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2016-04-24, 12:56 | #11 | ||
PR:BF2 Developer
Join Date: Jul 2011
Posts: 1,966
Belarus
Location: Minsk
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Re: Chopper flight models
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assetruler69: I've seen things you smurfs wouldn't believe. Apaches on the Kashan. I watched burned down tank hulls after the launch of the single TOW. All those moments will be lost in time, like tears in rain. Time to give up and respawn.
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2016-04-24, 15:45 | #12 |
Join Date: Jun 2009
Posts: 49
Finland
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Re: Chopper flight models
Here's my findings so far, I wrote them down in a document so it doesn't get lost.
Code:
========================================================================= ================== helicopter body properties: ========================== ========================================================================= eg. the root object of the chopper ======== physics: ======== gravityMultiplier: how strongly gravity affects the chopper. Should be 1.0 for realistic behaviour. Drag: air resistance multiplier DragModifier: per-axis multipliers for drag. For rotation only or what though?? Mass: slows down acceleration, doesn't affect speeds or whether or not the chopper can lift off. InertialModifier: moment of inertia of object. Basically adds mass to rotation only. Should be bigger for large choppers. ======================= PlayerControllerObject: ======================= controls camera and seat positions etc. as well as some input stuff RegulateVerticalPos: These seem to be multipliers for some autopilot PID controller that maintains level altitude. The two values control how strong the autopilot behaviour is I guess. Setting these to 0 will disable the behaviour. MaxVertRegAngle: ????? doesn't seem to affect much? NoVertRegAngle: the chopper tilt angle at which the altitude hold autopilot stops working. If neutral thrust is not close to hovering, will drop off sharply. Keep this angle small (10 degrees or so) and make sure neutral thrust is slightly below a hover. This way chopper can hover, and won't lift off the airfield or flip around on its own if pilot goes AFK. ========================================================================= ================== rotor engine properties: ============================= ========================================================================= the main rotor engine at least for british apache is kind of hidden in the editor. It's hierarchy path is gb_ahe_apahce->gb_ahe_apache_Rotorhead1->gb_ahe_apache_Rotorhead2-> gb_ahe_apache_rotor. Note the misleading name. Tail rotor engine is gb_ahe_apache-> gb_ahe_apahce-tailEngine, which is a lot less obscure. ======== physics: ======== torque: how much overall thrust can be had from rotor. Affects chopper tilt rates as well as far as I can tell. max angle of attack: upper limit of rotor blade angle default angle of attack: 'neutral' angle of rotor blades. range of movement is default +- difference to max from default, so minimum = default - (max - default) large negative minimum AoA should be avoided, otherwise barrel rolls and other weird behaviour becomes easier. torque and angle of attack of blades determine total lift from rotor. HorizontalSpeedMagnifier: magic value that converts upwards thrust into horizontal acceleration. Values other than 1 are nonphysical and should be avoided, otherwise behaviour (ratio of climb rate versus horizontal movement) will feel wrong. NoEffectAtPerpSpeed: percentage value that determines the percentage of maximum lift when moving at horizontal max speed. Used to decrease tail rotor effectiveness at higher speeds. ========= rotation: ========= max speed of rotation determines how long it will take for the rotor blades to reach maximum spin velocity. Rotor lift scales as a percentage value of max RPM - with lower RPM values, produced lift will be lower as well. Increasing max RPM won't increase lift directly however - only the speed relative to the maximum matters for lift generation. I still haven't been able to increase the max speed of the chopper though. Even after setting drag to 0 for all components, there's still something that causes drag. I did manage to make it go faster by increasing the gravityMultiplier as well as the torque, but it's not really that great either. It makes the chopper fall down too fast, and works a bit similiarly to the horizontalSpeedMultiplier. Here's some shitty keyboard and mouse aerobatics to show you how the apache works currently: https://dl.dropbox.com/s/57hw3k0fjko....28.38.09.webm |
2016-04-24, 15:50 | #13 |
PR:BF2 Lead Developer
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Re: Chopper flight models
Did you try out the modifying the differential already? On land vehicles torque+differential define speed.
Edit: And mass also has other physics influences e.g. what happens when you ram another vehicle. |
Mineral: TIL that Wire-guided missiles actually use wire
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2016-04-24, 15:56 | #14 | |
Join Date: Jun 2009
Posts: 49
Finland
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Re: Chopper flight models
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And yes I could guess that about the mass already. I have no idea what range it should be in though so I didn't include it there. | |
2016-04-24, 16:34 | #15 |
PR:BF2 Lead Developer
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Re: Chopper flight models
Then the other things that might influence speed are the rotorHeads. The rotation of the rotor heads controls how far the engine is in front of the chopper. Like this:
Maybe if engine is further away it increases speed? |
Mineral: TIL that Wire-guided missiles actually use wire
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2016-04-24, 17:02 | #16 | |
Join Date: Jun 2009
Posts: 49
Finland
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Re: Chopper flight models
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2016-04-24, 18:14 | #17 |
PR:BF2 Lead Developer
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Re: Chopper flight models
Thats how bf2 does it and we took over this system. Maybe there is a better one. No idea what is going to happen if you actually rotate the engine, right now it stays at same angle all the time. E.g. on apache it is at -86deg angle.
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Mineral: TIL that Wire-guided missiles actually use wire
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2016-04-25, 22:51 | #18 |
Join Date: Jun 2009
Posts: 49
Finland
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Re: Chopper flight models
It looks like the position of the engine relative to rotorhead1 controls how big is the torque imparted by steering movements of the rotor. So moving rotorhead1 away from chopper body while keeping the engine at the chopper center of mass makes the chopper quicker to turn. I guess that makes some sense at least.
Other than that, it seems the position of the engine doesn't have much to do with speed. Obviously it has to stay at (or very close to) the center of mass, otherwise the chopper will just fly out of control since the thrust is going to be imbalanced. The angle of the engine determines the angle of thrust imparted by the rotor, and that can't be adjusted too much either without causing issues (to make chopper hover you have to cancel out the angle of the rotor.) I'm not sure why the rotorhead2 even exists though, maybe it has some function as well. |
2016-04-26, 00:16 | #19 |
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Re: Chopper flight models
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2016-04-26, 09:33 | #20 |
PR:BF2 Lead Developer
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Re: Chopper flight models
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Mineral: TIL that Wire-guided missiles actually use wire
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Tags |
chopper, flight, models |
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