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#11
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On Saturday, February 8, 2014 11:50:52 AM UTC-5, Dan Marotta wrote:
The standard setup is to use a Schweizer hook which is rigidly mounted in pitch and can swivel around the yaw axis. Yeah but. Why does the tug pilot have to pull anything when a glider kites? The tug pilot should of course have the option to release at any time. Here is the 1870 patent for something that look a lot like the Schweitzer tow hook. Click on the thumbnail for a drawing. http://rec.aviation.soaring/ The Tost hook still requires the tug pilot to pull a lever (though the automatic "back release" on the glider side is nice.) |
#12
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That's a good question.
As a glider pilot, I don't want any part of an automatic release (back release excepted). As a tow pilot, I'd rather the glider be released automatically than have the tug upset and, possibly, driven to the ground. "son_of_flubber" wrote in message ... On Saturday, February 8, 2014 11:50:52 AM UTC-5, Dan Marotta wrote: The standard setup is to use a Schweizer hook which is rigidly mounted in pitch and can swivel around the yaw axis. Yeah but. Why does the tug pilot have to pull anything when a glider kites? The tug pilot should of course have the option to release at any time. Here is the 1870 patent for something that look a lot like the Schweitzer tow hook. Click on the thumbnail for a drawing. http://rec.aviation.soaring/ The Tost hook still requires the tug pilot to pull a lever (though the automatic "back release" on the glider side is nice.) |
#13
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On Saturday, February 8, 2014 6:42:52 PM UTC-5, son_of_flubber wrote:
Here is the 1870 patent for something that look a lot like the Schweitzer tow hook. Click on the thumbnail for a drawing. http://www.google.ca/patents/US102067 |
#14
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I've seen heavy duty gate (barn door) hinges used with auto tow start to pull apart.
If you use one, keep up on the inspections during the day! BillT |
#15
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On Sat, 08 Feb 2014 19:24:59 -0800, son_of_flubber wrote:
On Saturday, February 8, 2014 6:42:52 PM UTC-5, son_of_flubber wrote: Here is the 1870 patent for something that look a lot like the Schweitzer tow hook. Click on the thumbnail for a drawing. http://www.google.ca/patents/US102067 That doesn't look to be any more an automatically releasing hook than the Schweitzer is. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
#16
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That patented release mechanism appears to be superior to the Schweizer hook
by having a slot for the clevis to be captured within. With the Schweizer assembly, the ring can move forward (towards the release mechanism) and, with the high upward force applied by a kiting glider, render the release inoperative. Not so, apparently with the older design. "son_of_flubber" wrote in message ... On Saturday, February 8, 2014 6:42:52 PM UTC-5, son_of_flubber wrote: Here is the 1870 patent for something that look a lot like the Schweitzer tow hook. Click on the thumbnail for a drawing. http://www.google.ca/patents/US102067 |
#17
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On Saturday, February 8, 2014 10:50:52 AM UTC-6, Dan Marotta wrote:
The standard setup is to use a Schweizer hook which is rigidly mounted in pitch and can swivel around the yaw axis. So, if the glider kites, it exerts sufficient force on the release mechanism that the tow pilot may not have the strength to pull the lever. It's also possible that, should the glider get too wide, the axis of the release cable is too far off center to operate the release. So... Stay in position on tow! Dan, there is a 337 for an inverted mounting of the Schweizer hook on Pawnees - Turf soaring developed it many years ago. It simply mounts the fixed arm at the top, and the swinging arm at the bottom - so that when the glider kites, the rope tension is taken by the fixed arm and there isn't any additional pressure on the release gate (which is what makes the Schweizer hook so hard to release in an kiting situation). Roy Couillete at Turf may still have access to the 337 documentation, if you are interested. |
#18
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On Saturday, February 8, 2014 9:31:13 AM UTC-5, son_of_flubber wrote:
Returning for a moment to the 19th century tow hook designs that are on most tugs. Why does the pilot need to pull the release if the glider kites? Why is the release for a deadly tow position not fully automatic? Is a simple purely mechanical, totally foolproof and 100% automatic release not possible? As the guy in the glider, I would be fine with a 100% automatic release. If I kite, release me immediately. There was a design and prototype of a release like this created many years ago and published, I believe, in Soaring magazine. I know if no one that has adopted this which makes it fairly clear that this is not perceived as a huge problem. Many of us have inverted our Schweizer hooks to help avoid the problem of high release force when the glider is high. FWIW UH |
#19
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Thanks, Kirk, but the three tugs that I fly belong to Sundance Aviation in
Moriarty. I'll mention the 337 to the owner and see if he's interested. "kirk.stant" wrote in message ... On Saturday, February 8, 2014 10:50:52 AM UTC-6, Dan Marotta wrote: The standard setup is to use a Schweizer hook which is rigidly mounted in pitch and can swivel around the yaw axis. So, if the glider kites, it exerts sufficient force on the release mechanism that the tow pilot may not have the strength to pull the lever. It's also possible that, should the glider get too wide, the axis of the release cable is too far off center to operate the release. So... Stay in position on tow! Dan, there is a 337 for an inverted mounting of the Schweizer hook on Pawnees - Turf soaring developed it many years ago. It simply mounts the fixed arm at the top, and the swinging arm at the bottom - so that when the glider kites, the rope tension is taken by the fixed arm and there isn't any additional pressure on the release gate (which is what makes the Schweizer hook so hard to release in an kiting situation). Roy Couillete at Turf may still have access to the 337 documentation, if you are interested. |
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