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Old January 2nd 19, 06:10 PM posted to rec.aviation.soaring
Karl Striedieck[_2_]
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Default Winching - Reverse Auto Tow

We've been using an auto-mounted pulley launch system for over 50 years, and the idea came from the Dansville, NY club who've been using it since the Wright Bros.

Initially, launching a K-8, a 1965 V-6 Jeep was enough. A 300 ci Olds V-8 engine was installed when glass ships with ballast came along. Later, something with more muscle was needed to launch a ballasted Duo Discus so the vehicle used now is a supercharged 454 ci Chevy Suburban.

Traction has been a problem from day one, especially on early morning launches on wet grass. The jeep was equipped with chains on all four wheels which was still marginal during the soft ground in spring. To harness the 600 hp of the '99 Suburban a 350 foot paved strip was added, and this "launch pad" does the trick. Catapults to 150 feet altitude (all we need on the ridge top) take seven seconds for a 15M ship and 10 seconds for the Duo.

With the 2 to 1 reduction in required vehicle speed due to the pulley on the Suburban there is no need for the transmission to shift gears, so we use first gear, high range, 4wd. The glider releases from tow just as the Suburban reaches the end of the pavement. The throttle is floored until the glider calls "3,2,1,release" at which point the throttle is cut back.

Tow cable used is 3/16th galvanized. It lives outdoors. The pulley is a MG B trailing arm suspension welded to a 2 in coupling ball with the 13" steel wheel serving as the pulley. Totally indestructible, it has giving flawless service for 52 years.

Karl Striedieck