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B737NG TE Flap  
User currently offlineHAWK21M From India, joined Jan 2001, 31875 posts, RR: 54
Posted (12 years 2 months 3 weeks 2 days ago) and read 2494 times:

Why was the Fore flap deleted from the B737NG TE Flap.

Think of the brighter side!
7 replies: All unread, jump to last
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 66
Reply 1, posted (12 years 2 months 3 weeks 2 days ago) and read 2468 times:

While I said in my profile that I was not going to address any more questions that start with "why" I will note that the NG aircraft has a wing that is completely different from the earlier 737s. It is nearly 18 feet longer, of much greater chord, smoother, and possibly different in other ways as well. I have never seen the shockwave on this wing while it is visible on the earlier models much of the time.

Perhaps there is something here (lighter wing loading maybe) that permits the use of a simpler flap design.

Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineCdfMxTech From United States of America, joined Jul 2000, 1341 posts, RR: 24
Reply 2, posted (12 years 2 months 3 weeks 1 day 23 hours ago) and read 2457 times:

So Slamclick, do you want all questions asked in the form of any answer like Jeopardy?  Big thumbs up

User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 66
Reply 3, posted (12 years 2 months 3 weeks 1 day 23 hours ago) and read 2453 times:

CdfMxTech Well, I guess that does sort of limit my choices here doesn't it?.

Seriously, I might be qualified to lecture on a number of topics, like high-lift devices used on jet transports, but to presume to answer "why" the manufacturer chose not to use triple slotted flaps ignores the fact that I was not present when the decisions were made. I did not hear the alternatives.

A while back I gave some answers that were accurate enough for pilot groundschool at the airline level. I had an engineer lurking on the forum sharpshoot me. What I said was not exactly wrong but his education was better than mine in this area and I realized that I had probably said more than I could back up. Not wrong, just overextended.

"I'll take 737NG for a thousand, Alex"

Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlinePhollingsworth From United Kingdom, joined Mar 2004, 825 posts, RR: 4
Reply 4, posted (12 years 2 months 3 weeks 1 day 20 hours ago) and read 2438 times:

To put it simply, "save weight". The triple vs. double slotted flaps weight considerably more. Also there is not really a need for a triple slotted flap for the 737NG mission, so why add the mechanical complexity. Part of this stems from the new airfoil cross-section that the 737NGs use. As to how the specifics of all of this came about, I don't have too much insight. I do know the none of the other supercritical era wings of Boeing use triple slotted flaps. The wing loadings for the 737-400 and 737-900 are actually similar.

User currently offlineA330 From Belgium, joined May 1999, 674 posts, RR: 7
Reply 5, posted (12 years 2 months 2 weeks 4 days 17 hours ago) and read 2341 times:

And as a result, the B737NG has a higher approach speed than the Classics, and is less stable. B737 is not known for its good behaviour inflight, she can be quite a bit to handle, especially after an engine severe damage after V1.

User currently offlinePrebennorholm From Denmark, joined Mar 2000, 7142 posts, RR: 53
Reply 6, posted (12 years 2 months 2 weeks 4 days 14 hours ago) and read 2321 times:

Why no triple slotted flaps on 737NG?

Since (I presume) none of us were NG wing designers, then it is of course all guesswork.

But in addition to various reasons such as weight saving, manufacturing cost saving, maintenance cost saving, not really needed due to greater wing area etc, let me propose one more reason:

Lower noise during approach.

Any views on that last guess?

Happy landing, Preben Norholm

Always keep your number of landings equal to your number of take-offs
User currently offlineQantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 22
Reply 7, posted (12 years 2 months 2 weeks 4 days 13 hours ago) and read 2305 times:

...Lower noise during approach...Any views on that last guess?

"Smaller" ("less-than-triple-slotted") flaps certainly would reduce approach noise, but the question remains...was this the reason Boeing dropped a triple-slotted design? As you said, Prebennorholm, none of us were on the 737NG design team, and without some facts/insider knowledge we can't know for sure why they weren't used. Sure "smaller" flaps reduce noise and weight but, along with more positives, there are of course negatives, too. One major negative is that, because the potential lift/lift coefficient of the wing is being decreased, stall speed increases. Many other pluses and minuses present themselves, and 737NG designers obviously factored all those in and concluded that "smaller" flaps would be better for the intended use of the aircraft.


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