Date: Sat, 2 Mar 1996 11:34:02 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Learning to observe One of the things that I've been slowly learning as I work with my kites is to *observe* the kite as it is flying. If you don't see a problem, you'll never fix it... I'm working on soft kites. These are some of the things that I'm learning to look for: Inflation. The vent is at the front, but the cells fill from the rear - the trailing edge becomes fully inflated before the leading edge. Watch the way that an inflating kite responds to steering input - the side that you pull on inflates more quickly and starts flying instead of stalling, causing the kite to steer in the opposite direction to that intended. Observe how you can push a shock-wave along the canopy, to force a temporary moment of higher pressure into the part of the canopy where you need it. Observe how two quick a descent at the edge of the window will cause the air to catch the wrong side of the canopy and push it towards you. Watch how the upper leading edge is capable of folding down in a way that seals off the vent, making recovery difficult. Look at the leading edge. Is it even? Is it symetrical? Check the tips. Are they inflating to the same shape as the rest of the canopy? Do they drag behind? Observe the trailing edge. What shape is it? How well is it supported? (4-line: is it dragged down when the bottom pressure is meant to be off?) Does any part of the kite osscilate? Look at the bridle points. Compare the stress on the skin at different bridles. Let someone else fly. Take a different viewpoint. What is the shape of the canopy? How much does it curve? Are there kinks in it? What is the angle of attack? Does the angle of attack change towards the tips? Is there a step in the rib shape? Are there creases on the skin? How does the canopy change when you steer? Does the shape change smoothly? Does it seem limited? Is any part poorly supported? Where is the centre of turning? Does any part deflate? How does it recover? How does it respond to excess input? Look at the bridles. Are they all being used? All of the time? When? [thanks to Dan Rubesh for pointing out that sometimes the trailing edge bridle on the outside tip in a tight turn seems to be slack. I still need to think about this one] Look at the leading edge up close (photograph helps). What shape is it? Does it change? What angle does it fly at? How hard does it pull at that angle? How fast does it fly? How quickly does it accellerate? What happens when it luffs? How does it recover? Fly the kite in low wind. How well does it inflate? Run a 360. How slowly can you do it? How hard do you need to pull? Fly into a dive and go towards the kite. Does it glide away from you? Hold the kite in a stall - observe how it steers, which way it wants to re-inflate. Does it want to collapse? There is probably more, but that's enough for now. I've only talked about soft performance kites, but the same applies to any kite. Don't just look. Observe. Andrew -- If you buy rare and expensive kites and hang them on the wall, you won't understand, but if risk hand-painted washi-paper kites in the elements, you might find AoxomoxoA = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =