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billbooth

******...but it has certainly been the most "trouble free" device I have ever invented...




It's distressing that I have to write this, but historical accuracy demands it. I have been skydiving for 35 years, and I am as big a fan of Bill Booth as anybody, and in no way do I mean to denigrate him or his contributions to our sport. But he did not invent the skyhook. He may have redesigned it for skydiving rigs, but the first MARD system was invented by Mark Hewitt, on a base rig called the Sorcerer, and Bill knows this. Credit is deserved where credit is due.

The inventive idea in the Skyhook is not simply the idea of hooking the cutaway main to the reserve bridle. It is how to do this in such a way that the connection releases and gets out of the way when it is not needed, but stays connected when it is. A little history.

If you will look at the beginning of our "Skyhook Promotional Video" (#2 on UPT's website) you will see video evidence that I started working on MARDs in the early 1980's. The reason the skyhook didn't come out until 2003 was that it took me all those years to work out all the problems that need to be solved before such a device would be safe enough for sport jumping. During the 80's and 90's I designed and jumped several primitive MARD's, but none of them worked well enough to satisfy me. The Sorcerer system came out during this time period, but required a hand deployed reserve pilot chute, had no automatic release system, and wouldn't work with spring loaded, ripcord activated reserve systems. As has been noted elsewhere on DZ.com, I included mention of the Sorcerer in my patent application. Some of my first devices involved pins and loops similar to the Sorcerer, but these systems weren't reliable during rapidly spinning malfunctions.

You see, the MARD connection pulls on the reserve bridle near the midpoint, which means that it is pulling on both the bag and the pilot chute. If there is a lot of horizontal speed involved (spinning malfunction), then the pilot chute often generates enough force to prematurely release a simple pin/loop system, which will release as soon a the pilot chute loads at all. I needed to work out a system where it took a lot more force from the pilot chute to release the MARD connection in a partial malfunction than in a total malfunction. This is where the Skyhook lever/cam design came in. It is designed to require 5 times more force from the pilot chute than the weight of the packed freebag (25 - 60 lbs.) if you have a partial malfunction, yet release with a force of between 4 and 8 lbs. if you have a total malfunction. And it has to figure this out instantly, with no input from the jumper.

The lever idea worked well, but there was one more serious problem to address. Simply - What happens if the RSL side riser releases BEFORE the non-RSL side riser. This is a bad situation even with a "normal" RSL, and has resulted in several deaths due to main/reserve entanglement. But with a MARD, the situation practically GUARANTEES a fatality. I was stumped, so I put the Skyhook on a back burner for nearly 10 years. Then one day I was discussing the problem with a young engineer I had hired straight from Georgia Tech. After thinking about it for a moment he said," Why don't you simply connect the RSL riser to the cutaway cable leading to the other riser? I was stunned. There was the answer I had been looking for dropped right in my lap. The young man's name was Kyle Collins, and that's how the Collins' Lanyard, a necessary component of ANY MARD system was born. We had a working model that day, and you will notice that it is his name, not mine, on the patent.

So I put out the Skyhook immediately right. WRONG. I didn't want to put two new reserve related systems at once, so I fitted all of my existing and new tandem rigs with the Collins' Lanyard. I then waited the requisite 5 years to see if the Collins' Lanyard worked as expected. It did. Then, and only then, was I ready to release the Skyhook. The whole process took nearly 20 years from inspiration to implementation, but I think the result was worth it.

Don't mean to dig up an old thread...
I Just want to say that this was a really interesting read. I mean, I didn't understand all the terms in it (due to being an amateur with practically no experience) but found it quite interesting.

Good work Bill for having the fortitude to persist with it for so long, sounds like a great outcome.
_____
SPLAT

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Then why was my jumping ended at Skydive Nagambie in Australia by the CI Don Cross for asking as to why the student rigs did not have Skyhooks. I expected support form Mr BOOTH over this but got nothing. banned from ever jumping there !!! (For asking questions)

I was ahead of my time.. again Soon skyhooks will be on every student rig. Like in 1981 when jumpers laughed at me when I said automatic opening devices will be standard on rigs... AAD mandatory in Australia now !!!
I tend to be a bit different. enjoyed my time in the sport or is it an industry these days ??

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This guy's skyhook/ dropzone ban related posts make great reading. Not because they add value to the discussion (apart from entertainment value), but because he keeps repeating the same thing in all the posts and his arrogant know it all attitude despite still being a student. And the fact that he did 16 tandems before AFF!!!(19 total):D. I would very much like to read the orginal posts that resulted in his ban from the dropzone if anyone knows where they are.

