Helicopter's flight parameters

[RN Malboeuf 12]

It's possible to adjust plane flight model a bit with aileronSensitivity, elevatorSensitivity etc. I wonder if there's smth in helicopters config ? I found several parameters (they were in ofp too) with uknown meaning

Quote[/b] ] maxMainRotorDive = 0;

maxBackRotorDive = 0;

minMainRotorDive = 0;

minBackRotorDive = 0;

neutralBackRotorDive = 0;

neutralMainRotorDive = 0;

enableSweep = 0;

Any info on it ?

[RN Malboeuf 12]

silence...

ok, I did some research and now i can say that helicopter flight model is mostly defined by mass distribution. Higher mass center results in slower motion.

[ricki 0]

what does higher mass center mean ?

higher by mass value or its geometric position ?

[Guest RKSL-Rock]

what does higher mass center mean ?

higher by mass value or its geometric position ?

geometric position of the CofG.

Although positioning the CofG higher also has the effect increasing the yaq, pitch and roll rates.  But it does make it more stable in yaw.

I'm still experimenting with O2PE mass distribution to get the best handling.  but Ive gotten a fairly acceptable flight envelope on the Merlin now.  But its not as stable as the UH-60.

[RN Malboeuf 12]

Quote[/b] ]I'm still experimenting with O2PE mass distribution to get the best handling. but Ive gotten a fairly acceptable flight envelope on the Merlin now.

What is Merlin ? can you upload your example. What method douse finding best mass center ?

[Synide 0]

What method douse finding best mass center ?

i think there is only one method to find the best 'Center of Gravity' for a model in ArmA and therefore the best flight model for the aircraft and that is to alter the mass distribution by hand of one or more vertices in the Geometry LOD, a little at a time.

[Guest RKSL-Rock]

Quote[/b] ]I'm still experimenting with O2PE mass distribution to get the best handling.  but Ive gotten a fairly acceptable flight envelope on the Merlin now.

What is Merlin ? can you upload your example. What method douse finding best mass center ?

This is aEH101 Merlin

The best method is trial and error I’m afraid and adjust the mass by hand just as Synide says.  It’s taken me a lot of attempts to get it to fly acceptably.

I'm assuming you know how to apply and affect mass etc.  

Each different geo lod model will have different handling derived form its size and distribution of mass on the vertices.

TIPs:

1) Spread the mass out along the spine of the airframe.  This will help pitch rate. closer to the CofG and the helo will pitch faster.

2) the higher the CofG the less lightly the aircraft is to roll when using the rudder.

3) Make sure the mass distribution is symmetrical about the longitudinal axis.  Add more mass on one side will severely affect handling.

4) A Helicopters top speed and acceleration is governed by mass. More mass the faster it goes.

[RN Malboeuf 12]

Glad to see someone is working in the same direction

Quote[/b] ]The best method is trial and error

but you have to trial with some goal

Quote[/b] ]1) Spread the mass out along the spine of the airframe.  This will help pitch rate. closer to the CofG and the helo will pitch faster.

10x i'll try

Quote[/b] ]4) A Helicopters top speed and acceleration is governed by mass.  More mass the faster it goes.

No typo ? _More_ mass - more speed ? And what about speed in the config ? Is there any connection with model GeoLOD's size ?

Idea: What about making animated selection with half of mass in it and then move it along the axises directly in game ? (just don't forget add selection in resolution lod too - otherwise it won't be animated)

[Synide 0]

Idea: What about making animated selection with half of mass in it and then move it along the axises directly in game ? (just don't forget add selection in resolution lod too - otherwise it won't be animated)

...hmmm, that's actually a good idea... have to give that a try...

[RN Malboeuf 12]

Synide

Quote[/b] ]Geo lods are present in these example mlods... but the 'total mass' and 'mass of components' - and therefore the 'center of gravity' is not currently available.

(Or for that matter anything like vertices properties and any 'face' info) - this 'extra' info is being looked at, but not as much anymore 'cause it's better to play with the 'tools' and create stuff...

Maybe you will find some time to get rid of this ? GeoLOD's from standart models is smth we really missing...

[Guest RKSL-Rock]

No typo ? _More_ mass - more speed ? And what about speed in the config ? Is there any connection with model GeoLOD's size ?

1) No thats not a typo.  The larger the mass value the faster it accelerates and the higher the top speed.

2) The speed value in the config is just for the AI.  Purely a programmed max limit.

3) The geo lods size is only relevant in the handling not speed.  The further away from the cofg the slower it will roll, pitch and yaw.

Idea: What about making animated selection with half of mass in it and then move it along the axises directly in game ? (just don't forget add selection in resolution lod too - otherwise it won't be animated)

Well it’s not really going to make much difference. Yes you can affect the handling but the time that you need the handing is at low speed.  If you were to slide the mass closer to the centre of gravity it would become twitchier and more agile.  Making rudder turns easier but its at low speed when you need the stability.  It’s much better to set the mass up properly in the first place.  ArmA’s physics engine isn’t advanced enough to factor in all the real world concerns of mass vs lift etc.

[RN Malboeuf 12]

1) No thats not a typo.  The larger the mass value the faster it accelerates and the higher the top speed.

Sounds wierd but it's true... just tried. light heli's have to be heavy

[DBO_ 0]

yup , first noticed when i unbinned a heli p3d and mass was all messed to 0. it wouldnt even take off because mass is he way to the engines heart.

