if i have a wing planform where the ailerons are just flat pieces extending from the trailing edge of the airfoil (as popupar in fun fly airplanes) then in that case is my wing area only the area of the airfoil or does it include the aileron area as well

Don't know what other people will say but its my understanding that the wing area does include the ailerons, regardless of whether they're sectioned or not. i.e. wing area is independant of the aerofoil section. Though not shaped into the aerofoil section, the ailerons will still contribute to the overall lift of the wing so should be included.

Just my two cents!

Yes. What gizmo said is what ive been told and read many times. Ailerons are included.
Now for some after thoughts that I hope wont start a pissin contest between the aerodynamically educated.
When ailerons are flat they add to the cord therefore adding lift. (i think)
when turning, down ailer is increasing lift by deflection. (i think)
up ailer is DECREASING lift by deflection. (i think)
If lift is variable by ailer position. Should they be included in total lift calculation? (i wonder)
ALSO.
Why dont we add elevater size in the calculations for .oz per sq. ft.?
If ya cut it all off would it fly?
AND.
Why do we add the inches in the fuse area.
If ya built a wing with ribs shaped like most fuses would it fly?

easy answer -
the whole plane is part of the lift
lift is nothing but drag put to work for you.
when the drag no longer works against gravity -it ain't lift.

You can make fancy computations and theorize till the cows come home - but it still remains a fact - all of the plane is at somtimes or another - part of lift.
maybe lousy lift -but still lift.
Take a pair of scissors and cutout a shadow of the entire airframe - figure that area - - all of that, can be lift.
from old habits - and ease of comparison- many folks just use projected wing area -but that is not a true representation of all the lifting parts..
The formula for this is probably in some book -

fnp,

It makes the most sense to include aileron area in the calculation of wing area. This is also the interpretation that you would most likely find in the rules governing wing area in various contests.

banktoturn

Dick,

It is not accurate or intuitively useful to say that lift is simply "drag that is put to work for you".

While all of the plane may at various times contribute to lift, it does not make sense to consider all the projected area of the airframe to be comparable to the projected area of the wing. It is not just an arbitrary habit that the projected area of the wing is used. This practice is used because it makes sense, and because it is not beneficial, for most airframes, to generate lift with the other parts of the airframe.

banktoturn

Dick is sorta right on the concept although there are certain misconceptions on the statement. After all, most fuselages have an aproximated shape of a semi symmetrical airfoil therefore there is a contribution of lift from it. Besides, if a the fuselage wouldnt contribute to some part of the lift.....how would an airplane fly knife-edge?

If you measure the pressures above he area of the wing that is occluled by the fuselage it will be almost the same value as just outboard of the fuselage. So it makes sense to use that area to make a wing area based calculation. In other cases like a variable sweep wing a value is just decided on and you go with it. Usually the lowest sweep angle is used as it is most likely to be theoretically correct and the glove or leading edge strake is not considered. Of course there are probably other conventions used, depending on what the designer had for breakfast!

Not using the fuselage aft or forward of the wing is desirable since the CLalpha curves of the fuselage are not those of the wing, it would be like having apples and apple sauce put together (weird comparison and probably not meaningful). Not using the horizontal tail is also reasonable if only for ease of use even though the tail lift does get into the whole airplane lift which is included in the CLalpha of the airplane.

The effects of aileron deflections in low angles are almost identical to the effects of the airfoil camber following the same line.

Of course anything moving through the air will make lift and drag. Some things just are shaped to do it better. A wing is better than a fuselage shape for example. Knife edge flight is flying at it's most inefficient, interesting to watch but not flying (personal opinion). Kinda like hovering with an airplane, get a helicopter, they do it better.

I just got off my chain-of-thought. The main thing is to be consistent with the definitions. Even if it is not exactly right at least everyone useing the same methodology allows comparison of airplanes to be easier.

Thanx for the diferent comments that helped a lot i am now clear on the subject

Ben,

There is another good reason for not adding the area of the horizontal tail to the aircraft reference area. The wing of a longitudinally stable airplane will typically generate a nose-down pitching moment about the Center of Gravity (CG). The most common way to trim the airplane is to have a horizontal tail pushing downward to produce a nose-up pitching moment (reflex camber in the wing is another way, but that is often less efficient). You can see that the airplane in the link below has tail camber to help push down (thanks Souza):

[link=http://www.rcuniverse.com/forum/upfiles/32095/Mr39694.jpg]Tail Camber[/link]

As many have pointed out, the choice of "wing area" is somewhat arbitrary. One reason to choose a "good" wing area is that is will give you a better idea of how hard the wing is working. For example, a good way to compare the characteristics of two aircraft is by their wing loading ("cubic wing loading" may be better, but that's a different story). If two aircraft don't have sensible and CONSISTENT choices for their wing areas, then comparing their wing loading may not be very meaningful.

