Pietenpol-List: I have a tail
Posted: Thu Jan 10, 2008 4:05 pm
Original Posted By: "carson"
Gordon wrote-> Or better yet, for about 5 grand buy the more modern efficient NACA wing> design off of a Cub, T-Craft or Aeronca recover themThat would be a faster build than making Piet wings from scratch, but as far asefficiency consider these comments made by Mike Shuck, who analyzed the Pietairfoil and directly compared it (computationally) to the Cub wing:>Can I just use the Cub USA35b airfoil instead of the Pietenpol airfoil for betterperformance>since it has less drag and less negative pitching moment? Answer: Well, you could,but it wouldnt>be a Pietenpol anymore. And, the drag isnt that much less that youd see muchif any difference>in cruise. The USA35b airfoil here is 11.5% thick and the Pietenpol airfoil isonly 10.5% thick, so>the performance of the USA35b, if improved, could be from the fact that the wingwould be thicker,>therefore, lighter than the Pietenpol, too.> >Can I decrease the negative pitching moment of the Pietenpol airfoil and end upwith less trim drag>and have it fly faster. Yes. But you will have, as a consequence, less lift,too. And about the T'craft wing, Mike wrote:>a bit complicated, but you want as little trim drag as you can stand and yet stillhave enough lift>for your airplanes purpose or mission. This is most of the reason why C. G. TaylorsTaylorcraft>flies 10 miles per hour faster than his Cub design: the Taylorcraft airfoil usesa lower drag airfoil,>the NACA 23012, but this airfoil also has very little negative pitching moment,only about 0.012.>If you have an airfoil which has less drag and significantly less negative pitchingmoment, you will>also have less trim drag as well, and, quite likely, significantly improved cruisingspeed. Trade-offs, trade-offs... ;o)Oscar ZunigaSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: Pietenpol-List: I have a tail
Gordon wrote-> Or better yet, for about 5 grand buy the more modern efficient NACA wing> design off of a Cub, T-Craft or Aeronca recover themThat would be a faster build than making Piet wings from scratch, but as far asefficiency consider these comments made by Mike Shuck, who analyzed the Pietairfoil and directly compared it (computationally) to the Cub wing:>Can I just use the Cub USA35b airfoil instead of the Pietenpol airfoil for betterperformance>since it has less drag and less negative pitching moment? Answer: Well, you could,but it wouldnt>be a Pietenpol anymore. And, the drag isnt that much less that youd see muchif any difference>in cruise. The USA35b airfoil here is 11.5% thick and the Pietenpol airfoil isonly 10.5% thick, so>the performance of the USA35b, if improved, could be from the fact that the wingwould be thicker,>therefore, lighter than the Pietenpol, too.> >Can I decrease the negative pitching moment of the Pietenpol airfoil and end upwith less trim drag>and have it fly faster. Yes. But you will have, as a consequence, less lift,too. And about the T'craft wing, Mike wrote:>a bit complicated, but you want as little trim drag as you can stand and yet stillhave enough lift>for your airplanes purpose or mission. This is most of the reason why C. G. TaylorsTaylorcraft>flies 10 miles per hour faster than his Cub design: the Taylorcraft airfoil usesa lower drag airfoil,>the NACA 23012, but this airfoil also has very little negative pitching moment,only about 0.012.>If you have an airfoil which has less drag and significantly less negative pitchingmoment, you will>also have less trim drag as well, and, quite likely, significantly improved cruisingspeed. Trade-offs, trade-offs... ;o)Oscar ZunigaSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Subject: Pietenpol-List: I have a tail