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        Build Log Planktastic - 108cm (42in) flying wing

#1 slebetman Aug 08, 2011 01:16 AM

Planktastic - 108cm (42in) flying wing
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This is a design that I've been wanting to build for several years now. In fact, this is one of the reasons I got into RC in the first place - to get good enough at flying so that I can build and fly this plane!

I came up with the planform when trying to design my own walkalong glider. It is based loosely on Tyler MacCready's walkalong glider. It sucked as a walkalong glider (or rather, I sucked at flying walkalong gliders) but worked very well as a chuck glider. I sort of fell in love with the design. It has that that-thing-shouldnt-be-flying vibe.

I've already tried doing an RC version once but failed mostly because I couldn't fly the thing. This plane is very pitch sensitive. Now with two years of flight experience I've decided it's time to do the build.

Here are pictures of Tyler MacCready's walkalong glider and my chuck glider:

#2 slebetman Aug 08, 2011 01:33 AM

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OK on to the build.

The wing is generally made up of 3 sections: the central main wing and wingtips at each side. The wing tips basically act as horizontal stabilizers.

Most of the build will be with 3mm depron. There really isn't much of a plan like most foamy builds but more of a set of measurements. Most of the cuts are right angles and straight lines.

After the parts are cut I applied masking tape onto the outer surface. This is to prevent the foam from cracking when we fold it later. For the wing, a broad area of the upper surface is taped up because we will be bending it to form an airfoil shape.

#3 slebetman Aug 08, 2011 01:44 AM

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The main wing is made of a single piece of 3mm depron folded over to form a Clark-Y-ish airfoil. Of course, it's not really Clark-Y or any accurate airfoil due to the imprecise build method but is good enough. I'm aiming for a 10% thick, high lift airfoil.

I used a plastic broom handle to bend the wing. You just need something with a curved or round cross section to press the foam against. A rounded table edge would also work.

#4 slebetman Aug 08, 2011 01:46 AM

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Once evenly curved I folded the wing along its leading edge. I used a long ruler to fold against. The ruler is just needed to start a crease in the foam. Once started you can fold the foam freehand like folding paper.

#5 slebetman Aug 08, 2011 01:53 AM

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The wing tips are similarly made from folded over 3mm depron. I previously built and flew a prototype where I cut the wing and wing tips from a single piece of folded foam but found aligning the wing tips correctly difficult. So for this build I'm making the wing and wing tips separately.

Unlike the main wing, the wing tips don't need to be bent. We go straight to folding. To make the leading edge a bit more rounded I placed a pencil along the fold line while folding.

#6 slebetman Aug 08, 2011 02:00 AM

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Before I go on I'd like to explain why I'm posting the way I am. I normally post with lots of pictures per post with most of the write-up in the pictures comments. But the recent change in the attachment viewer means that that style of posting is less effective now and a bit harder to follow. I'm hoping this style of posting would be easier to follow even though it's a bit more work for me to write proper paragraphs of text.

Let me know if this posting style works for you or if you prefer the old picture-dump-with-comments style.

Back to the build...

I taped up the trailing edges of the wing and wing tips and laid them out on the floor for a "preview" of what the wing will look like assembled:

#7 slebetman Feb 22, 2012 11:16 PM

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Haven't updated this thread in a very long time. Almost forgotten about this until I came across some old pictures of my plane. Long story short the plane is now destroyed in a crash. But it did fly successfully for almost 3 months. One day the wind was too windy and it flipped on launch.

I thought I'd just update this thread with the rest of the build pictures and the final result. Too bad I don't have any pictures of it fully painted.

#8 derk Apr 15, 2012 05:40 AM

sweet, hows she fly?

#9 slebetman Apr 17, 2012 10:04 PM


Originally Posted by derk (Post 21335101)
sweet, hows she fly?

Flies quite well once you get used to its pitch sensitivity. Must be balanced quite nose heavy otherwise it would porpoise all day.

Being very pitch sensitive she loops like crazy. But having such a long wing span in proportion to her length roll rate was very-very slow. In fact I increased aileron rates to 120% to get acceptable handling.

But it does look good in the air. Her silhouette reminds me of soaring birds.

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