Rainbear Skydive Corps Simplified Low Altitude Drop System

Most of the summer of 2013 has been spent trying to simplify and lighten the Corps' traditional dropping system. During the time we were inactive, things happened: I got older and more physically limited and the trees the city planted at Golden Gardens (my local park) grew. The first meant that it is now more difficult for me to get to and cope with dropping on the ocean beaches and the second reduced the height I can drop from at Golden Gardens. I found that the old dropping system, used at the reduced height available at the Gardens, resulted in drops where the parachute barely got opened before landing. I needed a new system that would deploy the parachute much more quickly upon release. This in turn required smaller, lighter bears, lighter equipment, etc.

It was a summer of frustration as each change required testing, but there were very, very few days with enough wind, so development stretched out seemingly forever. I tried a number of ideas, some of which were moderately successful, but all of which somehow added complications and resulted in less dependable releases. This ended with a disastrous day in which we had more unsuccessful drops (and shocked kids: "Is the bear all right?") than were successful. Obviously, not a good thing. I went back to the drawing board. The result was a reduction of the dropping equipment from 21 oz. to 6 oz. A new weight limit of 1 lb. maximum for bears was established, with older bears over that weight honorably retired from the Corps and new, lighter recruits brought in. Our beloved old Adjutant, John Quincy Bear, who was the first bear I made and has been with the Corps for more than 20 years, made the required weight and stayed on to train the new recruits.

The basis of the new system was to eliminate the old four bear dropper, which is fairly large and had some heavy metal parts, in favor of a new single bear dropper that is much smaller and uses a rubber band rather than a spring. Parachute packs for the bears were also eliminated, helping to keep their weight down. Instead of a carefully packed pack with a rip cord that ate up space between the release height and ground, a nylon sleeve is attached to the dropper and the parachute is pulled up into the sleeve and clipped into the dropper by the string that runs across the vent opening at the top of the dome. With this system, the parachute opens almost instantly as it leaves the sleeve, giving the bear much more float time from the low (150 ft. or so) drop heights we can use.


We break here to show the new dropper design:



Pretty simple... The operating parts are enclosed between two pieces of thin wood to keep things rigid. The small nut above the rubber band is a hinge for the loose forward half. There's a tapered gap between the two halves above that point. The rearward blue wire twist is rigid. When the rig is run up and meets the upper pulley, the forward wire twist, which is on the hinged half, is forced toward the rear, closing the tapered gap at the top and opening the gap at the bottom, in which the string across the parachute vent is hung, allowing the chute to drop out.



Here is the rig ready to go aloft. The chute is pulled up into the sleeve and hooked into the gap at the bottom of the dropper, ready to be released.



Dropper Two

Everyone knows you have to have a backup, so I made one, incorporating a couple of changes:



For this one I didn't enclose the operating part with sides, just used two pieces of wood. I also added a leg to the opening, which seemed a little more secure to me.


Here's the other side, with a cutout to allow inserting the parachute hanger.


Here it is as it would be when it opens upon jamming against the upper pulley.


I did experience one field failure yesterday (third day of operation with this system). When I made the chutes I used a simple piece of string across the vent opening, with just a few stitches to hold it in. That was fine for just hanging the parachute up, but with th weight of the bears and the swinging that occurs as the dropper goes up, one of the strings worked loose and resulted in an early release. I went back today and sewed an actual nylon strap into each vent as well as adding a ring to take any wear from rubbing on the wood of the dropper.




OK, back to the main story line....

Along with lightening things in general, I moved away from having a separate parachute for each bear and made all new harnesses for the bears. The basic Corps kit now includes a set of parachutes in 18", 24", 30" and 36" diameters, all newly made with an improved suspension system that includes a spreader bar that helps greatly in preventing shroud twisting. Each chute is fitted with a pair of miniature carabiner clips that can be quickly and easily clipped to any bear's harness. Upon arrival and setup, the first jump is made by a heavier bear using a smaller chute, to establish the drop zone. From that point, different bears and chutes can be combined to insure continued safe drops without tree entanglements.

On Oct. 12, my frustrations ended. A day that started cloudy cleared off, a good 10 mph north wind came up and the Corps headed for the park. The result was a perfect day, with more than 20 perfect drops. Every aspect of the new system worked to perfection. It also happened that there was a good crowd at the park so we had a pretty constant spectator group, including plenty of kids (I almost ran out of bear chaser badges) and several tourists. A number of folks were taking pictures and I passed out cards hoping to get some copies. This really worked out well and this morning I got up to photo sets from Vlad and Lyudmila Grinberg and Kim and Marylou Elton. Between them they managed to catch shots I was able to sequence into a full series. I'm showing these pix larger than I usually do because the park was really at its best, with some autumn color beginning to show. Too bad I spend so much time there, but someone has to do it.. :^)

Note: I went back to the park today and it was a repeat... all perfect drops.



This is actually a pretty incredible shot. The leaves are obviously close, but the kite is actually at 300 feet and to the naked eye is barely a postage stamp. Good lenses!



Here is the very small dropper on the kite line, with the red nylyon sleeve hanging down. The parachute is pulled up into the sleeve and clipped into the dropper. Note the spreader bar and web tapes built in as part of the parachute shrouds.



The system for getting the bear aloft has not changed, a split line running from two pulleys on the ground to a pulley aloft. Here you can see the line split at ground level. Dropper and bear are going up on the far split while I pull on the near one.



Perfect shot of the moment of release... the parachute is just beginning to leave the sleeve.



And John Quincy Bear is on his way down.