Thursday, October 21, 2010

Bailout Issues: Thinking Aloud

The main safety issue I face in flying my wing in Alaska this winter is a catastrophic collapse of the wing. This is when the leading edge of the wing curls down and forward (for a number of reasons), blocking the intake vens that keep the wing inflated and thus in an aerodynamic shape that provides lift. Many wings, incluing mine, are designed to automatically recover from a collapse with slight or no pilot input into the controls; this assumes that one has sufficient altitude to make the recovery maneuvers or just let the wing recover on its own. Low-altitude collapses of this kind are very dangerous because you face hitting the ground before the wing recovers, but they can be avoided in part by thinking through the flight plan very carefully and avoiding obstacles that create turbulence and avoiding low-altitude turns, which is not always avoidable if you're landing in a constrained space. I address these issues below.

Many collapses occur in thermic conditions, when the air is turbulent; this can happen anywhere; at liftoff, in the air, or during the final landing phase. Launch collapses can be avoided by not launching in anything but perfect conditions, and in Alaska I will not launch except in perfect conditions which will be: (a) a steady (in speed and direction) 4-8mph wind coming right up the slope at me (I trust my ability to sense the wind speed and direction, but I'll be aided by setting up a wind sock at the launch site and by carrying a hand-held anenometer, which measures wind speed) and (b) good footing (e.g. firm rather than deep snow).

In the flight cruise phase, which I'll begin seconds after launch on mountaintops between 922 feet and 1,350 feet above the ground, I should not have collapse issues because I will not be flying in thermic conditions. In the event of a high collapse that doesn't 'self-recover', however, there are two options; in some cases one or two control inputs by the pilot can reinflate the wing, but if this fails the pilot can throw the bailout parachute. My bailout parachute is mounted on the lower back of my flying harness, and I'll come to that below.

In the landing phase I face potential collapses if the wind changes between launch and landing; to set up my landing the terrain I've identified for flying demands that I make a normal DBF approach, or Downwind, Base (crosswind) and then Final approach to the landing site. Doing this requires two 90 degree turns, one for the Base (crosswind) and one to set up the Final approach; in practice this might well be one long slow 'U-turn' to the right (one of my first DBF setups is here). I have made many of these approaches and I feel fine setting up such an approach where I will fly, based on my knowledge of how my wing performs and very close examination of maps of the terrain. I will be able to identify the landing site wind speed and direction because before flight I will have set up a luminous (glowing) windsock at the landing site to help inform my landing maneuvers. There are a few hours of light daily, even though it's Arctic Winter, and that should be enough to 'charge' the wind sock; if not I will also fit it with a small LED light which, I know from experience, can last hours, plenty of time for me to turn it on and then hike the mile or so (and about 1,000 feet up or so) to the launch site, launch, and land.

I'll begin setting up my landing phase maneuvers around 500 feet above ground, which is closing in on the bare minimum for throwing the bailout parachute and having enough time for it to open properly and support an emergency descent and landing. Landing under the bailout parachute is not as smooth as with the wing, so in the last moments before touchdown the pilot must prepare for a PLF or 'Parachute Landing Fall', which I've practiced, but need to practice more at the park by jumping off a step-ladder and landing with a rolling, flexed-body posture that disperses the energy of landing. I also will wear ankle-protecting braces that have been shown by military paratroopers to drastically reduce ankle injures during PLF's; I have to integrate these to my boots, which is a whole separate topic (my boots also have to be attached to my flying suit--itself a design issue--because I know from experience that a good way to lose one of these boots is to run in deep snow in them, as in a takeoff run).

In darkness, depending on the starlight and moonlight, the snowy terrain below might or might not be easy to spot, so I will fly with a powerful laser attached to my helmet; I'll switch the laser on on just after launch. This laser is powerful enough to burst a toy balloon, but is only the size of a roll of quarters; within 500 feet of the ground it puts a bright green spot on the snow which considerably helps to identify where the surface is, how quickly you're moving, and whether the terrain is rough or smooth; though I only made a few 2-3-second 'hops' two Winters ago (this Winter's flights, based on my calculations, should last around 300 seconds or 5 minutes) I found the laser to be enormously helpful in orienting myself, so mounting it and getting cold-resistant batteries for it, and making a clamp that keeps it on continuously (and that I can operate with gloves or mittens on--more about this below) because it presently has only a button that has to be held down to keep the beam on, is another task.