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I'm pretty sure the whole saga was in the Aussie forums. Not sure which ones. I know he's been perma-banned from them, so the original posts have likely been deleted.

AFAIK, he pretty much accused the DZO of being negligent and putting students in danger for using perfectly serviceable gear. Just gear that didn't have skyhooks.
"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

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radical_flyer

I would very much like to read the orginal posts



I am sad to relate that the skysurfer.com.au forums are now gone, probably forever :(

(dz.com seems to be the only skydiving forum that is still seeing a lot of traffic. And maybe a lot less than it used to. But I don't know for sure, guess that's another thread.)
--
"I'll tell you how all skydivers are judged, . They are judged by the laws of physics." - kkeenan

"You jump out, pull the string and either live or die. What's there to be good at?

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Alleging unsafe gear opens the barn door for personal injury lawyers. PI lawyers will cheerfully astonish the jury about something "unsafe" deep in the reserve container, while ignoring evidence that the student flew his main canopy into wires, hangars, lakes, etc.

Shock!
Did I just call lawyers ignorant?

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FastDaniel

In this case a skyhook would not be the best choice.

vimeo.com/189896296#t=3m30s




It certain would be the best choice. And if reserve opening while spinning is your concern, watch the vid again. He was still spinning when he deployed.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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Looks like the best argument for a Skyhook I've seen in a long time. He rode the malfunction for over 20 seconds, and then didn't saddle out on the reserve for nearly 6 seconds after cutaway! Glad he pulled high in the first place, because the malfunction ride, plus time between breakaway and reserve opening probably exceeded 2,500 ft.

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billbooth

Looks like the best argument for a Skyhook I've seen in a long time. He rode the malfunction for over 20 seconds, and then didn't saddle out on the reserve for nearly 6 seconds after cutaway! Glad he pulled high in the first place, because the malfunction ride, plus time between breakaway and reserve opening probably exceeded 2,500 ft.



He decided to wait to pull, which is EXACTLY why you used to be opposed to RSL's. So the jumper could control when the reserve was pulled. Still have copies of your white paper against RSL's that I used to hand out (and tell people to ignore) in the 80:s and 90's when people were trying to decide whether to get one on their new rig.
I'm old for my age.
Terry Urban
D-8631
FAA DPRE

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To Bill's credit, I've never seen him claim anything other than "Skyhook removes the reasons I was against RSLs", which I've always seen communicated consistently. There are disagreements from other people as to whether that is actually true and whether Skyhook can cause you to have reserve line twists, but from UPT's side the line has always been "our tests show Skyhook is less likely to have line twists than anything else, therefore Skyhook is a form of RSL we can recommend". Or at least I've never seen them claim otherwise.
"Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

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On the one hand, reserve line twists as a possibility. On the other hand, a violent meeting with the Earth. I can handle line twists better than the other. Any non cross connected RSL is better than no RSL and a MARD is better than a plain RSL. All other things being equal.

It's been long enough now that there is no longer any room for argument. Real experience has proven it.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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Line twists happen all the time on MAIN deployments, and the jumper was usually quite stable when he threw the pilot chute. A lot of things cause line twists, but the Skyhook is not one of them. As I've said many times before: The speed of Skyhook deployment lessens, not increases the chance of line twists. The Skyhook has been out there for more than a decade now, and I don't know of anyone who has gone in because of reserve line twists. However I can think of a lot of people who have gone in because of low cutaways without a MARD.

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There was a recent Russian fatality where the proximate cause was reserve twists, however it was not a Skyhook fatality. It was caused by a series of jumper's utter failures to plan and act, and happened despite, not because of a MARD.

I personally am glad to trade the very low risk of reserve line twists for everything that a MARD gives me. I'll also pick a standard RSL over nothing. A reserve with twists is infinitely better than no reserve at all.
"Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

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Agreed mathrick,
The deceased problems started when he bought a tiny reserve.

IOW if you bought such a tiny reserve - that you worry about reserve line twists - you bought too tiny a reserve.

And they used to ignore me when I grumbled about "stupid fat white men under Micro Ravens."

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Right-o, I meant it as "not a fatality where Skyhook could reasonably be blamed". I do believe it was likely a Skyhook deployment, your analysis is pretty convincing.
"Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

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