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Old Nov 28, 2015, 02:02 PM
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Depron/ balsa PW1211 plank

My PW51-plank flies okay, but still I noticed some room for improvement looking at flight-envelope in less than perfect circumstances.

Chord -> 30cm (actually 26cm - 28cm would be perfect)
Wingspan -> 100cm
Airfoil -> PW1211
Materials: Depron 6mm, Balsa 1mm, carbon-boom 8mm, glue UHU POR.
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Last edited by FlyingNiko; Dec 21, 2015 at 10:40 PM.
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Old Nov 28, 2015, 02:05 PM
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With hindsight... 30cm wingchord is a little too much and causes some challenge getting CG enough to the front.

I started with selecting this beautiful airfoil:

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Old Nov 28, 2015, 02:08 PM
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Then I cut out Depron wingsections, and I mean a lot of them. This took me approx. 30 minutes, so it is doable. I left space for elevons:

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Old Nov 28, 2015, 02:09 PM
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... I was really optimistic about getting CG right/ my light-weight-building skills for the rear-sections of this flying plank .
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Old Nov 28, 2015, 02:11 PM
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First piece of 1mm balsa is applied (thank you, rainforest, for this great piece of wood):

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Old Nov 28, 2015, 02:13 PM
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A few evenings of using UHU POR and applying 1mm Balsa (1000mm x 100mm), easy does it, as helps my relaxed nature:

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Old Nov 28, 2015, 02:14 PM
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... as you can see, I got suspicious about getting CG right and elonguated the nose by several inches.
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Old Nov 28, 2015, 02:16 PM
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Some GFK (49gr/m˛) and 24-hours-epoxy-resin was applied. The result is not perfect as it is all done by hand, not using vacuum-technique or so...

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Old Nov 28, 2015, 02:22 PM
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After a little sanding, primer and another round of sanding I followed my instincts and did what I like most, spraypainting this contraption:



AUW: 500gr
Wingarea: 30dm˛
Wingload: 16.6gr/dm˛ = 6.3oz/sqft
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Old Nov 29, 2015, 10:10 AM
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Nice colour, Sir! I don't think it will fly nice on the slopes, though. I think the wing will generate way too much lift and provide too much forward resistance for high-speed slope-manouvres.
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Old Dec 05, 2015, 10:47 AM
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Well, hoping for the best then :-).
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Old Dec 17, 2015, 08:53 AM
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Early this morning, I decided it was time for a maiden. I like a counter-intuitive approach and threw it of what looks like a slope with 3-4Bft:



Little expo here:



Flew great, set CG from 18% -> 20%. The wing picks up height quickly and it speeds up where needed. So far so good .

Do the more-experienced builders on this forum see some quick-wins? Is the reflex a good thing at all (apart from that it works). I would be happy with some answers/ remarks, anything!
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Old Dec 21, 2015, 10:36 PM
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PW1211 plank (1 min 20 sec)
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Old Dec 22, 2015, 06:41 AM
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Well done FlyingNiko, it flies! Yayyyyyyy
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Old Dec 22, 2015, 09:51 AM
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Quote:
Originally Posted by ChuckGlider View Post
Well done FlyingNiko, it flies! Yayyyyyyy


What he said!

congrats on your build and successful maiden.

Your plane is a plank in the truest sense. Very little if any wing taper.

I have used several of Peter Wick's airfoils with great success on my builds but mostly they have been more tapered wings and mild chevron shaped wings. The Weasel and its clones are a great plan form to build and fly.

The reflex in the foil is needed as you mentioned. It replaces the horizontal stab on a conventional airframe. Without the reflex the flying wing or plank would be so unstable and pitch sensitive as to be unflyable. It would simply tuck the leading edge over and roll under or go into a rotor effect like when you toss a long narrow strip of balsa up and watch it go into rotor mode.

Your plank build is more ambitious than what I would do - cutting all those ribs and sheeting them with balsa. I have done it but am now lazy and use a hotwire cutter and a PW airfoil template to cut two wings in less than 5 minutes. Then I can sheet it or usually just iron 74 micron laminate on them to make them crash proof. Super easy and fast which is especially good for me to build, fly, crash, build another. Plus I have found free foam sources and filled my garage with lots of EPS and XPS foam sheets.

Keep building and flying! and sharing video!

Steve
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