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Hodge7

Ridge lift in CumulusX

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I have flown quite a few missions using the latest cumulusx which is really great, however I have some questions regarding the ridge lift component. Although the lift high on a mountain slope appears to be a good simulation of reality, I am questioning the reality of ridge lift which remains consistently strong right down deep in a valley with a major mountain immediately upwind. Because the width of the slopes at the bases of mountains are naturally wider that at the top, we have a situation at present where the fastest times are being achieved by speeding from the start line down to near the valley floor at 130kts and then flying along slopes near the valley floor.

Maybe someone with more real life glider experience than myself could comment on the reality of this situation. Also I would appreciate your thoughts Peter. My own expectation on this is that as I fly lower on a mountain (with another mountain upwind), the lift would progressively decrease with altitude.

Hodge

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Hi Hodge,

I'm currently discussing the question of the correct decay with Ian. We made some progress here thereby investigating into scientific literature. The matter is rather complex, as several things have to be combined. Realism suggests you to do finite-element Navier-Stokes. Efficiency excludes this. Plausibility requires that there must be no effects, which are in obvious contradiction to what you would reasonable expect from the landscape. Last, the outcome should also be compatible with real weather settings in FSX which mostly have lower windspeed close to round and such less lift anyway.

I'd like to avoid a snaphsot, requiring more fix later on. It would be an obstacle for all serious competions, if people are urged constantly updating to the lates versions because of performance differences. At the end I would also like to keep the improvements in 3D-analysis of the nearby environment.

Code-wise, the modification will be somewhat more work as Ian anticipated, is it requires more probes as now, which might impact FPS, if not handles carefully.

Due to job issues I expect this not before mid April with a new release 1.7.

A possible workaround for the time being is to set up weather conditions such that wind speed decays sufficiently at valley ground level. I myself also frequently set windspeed uniformly from ground to altitude, which in itself is not realistic, too, and consequently get to much ridge lift at the base of a mountain.

best regards,

Peter

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Thanks Peter, there are obviously quite a few technical issues involved and I for one certainly appreciate your large contribution to the world of virtual soaring realism.

thanks again

Jeff

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