| Topic for open discussion: Vortex Lift
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| Dec. 3, 2016 (old forum), post by Dave Santos Delta-Wing Vortex-Lift (how the old NPW keeps up with the new Uniq) The Asian Delta Kite is ancient, but lacked the turbulence-compliant wing spars of the modern delta kite perfected along the Texas-Mexico border (Pharr, TX; where Gayla Kite was founded, just five miles from my mother's hometown, Edinburg, TX, where the HG/PG World Record Encampment occurs). The Tex-Mex delta kite is now the dominant toy kite design worldwide. These cheap wings perform so well, they fly almost as well as expensive professional UL (ultra-light wind) kites. The AWES Forum has long explored delta kite dynamics, and conjectured about their vortex-lift capability. Lately we reviewed LEV (leading-edge-vortex) lift of biological wings (insects, birds, bats, seeds), and the low-Re regime confirms that vortex-lift is one of the delta kite's secrets. I have been flying SS (single-skin) power kites almost every day in recent weeks, alternating between the delta planform NPWs and new oval planform Peter Lynn Uniq SS kites. The surprise conclusion is that the NPW is comparable or superior in performance to the Uniq, which apparently needs more time to evolve beyond NPW performance. The Uniq is a flatter thinner wing, so how is the NPW keeping up? The answer must be, in part, delta-wing vortex-lift. The NPW is itself evolving flatter and thinner and wider, and we may soon see a full synthesis of NPW and Uniq design; a very flat thin delta soft-kite planform. Here is Wikipedia on Delta-Wing Vortex Lift, which is increasingly well understood and closely related to rapidly advancing LEV theory. It seems kite vortex lift will scale up, since constant wind-field velocity corresponds to lowered dimensionless velocity as kites are made bigger. |
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