Comment by Tj Bordelon on May 3, 2010 at 5:11pm

Looks neat I admit. For whatever reason when I tried this configuration, the interference from the front wing made the rear wing far less effective than it would be. So as a result, it was sorely inefficient.

Comment by Rana on May 3, 2010 at 5:50pm

Ti, please look at another picture once again;

If you implimented exactly same in your design then front wing should not create and issue for the rear elevator type of wing.

Comment by Nima K on May 3, 2010 at 5:54pm

Tj,

That's usually the problem with tandem wing designs. The font wing also creates a downdraft that reduces the angle of attack of the rear wing. I suppose the advantages are that both wings are lifting rather than a lift/push-down standard configuration. The cargo can also be placed in the middle which I guess is more convenient.

However the aspect ratios of the wings are much less than a single wing with equal area so you will get a higher induced drag penalty. The wash from the propeller also reduces the efficiency of both wings. The rear wing is riding the wash of both the propeller and the front wing (in certain AoA).

Developer Comment by Sandro Benigno on May 3, 2010 at 6:33pm

Tj, there is a video here: http://www.draganfly.com/uav-airplane/tango/gallery/videos/
Do you see any wrong aspect on the its fly.

Comment by Rory Paul on May 3, 2010 at 8:03pm

If I remember correctly they were using an MP autopilot at one point. There is an image of their carrying case and it has a radio modem box that is a match for the type used by MP. The design looks interesting but those wings look like they would not survive the first bad landing much to flimsy for serious hard terrain operation (think this actually has come up before).

Developer Comment by Ryan Beall on May 3, 2010 at 8:20pm

They are selling "cool factor" not aerodynamics that's for sure. Stable = cool = inefficient I guess

Comment by Taylor Cox on May 3, 2010 at 8:26pm

It looks like it flies just fine. And I'm sure it does help stabilize the camera.

Comment by Taylor Cox on May 3, 2010 at 8:27pm

I mean, why would they spend so much money and make something radical (design wise) that isn't efficient. I sure there is a reason for the wings being like that.

Moderator Comment by Brian on May 3, 2010 at 9:55pm

I'm building a similar design right now, except mine is a pusher with conventional vert stab/rudder. Front and rear wings are different foamies from PZ planes. Initial glide tests showed promise and allowed me to easily chuck the mockup across the yard. I'm playing with the angle of the two sets of main wings to adjust the amount of extra lift the front wing gets at very reduced speeds. At faster speeds it seems very stable. I'm not sure if I'll resort to a canard tied into stablization to help controll the slow speed pitchup. I hope not to need to go there and stick only with the tandem setup.

Moderator Comment by Gary Mortimer on May 3, 2010 at 10:54pm

Rory is right this design has been around for a few years and as yet its not widely adopted, has to be a reason. As ever they make some mighty big claims for the airframe.

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