On Friday, May 15, 2020 at 8:38:49 AM UTC-4, wrote:
KGARS – Kiting Glider Automatic Release System

About 10 years ago I assembled an auto tow hitch that utilized a TOST release and a small pneumatic cylinder. With a small air bottle at ~100 psi and a solenoid valve and a switch I was able to put the switch in the car for the driver in case there was a need to release the cable. Worked fine and opened in a fraction of a second. Links to a picture and old .AVI video below…

Leaving the concerns of certification, 337s, etc. towards the end of the project, I think a similar system could be designed that would detect an “beyond normal” aft stick input of the towpilot and automatically release the towplane end of the towrope. An aft stick input is probably the first input that occurs, intuitively and with minimal delay, in a upset event.

A simple pitot/static pressure switch could prevent the release from opening if the towplane was on the ground.

I suspect that installing the actuator in the cockpit in parallel with the manual release would probably makes the most sense. Keeping the manual release preserves the ability of the towpilot to release in case of failure or if things are going poorly for other reasons. Installing a “dump” switch could also afford the pilot the option to use the actuator if he/she so chose.

Supplying pressure for the system could be as simple as utilizing a 12g CO2 cartridge. The stroke volume of the cylinder I used was small and keeping a few spare cartridges in the towplane would make refilling cheap and convenient if needed.

Given the wealth of expertise of this group, I’m certain a system could be designed and FAA paperwork completed if there was a group willing to work on this type of project.

While admonishing glider pilots to release if they lose sight of the towplane is valid, the kiting event I saw recently occurred due to aft seat back movement and in the first 1-2 seconds there was no way the pilot could get to the relase. Fortunatly, that event ended as well as could be hoped for. Something that’s automatic and very fast acting would probably enhance towpilot safety.

With all due respect,

Mark

http://daziv.com/kgars/hitch.jpg

http://daziv.com/kgars/release.avi

Hi Mark,

that system could be adapted to be put into the tail of a tow plane.
The actuation of the release is - as far as I know - always via a cable. Now imagine a secondary cable connected to the actuation lever which is nearly taught in it's normal condition. The function of the manual release via the handle in the cockpit is not impeded. In an emergency, the pilot triggers the electric switch on the stick which then fires the secondary mechanism without having to reach the lever on the floor. The energy source for the emergency release is up for discussion: a solenoid, spring, CO2 cartridge, etc. - all with their own pros and cons.

Thoughts?

Uli
'AS'