UAV from Draganfly - weird design but interesting technical approach - Blogs

Ron Jacobs May 5, 2010 at 12:08pm

Are there different considerations for scale RC size aircraft than a full size Quickie?

Is the seperation of the wings enough to minimize effects due to turbulence, at the scale of the Tango?

Just throwing these out there, one assumes that the Tango must be stable and somewhat efficient as it is commercially available.

Jason Robert May 5, 2010 at 6:14am

With all due respect to everyone here, as far as efficiency goes, this design was first adopted by Burt Rutan with the Quickie aircraft. That aircraft is arguably the most efficient plane he ever put on the market. I am not saying that I know anything about how efficient this aircraft is or is not, but My Quickie is VERY efficient, and Stable. I don't know the answer to these questions but Burt makes some cool planes and he knows allot about efficiency. My guess is that if it is less efficient than another, its not by much and it makes up for it in stability.
Just My thoughts.

Ben May 5, 2010 at 12:32am

There is an old, but interesting article I found on tandem wing designs, which states some advantages/disadvantages of this approach:
http://www.flightglobal.com/pdfarchive/view/1944/1944%20-%200854.html

Ron Jacobs May 4, 2010 at 7:13am

Would be interesting to know what the patent covers on this plane. Before anyone goes out and tries to copy it or anything.

Also, it would be interesting to see some detailed specs on the plane. I read the website info and fot the impression autonomous flight was possible, but didn't real get the feeling it was included as part of the standard package for this plane.

I think I got a quote on this a couple years ago and the pricing was up there (60,000 rings a bell). Not sure though.

It is a nice looking plane that looks like it should have lots of lift, but hard to judge even the scale of the plane.

THOUGH.IT

Developer

Sandro Benigno May 4, 2010 at 6:24am

@Tj - Thanks for your explanation. Now I understood your point. Maybe Rutan used a lot of resources to achieve that results.
I don't believe that those guys with a lot of technical resources and money doesn't test his designs in a virtual or real wind-tunnel or something like that. So is very ingenuous by our part to look at one photo and say "this is not efficient". Of course you can say "it's hard to achieve a optimal setup with that kind of design, especially on my backyard or limited lab". But that's the point of a forum like this. I didn't knew that things. I didn't knew the existence of that hard way to tuning it. Now, I know that. :p A lot of learning here.

Troy Reabe May 4, 2010 at 5:34am

http://en.wikipedia.org/wiki/Scaled_Composites_Proteus
You can have an efficient airframe using a setup like the dragon fly but you need to get the rear wing clear of the wash from the front. If you want to play with some fun designs that also are efficient look at some of Burt Rutans designs. I do really like the starship that beachcraft made.

Tj Bordelon May 4, 2010 at 4:59am

@ Sandro Benigno - I never said it would fly terribly. All I said was inefficient. The downwash from the first wing disturbs the airflow over the second wing. I don't care that it's below the first wing, in fact that makes it worse. When I tried this config, it flew beautifully, but it did not give me the performance I was expecting. I thought the 2nd wing would give me at least 80% of the lift as the first wing, and the AC would be roughly in the middle or at least close. I discovered to my dismay that the rear wing was at best 40% as efficient as the front wing. Same for bi-planes. It does let you fly slower but if you are going for efficiency, this isn't a good choice. Some might point at Rutan's designs and I'm at a loss to explain things like his Proteus. I probably have more to learn in this area.

Tj Bordelon May 4, 2010 at 4:51am

@Nima K - One thing I did discover which is not an intuitive find... You can get a lifting wing and tail in a conventional design, so long as the CG is behind the 1/4 chord of the main wing. You can still have stability if the AC is still behind this point, and it is possible to do. Of course a lifting tail is draggy because the tail is inefficient due to its aspect ratio, so it isn't as good.

Tj Bordelon May 4, 2010 at 4:47am

Hey guys-- I was just saying that when *I* tried it it was inefficient. I was not faulting their design. In fact I like it!

Developer

Sandro Benigno May 4, 2010 at 12:25am

Hey, Chris. I did never seen nothing about it before. Today was the first time that I saw it on the first page of Draganfly. Sorry about it! ;/

Anyway, it seems that a lot of people did not know this too. I will edit the title.

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