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Aug 21, 2006, 02:56 AM
Launchpad McQuack
Prop-er's Avatar
Thread OP

···Depron Duplex Delta··· (updated free plans)

While reading a bundled collection of 50's Aeromodeller mags, I came across a great looking free plan of the "Duplex Delta", designed by Peter Holland. (published in the november 1959 issue)

Originally meant for Control line operation, and constructed from balsa, it looked way too cool, and consisted of just a few parts. According to the designer, it's very rugged, and can take some beating. The original flew very easy, really suited for beginners.

I fancied a modern Depron RC version, and this is what I came up with:

I've added some nose length, and made a round Firewall, to mount a Brushless.


Wingspan: 20" (508mm)
Material: FFF or 6mm Depron
Empty weight: 3,5 Oz (100 gr)
Auw weight: 7 - 12 Oz (200 - 350 gr)
Power: 50 - 120 Watt
Prop size: 7x4 - 9x4

Plans (free for personal, non-commercial use):

Can be downloaded from:

This plane consist of just nine parts: Top wing, bottom wing, fuse sides, formers and canopy.

You can try making one out of balsa too, empty weight will be doubled, but durability will increase greatly.

I haven't build this plane yet. (busy moving, made the plans during lunch breaks) I'm sure it will fly, though. The plans are new, and although I always try to make "proper" plans, they could have little mistakes in them. Let me know and I'll fix them.

BTW, Willin tried to make one out of Bluecore. Don't know what became of it:

If you build one, please post some pix here.

Links to my other plans:
Rafale XL

Good luck building this very funky plane. Still not convinced it will fly? You better check out these comments:

Wide speed range, control down to verly low speed, no real pitch sensitivity at speed, just perfect!
My current favorite for a windy-day plane!
it flew BEAUTIFULLY. I had several club members that were watching, and absolutely loved it!! They couldn't believe how well it glided!!! I landed it perfectly with no power, THIS PLANE FLIES GREAT!!
Last edited by Prop-er; Apr 02, 2007 at 02:41 PM.
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Aug 21, 2006, 10:29 AM
Registered User
wowowow...heheh kinda crazy plane.but nice and intresting on the other side
PS.ask JAM to add this to the free plan list ,coz this is just killer to miss
Last edited by Foamaster :); Aug 21, 2006 at 11:13 AM.
Aug 22, 2006, 06:57 AM
Launchpad McQuack
Prop-er's Avatar
Thread OP
Good idea. Did just that.
Aug 22, 2006, 07:29 AM
MaxAmps CMO
JAM's Avatar
I'm gonna do some yard work after I take the wife to work ( I have the day off ) but I will put it up in the list when my honey do list is done. Proper what 3D program are u using these days to get the great shots like that? I tried getting an eval copy of solid edge but the clowns in there rep department have been really poor in how they handle this proceedure so I told them to forget it. Thay lost me as a potential customer.

Aug 22, 2006, 09:56 AM
Launchpad McQuack
Prop-er's Avatar
Thread OP
I'm using Rhinoceros 3D. It's just an amazing program. It's only drawback is it lacks parametric design.

I've got an official evaluation version, which saves 25 times. Funny thing is, when I run the program, and open it again (two Rhino programs running simultaniously), the amount of available saves springs back to 25...

I'm using version 3, SR2. I'm pretty sure the newer SR5 doesn't have this little programming mistake.

You're really prepared to pay in excess of $5000,- for a 3D solid program?

Otherwise check out the free version of Alibre 3D software.
Aug 22, 2006, 11:17 AM
MaxAmps CMO
JAM's Avatar
If I want to get it I can get it from a relative who is in the design buisness.......shouldn't cost me a whole lot.......I think i will keep looking though.

Aug 22, 2006, 12:42 PM
Retired CAD guy
birdofplay's Avatar
If you have a kid in school Rhino3D student is less than $200 !

I'm an old MicroStation and Solid Edge guy and I love RHINO for hobby model development.

