kbuf737
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Joined: Thu Dec 04, 2003 2:22 pm

Slotted Flaps A Thing Of The Past

Wed Mar 31, 2004 6:28 pm

Are slotted flaps, which used to be considered such a breakthrough more of a thing of the past? I notice more and more newer planes appear to have more "single unit" style flaps which look more blunt and drag enducing imo.
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Ralgha
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RE: Slotted Flaps A Thing Of The Past

Thu Apr 01, 2004 2:38 am

Cessnas use slotted flaps. 'nuff said.
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Dufo
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RE: Slotted Flaps A Thing Of The Past

Thu Apr 01, 2004 3:04 am

Which ones, Ralgha?

. .
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Ralgha
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RE: Slotted Flaps A Thing Of The Past

Thu Apr 01, 2004 1:23 pm

Most of the single engines. Some of the older models don't have any flaps, and some of the older ones may be plain flaps, but most are slotted.
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NWA ARJ
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RE: Slotted Flaps A Thing Of The Past

Fri Apr 02, 2004 11:54 am

Our Warriors at UND also use the slotted flaps. I would not say that they are a thing of the past.
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7574EVER
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RE: Slotted Flaps A Thing Of The Past

Fri Apr 02, 2004 1:03 pm

I think KBUF737 may be referring to the flaps on airliners that come out in sections rather than one piece. The 737 for example:


737-300 "old flaps"


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737-800 "new flaps"


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If this is what you meant then you are just mistaken about what a slotted flap is. (no worries, I can easily see why you may make this mistake) It doesn't mean that it comes out in sections but rather there is a gap between the flap and the trailing edge of the wing where some of the air from below the wing can come up and move over the top of the flap.
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kbuf737
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Joined: Thu Dec 04, 2003 2:22 pm

RE: Slotted Flaps A Thing Of The Past

Fri Apr 02, 2004 5:50 pm

Yeah thats what i mean. They seem to be shying away from those sectioned flaps.
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musang
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RE: Slotted Flaps A Thing Of The Past

Sat Apr 03, 2004 2:37 am

Cessnas and pre-NG 737s both had slotted flaps. Cessnas are single slotted, Boeings are up to Triple slotted. As long as there's a slot somewhere.

Its a question of efficiency vs. weight/complexity.

Multiple slotted flaps are traditionally more efficient, but heavy and complicated. Apparently Boeing now have found a double slotted design for the NG 737s which does as well as the original triple slotted types.

The 747SP used a single slotted flap, the other versions used a triple. Less weight, less drag through not needing such large track fairings, but I believe I'm correct in saying it wasn't as efficient. It didn't need to be however, since the same wing (dimensionally) was lifting a much smaller airplane, and reasonable take-off/approach speeds were attainable.

Incidentally the SP flap translation path was interesting. The flap leading edge didn't simply move aft along a track like a Cessna while the trailing edge moved aft/down. The LE moved aft and down on a pivot arm, so it was significantly below the undersurface of the wing. This I recall from the diagrams in a South African Airways 747SP differences manual I read on the flight deck of one over the Indian Ocean, and look forward to a more accurate description from someone who knows what he/she is talking about!!

Regards - Musang

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