On Tuesday, November 22, 2011, David Reitter wrote: > On Nov 22, 2011, at 4:06 PM, Andreas Pfaller wrote: > > On Tuesday, November 22, 2011, David Reitter wrote: > >> It seems that users find the need to play "what if", and they > >> manipulate MC to do so (and for other wrong reasons, as you point > >> out). So there's a need to let them do that, is there not? > > > > The can play with the MC setting however they like for "what if" > > scenarios. I probably even makes sense. xcsoar will happily calculate > > an answer to that "what if" scenarios. Depending on the input the > > answers may be extreme or indicated as not achieveable, i.e. with low > > MC value and high headwind, where older devices might give a nice > > looking number suiting the user which is wrong. > > If not achievable, why not show a message the moment MC is changed? > "<WAYPOINT-NAME> needs MC>X due wind drift" (if the waypoint is not > achievable at current MC settings due to wind drift). I have assumed that this condition is fairly obvious, at least if you are the one changing the MC value. If something is not achievable the glide bar disappears and the relevant infoboxes show "---". And while achievable/not achievable is a black/white condition the corner cases where someting is theoretically achievable or pratically achievable are difficult to decide automatically. Theoretically it might be possible to thermal for a couple of hours to gain the required height, in practice it is probably not.
> Besides I was referring to a "what if I flew speed Vx" scenario. > Concretely, I would want to know the range of speeds that would allow me > to get to my destination above minimum safe arrival altitude. There may > be various reasons why people would want to fly faster or slower without > circling, i.e., while still assuming MC=0. If you are in a final glide condition (i.e. have sufficient height to not need thermalling) xcsoar can calculate the speed to fly automatically. It will switch to "Final Glide Mode". Set "Auto MC Mode" to either "Both" or "Final Glide" mode. This mode will constantly adjust your MC and the "Speed to Fly" infobox values so that you reach your target at the safety height. Personally I think coupling this to the MC setting is problematic since it again uses MC for something where it should not be used leading to confusion of users. If you read some of Max mails in this discussion you will see he thinks the same, others disagree. But it is currently implemented like that due to historic reasons. You can also adjust the MC manually while in "Final Glide Mode" and xcsoar will show the results, possibly dropping out of final glide mode temporarily while your manual MC setting does not allow to reach your target. But I never use this auto adjustment mode so I am no expert in it. Andreas ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Xcsoar-user mailing list Xcsoar-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xcsoar-user
