Re: [robinheid] Service Bulletin: Squirrel Stronglite Containers
robinheid wrote:
MrAW wrote:
So I'll admit, here I was thinking my rig was totally overbuilt and failure-proof so long as it wasn't damaged, and now this happens.
Obviously all our gear has its limits. I would have thought that a canopy would rip under extreme loads, lines or attachment points could break or I might be injured myself as the result of a hard opening but until now I thought that the container at least would hold together.
Anyone else surprised by this or was I just naive?
Not naive, just a little behind the information curve.
Military gear was always overbuilt and essentially failure-proof but gear manufacturers since civilian parachuting first took off have been cutting into the overbuild and failure-proof margin in their quest to make lighter (and sometimes simpler) gear.
Nothing wrong with that, but sometimes they go too far or they make a mistake in redesign and/or new construction techniques or in some other way alter the puzzle to the point that Murphy's cousin Unintended Consequences jumps into the equation.
I know of two very pronounced examples:
The first was, IIRC Green County Systems rigs ..
Second one was a Sandy Reid rig, a Talon, where they narrowed the reserve container to accommodate the narrower shoulders of female jumpers. It was all good until one girl had a total and when she pulled the reserve, nothing happened. She literally clawed open the reserve container and lived.
Good thing, too; they duplicated the failure on the table -- turns out by changing the flap geometry, it created an interlock that the pilot chute didn't have the power to pierce. They fixed that one without further adventures or any fatalities. ..."
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I was in the middle of that mess 20 years ago.
The Talon problem started with metallurgy and ended with geometry.
Part of the problem was that 1980s vintage springs did not retain their "springiness" for thousands of jumps. The solution was updating the steel alloy used in pilot-chute springs. These days Talon reserve pilot-chutes should be painted red or black. Any metal-coloured pilot-chute springs should have been grounded decades ago.
The other problem was scaling. You can only down-size a pattern-set before you create problems, because some components do not down-size gracefully. Talons started out with 8 inch diameter reserve pilot-chute caps. Those wide pilot-chute caps worked great when containers were 14 or 16 inches wide, but when reserve containers shrank to only 9 inches across the top, then we started experiencing pilot-chute hesitations.
The Talon 1 in question was one of the first "B" sized Talons built for a Raven 150 reserve, then one of the smallest reserves on the market. "B" was the smallest size of Talon 1 ever built. When she pulled the ripcord, the pilot-chute had difficulty pushing the reserve flaps out of the way.
Back at the factory, they discovered that the pilot-chute spring pushed less than the MIL SPEC 18 pounds. Rigging Innovations went through a variety of reserve pilot-chutes with progressively stronger springs. At one point, I was mailing out a dozen replacement pilot-chutes per week.
That Service Bulletin must have ruined the profit margin!!!!
The scaling problem was eventually solved by converting production to the smaller diameter (4 inch) Stealth pilot-chute, which was introduced in 1991 with the revolutionary Flexon harness/container. The Talon 2, Talon FX, Talon FS, Telesis 2, Telesis 3, Aviator and Voodoo all use small diameter Stealth pilot-chutes.
Rigging Innovations learned an expensive lesson without killing anyone.
The bottom line is: you can only scale down a pattern set so far before you encounter scaling problems.
