smokenjoe50 wrote: ↑Tue Apr 17, 2018 8:17 pm....Why did you decide to use rubber tubing? I was thinking of using that bungee cord Wills has for retracting harness zipper pulls.
Good question. Some pilots stay put at one angle and for them it's not an issue. I rock up and down a lot so my head/helmet moves up and down by maybe 15" top to bottom. Bungee cord has a very rapid rise or drop-off in pull force and would jerk my neck even if I used a longer length and ran it through one or two pulleys which I have already tried. The 1/16 x 1/16 latex tube has a really even pull as it stretches and I don't notice the change in pull from head down to rocked up. Another reason I use it is because it can be stretched 4X its own length versus less than 1X for bungee cord. Since I'm using the pulleys I need the drop line to stay up against the keel when I'm standing so it's doesn't snag on anything. When you fly in turbulence or are just getting jerked around on the ramp, any slack in the drop line can quickly turn into a nightmare. I now have over 700 hours on this system and it more than doubles my flying endurance plus it make turbulence easier for me to tolerate.
Another thing to consider is that the pitch limiter line on a harness can fail in a bad landing and allow the distance from the helmet to the attachment point to far exceed the stretch limit of a bungee cord or a spring reel. If the connection from the helmet to drop line does not let go at only a moderate force the pilot's neck can probably get bent back far enough to fracture vertebrae and either damage or sever the spinal cord killing or paralyzing the pilot. So the system really needs to be tolerant of incidents that are beyond our control or belief.
Since I began this sport in 1973, I would guess that between 70 and 100 pilots who I knew have been killed, paralyzed or have wound up with TBI. Honestly it's probably over 100 when you include powered ultralights and PGs. Why water it down? I would guess the majority of these dead and broken pilots have said to themselves, "Well, that'll never happen to me....." in response to someone else's tragedy at least once. Many of these were equipment-related A figure I left out is the number of pilots who I have known that have negligently contributed to the deaths and crippling of other pilots. Often these individuals would similarly talk out their butts then blame the injured/dead pilot for their own demise. The whole thing is a giant circle-jerk of the saddest kind.
It's just as easy to over-design a device for the sake of safety and wind up making it more dangerous than if it were left alone. That's the nature of the beast as I think many of us already know. So there's a long story behind why I use a long section of 1/16 x 1/16 latex tube and run it through two pulleys. It's more than you asked but I meet people all the time from around the world who read the things I post here and elsewhere but will never comment online or even write to me but when they see me they typically say something. I know I'll be asked about my design philosophy on this project. So there you have it. If you need any assistance in case you build one just give me a holler. I know you are a better fabricator than I am. I've seen your work. You will probably come up with a better version that I will copy for myself or adapt.