Quick release for drop testing?

The Valdotain-tresse is, say 5mm and is made on the main strand of 10mm or fatter. For the release, we've used 5mm. Feed the release through the three strands of the Valdotain using either a retraced or overhand on a bight to make the loop. The release will loosen the Valdotain and push the tresse off the end of the main strand. It's like the old Chinese finger cuffs - you can't pull them, you have to push them off.

I haven't used them for drop testing but it occurred me right away that this would be a good application. I attended an ITRS conference a year and a half ago and one presentation was on how well Prusiks grabbed rescue loads (2kn I think). They were using the "cut the rope" technique and it worked. It places a person in an awkward position with a knife and a highly tensioned cord...

Good luck with the project. I'd love to hear how it goes. We have some drop testing we'd like to do, too.

20 kN wrote:Any suggestions?

In the world of Hang Gliding we often use barrel releases which are designed to be very easy to release, very simple, and can withstand high tensions without releasing.



There are also "Primary Releases" that come in a variety of flavors, some are similar to the one in the original post
For example:

Here's my favorite:
estore.hanglide.com/Aerotow…

Might consider an archery compound bow release. You could rig it up to drop a verticle load from a highline pretty easily. Most bows have about a 70 lb drew weight but I would think they could handle 150 lbs. You can pick them up for around 20$.

20 kN wrote: Because I have to conduct 30+ drop samples. But more importantly, I am conducting drop tests on a highline, so I will be on the ground and I need to release the load remotely, presumably by pulling on a rope connected to some type of release mechanism. For the most part, I only need to drop 150 lb samples, so maybe some type of quick-release knot would work. The catch is that if I use a knot the knot needs to completely release from the highline so the weight can free fall.

you will likely have to go back up to re-set the weight each time(?) so why do it from the bottom? it seems like it might be easier to do it from one of the highline anchor points, which would make the long cord fairly easy(?).

Can you rig a gri-gri with a short tail, like 6 inches? I seem to remember this from something I read or saw on a video. Maybe Dan Osman?

I know this is an old thread, but what did you end up going with?  I plan on doing some drop testing soon, and I'm looking for a quick release mechanism.  

I did change out the ring with a sturdy keychain ring that I wrapped around itself a couple times with pliars, but I've been dropping 200lb loads with it for the last few years with no issues.

Sailing Snap Shackles

Luc-514 wrote:

Sailing Snap Shackles

Those dont release under load for crap. I had one of those loaded to 450 lbs (less than 1/10th breaking strength) and I broke the pin pulling on it so hard. It still dident release.

Thanks for the replies!  I want to be able to drop 282 pounds (ANSI Z359 test weight) or more for a two-person load, so I'm hesitant about the snap shackle.  For the price, it is probably worth a try.  I've also been looking into the 3 ring release system and rigged something up from parts I had.  Seems to work ok, but I haven't tried it with any significant load yet...

20 kN wrote:

Those dont release under load for crap. I had one of those loaded to 450 lbs (less than 1/10th breaking strength) and I broke the pin pulling on it so hard. It still dident release.

Wrong product, you want the Wichard Trigger snap shackle "Speedlink".

I use a self-made pelican hook design with an electrical actuator but it could just as well be pneumatic I guess, just didn´t have cylinder lying around that day. A length of cord would work well enough as well.

20 kN wrote: Interestingly enough, I am having a bit of trouble finding an economical device which can drop a hanging load on cue. I started with a snap shackle like this... ...but quickly found that the device does not open very well when loaded. I have seen this device used for drop testing and it works great... ...but it comes with a very high price tag. Any suggestions?

You might look at horse-back riding supply stores, they usually use a quick-release shackle for connecting the stirrup to the saddle that will release under load -- the load being the rider being dragged by the horse if a foot is caught in the stirrup after a fall.  I've tested them under body-weight loads, and they do release easily, and they're also relatively inexpensive.