shok posted 02-08-99 11:56 PM ET (US)     

What are the distinctions between the following types of flaps and ailerons? What makes them different from the 'regular' kind of flaps?

1. Fowler flaps

2. Split flaps

3. Frise-type ailerons

4. Cowl flaps

5. Slotted flaps

6. Camber-changing flaps

7. Flaperons

8. Leading-edge slots

Wells posted 02-09-99 12:50 AM ET (US)            

Fowler flaps move backwards as well as deflect down, so they increase the wing area at the same time as they deflect down. Split flaps are hinged from the bottom of the wing only. Frise ailerons have the hinge line moved slightly behind the leading edge of the aileron, so when deflected up, the leading edge sticks down a little bit to help even out the drag. They are also easier to mass balance by placing weight in the leading edge of the aileron. Cowl flaps are on the engine cowl and open to allow more cooling of the engine. Slotted flaps have a 'slot' or a gap between the wing trailing edge and the flap leading edge. High speed airflow flows through this slot and helps to increase lift slightly. All flaps change the camber (or curvature) of the wing. Flapperons are ailerons that can droop like flaps and still be used as ailerons as well. The 109's and 110's had these where the ailerons would droop about 10 degrees for 40 degrees of flap movement. This way, more lift can be had without losing all aileron control.

Aerobat 111th FG posted 02-09-99 11:06 AM ET (US)            

I believe Split flaps were invented by Orville Wright and are the one type of flap that doesn't increase the chamber (increases drag without increasing lift).

Leading edge slats (I don't think it's slots, BOTOH I've never flown a plane that has them!) allow more airflow over the wing (and thus creates more lift) at high angles of attack.

worr posted 02-09-99 02:06 PM ET (US)            

shok wrote:

What are the distinctions between the following types of flaps and ailerons? What makes them different from the 'regular' kind of flaps?

++++

Why do you want to know?

One could write quite a bit on the subjects you mention and still not answer your question.

FWIW...I think you have several flaps confused with one another. Cowl flaps and fowler flaps are on a different playing field one being in the realm of aerodynamics and the other with regard to engine performance.

Worr, out

shok posted 02-09-99 03:27 PM ET (US)         

Why do I want to know? Because everytime you crack open a book on these fabulous Warbirds, you get these technical terms that are simply not explained at all! The distinctions, now that they have been explained, are quite significant. I didn't know that Fowler flaps were those that extended back, though I have long seen them in action on commercial airliners (that's why I sit near the window).

Take the Bf 109, for instance. It has the following: leading-edge slots, Frise type ailerons, slotted flaps, plus flaperons! Now that makes for quite a complex wing and control surface design, and the analysis of its aero properties should be similarly complex. The questions then arise: how closely does the WB flight model approximate the actual effects of these complex control surfaces?

From the explanations by Wells and others, we should see the ff: better tolerance for high-alpha due to the slots, i.e., greater lift before stall; perhaps less adverse yaw due to better balanced aileron drag; higher lift with less drag due to slotted flaps (might be impt in a turn fight?); and the flaperons provide good roll control even when the flaps are down (uh, maybe when you need to land on a carrier?).

I think this is cool stuff to know.

BadMan 4thFG posted 02-09-99 03:48 PM ET (US)            

Hay Worr!

What do you have against someone wanting to increase his knowledge?

Shok,

The study of wings types and control surfaces is as big as Worr alludes to. My advice is to go to your public library and do some research. It's a very interesting topic but kind of dangerous. I went to the library once and forgot to eat for about 8 hours.

worr posted 02-09-99 04:08 PM ET (US)            

shok wrote:

I didn't know that Fowler flaps were those that extended back, though I have long seen them in action on commercial airliners

++++

The P-38 was the first to use them. They give a double effeciency as before stated, they also lent themselves well to combat where you could litterally "snap" them back 8 degrees to tighten a turn.

Later air craft also employed a type of "combat flap" that the Americans perfected much sooner than their counter parts.

