That is a well worded and even logical argument but reality trumps theory. A boat needs close to a balanced wing in lighter winds.... or it will run you crazy... unless you have total control over the wing. Have you ever lost all wind while sailing in rough sea?
---------- Original Message ----------
From: "taladorwood@yahoo.com.au [harryproa]" <harryproa@yahoogroups.com.au>
To: <harryproa@yahoogroups.com.au>
Subject: [harryproa] Re:: Greenbird wing design
Date: 25 Jun 2015 08:53:35 -0700
---------- Original Message ----------
From: "taladorwood@yahoo.com.au [harryproa]" <harryproa@yahoogroups.com.au>
To: <harryproa@yahoogroups.com.au>
Subject: [harryproa] Re:: Greenbird wing design
Date: 25 Jun 2015 08:53:35 -0700
Proaskip, "I was also of the unbalanced persuasion based on land sailors experience until I tried it on the broomstick.
Mass balancing is important.
First if the wing axis isn't exactly vertical gravity will trump aero forces in light wind situations."
Sure... I don't really understand the problem? The elevator is going to swing around of course but the forces are going to be low and the swinging actually helps dissipate them.
Proaskip, "Inertial forces bobbing in a seaway are very chaotic making anchoring in a breeze questionable."
The added weight increases the wings moment of inertia, which slows its rate of twisting and response to the wind, which adds to the force on the spar from the boat rolling in the waves. It was that increased moment on Atlantis's wing that started destroying the wings trailing edges from the passing wakes.
I guess the choice is the elevator jumping back and forth with each wave, or much bigger loads on the mast from the heavy wing as it bobs back and forth in the waves.
I need to reemphasize that this is all based on the wings rotation point being in the center of the aerodynamic effort.
To me this emphasizes the importance of the bearings, their tight tolerances, and smooth easy action. If the wing isn't free to rotate (feathered easily) it is a disaster waiting to happen. A counter weight to the aileron impedes that rotation and could set up a harmonic oscillation if the waves are the right frequency. Think the Tacoma narrows bridge : )
Talador
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Posted by: "jhargrovewright2@juno.com" <jhargrovewright2@juno.com>
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