Fixed Wing Flight Model (dev branch)

[maddogx 13]

> thread's over

Why? Nobody wants to help to improve airplanes?

I'm going to guess that when you said "we do not plan to do any major re-examination of our airplanes", you weren't ruling out tweaks to the current flight model to improve it. :)

In other words, a whole new plane flight model (DLC or otherwise) is off the table for now, but some suggested changes to the current one could be implemented?

If so, at least some basic changes like this one should be considered.

[dr. hladik 231]

> but some suggested changes to the current one could be implemented?

Yes, exactly. That is what I said - "All I can help you with now is configuration of your airplanes, extend some paramaters or to extend forces diag_mode (if it is even enabled now)."

> If so, at least some basic changes like this one should be considered.

Unfortunately that math is not complex enough.

Edited September 25, 2014 by Dr. Hladik

[aggressorblue 2]

FWIW, I can see where BI is coming from with not wanting to deal with Fixed wing lib. And making that any fun in the title would require way more work than a DLC package.

This engine isn't great for modern combat fixed wing flight, which require comparatively vast visual draw distances or else your cheated out of being able to see what's around you. It would also destroy anything but top tier hardware to render this environment in real time at the speeds modern jets cruise at.

In addition, you'd need much larger maps (and Altis is already huge by open world FPS standards), as lighting the afterburner would let you dart from one side of the map to the other in seconds.

Arma instead trades raw draw distance for near-field detail (and does so very, very well IMO). Helo combat works here, because Helis in a combat role are in closer with the troops, fly slower, and often work with the environment to mask their movements.

You could perhaps focus a DLC level package on planes like the AT-6B, er sorry, I meant to say [insert ridiculously over designed stealth-turbo-stealth-prop-stealth-GIJOE-stealth-plane here], which would slow the action down a bit and be a bit more in-line with the environment, but at that point why not jump in a helo?

[five_seven5-7 56]

Rudder - not everyone agrees.

> thread's over

Why? Nobody wants to help to improve airplanes?

[five_seven5-7 56]

So, hot it works

(Simplified version, do not crucify if i missed some parameter. Also I'm a programmer and I don't do configs)

All the forces are computed in model space (so they do rotate with airplane)

Lift

- force size is affected by flaps

- force size is affected by altitude

- force size is affected by groundEff

- force size is affected by envelope array (speed dependent)

- force size is affected angleOfIndicence

Thrust

- force size is affected by thrustCoef array (speed dependent)

- force size is affected by altitude

- force size is affected by rpm/thrust

- direction is forward (forward or up for vtol)

Ailerons

- torque size is affected by aileronSensitivity parameter

- torque size is affected by aileronCoef array (speed dependent)

- adds torque (roll)

Elevator

- torque size is affected by elevatorSensitivity parameter

- torque size is affected by elevatorCoef array (speed dependent)

- adds torque (pitch)

Rudder

- torque size is affected by elevatorSensitivity parameter

- torque size is affected by rudderCoef array (speed dependent)

- adds torque (yaw)

Draconic forces (there are forces keeping plane aligned with its speed direction)

- force size is affected by speed

- force size is affected by airplane speed and direction deviation

- force size is affected by draconicForceXCoef, draconicForceYCoef, draconicForceZCoef parameters

- adds forces keeping plane aligned with its speed direction

Draconic torque

- torque size is affected by speed

- torque size is affected by airplane speed and direction deviation

- torque size is affected by draconicForceYCoef, draconicTorqueYCoef parameters

- adds torque that will align plane so that it flies forward

Friction & Gravity

- also there (gravity in world space)

Why tilted airplane does not turn?

By default our airplanes don't clim up - our lift force is not very strong by default.

If you tilt your airplane, lift force is also tilted also so you should start turning, descending and in some cases, your nose should go up/down.

However, if draconic forces are strong enough, they will do the exact opposite and stabilize your airplane.

I'm not and aircraft engineer, so if we are missing some force or some speed based curve, please tell me, I will add it.

If you find better configuration for airplanes, please tell me.

Is possible to give us the complete complex version of the parameters, i´ve searched on the wiki but few parametres apared. Also if possible the 3 planes data (weight; Thrust;etc)

I have no programming expertise in ArmA or in any other. I`m just a player enjoying the ArmA.