+++++

shok went on to say:

Take the Bf 109, for instance. It has the following: leading-edge slots, Frise type ailerons, slotted flaps, plus flaperons!

++++++

It was a mixed bag for the 109. Very revolutionary design and the 109 did have some kinder gentler stall characteristics, but it wasn't enough to generate a "combat edge" such as manuvering flaps could provide.

Such novel designs can only enhance a good platform. No other air craft was produced in larger numbesr than the 109 during the second World War. But there weere still air craft doing what the 109 did--turning, climbing, rolling--without all these extra things.

Keep in mind the 109 was on the drawing table back in 1933...and most of the more advanced designs of WWII didn't go into production until 1940 or later. Upgrades to the 109--new enginges, better armement and armour--went far beyond the what the original air frame could aborb.

And yes, WB does model the stall effects of the leading edge slats.

As far as BadMan's poke I appreciate the humor! But I really did ask the why question because the topic is huge and I was curious what you were reading to even get as far as listing vocabulary that most don't even understand or use.

Worr, out

Wells posted 02-09-99 05:54 PM ET (US)            

The thing with the 109 was that it was one of the first monoplane designs. It was designed to achieve maximum speeds, so wing area was kept to a minimum. The only way to achieve acceptable stall speeds and characteristics without increasing wing area was to add all those features. Speed and climb were the only edge's in combat that were important 'at that time'. Monoplane's were not expected to have the maneuverability and turn performance of the biplanes. The British on the other hand, seemed more interested in maneuverability compared to biplanes and as such, planes like the Hurricane and Spitfire had much greater wing area. The Spitfire was found to not even require flaps as the landing speed was 'acceptable'. However, the glide angle was so shallow that the pilot couldn't see where he was headed. The split flaps that have only one setting (90 degrees down) were implemented to add drag and steepen the decent.

Gazoo posted 02-09-99 06:35 PM ET (US)            

The split flaps that have only one setting (90 degrees down)

I have to do this, well because this may be my one and only chance to correct Wells.

But I belive the spit flaps only rotated 80 degrees down

"Just Plane Nuts"

F/O Gazoo, 401 Squadron, RCAF Rams

Quagmire posted 02-09-99 06:54 PM ET (US)            

Okay then, I've heard the KI84 has "Butterfly flaps". What, pray tell, are these?

Quagmire

The Volunteers

Havloc posted 02-09-99 07:49 PM ET (US)            

>>The thing with the 109 was that it was one of the first monoplane designs.<<

It would be more correct to say it was one of the first metal skined monoplane designs.

Havloc

Manx posted 02-10-99 01:02 AM ET (US)            

Okay then, I've heard the KI84 has "Butterfly flaps". What, pray tell, are these?

Butterfly flaps are similar to Fowler flaps, but designed to be deployed at combat speed. It was initially designed for Ki-44 Tojo, but was incorporated into Ki-43 Oscar to improve Oscar's performance (which wasn't really needed, Oscar pilots hardly used them and wished for better guns instead). Ki-84 also had them.

-manx-

II./JG54

burbank posted 02-10-99 09:05 AM ET (US)            

Slots and Slats haven't been covered yet

a small strip with an aerofoil shape can be attached to the leading edge of the wing to help control boundary layer (airflow). It can be fixed ahead of the wing, or can be moveable i.e. nest into the wing and pop out at low speeds. The gap formed is called the slot.

A slot can also be literally a slot in the wing itself with no separate slat - just the normal wing leading edge.

They keep the airflow following over the wing surface longer and more evenly. They add drag at high speeds.

Fowler flaps are the bottom half of the aerofoil moving back and down (split flap which moves back). When the whole back portion of the aerofoil moves back and down it is called a Slotted flap - or if in two parallel segments like an airliner - a Double-slotted flap.

Another type is the Kruger flap. On the leading edge it moves out and down without creating a gap (slot)

burbank

I./JG54