Re: Chief Silk

From: SD
Activity_Date: 8/23/01
Remote Name: 4.33.112.238

Comments

Bruce,

I would need more info to comment on the initial gyration, but it seems distant and not directly related to your need to deploy. From your article, it appears your decision to deploy was a good one. A more experienced pilot might have been able to clear the cravat in the available time remaining, but your were clearly overmatched and survived to fly another day.

Your incident requires in-depth discussion of basic advanced canopy control principles, but briefly:

If the canopy gets below the horizon without a centrifugal load, the lines will go slack as you fall through. If your lines go slack, you have enabled one of the ingredients for a caveat, which you encountered. When the wing cravats, you have a lot of drag on one side. The asymmetric drag can result in a spiral or sometimes a spin. Since the drag is proportional to the square of the airspeed, a spiral dive will can accelerate exponentially if you don’t arrest it immediately.

You should get your aircraft under control prior to clearing cravats and tucks (a full stall is a controlled maneuver).

You clear a cravat by unloading the lines and shaking the canopy. If it’s a small one out near the tip, you can deflate one side by pulling on the “A” riser (1/2 big ears). If it’s inboard you need to full stall the canopy and let it shake out, then recover from the stall.

When flying in active air, angle of attack is the most important parameter to control. You may want to read some of the articles in my comments section on paraglide.net http://paraglide.net/comment/index.htm relating to angle of attack. I’ve learned the hard way that you need to avoid getting the canopy below you at all cost. On occasion, this may require aggressive breaking with a lot of muscle (50 lbs + per side??). I also recommend watching Jocky’s video, “Security in Flight”, numerous times over the course of a season. (please buy a legal copy to support the production of additional material)

You also need to do more than understand the dynamics academically. You lost control of the canopy, and rather than dampen the gyrations, your control input timing aggravated the oscillation to the point of almost getting shrink wrapped. Practice your maneuvers, starting with mild fore and aft surges and working up to more advanced stuff. You have to build an automatic intuitive response. I learned most of my stuff through OJT, but didn’t always work it out before hitting the ground.

For confirmation, there are a couple of things in your article that don’t add up. For example, you said that your entered a spiral to the left with a cravat on the outside of the spiral. I think you were probably overloaded and your recollection may be distorted.

Tom Truax