[dr. hladik 231]

Is possible to give us the complete complex version of the parameters, i´ve searched on the wiki but few parametres apared. Also if possible the 3 planes data (weight; Thrust;etc)

I have no programming expertise in ArmA or in any other. I`m just a player enjoying the ArmA.

default values:

//max rudder effect, value is (speed.Z() / sqrt(speed.Z()^2 + speed.X()^2)), default is cos 5 deg

rudderInfluence = 0.9619469809;

/// angle of incidence - difference between forward and airfold chord line - def. val is 3*H_PI/180;

angleOfIndicence = 0.05235987;

/// lift (G) based on speed

envelope[]=

{

// speed relative to max. speed -> lift

// 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 // rel. to maxSpeed

0.0,0.2,0.9,2.1,2.5,3.3,3.5,3.2,2.5,2.0,1.5,1.0 // lift

};

/// forces keeping plane aligned with its speed direction

draconicForceXCoef = 7.5;

draconicForceYCoef = 1.0;

draconicForceZCoef = 1.0;

draconicTorqueXCoef = 0.15;

draconicTorqueYCoef = 1.0;

/// rudder, elevator, aileron, thrust effectiveness; if empty old settings is used

// effectiveness according to current speed and maxSpeed ratio

// last value goes for 150% of max speed

thrustCoef[]= {};

elevatorCoef[]= {}; //default value is 1

aileronCoef[]= {}; //default value is 1

rudderCoef[]= {}; //default value is fabs(speed.Z())*InvSqrt(Square(speed.X())+Square(speed.Z()));

//! coefficient of player's controller sensitivity (does not affect AI)

elevatorControlsSensitivityCoef = 4;

aileronControlsSensitivityCoef = 4;

rudderControlsSensitivityCoef = 4;

// relative aileron sensitivity

aileronSensitivity = 1;

// relative elevator sensitivity

elevatorSensitivity = 1;

[five_seven5-7 56]

From what i`ve understand so far:

Lift its based only from speed, was neglected the air density (altitute); wing area; lift coefficient of the airfoil (NACA 6716 in A-10 case) at desire angle of incidence.

angle of incidence its constant

thrust effectiveness; if empty old settings is used -> this parameter its the T/W (thrust to weight ratio)?

[x3kj 1247]

Why tilted airplane does not turn?

By default our airplanes don't clim up - our lift force is not very strong by default.

If you tilt your airplane, lift force is also tilted also so you should start turning, descending and in some cases, your nose should go up/down.

However, if draconic forces are strong enough, they will do the exact opposite and stabilize your airplane.

I'm not and aircraft engineer, so if we are missing some force or some speed based curve, please tell me, I will add it.

If you find better configuration for airplanes, please tell me.

I don't know why it doesn't turn. But it's annoying. And there is not even a single degree course change if you slightly roll to the side. Maybe it's just a config problem? Everything has to be compensated with rudder usage plus erratic rolling and elevating. Maybe this is not such a huge problem when flying with topdolla flight equipment. But for Keyboard+Mouse it makes it very hard to make precise ground attacks, as at least one of the 3 controll motions is digital (by default rudder), so one controll is always jerky and produces "wobbling" if you try to correct your course slightly. I don't remember Arma 2 having this behaviour (or maybe i just pushed it out my mind?).

http://www.grc.nasa.gov/WWW/k-12/airplane/turns.html

Edited September 27, 2014 by Fennek

[oukej 2910]

I don't remember Arma 2 having this behaviour (or maybe i just pushed it out my mind?).

Ref. http://feedback.arma3.com/view.php?id=14899

In Arma 2 it was achieved by the "auto-rudder" that would "assist" the turn as you rolled the airplane. This wasn't a correct approach, so Dr.Hladik removed it.

If you take a look at the A-164 Wipeout, you'll notice, that unlike the other two airplanes there is a slight tendency to turn under a roll angle. (It's not exactly how an A10 wing and fuselage shape would behave, but there's a glimpse of the correct behavior ;)).

We welcome you to tweak the parameters in airplane's configuration (mentioned here). Let us please know what were you able to achieve or if you bumped into a limitation somewhere. Thanks a lot!

[blackpixxel 53]

A simple and dirty solution would be to bring the autorudder effect back, but without a visual movement of the rudder.

[roshnak 41]

A simple and dirty solution would be to bring the autorudder effect back, but without a visual movement of the rudder.

That does not sound like the correct approach to this sort of thing.

[CaptainObvious 95]

A simple and dirty solution would be to bring the autorudder effect back, but without a visual movement of the rudder.

That does not sound like the correct approach to this sort of thing.

Yep, even if the auto-rudder is kind of 'cheating', the outcome of it is much better than what we currently have.

Fixed wing flight model overall isn't a simulation of the real thing so I don't see any reason to not artificially make the planes behave correctly.

[x3kj 1247]

That does not sound like the correct approach to this sort of thing.

to hell with correctness, if it's optional and the configs are not proper anyway (i assume?), what other option do you have in mind to fix this debacle? Because apparently BIS doesnt want to test and change the configs until they behave like real planes themself...

[CaptainAzimuth 714]

To hell with incorrectness, as it stands, dirty cheats, and workarounds have a major presence as of right now, and that needs to end if BI are to ever excel in making a better product. Yeah sure, it's made them money, but there comes a time, when those work a rounds, and those bridges patched up with bubble-gum will come crashing down in the future. Ponds don't exist. The clouds were downgraded. The view distance in multiplayer is hard coded to a few thousand meters, and flight physics are done by scripting in aircraft movements not done by the player to make it seem as if the plane is doing what it's supposed to do. This is really, really dirty. Having the rudders move, and than you apply rudder on top of that, will basically have no effect, due to the plane already applying rudder. Your just adding the final bit of rubber movement left. It's a bad solution. I'm sure there are ways it can be done, like many things, the RV4 engine is probably capable of it. It just needs time and focus. Maybe when BI has the time though, as i'm going to guess, they're super busy with Multiplayer improvements, and they have a month (roughly) till Helicopters DLC is out.

[x3kj 1247]

dirty cheats, and workarounds have a major presence as of right now, and that needs to end if BI are to ever excel in making a better product

they said it several times, its a game not a sim. What's so bad to have the option to turn it on or off, what's the problem?

Having the rudders move, and than you apply rudder on top of that, will basically have no effect, due to the plane already applying rudder.

And why do you think that is a problem ? It's not worse then before, but for keyboard users certainly better if the option is turned on.

I'm not and aircraft engineer, so if we are missing some force or some speed based curve, please tell me, I will add it.

Not related to turning, but wind... At least a basic force in the direction of wind. 3 config values: frontal cross section, side crossection, top crossection. And with the respective angles to front/side/top you can create the forces that wind has. Currently you can fly at windspeeds of 100kph... no problemo.

Edited September 29, 2014 by Fennek

[EricJ 724]

As long as they fix the poor turn rate of the Wipeout I'd be happy as a gripe larger wing aircraft (like it's progenitor, the A-10) can out turn many other high performance aircraft due to lower speed and larger wing area. It's odd that the Buzzard and the Neophron have really good turn rates while the Wipeout doesn't, so that's one thing to think on devs...

[CaptainAzimuth 714]

they said it several times, its a game not a sim. What's so bad to have the option to turn it on or off ?

Not related to turning, but wind... At least a basic force in the direction of wind. 3 config values: frontal cross section, side crossection, top crossection. And with the respective angles to front/side/top you can create the forces that wind has.

It's not a sim, but it's close enough, and with them adding in more aspects of sim so often, it makes it all the better. So leaving out a fixed wing improvement that could even remotely add a little bit of flavor in a simple way without using an Auto Rudder version of it is heavily welcomed. Maybe if they take a look at similar engines that pull off such a thing. You never know. But a proper fix doesn't make a game a simulator. It makes a game a better game.

[x3kj 1247]

I prefer a stop gap solution to no solution at all.

[John Spartan 89]

I would like to add regarding the atorudder dispute - it's worth keeping it as an optional thing via unit cfgvehicles config [autorudder = true/false;] many todays airframes, especially modern fighter jets have sophisticated fly by wire systems, that heavily monitor and if setup adjust pilots input. So for this reason alone I would like to see such feature optional.

As for other parts of flight model, then to me ARMA is a combined arms game with a high level of authenticity, if I want simulation there are other platforms [but with no combined arms aspect]. I would be more happy to see fixed wing simulation to be complimented with additional features, rather then just a flight model, it's more or less ok for game as ARMA, but collision for instance or targeting could use some polish.

FEEDBACK:

Flight model params:

draconicForceXCoef = 8.5;

draconicForceYCoef = 2.0;

draconicForceZCoef = 1.0;

draconicTorqueXCoef = 0.15;

draconicTorqueYCoef = 1.0;

these new values seems to be doing what they are meant to, regardless of airplane/airplaneX simulation. Maybe a better documentation with some vsual images on BI WIKI could help people to understand and use it in the mods.

flapsFrictionCoef = 0.4;

Can we have some detailed intel on how this value is tied down to speed, and stall speed. To me it still behaves a bit awkward, maybe just my messed up config.

In general with the set of confing entries we have we can recreate an authentic behaviour, problem is lack of knowledge that turns people away. I ended up spending few month's on basic flight model setup's and still I am not happy with result. Documentation please.

