Dihedral for Lateral Stability on The Crash Cast Tagged with: Building, CrashCast, Designing, Dihedral, Podcast Monday, February 20th, 2012 09:54 am GMT -6 Monday, February 20th, 2012 09:54 am GMT -6Monday, February 20th, 2012 09:54 am GMT -6 What is lateral stability? How does dihedral work to maintain it? How much dihedral do you need? Why might you need less? Why might you need more? Listen in to find out! Share this: Recommend on Facebook Share on Google+ Tweet about it Tell a friend Related posts: Builder’s Mistakes on Raspberry Pi Crash Cast V Tails on The Crash Cast Dihedral and Wing Sweep on The Crash Cast Crash Cast about my HALE UAV Work Pitch Stability Part 2 on Crash Cast Pitch Stability Part 1 on Crash Cast What Makes an Airplane? Milliken Tegris on The Crash Cast (Audio) Website Review: Soaring Cafe Becoming a Better Pilot on The Crash Cast Learning Aerobatics on The Crash Cast Serendipity, or Creating Your Own Luck Logging In... Add Comment Register Profile cancel Sign in with Twitter Sign in with Facebook or Name EmailNot published Website Comment Sure! Also send me the free email newsletter. 2 Replies 2 Comments 0 Tweets 0 Facebook 0 Pingbacks Last reply was Tuesday, February 28th, 2012 05:53 pm GMT -6 Charles Nowell View <abbr class='timeago' title='2012-02-29 00:11:47Z'>Tuesday, February 28th, 2012 05:11 pm GMT -6</abbr> Usually your explanations are pretty much on, but on dihedral, you got it all wrong Carlos. The projected wing area description of dihedral has been shown wrong multiple times in multiple sources. Get a good reference like Martin Simons, or some other text. Dihedral works because in a gust the airplane side-slips because the total lift vector gets rolled. Once side-slipping the wing in the slip direction has a higher angle of attack due to the dihedral angle and causes the correction. This is only true if the fin is small enough to not weather-vane. Dihedral stability only occurs is the fin area and dihedral are matched properly for this reason. If the fin is too large with too little dihedral, the slip ends up being coordinated and there is no correction. This is the dreaded spiral dive in old free flight designs and why they had such small fins. Sweep acts like dihedral for similar reasons, the wing side to the slip sees more perpendicular flow to the leading edge. The trailing panel sees more span-wise flow, and therefore less lift. Look it up. Carlosreplied: View <abbr class='timeago' title='2012-02-29 00:53:22Z'>Tuesday, February 28th, 2012 05:53 pm GMT -6</abbr> Most of what you say is right. What I said is right, too. My explanation of how dihedral works to correct an unwanted roll is correct. I agree that yaw and roll stability are intimately tied in an airplane. That is why sometimes you see strange behaviors like Dutch rolls.