A Rough Day Towing

What size rope were you using? Was there an weak link?

Boggs

On Tuesday, June 5, 2012 7:25:16 AM UTC-5, GARY BOGGS wrote:
What size rope were you using? Was there an weak link?

Boggs

What type of release mechanism?

The glider's release mechanism is the standard Dick Schreder design.
http://www.soaridaho.com/Schreder/Co...k/Tow_Hook.htm

Here is a photo of the mechanism as it appears in HP-14T blue-prints.
http://www.soaridaho.com/Schreder/HP..._Tow_Hitch.jpg

This hook has been very reliable for the past 50+ years. The concept has
been copied and install on other sailplane designs including the 1-35A

Wayne
http://www.soaridaho.com/Schreder



"150flivver" wrote in message
...

On Tuesday, June 5, 2012 7:25:16 AM UTC-5, GARY BOGGS wrote:
What size rope were you using? Was there an weak link?

Boggs

What type of release mechanism?

On 6/5/2012 9:27 AM, Wayne Paul wrote:
The glider's release mechanism is the standard Dick Schreder design.
http://www.soaridaho.com/Schreder/Co...k/Tow_Hook.htm

Here is a photo of the mechanism as it appears in HP-14T blue-prints.
http://www.soaridaho.com/Schreder/HP..._Tow_Hitch.jpg

This hook has been very reliable for the past 50+ years. The concept has been
copied and install on other sailplane designs including the 1-35A

And also - at least conceptually/functionally - George Applebay's Zuni design
(though some may now/have-had Tost releases); I can't speak for
dimensionally/geometrically. Difficult (for me) to imagine a simpler release
mechanism.

I never had release a release problem in 106 HP-14 and 655 Zuni aerotows. Had
1-each back release in both ships, from BIG bows in the rope...as should have
happened.

Bob W.


Wayne
http://www.soaridaho.com/Schreder



"150flivver" wrote in message
...

Snip...

What type of release mechanism?

I think the rope is 3/8 polypropylene. The rope strength is within FAA
requirements for the gliders we tow. We use a weak link with a tost ring,
but not with the Schweizer. There's a Schweizer release on the tug.


"GARY BOGGS" wrote in message
...
What size rope were you using? Was there an weak link?

Boggs

I have been a bit concerned with the ropes some places use.

http://www.engineeringtoolbox.com/po...th-d_1516.html
shows the following minimum breaking strength

1/4 1125 lbf 80%= 900 lb minimum glider weight
5/16 1710 lbf 80%= 1368 lb minimum glider weight
3/8 2430 lbf 80%= 1944 lb minimum glider weight

I prefer towing behind 1/4" rope I have seen a few rope breaks with
1/4" all seemed warranted with a rope in good condition.
It seem to me that unless you are towing a fully loaded ASG29 or a two
place that 1/4 rope is probably what should be used unless of course a
weak link is used. And even then 1/4" rope should be adequate at the
200% rating or less.
Am I missing something?

Brian

Wear on the runway, UV degradation.


"Brian" wrote in message
...
I have been a bit concerned with the ropes some places use.

http://www.engineeringtoolbox.com/po...th-d_1516.html
shows the following minimum breaking strength

1/4 1125 lbf 80%= 900 lb minimum glider weight
5/16 1710 lbf 80%= 1368 lb minimum glider weight
3/8 2430 lbf 80%= 1944 lb minimum glider weight

I prefer towing behind 1/4" rope I have seen a few rope breaks with
1/4" all seemed warranted with a rope in good condition.
It seem to me that unless you are towing a fully loaded ASG29 or a two
place that 1/4 rope is probably what should be used unless of course a
weak link is used. And even then 1/4" rope should be adequate at the
200% rating or less.
Am I missing something?

Brian