Sunday, January 8, 2012


Just a few PSI in the suit puts significant stresses on the various components. This is fascinating stuff! Above you can see the helmet hold-down cables: I removed the originals that came with the helmet, for a number of reasons, and replaced them with my own 1/16" steel cable, which I swaged on each end. The cable attaches in front to a strap sewn into the crotch of the suit, and then rises up through the fittings on the L and R sides of the helment, and then descend the back of the suit to two fittings on the mid-back. This prevents the helmet from rising up over the head when pressurizing the suit. The photos show the back of suit with its cables, and closeups of the chinzy split rings I used for the front connection, coming apart under the pressure of just 2psi, and a closeup of the hold-down cable having shifted out if its hold-down track pulley fitting! This is probably because I reversed this fitting, for various reasons, but will now return to their normal position. Every time I pressurize the suit and solve problems like this, I am learning life-saving design lessons! Another photo, added just a moment ago, shows the blown-out split rings from the helmet hold-down when I brought pressure up to normal, with the hold-downs somewhat cinched down. Completely destroyed. A reminder to always wear eye protection when dealing with pressurized gas. The failure was simply a dramatic 'pop', one of more than a few I've heard on this project, and something I don't want to hear again.


Gregory said...

Maybe try a Rappel Ring? They make cheaper ones, any climbing shop would have them.

Cameron McPherson Smith said...

Hi, Gregory, you'll see that I've used a small pulley, in later photos. The problem with the rappel ring is that it would want to turn to be aligned with sternum longways, that is, sticking out from the suit an inch or so, and putting that small area of pressure on the suit itself. The little pulley seems to be doing it. Can't believe how much strain comes onto these elements when pressurized! Cheers Cameron