On Sep 8, 2004, at 1:06 PM, Robert MacDonald wrote: > > Not entirely true. The blade produces a force that has a component in > the forward direction, also one across the boat. The force is > produced by flow across the blade, from one edge to another. On an > airplane, with more or less horizontal foils, the components of the > force produced by a foil are called "lift" and "drag", one vertical > and one against the direction of motion. For a paddle, we must break > the force into slightly different vector components, with new names, > as we are not trying to support a heavier-than-air craft, but push a > boat. I suggest we call the forces components "drive" (forward) and > "cross-boat". Obviously the blade produces a force that has a forward direction, otherwise the boat would not move forward. This does not mean that any of that force is produced by lift. It could just as easily be produced by drag. You say the force is produced by flow, but I'm uncertain how you know this. I'm sure that the forces produced by your paddle are not perfectly parallel or perpendicular to the direction you want to go. There is almost certainly some component of "lift" type forces in the "drive" direction, but this doesn't mean it is the primary source of propulsion. Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Wed Sep 08 2004 - 14:02:22 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:31:17 PDT