Nov 18, 2010, 02:10 PM agony sweetns the victory Any Flying Field Across America Joined Jul 2005 3,543 Posts Discussion 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
 Nov 21, 2010, 07:21 AM Registered User UK, Coventry Joined Aug 2005 600 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
 Nov 21, 2010, 12:55 PM agony sweetns the victory Any Flying Field Across America Joined Jul 2005 3,543 Posts That's probably a good rule of thumb; however, by measurements the Windfreak used 1inch for every 14.75inches of span.
 Nov 27, 2010, 11:18 PM Registered User Bellevue, WA, USA Joined Jan 2008 155 Posts 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
Jan 28, 2014, 04:06 PM
Registered User
The Willamette Valley, Oregon
Joined Dec 2008
1,302 Posts
planks, dihedral and roll trim

Quote:
 Originally Posted by Chuck Clemans 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
 Feb 02, 2014, 02:05 PM Whiskey Tango Foxtrot Australia, QLD, Maryborough Joined Jan 2013 246 Posts 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. Last edited by guitarcher; Feb 02, 2014 at 02:10 PM. Reason: copy of OP post in another forum