I'm sorry, I sure see good points for both, so: Are you all discussing the same thing?
Arrival altitude may be calculated on the same theory as speed to fly, but it has a completely different meaning to the pilot in flight. Arrival altitude is something used to determine airfields within range (or not) in a final glide approach. Final glide is by definition without circling. If I need to circle to reach it, an airfield is not within range. Then, I'd expect my glide computer to tell me how far I am below glide path, by displaying a corresponding negative arrival altitude. And I sure want the glide bar to be displayed, be it with a negative arrival altitude. So, to mark fields reachable or not, straight glide path calculations, maybe around obstacles, with MC optimized speed to fly and a safety margin is what is needed. This has been working quite well with the old math. Computing the best speed to fly, time and range for tactical reasons is a whole different thing. It needs to calculate drift while circling, of course, and thermal lift to expect. Else, flying MC theory would make no sense, and it sure makes sense. It even makes sense to have output like Ramy outlined, with a bottom line that tells the pilot he' s never going to get there in time, if he needs to circle, or which TP is faster to reach under given wind and MC estimates. The new solver appears to do this better. So, instead of having the user decide which one to use, maybe the discussion should be about which solver to use for what function - task optimizing or finding fields within glide range - as they both appear to have their specific advantages. Viele Grüße, Martin Kopplow --- Am 21.11.2011 um 17:09 schrieb Ramy Yanetz <ryan...@yahoo.com>: > Arrival altitude should NEVER consider circling! I never heard of such > theory. Arrival altitude should only consider polar, degradation, wind and > MC, although it would be fine without considering MC at all. But trying to > guess your climb and your drift while climbing is completely wrong. We are > not trying to predict the future, we are trying to tell the pilot if he can > safely reach an airport or how much he needs to climb. > > Ramy > > On Nov 21, 2011, at 5:43 PM, Tobias Bieniek <tobias.bien...@gmx.de> wrote: > >> John, I think this is inconsistent behaviour... either if you can't >> climb you shouldn't see the pure glide value, or if you have a MC >> above 0 you shouldn't consider the wind effect while circling. Maybe >> for internal calculations we should supply both values and let the >> user decide what he wants to see. >> >> Turbo >> >> >> >> 2011/11/21 John Wharington <jwharing...@gmail.com>: >>> This is not a bug. >>> >>> At MC=0, you cannot climb, so the value reported (-500 feet) indicates >>> you magically need to gain 500 feet in order to glide at MC=0. >>> >>> At MC=0.5, you are telling the computer you can climb, and with that >>> headwind and a slow climb rate (0.5), you need to climb a lot more. >>> In this case, the 500 feet isnt obtained magically, and so the height >>> required takes the downwind drift from circling into account. >>> >>> On Tue, Nov 22, 2011 at 1:34 AM, Ramy Yanetz <ryan...@yahoo.com> wrote: >>>> Arrival altitude was at MC =0 was something like -500 feet (500 feet below >>>> glide) which was correct. However, With MC=0.5 it was -6000 feet!!! This >>>> is obviously a bug since the slight increase in MC will never result in >>>> 5000 feet loss. >>> >>> ------------------------------------------------------------------------------ >>> 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 >>> > > ------------------------------------------------------------------------------ > 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 ------------------------------------------------------------------------------ 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