I note several guys using it here in the forums

BTW did I miss the Hyperbipe plans click ???
I scrolled and scrolled and coundnt find it anywhere. :-(
Last edited by birdofplay; Aug 22, 2006 at 12:49 PM.
Aug 22, 2006, 10:21 PM
Crash Master
Gene Bond's Avatar
Looks like a cool quick one, Prop-er. May have to give it a go!
Aug 23, 2006, 01:36 AM
Launchpad McQuack
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Thread OP
Yeeeharrr!!! That would be really nice, Gene. Couldn't be more than a few evenings work indeed.
Aug 23, 2006, 06:02 PM
Can glue better than fly!
Very cool! Should be pretty fast huh? Is it just going with rudder and elev, or are you going to mix elevons and have rudder? Basically how ya controlling her?

Aug 24, 2006, 03:18 AM
Amazingly new design
I want to see it flies
Aug 24, 2006, 05:41 AM
Launchpad McQuack
Prop-er's Avatar
Thread OP
Originally Posted by Spitfireski
Very cool! Should be pretty fast huh? Is it just going with rudder and elev, or are you going to mix elevons and have rudder? Basically how ya controlling her?

Hi Chris,

The full-size drawing has all the info you need about the three controlling possibilities.
Aug 24, 2006, 08:27 PM
Prop-er, I am so glad you decided to give this one a go. As for mine I have not gotten any further than I have shown in my thread.

Isn't this just one of the coolest designs you ever saw? I couldn't help myself when I saw it and you have seen the result thus far.
I have done quite a bit of studying on the design and though it was originally meant for U control I just knew it could be made to work with modern light R/C gear. The design should fly very simply like a flat plate design such as a flying stop sign or flying pizza. Controls should be just elevons on the bottom wing at the rear plus throttle. I do believe you could add rudder if you really wanted to but you need to make it have a large area for it to have effect. I personally don't think it needs rudder control to be a nice flyer.

I like what you have done with the design lengthening the nose and then transistioning it to be round. Looks nice. Should make the design a little less pitch sensitive than I expect mine to be but at the same time might make it a bit more difficult to balance. Now if you were to extend the tail moment an eaqual amount or a little more you might like the flight characteristics better. This too would make the rudder more effective and less twitchy in response.

Thank you for noticing my effort and bringing notice to it.I can see now I need to get it underway again. By the way the span on mine is about 26.5"

Have you given any thought to Landing gear? I know it just adds weight and in the beginning I was leaving it out but I do think secondary versions would look really cool with either tail dragger or trike gear.

Aug 25, 2006, 03:04 AM
Launchpad McQuack
Prop-er's Avatar
Thread OP
Hi Robert,

I'm glad you found this thread! I haven't changed the basic design, since I was too lazy to be bothered with calculating the new CG. With the current drawing, one knows pretty much for sure what to expect.

The only experimental thing is controlling it. Adding a rudder isn't that much work, and if it doesn't work, one can always choose not to use it.

A landing gear would be nice indeed. Bend some wire, make the former out of ply, and expoxy them together. Add some nice light balloon wheels, for a real vintage look! (I would prefer a tail dragger)

I'm thinking about posting a scan of the original Duplex delta article from the 1959 Aeromodeller here. What about the copyright on a 47 years old magazine? (Does Aeromodeller still exists?)
Last edited by Prop-er; Aug 25, 2006 at 03:16 AM.
Aug 26, 2006, 11:58 PM
Crash Master
Gene Bond's Avatar
Just cut and joined the tiled (letter) plans. Not too bad. On the fuse, there's no join mark, so you must just butt them, after turning one of them over to match the angle cut. Perhaps some overlap when cutting would help. Butt joints with tape is not that great. Really, on the drawing, you should flip the front part of the fuse over, so it doesn't have to be flipped once cut. (mirror)

Gonna cut some foam tommorrow (later today ) after this beer wears off!

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