Horten Xc - The ultimate hang glider-part 2 - RC Groups
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Dec 26, 2011, 11:27 AM
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Knoll53's Avatar
Build Log

Horten Xc - The ultimate hang glider-part 2

This is a continuation of the build log started in the scale sailplane section. See https://www.rcgroups.com/forums/show...2#post20235183 for part One.

The plywood skins are pre-stained and finished now and the ribs received a light sanding to knock off the square cut edges. They are sanded just to remove the light brown laser cut. Indeed that light brown color is a "guide coat" for the sanding process. Leaving a sliver of brown on the edge is perfect in my book.

Last edited by Knoll53; Dec 26, 2011 at 03:53 PM.
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Dec 27, 2011, 08:24 AM
Deniable plausibility
Shedofdread's Avatar
As much as I may be 'composites' kind of chap, I do so like to see a structure like that taking shape Looking good!
Dec 27, 2011, 10:49 AM
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Knoll53's Avatar
Congradulations Shed, you found our new Nurflügel section!

I promise to not tell the composite community that you have been hanging out in the woodie section. Plywood is a "type" of composite.

Stay tuned. There will be some layup for you soon. Which begs the question.....(see pic)
Dec 27, 2011, 11:45 AM
Deniable plausibility
Shedofdread's Avatar
Hmmmm.... Is it a 'thingy' for pulling carbon tow through? Is it? Do I win?
Dec 27, 2011, 12:50 PM
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Knoll53's Avatar
Ding Ding Ding ! We have a winner.

It is a "tow" wetter. We will see soon if I got the Faraday angle right or if needs some more Gewürztraminer.
Dec 30, 2011, 09:02 PM
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Spar Lay Up

The spar is built up from layers of 1/8 x 1/2 spruce and carbon tow. The tow is sandwiched between 2 spruce spar caps at the root area and continues out to the tip. Where the tow is sandwiched between the wood caps, it will be well supported against buckling in compression. This should fully develop the carbon as opposed to other placements.

The wood spar caps step down the farther out on the span until they end up as 1/16 plywood at the tips.

The Tow wetter worked well, but I will tweak it for the next layup. I would have continued with more layup, but ran out of clamps.

Carbon Tow Wetter (1 min 39 sec)

Last edited by Knoll53; Dec 31, 2011 at 12:01 AM.
Dec 31, 2011, 04:41 PM
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Tweaked Tow Wetter & the other wing

I removed the foam squeegie from the exit of the wetter and the tow comes out much more resin rich, which is a good thing when laying up against wood.

Today saw the other wing getting the spar lay up and the TE layup. On this side, nearly the whole spar is wrapped with Kevlar tow. This replaced the clamps, so I was able to lay up the TE plywood skin too.

The TE has one length of Tow from the root to the elevon just to add a tension tie at this location. A hard nose in crash can break the TE and this one is just 1/32" plywood, no spar caps. The tow may not be needed here or in the main spar, but it is cheap insurance.

Jan 08, 2012, 08:05 PM
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Plywood skins

Added a balsa sanding strip on top of the spar. Sanded it flush with the ribs at the D-tube. Made special sander to help prevent knocking down the ribs at the open structure.

Plywood skins at the D-tube were installed with contact cement, my favorite method. For the whole story, see this. With D-tube complete, the wing twist is set....forever.


Sanding Spar Cap (0 min 29 sec)
Jan 09, 2012, 12:21 AM
internet gadfly
nmasters's Avatar
Oh my... it's huge
Jan 09, 2012, 03:19 AM
You know nothing....
Stuart A's Avatar
An object lesson in how to do a build log.(there was a moment of" how long are this guys arms "when you were pulling the tow!) Any chance you could post a sketch of the pulley system?
Regards Stuart
Jan 09, 2012, 07:47 AM
Registered User
Vernon Hunt's Avatar

Oh yea! She's gonna be a beauty.

Jan 09, 2012, 08:31 AM
Deniable plausibility
Shedofdread's Avatar
Looks stunning! I think something like that would look good hung on the wall.

Thinking I may have to pop over for the test flight...
Jan 09, 2012, 10:19 AM
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Knoll53's Avatar
Thanks guys.

I was eager to connect the wing halves last night but thought better of it.... it is huge, and one piece.

The pulleys are probably next. Now the structure is largely complete, it's time to tackle the hardest part of this project.

Shed: I might hang this one. Maybe a charging station that doubles as a ceiling hook. Hopefully I can save you the trip of "popping over" with some HD video and a Vimeo account. Andres has set the bar rather high with this one.

RJF Horten-Beluga (4 min 50 sec)

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