Wing type questions

[leonr]

Hi!

I have built my first proper plane (above 2 channel) out of depron using the free mini funtana plans. With help from rcgroups in which electronic parts to choose and various other things and its been a great success!

I feel I've made my plane a little over weight (I know what areas I need to improove on) so I was considering rebuilding it.

I'm thinking of building another plane using roughly the same dimensions, but maybe adding a proper aerofoil (?) wing? If I was to do this, the wing would be biased to creating lift underneath the wing? So this would mean roll's could me unstable under inverted flight?

I've seen some wing profiles that are symetrical, but still aerofoil shaped, is this a good move for a acrobatic plane?

Im sure its a fairly simple question, I just didnt want to build it and realise its actually trying to fly towards the ground when upside down!


Can a proper wing fly as fast as my mini funtana "flat" wing? or will it be biased to climbing constantly?


Just a few of my questions!

Thanks!! :D

[BMatthews]

For small 3d aerobatics there is no need for more than a flat plate. For the weight and flying speeds involved the flat plate works just fine.

Also why would you put a cambered airfoil on a model that will spend roughly 1/2 its life upside down or doing negative G maneuvers?

Or if you intended to say a symetrical airfoil that's different. But in that case do consider that the cheezy looking flat plate airfoil is actually the ideal airfoil for 3D style aerobatics. The tendency for an early and very abrupt stall is just what you want when it's time to transition from regular flight to a sudden stop and hover manuever. A "proper" symetrical airfoil will try to resist the stall and fly the airplane into a vertical climb instead of just skid to a stop and then hang on the prop as intended.

It's all about choosing the right tool for the job. And for small model 3D flying that the mini Funtana is intended for a flat plate IS the right tool.

Now if you want to fly the model in a different style then a true symetrical airfoil may be what you need. But keep in mind that by adding the "volume" to the wing that a proper thick airfoil will have means that it's going to be hard to keep that weight down again.

[leonr]

Ok, that makes more sense now!

I see a flat wing as the plane being "pulled" through the air, so its more like a stabaliser to the power source (the prop being at the front in this case).

I don't know enough to know what types of flying are best for me really. As it stands my mini funtana can do small loops, rolls, hard turns, fly inverted etc etc and I find that quite fun.

Basically all I do is chuck it around as much as possible in a big open space :D, Im not to bothered about finish and all that, just fun :)

Sounds like the plane I have is ideal as it stands in that case! I could do with shaving some weight off it rather than change wings I guess.



Thanks!

[lincoln]

If you want better slow flight without giving up the aerobatics, use a symmetrical foil. This will also raise your top speed slightly, which may not be a good thing with a foamy. You can probably find symmetrical airfoils with sharp stalls, and, if not, one can always sharpen the leading edge. For snap rolls, to that out at the tips. Full scale aircraft that are NOT meant for aerobatics, will use a sharpened l.e. near the root so it stalls there first, so that a spin is less likely.

I think usually they are larger than is shown here:
http://en.wikipedia.org/wiki/Stall_strip