text: Flap Types - Airliners.net
  Thu Nov 08, 2001 1:35 am
  I was searching all forums about this topic... I am sure that last year I saw something posted about flap types... but I can not find it now with the search function
  I would like some help on how to reach that same post through any specific word or if you know how to get, or directly if you can tell me the flap types that exists on airliners, Boeings, Airbuses, Tupolevs and so on... may be they are the same for small size aircrafts but if not I do not care them...
  Mostly, I am interested on the B737-200, for example vs. a MD-88.
  If I am correct, a kind of flap is called "Fowler" but I am not sure, that is why I am asking you all
  Well, thank you very much guys !!!
  Martìn Cabrera
  RE: Flap Types
  Thu Nov 08, 2001 2:28 am
  I'll try to explain, but it will be difficult without actually seeing illustrations and having to explain other terms herein: 737-200 uses triple-slotted fowler flaps. The flaps are mounted on roller bearing carriages and roll down tracks, with the sequencing of the fore, mid, and aft flap being accomplished via cables/linkages. -- The flap tracks curve down progressively more sharply the farther aft they are. -- The fowler flap design allows the first few units of movement to be more or less paralell with the upper camber of the wing- thus increasing wing chord and of course lift. As the flaps travel further down they curve down and produce more and more drag. -- The whole DC9/MD8X series uses basically a simple hinged ( double-slotted ) flap design, but even this description is a bit oversimplified: They are hinged in such a manner ( with the fulcrum being about a foot below the wing in farings ) so that the first part of their travel they are, in effect, fowler flaps. The further the travel the more sharply they go down. -- The MD's use simple linear hydraulic actuators ( located in the hinge fairings ) and the 737 uses jacksrews/ballnuts. It should be noted that not all fowler flaps are deployed with jackscrews though. --
  A short description(however, not as nearly exact like NKP S2's):
  Split Flap - just a part of the wing(lower, trailing edge) deflecting downwards. Movement doesn't affect the wing's upper surface. Used on DH Comet, Avro Lancaster, Shackleton and some other types
  "Simple" flap - moves back, extending the wing chorde, apparently deflecting also downwards
  Fowler Flap - moves back AND down from the flap well, deflecting simultaneously downwards. Used on: Il-62, Lockheed Electra, Vickers Vanguard, Convair CV 440/550
  Slotted, Double-slotted and Triple-Slotted flaps: here, the flap isn't just a single slab of metal, but consists of more than one section. The clue is, the sections are divided in line more or less paralel to the wing's trailing edge. Further, there is a small gap between the sections left intentionally to accelerate airstream going through and then passing over the flap's upper surface(gives a bit extra lift). Slotted flaps have only one such gap between wing and flap, double slotted flaps consist of two sections and tripple slotted of three. Used on(most prominent examples): B727, Tu-154. Also, Folwer-flaps could be of slotted type.
  For further informations check the photos here, there are some really good ones where you can see what it's all about.