TAS values in Route Plan

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TAS values in Route Plan

Author	Message
Tim Dawson	Tim Dawson posted 1/21/2014 5:13:22 PM Post Details Share Post
Group: Forum Members Posts: 8.1K, Visits: 9.3K	Thanks, you're right, there was a weighting error which would surface on relatively short climbs that would result in the averaged TAS over the climb leg being slightly higher than it should be, due to incorporating part of the cruise leg calculations. This bug has been fixed ready for the next version of SkyDemon.
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lhe	lhe posted 1/19/2014 12:58:15 PM Topic Details Share Topic
Group: Forum Members Posts: 154, Visits: 445	Something seems wrong with the way SkyDemon computes and/or presents TAS values in the Route Plan. I have the following (test) setup: - An aircraft with a climb speed of 78 KIAS, a descent speed of 119 KIAS and a cruise profile with 108 KTAS cruise speed. - A route with three legs, a climb leg (to 2500 ft), an cruise leg and a descent leg. That is, two waypoints, one at TOC and one at TOD. Or rather -- close to TOC and TOD as it is impossible in practise to set the waypoints exactly at TOC and TOD. If the first waypoint is set slightly (a few 100 metres) before TOC and the second waypoint is set slightly (a few 100 metres) after TOD, then TAS values on the Route Plan look right: 80 KTAS for the climb leg, 108 KTAS for the cruise leg and 120 KTAS for the descent leg. (That TAS for the climb and descent legs are slightly higher than the IAS given in the aircraft properties is to be expected as TAS increases with altitude for a given IAS.) BUT -- if I set the first waypoint slightly after the TOC (again we are talking 100s of metres), so that a tiny part of level flight is included, the TAS for the climb leg jumps to 86! Since the entire climb leg is about 5 NM, there is no way that a few 100 metres at cruise speed (108 KTAS) could bring the average for the climb leg up to 86 KTAS. Something must be wrong with the TAS computation. The same phenomenon happens with the descent leg if I move the second waypoint to a position slightly before TOD. (Although less pronounced since the aircraft properties have a lower descent rate than climb rate so the descent leg is longer.) Addendum: I am using Skydemon Plan (PC) version 3.0.3.0. Edited 1/19/2014 6:32:11 PM by lhe
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