Outerra forum
User mods, screenshots & videos => Aircraft => Flight Model Development => Topic started by: bomber on May 30, 2015, 03:36:37 pm
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Ok can anyone spot the school boy mistake I made in this code....
All the code does is dampen the roll, the faster the roll the more wind resistance and the more dampening occurs... in theory this should work and does in the present moment section of the flight models, however I've always thought the planes were too sensitive with insufficient dampening.. but just dampening for the sake of dampening isn't my bag and to do so would have meant adding a 'magic number' which I hate to see in flight models. And would basically have meant that my flight model was bogus and wouldn't have stood up to a challenge in this area....
Anyway this week I've been working on the float pontoons for float planes and as such needed water density (big clue this) for drag and such, so I pulled in this code to use and noticed that the air density I'm using is in slugs and not lbs.... only out by a factor of 32.17 which makes a big difference to the present flight models...
expect an update.
<fcs_function name="T4T/moments/Roll_dampening_rotate-lbsft">
<function>
<description>dampening roll</description>
<product>
<!-- Dynamic Pressure -->
<value> 0.5 </value>
<!-- Air Density -->
<property>atmosphere/rho-slugs_ft3</property>
<!-- V2 -->
<pow>
<product>
<!-- Revolutions per Second -->
<quotient>
<property>velocities/p-aero-rad_sec</property>
<value> 6.284 </value>
</quotient>
<!-- Circumference -->
<value> 3.142 </value>
<property>metrics/bw-ft</property>
</product>
<value> 2 </value>
</pow>
<!-- Area -->
<sum>
<property>metrics/Sw-sqft</property>
<property>metrics/Sh-sqft</property>
<property>metrics/Sv-sqft</property>
</sum>
<table>
<independentVar>velocities/p-aero-rad_sec</independentVar>
<tableData>
-0.1 1.28
0.0 0
0.1 -1.28
</tableData>
</table>
<property>metrics/bw-ft</property> <!-- Armature Distance -->
</product>
</function>
</fcs_function>
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I'll have to look in more detail to your code, and I am not familiar with the underlying model and the XML used to code it, but roll, yaw and pitch "stick" forces are all affected by q.
If the question is on how much the flight controls "feel" that dampening, than that's another story, and different simulators use different approaches, specially to overcome the limitations imposed by thekind of hardware we use in our desktop flight simulators.
I always suggest an algorithm based on "q" do determine "stick forces". MSFS has it's own core filter, x-plane gives their users the chance to design their own either through Plane Maker or dataref manipulation, but ortherwise imposes no stick forces, which makes "flying" it's aircraft really weird....
I know that in the gliders I fly IRL I sometimes have to use both hands to counter the aerodynamic forces, or turbulence effects :)
If, OTOH, you're referring to aerodynamic roll damping, like in here (http://www.av8n.com/how/htm/vdamp.html#sec-roll-damping) then that's a different story :)
A source of some interesting MSFS-related documents is here (http://www.aero.sors.fr/fsairfile.html) at Hervé's site. Yves Guillaume's article is a Great read!
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Well, welcome aboard Jcomm. :) I hope you find Outerra has enough potential to hold your interest. With all of your experience, I think you could really help.
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Well, welcome aboard Jcomm. :) I hope you find Outerra has the potential to hold your interest.
Thank you HiFlyer. It certainly has :-) And thas for your frequent updates at AVSIM, helping this great project to become even better known to the simmer community around there !