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Old Jun 27, 2012, 01:08 PM
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C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
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What's up with plank wings?

I've noticed that planks seem to be really popular in the sloping circles, but I see very few powered ones. I really like the look of some of them and I've thought about building one, but the fact that I rarely see them with power sort of scares me off. What's the deal?

I know the CG is extremely touchy with them and they can be picky about airfoils, but how hard can it really be?
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Old Jun 27, 2012, 07:03 PM
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Joined Oct 2009
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Hi

planks are your all around great flying machines. the critical c/g thing is hipe unless your trying to get crazy. have a look at the http://www.rcgroups.com/forums/showthread.php?t=502443 Simitar Astron Pole Star Classic Wiseguy group there are plans and a lot of years of experance to help and guide you. i have built several of these and maybe 20 of my own designs (ya i've been around a while) been flying r/c from 1977 to today and hope to still be at it another 40 or so years. "Planks" come in all shapes and sizes, with airfoils and flat plate, from very fast to fantastic soaring ships. they can be very simple and still be a real hoot to fly. if you are playing with electrics , foamies are cheep and quick to build so experiment a lot and have fun!!!!!!!!!! also a slight forward sweep 1.5 or 2 deg. will also add a new dimention to you designs...i currently drive a big rig so my flying is chooped up a bit and it can be hard to reach me. if you can pm me e-mail wooks good or i can try to check back in. have a good one
nich
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Old Jun 27, 2012, 07:43 PM
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Moses Lake, Wa.
Joined Apr 2008
480 Posts
Hi,

I cut foam wing cores for planks, so if you are in need for some cores let me
know.
www.mwcores.com


Jeff
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Old Jul 01, 2012, 02:18 AM
C'mon more Energy
Swoopdown's Avatar
Melbourne, Australia
Joined Mar 2005
3,217 Posts
CG on planks are soooo imprtant. Some planks more than others. Im talking 0.5mm will make them come alive and 1mm out they will fly like pigs.
So much so that if I was building a plank I would probably glue my battery in so there was no chance of it moving even 1 or 2mm forwards or back.
Planks are much more efficient than chevron wings and it is convention to have a central tail so for this reason and stability it would make more sense to have a puller rater than a pusher.
Use a specialised Plan aerofoil (like a PW51).
Also for elevator movement you will be wanting a total elevator throw (full up to full down) of no more than 3 or 4mm or even less. This means no slop in servos or linkages. Also test flying can be a PITA till you get the CG and setup right.
This is the reason why no one makes planks for electric wings as ease of setup and forgiving CG and setup characteristics make up for the lack of efficiency.
If I were going to do an electric wing I would start with something like a Moth slope soarer and mod it with a hot brushless. Would make a very cool project.
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Old Jul 24, 2012, 10:08 AM
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c/g ain't every thing

good morning
swoopdown i agree cg can be very critical IF you are trying to get the N/th out of a hi preformance design. even so it is not so critical if you are PLAYING with a plank for fun. i thought that r/c was for fun. please don't get me wrong i have done my fair share of research in the hard core study of flight and will do more still, and have placed well up in contest standings so i know how to push for altamat preformance. please do your self a favor, grab a 1/2" or 3/4" sheet of foam (1 pound to 6pound density) and knock out some cheep beaters and go bang around. gust ball park the cg and only round the edges avoid trying for an airfoil and see how much fun you can have. then should getting the N/th out of it is your idea of fun MAN GO FOR IT WITH ALL YOU GOT AND HAVE A BALL. but please lets not scare off those that would try something new by suggesting that a thing is hard or critical.
please understand i am not picking on you or trying to put you down. have fun.
all my best to all.
nich
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Old Jul 24, 2012, 12:54 PM
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C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
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Quote:
but please lets not scare off those that would try something new by suggesting that a thing is hard or critical.
You're saying that I would be scared off because the CG and airfoil might be a little sensitive? Gimme a break John Kennedy said it best: "We choose to do these things not because they are easy, but because they are hard".

I'm not sure when I'll have the time and money to pursue this one, but it's definitely on the list.

Hang on... I technically HAVE built a plank wing before and it flew very well. It was actually a Pizza Box Flyer, but it certainly fits the criteria.
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Old Jul 24, 2012, 01:32 PM
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:cool:

Hi,

According to the ds speed list a motor is not beneficial

Anyway, if the plank is heavy (50g/dm2+) it might make the launch easier by using a simple bungee catapult.
I just use a bungee cord from the sailor shop (8mm/5-10m) and hold the plane in my left hand at launch.
Bungee launch is safe, easy and predictable, it works exactly the same every time, and it might be beneficial on a slightly heavy plank.

Sharp turns!

Regards
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Old Jul 25, 2012, 10:34 AM
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no just trying to quail the mith that cg and air foil are touchy
gave a good one
nich
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Old Aug 03, 2012, 10:53 AM
C'mon more Energy
Swoopdown's Avatar
Melbourne, Australia
Joined Mar 2005
3,217 Posts
Didnt mean to scare or put anyone off. Just saying if you want to make a plank pizza box flyer that's cool.
I was just pointing out that the reason why planks are popular in slope and DS circles (excuse the pun) is there efficiency and speed. when your after efficiency and speed your foil, cg, throws, setup etc become a lot more critical on a plank than a chevron.
I still think a Moth or M60 would make an awesome electric model.
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Old Aug 03, 2012, 11:25 PM
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United States, OH, The Plains
Joined Jan 2011
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While a small step away from foam and tape, here is a motorized plank wing - http://shop.traplet.com/product.aspx?c=3792 and on a slightly larger scale - http://shop.traplet.com/product.aspx?c=2757 and there is even a short kit for the big one - http://shop.traplet.com/product.aspx?c=2776

Mark
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