Flap Type and Efficiency

[Stoney]

Why is it everyone thinks Fowler flaps, as a flap design type, are more efficient than all other flaps?  For what its worth, you could design a Fowler Flap that was less efficient than a Split Flap, depending on how its designed.  The type of flap, taken by itself, has no bearing on how efficient a flap system is on a particular airplane.

[Krusty]

Probably because in this game they're modeled as anti-gravity repulsor lifts.

[FLS]

I can't speak for everyone but I believe it's because they increase the wing area and lower the wing loading.

[Karnak]

Probably because in this game they're modeled as anti-gravity repulsor lifts.

Evidence?

Thought so.

[Soulyss]

Why is it everyone thinks Fowler flaps, as a flap design type, are more efficient than all other flaps?  For what its worth, you could design a Fowler Flap that was less efficient than a Split Flap, depending on how its designed.  The type of flap, taken by itself, has no bearing on how efficient a flap system is on a particular airplane.

Because the Book of Kelly Johnson tell us so?

[Delirium]

Probably because in this game they're modeled as anti-gravity repulsor lifts.

If Krusty says so, it has to be true.

[Captain Virgil Hilts]

Why is it everyone thinks Fowler flaps, as a flap design type, are more efficient than all other flaps?  For what its worth, you could design a Fowler Flap that was less efficient than a Split Flap, depending on how its designed.  The type of flap, taken by itself, has no bearing on how efficient a flap system is on a particular airplane.

I'm sure you could design a screwed up Fowler flap that wasn't efficient. If you tried. If you had the desire. Although I don't know why anyone would want to.

And what I've read over the years does not agree with the text in bold above.

[Chalenge]

Your starting to baffle me Stoney because you usually think things through better than you are today. 

[Krusty]

The reason folks say "Oh, Fowler flaps? They're super!" is because of their experience with this game.

Regardless of how correct this game is (that's another issue), it models them so lovingly and so beneficial to use that folks just chime in "Oh they're efficient!" -- meaning they base their opinions off the game.

That's what my post meant. Sorry that 2 of you can't get my point.

[Raptor]

This image is coming in very handy lately...

[Stoney]

This image is coming in very handy lately...
(Image removed from quote.)

I'm familiar with this.  All things being equal the same flapped area, using a Fowler design can be more efficient.  But, there are considerations beyond simply the aerodynamic function of the things.  The mechanism is a lot more complicated and usually, much heavier.  It is conceivable that there could be Fowler designs that, while aerodynamic marvels, create such a weight penalty that they lose their efficiency to simpler designs.  There are other situations where the designer has a limited flapped area to use for the system, and chooses a fowler design to maximize the limited space.  The disclaimer at the bottom of that chart states as much.

My point in beginning this thread was to express my dismay when I hear people say "its flaps are more efficient because they're fowlers".  For the P-38, the most oft used example, the flaps may be more efficient, but its because its a more efficient design overall, not merely because its a fowler design. 

[Chalenge]

Flaps usage in AH seem to be calculated from theoretical formulas but... all I have is anecdotal evidence and evidence from Warren Philips that indicates about a 20% error in effectiveness... but I want the evidence to be there so maybe Im just not doing it right. Im still trying to work this stuff out in between other projects.

[thorsim]

i've seen a diagram posted that the poster claims shows different conclusions from that chart on another board,
unfortunately the discussion is old and the original has been removed, the remaining thumbnail is too small to make out.

the data sheet chase can be very disappointing ...

+S+

t

[Chalenge]

Even if my work varifies my suspicions it will not in any way support your assertions.

[Raptor]

I'm familiar with this.  All things being equal the same flapped area, using a Fowler design can be more efficient.  But, there are considerations beyond simply the aerodynamic function of the things.  The mechanism is a lot more complicated and usually, much heavier.  It is conceivable that there could be Fowler designs that, while aerodynamic marvels, create such a weight penalty that they lose their efficiency to simpler designs.  There are other situations where the designer has a limited flapped area to use for the system, and chooses a fowler design to maximize the limited space.  The disclaimer at the bottom of that chart states as much.

My point in beginning this thread was to express my dismay when I hear people say "its flaps are more efficient because they're fowlers".  For the P-38, the most oft used example, the flaps may be more efficient, but its because its a more efficient design overall, not merely because its a fowler design. 

Ok I have a better comprehension of what you are getting at now. It would be interesting to see what a fowler design would have on say a spitfire. I still feel as if it would be an enhancement over a split design or a plain flap.. Take the ki-84 for example, it has a very similar flap design on a very different wing, yet it has a much increased turn performance with the use of flaps.