Although a collapse during any phase this Winter is exceedingly unlikely because of the strict rules I'll impose on myself for launch and flight, I do need to prepare for it by making the bailout parachute easy to deploy in a way that guarantees that it will open up properly above me.

To do this I've unpacked the bailout parachute from harness to the main parachute bundle (photo below). Here you can see the parachute risers leading from my harness to the bailout parachute. Minute inspection of the lines revealed no weak spots, but one possible tangle-inducing kink.

I removed the kink from the risers nearer the parachute bundle, and packed the lines carefully in their quick-deploying rubber band constraints (photo below).

After this I packed the parachute bundle in its pouch in the lower back of the harness (photo below) and closed the flaps in the correct sequence, finally inserting the release pin (more photos below).

With the bailout parachute carefully packed for a 'clean' deployment, I put on the harness and reached back on the right for the handle, as I would during flight; pulling the handle rather forcefully (needs quite a yank, actually) removes the release pin and in one long yank the parachute bundle flies out to the side, followed (in a clean deployment) by the risers being torn from their rubber bands by air resistance and, soon thereafter, the opening of the bailout parachute.

Without gloves, finding the release handle is easy enough (photo below). But I cannot fly in -20F or -40F without gloves.

The mitts I prefer to use are so clumsy for this task (photo below) that finding the release harness is not easy; and, remember, I may only have seconds to do it in the moments after an unrecoverable collapse. Though mitts are always warmer than gloves, the loss of dexterity simply isn't acceptable.

Wearing medium-thickness gloves rather than mitts (photos below) make it easier to feel and find the release handle, but, still, neither of these gloves are acceptable; they're still just too clumsy to find the handle quickly and flawlessly; and the bailout throw has to be quick and flawless.

Wearing very thin gloves seems to be the solution, but they're not warm enough; I know that much from many bitter, bitter experiences. One side of one finger in fact is permanently numb since a trip to Iceland in 2001. And one of my closest shaves was during my first trip to Alaska, where my hands froze on a completely calm, perfect -30F day (I was testing a clothing system that, obviously, didn't work), preventing me from even zipping up my parka (my fingers wouldn't clamp around the zipper pull) which led to my torso freezing and my coming very close to hypothermia as I battled for three hours to set up my tent, light the stove with matches clamped in my teeth, and just barely avoiding becoming a human popsickle. So I take very good care of my hands, now.

If I need thin gloves to feel the bailout handle, but normal thin gloves are too 'cold' to work with (at -30F it only take about a minute to freeze my hands without good gloves or mitts), one option is battery-powered gloves (pictures below); these have wires threaded through the fingers which the batteries warm. But these are a poor solution; batteries fail, wire leads break, and, finally, these gloves aren't windproof, and wind cuts right through them. No good, either.

Solution? I don't know, yet. Lighter, windproof gloves _over_ the battery-warmer gloves might work (photos below) but I hate to rely on batteries, again, and even so this still makes for pretty crummy dexterity and the chance that I won't be able to find the bailout handle in time. So this is the dilemma; what hand-insulating system do I devise that keeps my hands from freezing but also makes finding the bailout handle possible, nay, guaranteed and instant?

These are the kinds of details wake me up at 3am. I envision a collapse and a fumbling for the handle as I plummet down towards the sea ice. These are the kind of details that make for the difference between life and death, and they're precisely the kind of details that accident investigators piece together to find the ultimate reason for the disaster: "He had plenty of altitude and a good bailout chute, but he couldn't get at the handle because his gloves were too clumsy."

I'm confident I can solve the problem (I won't fly without a solution), but finding it will take time and experiments.


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