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Old Nov 18, 2010, 02:10 PM
agony sweetns the victory
atjurhs's Avatar
Any Flying Field Across America
Joined Jul 2005
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Dihedral for Thermal Planks

Hey guys,

I'm in the middle of building a thermal plank

http://www.rcgroups.com/forums/showthread.php?t=536530

Trouble is, I have no idea how much dihedral (EDA) I should build for. Yes, I can look at the plans that I have for the WindFreak, but my wing is different than that one.

Does anyone know of a calculation/formula for determining how much EDA I should use?

Thanks!

Todd
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Old Nov 21, 2010, 07:21 AM
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mhodgson's Avatar
UK, Coventry
Joined Aug 2005
533 Posts
A good rule of thumb I was given that seems to work well is 1" per foot of span under each wing tip, so a 6 foot wing would have 6" under each tip.
Your 10 foot plank would have 10" under each tip.
Add another inch if in doubt
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Old Nov 21, 2010, 12:55 PM
agony sweetns the victory
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Any Flying Field Across America
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That's probably a good rule of thumb; however, by measurements the Windfreak used 1inch for every 14.75inches of span.
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Old Nov 27, 2010, 11:18 PM
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Bellevue, WA, USA
Joined Jan 2008
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Plank Dihedral

For my planks with elevons I use 4 degrees which is close to the Wind Freak's 3.88 degrees. For rudder only planks, I use six degrees under each wing.

It really depends on how much stability is desired. I also fly planks with elevons and zero dihedral, but they have be flown all the time which is very tiring when thermaling.

Chuck
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Old Jan 28, 2014, 04:06 PM
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The Willamette Valley, Oregon
Joined Dec 2008
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planks, dihedral and roll trim

Quote:
Originally Posted by Chuck Clemans View Post
For my planks with elevons I use 4 degrees which is close to the Wind Freak's 3.88 degrees. For rudder only planks, I use six degrees under each wing.

It really depends on how much stability is desired. I also fly planks with elevons and zero dihedral, but they have be flown all the time which is very tiring when thermaling.

Chuck
If any people on this thread or with similar experience are still active on-line, I'm wondering what aileron (elevon) input is typically needed to hold the bank angle constant while circling near the min-sink angle-of-attack, in the case of a Plank plank with this sort of configuration (about 4 degrees dihedral.) Typically a bit of outside aileron, or inside aileron, or neutral aileron? How do you think that would change if we eliminated all the dihedral?

Thanks, Steve
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Old Feb 02, 2014, 02:05 PM
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Australia, QLD, Maryborough
Joined Jan 2013
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Steve, my thermal planks , with 3/4"per foot dihedral require a small amount of opposite aileron and some up elevator to maintain constant bank thermal turns depending on conditions.

My smaller slope planks with no dihedral do not require opposite aileron.

I do not use use an active rudder.

Hope this helps.

Greg.
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Last edited by guitarcher; Feb 02, 2014 at 02:10 PM. Reason: copy of OP post in another forum
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