But these rear rudders were ubiquitous even on sailing ships: https://en.wikipedia.org/wiki/Rudder Here's something I just learned from Wikipedia: "Rudder post and mast placement defines the difference between a ketch and a yawl, as these two-masted vessels are similar. Yawls are defined as having the mizzen mast abaft (i.e. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post." At 04:13 PM 6/24/2013, Fred lunnon wrote:
On a small motor vessel driven by a single screw propeller, a considerable amount of steering force is generated by the action of the propeller stream on the rudder, which therefore has to be in line with and adjacent to the propeller.
If you imagine a boat following any course and steering alternately port and starbord to maintain any average bearing, it's obvious that the bow and stern can follow very different paths. Easily included in this is a path where one end swung wildly while the other maintained close to the average bearing. The swinging end obviously travels significantly further than the stable end.
Symmetry considerations also dictate that a single rudder must lie along the axis, even on a sail-driven vessel. One point that's worth making --- whether about boats or aircraft --- is that turning the rudder alone has almost no useful effect on changing the direction in which the craft is moving. All the rudder does is change the direction in which the craft is pointing, which is not the same thing at all. As John Aspinall pointed out, changing direction of travel involves the application of a (relatively large) force, supplied on water either by a propeller or the action of the wind on appropriately re-positioned sails; in the air by lift on the wings as the plane banks into the turn. WFL On 6/25/13, Henry Baker <hbaker1@pipeline.com> wrote:
But these rear rudders were ubiquitous even on sailing ships:
https://en.wikipedia.org/wiki/Rudder
Here's something I just learned from Wikipedia:
"Rudder post and mast placement defines the difference between a ketch and a yawl, as these two-masted vessels are similar. Yawls are defined as having the mizzen mast abaft (i.e. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post."
At 04:13 PM 6/24/2013, Fred lunnon wrote:
On a small motor vessel driven by a single screw propeller, a considerable amount of steering force is generated by the action of the propeller stream on the rudder, which therefore has to be in line with and adjacent to the propeller.
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On 6/24/2013 5:56 PM, Fred lunnon wrote:
Symmetry considerations also dictate that a single rudder must lie along the axis, even on a sail-driven vessel.
That's not true. In fact the first 'rudders' were just specialized oars held over one side at the stern. This was the steerboard and that side (conventionally the right) was called the starboard side. Because you didn't want to hit a dock or other ship with your steerboard, you always loaded and unloaded on the other side; so it was called the larboard. These two words were considered to similar and subject to confusion, so navy's adopted the terminology "port". Brent
One point that's worth making --- whether about boats or aircraft --- is that turning the rudder alone has almost no useful effect on changing the direction in which the craft is moving. All the rudder does is change the direction in which the craft is pointing, which is not the same thing at all.
As John Aspinall pointed out, changing direction of travel involves the application of a (relatively large) force, supplied on water either by a propeller or the action of the wind on appropriately re-positioned sails; in the air by lift on the wings as the plane banks into the turn.
WFL
On 6/25/13, Henry Baker <hbaker1@pipeline.com> wrote:
But these rear rudders were ubiquitous even on sailing ships:
https://en.wikipedia.org/wiki/Rudder
Here's something I just learned from Wikipedia:
"Rudder post and mast placement defines the difference between a ketch and a yawl, as these two-masted vessels are similar. Yawls are defined as having the mizzen mast abaft (i.e. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post."
At 04:13 PM 6/24/2013, Fred lunnon wrote:
On a small motor vessel driven by a single screw propeller, a considerable amount of steering force is generated by the action of the propeller stream on the rudder, which therefore has to be in line with and adjacent to the propeller.
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