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jlder
Pulcino
France
34 Posts |
Posted - 08/09/2016 : 18:37:03
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One feature I am missing in LK8000 is help for wave flying.
Wave flying can be complex but I have been given a simple rule which happens to work well most of the time. It consists in flying at a distance from the ridge which is supposed to be 1/10 of the wind velocity. It is of course necessary to correct from the angle of the wind on the ridge. For example, if you have an east-west ridge with 60 kmh of wind coming from nort-east (45°), you should be hunting for positive wave lift ~ 60 / 10 * sinus (45) = 4 km south, parallel of the ridge.
For LK8000 to help, it would be great to display an adjustable distance ring around the glider in order to fly at the expected distance downwind of the ridges which are supposed to generate the wave. Then the fruit on the cake would be to add specific lines for the “good” ridges in the topology file. With the example above, we would select 4km for the distance ring and would fly the glider to have the ring on the ridges which are supposed to generate wave.
Thanks, JL |
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jlder
Pulcino
France
34 Posts |
Posted - 16/09/2016 : 18:22:14
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Maybe this is a crazy request. If so, I would be curious to hear how pilots looking at this forum manage wave flights, in particular when humidity is low and there are no clouds (typical wave conditions with north wind in France). Thanks, JL |
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davesalmon
Pterodattilo
United Kingdom
1620 Posts |
Posted - 16/09/2016 : 19:56:44
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Where I fly in the UK, we often get crazy, mixed up wave, with small areas of lift, rather than classic wave bars. Often no indication at all of lift, till you run into it. So I use the snail trail, and cruise mode (so it does not keep switching to thermal mode). Also I do quite a lot of flying slowly into wind, until the lift drops off, then circling and drifting back, and repeating. I probably do more circling or S turning, than flying S & L. Years ago, I suggested it would be useful to have a mode that integrated lift and sink over an area, so that a pattern could be established, if there was one. Areas of lift and sink would gradually change colour, say getting stronger colour each time you flew over an area of lift or of sink. A 250m grid weould probably be fine enough to work, though 100m would be better, and it would only need to coveer relatively small areas, say 10/20k square. I think our patterns are built up from different hills producing interference patters, adding when in phase, and cancelling out when out of phase. A week or two ago the initial climb was restricted to approx a 2.5k diameter under airspace, then a similar area 7k downwind clear of airspace, followed by another similar area 10k across wind. After the first climb it was just local knowledge and guesswork, but once in the lift, then using the snail trail. So no bars at all, just small areas. |
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jlder
Pulcino
France
34 Posts |
Posted - 16/09/2016 : 21:25:28
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Thanks for the feedback.
Indeed, in your case a generic tool would not help much due to the intermixed nature of the wave.
A few of us have the luxury to fly in the Alps or the Pyrénées and, even if there are unusual and complex wave situations in some areas, there are also many areas where the theory works pretty well and the rule of thumb I exposed above works very well. When wind is strong enough, it allows to fly good straight distances while staying in positive lift. One of the reasons to use help from LK8000 is that the higher you fly, the more difficult it is to estimate your distance to a ridge. This is the reason why I would really enjoy having distance rings around the glider to help me stay in the rather narrow distance range where there is lift.
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davesalmon
Pterodattilo
United Kingdom
1620 Posts |
Posted - 17/09/2016 : 00:12:39
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How about using the track line? When you are in the lift, change heading until your track line (Config p13) is parallel with the hill. |
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steveb
Pulcino
USA
27 Posts |
Posted - 27/09/2016 : 05:12:03
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I like the ring idea. With a label make I made numbered tick marks that match the map scale and stuck them to the side of the Oudie display. This lets me see quickly my distance from ground features or Flarm traffic. Rings would be better. Steve |
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