The tow release mechanism is finished, shy of welding and a 3/4-inch hole. I think it looks awesome. Here are pictures for both latched and unlatched. The release arm takes somewhere around 3-10lb of pull pressure to activate the release.
The only difficulty was the tolerance stack-up of the thicknesses of the metal made the latch just a bit on the tight side, so I thinned the latch arm and washers by lapping them on 800 grit sandpaper. This also polished those parts so they slide smoothly. I think it looks awesome as a result of the polishing. I will just increase the spacing of the slots if I ever make this again.
The 3/4-inch hole for the bolt to the hitch is larger than any drill bits that I have, so I'm still working on finding a large bit. But, a quick test with the 3D printed mechanism with a slightly loose locknut suggests it'll be able to rotate in the yaw direction on the hitch. (Alan, thanks for the heads-up that is definitely needed)
I haven't figured out how to manage the line tension overall. Placing a strain-gauge on the hitch metal could work! For the first flights, I'm hoping to get away without knowing or managing the tension directly.
Welding stuff arrives in a few days... Thursday's high is 29F, so TBD on how quickly I can actually get to trying it all out though.
1 comment:
Hi Dan,
Disregard the following if it has already been considered.
While towing hang gliders in strong thermal conditions I have attained in excess of 1600 feet on a 2000 foot tow line. The angle of the tow line can get quite steep. If the release is not going to be able to rotate vertically, then it would be a good idea to also test under load (150-200 lb) with the tow line coming in at a vertical angle (maybe 45 - 60 degrees) to ensure the design has catered for the additional loading on the release lever.
cheers Alan
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