Collision PhysX:

with airplaneX class landing on another object is impossible [boooom]. Airplane simulation still allows this. PhysiX support for helicopter simulation is way advanced. See Gnat's landing ship. A movable ship, helo lands while ship in motion, no explosion. Player can disembark [via scripted solution but that's fine] and helicopter will still remain "attached" to the deck of moving ship - bravo. Same deal with few vehicles - it works. Can the same be done for fixed wing simulation? That would mean a movable carrier in ARMA [even without an infantry being able to move around deck while in motion, I would consider that as a major achievement]

Miscellaneous

All carX simulation class vehicles have newly added brake/throttle animation sources. Used for crew anims [like accelerator pedal and brake pedal]. Heli simulation has it, can it be added to fixed wing? Reason - possibility to acquire players input with out scripted workarounds when thrust/brake engaged to simulate more authentic afterburner effects if needed. That would allow a dynamic intensity to be added to afterburners.

Edited September 30, 2014 by John_Spartan
my sh.... grammar

[five_seven5-7 56]

FEEDBACK:

these new values seems to be doing what they are meant to, regardless of airplane/airplaneX simulation. Maybe a better documentation with some vsual images on BI WIKI could help people to understand and use it in the mods.

Can we have some detailed intel on how this value is tied down to speed, and stall speed. To me it still behaves a bit awkward, maybe just my messed up config.

I did not understand the concept behind the draconic, is this resultant forces in a airplane?

Resultant forces

I didnt make any conclusion about the stall speed, sometimes in takeoff with no flaps it flew. In others planes continued on ground at high speeds. maybe stall speed only related to the resultant forces and no also related to flow separation at X AoA. I did get the A-10 flying at low speed almost at 90º AoA without stalling.

All three models have a fowler flaps ( and one model a slat).

My idea was to divide the:

/// lift (G) based on speed

envelope[]=

{

// speed relative to max. speed -> lift

// 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 // rel. to maxSpeed

0.0,0.2,0.9,2.1,2.5,3.3,3.5,3.2,2.5,2.0,1.5,1.0 // lift

};

Into three parameters (no flaps (crusing); 1 flap down (take-off/Bombing); 2 flaps down (landing)) with unique speed limits and diferents lifts.

The thrust also need a afterburner stage IMO the accelaration it is not so accentuated.

[the_demongod 31]

I don't even want to talk about stalling right now - it's so nonexistent that I don't think it's worth worrying about, it's going to be a while until we see that drastic a change to the fixed wing flight model. The aircraft don't stall. They only stall when you are going slowly. You can't actually stall (lose effective list) while going at high speed (which you should be able to). It's not even remotely simulated.

[x3kj 1247]

Changed: Adjusted how rudderCoef is applied.

fixed wing model i assume? can we get any more info on this (before/after)?

[oukej 2910]

Changed: Adjusted how rudderCoef is applied.

fixed wing model i assume? can we get any more info on this (before/after)?

Currently nothing you'd be able to see in the game, but rudderCoef now allows for more freedom in rudder configuration.

[x3kj 1247]

but rudderCoef now allows for more freedom in rudder configuration.

and how? (thinking of modding)

I tested my own plane a bit and played with the lift envelope, at slow speeds really low, at middle speeds really high and at high speed very low again.

With high lift, my aircraft goes nose up and with low lift nose goes down.

Where is this force applied/determined in regards to the model position? I have the center of weight (geometry LOD) of my plane at the origin of the model itself.

Wouldn't an ideally balanced plane stay level no matter how much lift you have? Can the balance even be influenced by model settings or is this some hardcoded stuff?

With with the high lift i turn automatically, but only because the nose goes up. So its not any different then turning in and pulling up manually. I don't think its a lack of lift on vanilla airplanes. It's something else that must be missing.

Also, there is an error with the model.cfg rotor source - if you use the speed brake, the rotors start to turn in opposite direction. I dont think that would work for real jets and or prop planes... There are ways to turn the thrust in opposite direction, but it's not achieved by stopping the turbine and turn it in the opposite direction. Haven't checked if it's used on boats. So maybe instead of changing it, an additional animationsource could be implemented? Maybe call it planerotor that only turns in one direction (slowest rotationspeed at maximum brake "thrust" but no stillstand and highest rotation speed at max thrust)

Edited October 6, 2014 by Fennek

[five_seven5-7 56]

Also, there is an error with the model.cfg rotor source - if you use the speed brake, the rotors start to turn in opposite direction. I dont think that would work for real jets and or prop planes... There are ways to turn the thrust in opposite direction, but it's not achieved by stopping the turbine and turn it in the opposite direction. Haven't checked if it's used on boats. So maybe instead of changing it, an additional animationsource could be implemented? Maybe call it planerotor that only turns in one direction (slowest rotationspeed at maximum brake "thrust" but no stillstand and highest rotation speed at max thrust)

If what you say its right. The air brakes in a plane only increase the drag in the plane (cars are using the same principle in braking), nothing to do with the thrust. Then air brake and other functions should be separate in different keys:

Q - Acceleration

Z - Reduce thrust, in ground should be reverse thrust

Shift - Afterburners

B - Air brakes