Hey everybody. Welcome to my new site. I’ve shut down Sasquatch.aero and am throwing my support for online skydiving equipment sales to the awesome team at Parafunalia.ca. I’ll get into the details of my new direction later. First I need to express my concern about the magnetic deployment bags in use.
This past week I encountered two sets of gear that failed to open properly. Both were equipped with magnetically sealed deployment bags. The first resulted in the video below showing severe line twists which led to a high speed cutaway and the second was a hard opening that blew apart the top skin and destroyed the canopy.
I can’t know for sure, but it seems plausible to me that both of the failed openings could be the result of bag strip. This is when the pilot chute yanks the deployment bag out of the container so quickly it leaves the canopy behind. Just like yanking a table cloth out from underneath the dishes on the table. When your canopy comes out of the deployment bag before you’ve achieved line stretch, bad things are likely to follow.
Watch Jordan Irons cutaway an improperly sequenced opening:
There are a few critical forces in play in the initial stage of your canopy’s deployment. First, there is the snatch force created from the difference in speed between the falling jumper and the pilot chute as it anchors itself in the wind. Then we have the mass of the canopy itself resisting the change in inertia ( objects in motion staying in motion, etc. ) Finally, there is the force of the locking mechanism, be it magnets or rubber bands, working to keep your deployment bag securely wrapped around your parachute until a bunch of other important things have happened.
I don’t know the numbers on what the forces around a deployment bag measure out to, but I know it’s a lot harder for me to break a rubber band than it is for me to separate the magnets on a stowless bag. Rubber bands also have the advantage of an elastic range before they snap. Magnets just snap when the forces hit a magic number. Or worse, they can slide apart with far less effort than you might expect.
Your gear was manufactured, tested and approved to be used with a specific deployment bag. If your manufacturer doesn’t offer or endorse a stowless or semi-stowless deployment bag, it’s because they haven’t tested one.`Personally, I think testing is kind of a good thing.
Canopies are designed to open in ordered stages. Use gear approved by your manufacturer. Double wrap your stows. Spend less on repacks and ruined gear. Live longer.