Getting back to the question of horizontal tail area: you could have a very large conventional horizontal tail, but it would have virtually the same effect on wing loading as a very small horizontal tail. Both tails would need to generate roughly the same down force to balance the wing's pitching moment. The bottom line is that the horizontal tail area normally has little to no effect on the aircraft wing loading (or aircraft CL), which is typically what wing area is used to determine.

I get the idea, some think I am poking fun at the science of aerodynamics.
Far from it.
My offhanded remarks simply reflect my thoughts that we often fail to see the forest because of all the trees--
Fuselage lift -for example -is extremely important , even in the big boxes we travel around in. (airliners).
On the stealth fighters/bombers- where is the wing? Or the fuselage?


On a good, powered, aerobatic model -- the transition from level to knife to level is greatly infuenced by the area of the fuselage AND - where that area is greatest. (relative cg to wing)
If we were only to use projected area for figuring "wing area "-- then how do we figure span loading??
When doing a tight tumble --the location of the horizontal tailplane, will greatly influence how rapidly the tumbling energy is bled off.
In the early years of working with models - I was always amazed at how very carefully developed airfoils were claimed to be the reason the model flew so well.
Hands on testing showed that in our models - these airfoils were really very minor points of the whole picture.
Powerloading , wing aspect ratio and wing loading probably get my vote as the three most influential points in developing almost any powered model.

-

Shoe

There have been some spirited debates about the direction of tail lift in the forums.

For a fully symmetrical airfoil wing with the CG location aft of the 25% chord of the MAC the tail lift is UP.

For a fully symmetrical airfoil wing with the CG location forward of the 25% chord of the MAC the tail lift is down.

Do moment diagrams. The wing lift is at 25% wing mac. The CG is at 30% wing mac. What direction is the force required at the tail to keep the airplane unaccelerated in pitch during flight. It is up at the tail. You can have up elevator but it just lessens the up load, not make the load go in a down direction.

Put on a big flap or undercamber deflection which makes a nose down moment. If it is sufficiently large the tail load will change to a down direction.

Keep in mind that when you look at just a wing the pitching moment is nose down. Then you think put a tail on it and have it lift down and it takes care of the nose down moment. The thing is that the Neutral Point of the airplane moved aft when the tail was put on and so the total pitching moment changes.

The airplane in the link has strong nose down moments due to choices in airfoil, flap and probably CG location. Whether or not camber is a better choice than just negative incidence at the tail is hopefully something that they worked out before building it.

But as I noted above, consider our typical pattern ship and the tail lift is up.

Ben,

Good point that the tail of a typical pattern ship pushes up. Even so, I still think it normally doesn't make sense to include its area in the aircraft reference area. The tail only needs to provide a certain amount of up or down force to balance the wing's pitching moment about the CG (making it bigger doesn't mean that it pushes up or down any more). Increasing the tail area therefore doesn't directly affect the wing loading. You make another good point that the tail shifts the aerodynamic center/neutral point aft. A bigger tail allows you to shift the CG aft without degrading static longitudinal stability. Moving the CG aft would unload the wing, but you typically pay and induced drag penalty when you shift lift from the wing to the tail (the wing is normally a more efficient lift provider). Thanks for the response!

Ha Dick Hanson...good answers and how old is the puppy in your avitar now????

Libby turns one this month - she is still a bundle of energy.
I have been flying a lot of FOAMIE stuff recently-and at 4 oz ft wing loading - a lot of the theory of "wings " seems quite unrelated.
these very low aspect ratio setups typically have the cg at about /3 the chord
I picked a stubby elliptical planform on this setup simply cn't be made to "snap out at high g's
but the durn thing will snap on a full deflection of all surfaces
These things should be "required flying" for anyone who believes that the simple flat plate is not a good wing.
At this point in time - I firmly believe that a very thin flat plate - if it was capable of resisting any twist - yet was able to flex slightly spanwise under airloads-
would prove to be a superior wing for any small model - provide the wing loading was low enough

Basically all of you are correct. The tail lift is usually not considered in the total lift merely by convention. The equations/curves used to develop stability and control and other performance parameters take this into account because they are derived using wind tunnel or CFD data. When designing a modern airliner or military airplane the above method is used for preliminary work and once a configuration is chosen, then detail analysis of the contribution of every part is performed (costs a lot of money and requires many computers and engineers).

cirrus
Aeronautical Engineer (among other things) and RC newby

Addendum:

Just to clarify. The tail area is not used for calculating total lifting area. It is obviously used to calculate stability and control.

cirrus
my mind needs clarification