, 2017 2:46 am

BoeingGuy wrote:
What's a MAD? I personally work with the Boeing P-8 Chief Pilot (who also supports the KC-46 program) and I have no idea what a MAD is. Makes me suspect no-one else knows what it is either.


Magnetic Anomaly Detector. Used for anti-sub warfare.

http://www.globalsecurity.org/military/ ... t/asw3.htm
 
BoeingGuy
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Re: 737max: why not raked wingtips?

Mon Jun 26, 2017 5:00 am

ha763 wrote:
BoeingGuy wrote:
What's a MAD? I personally work with the Boeing P-8 Chief Pilot (who also supports the KC-46 program) and I have no idea what a MAD is. Makes me suspect no-one else knows what it is either.


Magnetic Anomaly Detector. Used for anti-sub warfare.

http://www.globalsecurity.org/military/ ... t/asw3.htm


Thanks. Silly me for not knowing that. ;)
 
mjoelnir
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Re: 737max: why not raked wingtips?

Mon Jun 26, 2017 10:24 am

tjh8402 wrote:
The P-8s are not intended for low and slow. They are designed for operating their missions at high altitudes. That's a main reason they lack a MAD. They are also planned to be equipped with torpedos that can be launched from 30,000 ft and higher.

https://www.flightglobal.com/news/artic ... on-435653/

Despite the company’s marketing, the navy’s ASW community were already eager to dispense with such laborious low-altitude operations, Rossi says. Indeed, the navy deleted the magnetic anomaly detector from the P-8A configuration, the only sensor that demands the aircraft fly at low altitudes.

“If it’s not something that drives you to low altitude, I’m not sure why you would go there,” Rossi says.

The P-8A has “no problem with low-altitude,” Rossi says. But the navy prefers to operate the aircraft at higher altitudes, where crews are less fatigues and can take full advantage of the Poseidon’s sensor suite, including a multi-mode radar, electro-optical/infrared camera and a multi-static active coherent acoustic system.


I had heard a while ago that raked wing tips do better over long cruises (hence their application on LH frames and the endurance focused P-8), whereas the winglets styles do better in climb and therefore the shorter flights typical of the 737. There's also the issue raised in the article already posted: raked wing tips cause increased wingspan which affects gate space.


It is not as simple as one is better than the other. There are a lot of factors influencing what is best in each case, it is not only fuel burn, but also things as wake turbulence and wing loading. Especially if the wing span of a frame is nearing a hard limit, you look at the best solution inside a limited span and than winglets can do a better job than raked wing tips.
 
PC12Fan
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Re: 737max: why not raked wingtips?

Mon Jun 26, 2017 3:12 pm

Question - if raked are better for high and fast, why were raked not considered for the BBJ line? Gate space is really not a concern there. Unless I overlooked the better performance numbers earlier. Saw that one was better than the other but I couldn't decipher which one was better.
Just when I think you've said the stupidest thing ever, you keep talkin'!

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