Hi guys,

I dont know anything about the theory..... But I can make a guess, a 3D comes with big control surfaces(and with big throws) , big ailerons,big rudder and big elevator.

From what I have seen up to now you need very very big elevator/s for a 3D plane. I think they are to control a (slow) plane with an aft CG. Other wise a nose heavy plane will not benefit too much from a big elevator. Or with a very fast plane, you get flutter at speeds more likely. So what is the difference between a plane with normal elevator and a plane with big elevator/s. Is elevator stab helping the plane to float ( as a surface like wings do ).

Could anyone tell us about those stuff with a language that we can all understand.

Happy new years.

Regards.

Zafer

Well ot always!

I learnt to prohang a bit on an old Tutor 40 which has very little in terms of control surface size. I think the reason they are big is too give loads of throw (like 70 degrees) but with less drag than a smaller surfaces, and hence more response. Imagine a surface 1 wich wide, say an elevator. Than one 3 inches wide. Which one will give a smoother airflow? The 3 inch one.

Back to the topic title, I know its a 3d plane because it has got "3d" or "freestyle" in the name. Usualy the manufacturer describes it as a 3d plane anyway. A another good point, is weight, 5lb is usually the heaviest most 50 size 3d planes get though some weigh more. And also wingloading can tell you wether a 3d plane is a 3d plane or not. All this is linked to control surface size etc but more to wingpasn as well.

Im sure someone will build on what I've said here

Shahid

wouldn't a bigger surface create more drag? I know what you are getting at but I just think this might sound wrong to somebody who doesn't know about it, I'm not an expert at the subject but i imagine the big elevators are simply to increase tail moment, and if anything, create more drag.
Also, a big surface moving a small distance would have the same effect as a small surface moving a big distance, so less movement is needed to get the desired effect.

Large surfaces are to allow corrections at low or no (prop wash) air speeds

Hit the nail on the head, sorry for the misconception should be like. A bigger surface would have a more smoother airflow, if it moved at 30 degrees the transition of air from one direction to the other would be smoother and less dramatic than 30 degrees of movemt on a smaller surface.

So there would be less air getting thrown off on the big surface is you get what I mean at extreme throws, less seperation.

What you two guys have pointed out is correct, I forgot that a large surface when deflected would have more area exposed to the propwash.

And the most important factor, big control surfaces make you look cool. "Look mine are bigger than yours"

Plane also needs an airfoil that can handle the low speeds with a light wing loading.

Back to the question......

What makes a 3D plane? Well for a good 3D plane, it has to be stable yet very unstable. The stability should come from proper lateral balnce and a light wing loading. The instability will come from an AFT CG and a MID or LOW wing mountingwith little if any dihedral. A 3D plane needs to be able to perform well upright and inverted, so a MID WING is desireable. A 3D plane also needs to perform very well at slow speeds and high alpha manuevers (wing stalled conditions)

Yes large control surface and throw are also desireable, but not 100% necessary for all 3D manuevers. Hovering can actually be performed with small tail surfaces. The purpose of the large surfaces/throws is for 2 reasons. First reason is for very violent manuevers and the second is for more control at slower speeds.

You can have a really good performing 3D plane that doesn't look like a CAP, EDGE or EXTRA, but these are typically the best

The main characteristic of a good 3D plane is lightness... An aft CG and large surfaces help too..

Yes heres another point.

Power is not everything for example, well it IS but take a look at this:

Take two identical funflies, one is powered by a 36 size engine the other is powered by a 46 size engine. The 46 size engine funfly is HEAVIER but has more powerful, BUT now which one would you pick? The thing here is whilst the 46 one is more powered, the 36 has better agility, can turn tighter and fly slower

Power most of time comes at the cost of wingloading and weight, though sometimes. It is better to have a heavier engine upfront to cope with a tail heavy plane than have a light engine and load of lead. One thing you don't want is "dead weight"

3d planes are able to fly on their control surfaces not just wing and stab. a 3d plane must be able to transition between standard flight and 3d smoothly - this is where light weight is important - heavy planes don't transition very well. engine needs to be just big enough to create necessary airforce to hold up the plane while it is stalled. an engine and big control surfaces are not required for 3d - you can do many 3d manuevers on a slope with 30 mph wind letting mother nature provide airforce/uplift for free.

Not always the thickest funfly airfoil is the best either, some of these do not tend to stall cleanly in a harrier (wing rock) or do not stall at all for a harrier. But then again these funfly types are great for prophanging training because they wern't meant to stall like that

What would you guys say an ideal wingloading might be in oz/sq ft? I have read that the Funtana 90 typically sits around the 21oz/ft- or somewhere around there. Seems high to me- but is is a bigger wing so that should make it "feel" like it has a lighter wing loading.

any comments- or just get it as low can as you go?