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YASim: Difference between revisions
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→New features and bugfixes in version 2017.2
Red Leader (talk | contribs) |
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The following is under development and hopefully finds its way into FG version 2017.2 | The following is under development and hopefully finds its way into FG version 2017.2 | ||
=== XML parser support for metric and imperial units === | === XML parser === | ||
==== support for metric and imperial units ==== | |||
To make life easier for aircraft developers, the parser supports new additional attributes with a unit suffix, e.g. speed-kt for knots and speed-kmh for kilometers per hour. | To make life easier for aircraft developers, the parser supports new additional attributes with a unit suffix, e.g. speed-kt for knots and speed-kmh for kilometers per hour. | ||
* <code><airplane {mass, mass-lbs, mass-kg}="12345" ></code> | * <code><airplane {mass, mass-lbs, mass-kg}="12345" ></code> | ||
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{{Note|Aircraft using this new attributes will not run on older versions of FlightGear, so it is probably wise to publish those only after a reasonable number of users switched version 2017.2 or newer.}} | {{Note|Aircraft using this new attributes will not run on older versions of FlightGear, so it is probably wise to publish those only after a reasonable number of users switched version 2017.2 or newer.}} | ||
==== CG tuning help ==== | |||
{{Note| The feature described in this section is not fully implemented yet, however, it may be of some help already. | |||
It is currently implemented for the yasim CLI tool only. It does not affect the airplane behaviour while running FlightGear. }} | |||
New attributes have been added to <airplane> to assist tuning the center of gravity (CG). | |||
The CG position is often expressed relative to the [https://en.wikipedia.org/wiki/Chord_(aeronautics)#Mean_aerodynamic_chord MAC] of the wing in percent. You can specify a desired range for CG in % relative to MAC, it will show up in the output of the yasim CLI tool (see example below): | |||
* cg-min: default 25% (just a guess, better numbers are welcome) | |||
* cg-max: default 30% (just a guess, better numbers are welcome) | |||
* auto-ballast: not implemented yet | |||
{{Note| By convention 0% is leading edge, 100% is trailing edge, however the absolute values on x-axis are the other way round, e.g. nose is +x, tail is -x }} | |||
{{warning|The MAC calculation currently works only on the <wing> element. Numbers will be wrong, if your model uses a combination of <wing> and <mstab> to build a wing with two or more segments.}} | |||
YASim will print the leading edge coordinates of the MAC (x,y) and its length. | |||
'''Example output''' | |||
<pre> | |||
$ yasim Citation-II-yasim.xml | |||
This aircraft uses yasim version '2017.2' | |||
========================== | |||
= YASim solution results = | |||
========================== | |||
Iterations: 2210 | |||
Drag Coefficient: 12.304669 | |||
Lift Ratio: 85.317558 | |||
Cruise AoA: 4.016746 deg | |||
Tail Incidence: -3.053278 deg | |||
Approach Elevator: -0.377542 | |||
CG: x:-6.543, y:-0.000, z:0.044 | |||
Wing MAC (*1): x:-6.00, y:3.83, length:2.0 | |||
CG-x rel. MAC: 0.272 | |||
CG-x desired: -6.599 < -6.543 < -6.198 | |||
Inertia tensor [kg*m^2], origo at CG: | |||
18009.289, -0.000, 7120.470 | |||
-0.000, 42459.316, 0.000 | |||
7120.470, 0.000, 56980.656 | |||
(*1) MAC calculation works on <wing> only! Numbers will be wrong for segmented wings, e.g. <wing>+<mstab>. | |||
</pre> | |||
=== Export of YASim internals to property tree === | === Export of YASim internals to property tree === | ||