Wings in series

[AmokCrow]

I'm thinking of making a parkflyer as per the picture, but I have no experience of bipes or other more-than-two-wings designs.
What I'd like to know is whether placing the wings in series has any special aerodynamic effects. And I suppose the effects will vary with speed? :confused:
Also, if wings CAN be placed on the same level like this, should they be at some angle to each other?
And if I were to make one with ailerons, would having them in front or rear make any difference?

Any help appreciated

-Michael

EDIT:The pic got #¤%&/@ed. Oh, well, use your imagination

[Sparky Paul]

Tandem winged planes can fly, albeit less efficiently than a normal wing-tail configuration.
Look at Andy Lennon's book on R/C design, he goes into tandems to a serious degree.

[AmokCrow]

I'll see if I can find the book, thanks.
Takes time to find one here though.

Okay, does anybody have any personal experience on tandems?

[Ollie]

See Basics of Model Aircraft Design:
http://www.rcstore.com/RS/general/detail.asp?catnum=2023&catego=BO

The first wing has downwash behind it. The second wing flies in the first wing's downwash. That is the problem. The second wing is not efficient because the air speed is lower lift due to downwash and the turbulance in downwash makes drag higher.

[BMatthews]

Also the rear wing must operate at a lower lift coefficient or it won't be stable. That further reduces the effectiveness of that wing.

But all in all you will get a lift from that rear area.

The forward wing should have more camber than the rear and it will probably need to have a degree or two of incidence compared to the rear wing.

For some fun try a simple all sheet balsa glider. Make it from two 12 x 3 inch wings of 1/16 with a 12 inch long fuselage. Start with a balance point just ahead of the 1/2 way between the two 1/4 chord points. You'll need a 1/2 inch of dihedral under each wing and a tail fin of some form.

[Troy]

A nice multi wing.. He solved a few of the in-line issues by not making them in-line ;)
http://www.donatelli.net/_write/contest2006/attachments/36/PTWfrontqtr.jpg

[gouch]

Nothing to add technically, but thought I'd throw this photo up I took at an airshow a few years back. It flew nicely enough....when he finally got the engine working...

Interesting to note the differences in the two wings.

Cheers
Paul