On this subject is there link between cofg and the pivot point , i know it sounds obvious but the default class really feel like a puppet on a string and it all seems to be centerd about 1-2 meters above the rotars is there a named selection for this and can we mess with it (assuming it aint the cofg because thats not 1-2 meters above the rotars)?

[Guest RKSL-Rock]

yup , first noticed when i unbinned a heli p3d and mass was all messed to 0. it wouldnt even take off because mass is he way to the engines heart.

On this subject is there link between cofg and the pivot point , i know it sounds obvious but the default class really feel like a puppet on a string and it all seems to be centerd about 1-2 meters above the rotars is there a named selection for this and can we mess with it (assuming it aint the cofg because thats not 1-2 meters above the rotars)?

Ever since 1.08 the CofG is the pivot point.  you may be thinking about the camera pivot

[DBO_ 0]

Quote[/b] ]you may be thinking about the camera pivot

thats indeed what i was thinking of, i havent seen any change in 1.08 though regaurds the pivotal axis point and its relative 1-2 meters above the rotars . is this point defineable in the model memmory ?

[RN Malboeuf 12]

Quote[/b] ]you may be thinking about the camera pivot

thats indeed what i was thinking of, i havent seen any change in 1.08 though regaurds the pivotal axis point and its relative 1-2 meters above the rotars . is this point defineable in the model memmory ?

camera point is not inherited with the model. It's defined via config entry - extCameraPosition

[DBO_ 0]

thanks all ,i will check both cofg and extcam see if i can find a nice medium extCameraPosition.

[flaber 0]

Hello, i have been making tests with mass to avoid that the helicopter make a loop in only 5 meters, and I think y have found a solution, not an ideal solution, but the flight looks more real, and more similar to blackhawk's .

At first I've try to put a lot of weight in the main rotor, so the gravity center goes up. but wasn't enought, no matter the weight i put in the main rotor, the helicopter still making fast loops.

THe solution comes adding mass to the blades of the main rotor, if the helicopter have a total mass of 3250kg, the blades are about 400kg of all the mass. more mass to the blades, harder to make fast loops.

ok, my english is not so good, an example: (helicopter total mass 3250kg).

blades total mass: 50kg -> seems like flying an rc helicopter, very fast movements..

blades total mass: 250kg -> like if you flying a littlebird.

blades total mass: 450kg -> like flying a blackhawk.

blades total mass: 1000kg -> like flying an elephant, very slow movements.

here is a video flying the ab-212 we are making in ffaa mod.

hope this helps you make nice helicopters.

Flaber.

www.ffaa.es

[Guest RKSL-Rock]

The problem with adding mass to the blades is that above a certain speed the helicopter starts to oscilate and shake. You can see this in the RKSL Lynx Demo video at the end of the film.

I suspect that since your total mass is only 3250kg you dont have very high speeds. Mostly likely around 130kph max at a guess you'll need to add more mass to make it reach the 212's max speed is 240.5kph And when you do I suspec tyou'll see alot of handling problems.

[ArMoGaDoN 0]

"envelope"

All I can find information about this is that it's a float array, which is pretty obvious.

Does documentation exist ANYWHERE that details the finer points of all this stuff?  The Wiki just says 'float array', so where can I/we find information regarding what all these things mean?

Searched wiki, searched here, no joy.

I have always tried to struggle on by testing and trial/error, however on things like this I find the lack of proper documentation much more than simply annoying - something I should be able to do with at least some idea of where the values I want to change are to be found - would instead take many many hours of farting around test/re-test/unload/reload ArmA with new PBO etc. just to discover what values do what thing - No way that amount of effort or time is being spent!!!

@BIS : Where is the documentation about this array and other flight-tuning parameters that lurk in the config.cpp?

Why is this information so difficult/impossible to find??

Does it even exist???

edit: if the  "envelope" is meaning rotor-lift or similar, then I would ASSUME this to be amount of lift at points along the percentage of the vehicles speed axis?  What speed parameter is this measured against?  I read above that topspeed limit is just for AI, so what scale does this envelope measure against?  Does it even do that?  Are we just supposed to be psychic here? p.s. it does seem to measure against the maxSpeed value by the way..!

Help???

[flaber 0]

The speed i have reached is 165 (and no vibrations).

[Guest RKSL-Rock]

The speed i have reached is 165 (and no vibrations).

Thats pretty slow for a Bell 212.  Even the BIS littlebird manages 200+ Kph.

WarWolf @ Sep. 19 2007,11:39)]"envelope"

All I can find information about this is that it's a float array, which is pretty obvious.

Does documentation exist ANYWHERE that details the finer points of all this stuff?  The Wiki just says 'float array', so where can I/we find information regarding what all these things mean?

Searched wiki, searched here, no joy.

I have always tried to struggle on by testing and trial/error, however on things like this I find the lack of proper documentation much more than simply annoying - something I should be able to do with at least some idea of where the values I want to change are to be found - would instead take many many hours of farting around test/re-test/unload/reload ArmA with new PBO etc. just to discover what values do what thing - No way that amount of effort or time is being spent!!!

@BIS : Where is the documentation about this array and other flight-tuning parameters that lurk in the config.cpp?

Why is this information so difficult/impossible to find??

Does it even exist???

edit: if the  "envelope" is meaning rotor-lift or similar, then I would ASSUME this to be amount of lift at points along the percentage of the vehicles speed axis?  What speed parameter is this measured against?  I read above that topspeed limit is just for AI, so what scale does this envelope measure against?  Does it even do that?  Are we just supposed to be psychic here?  p.s. it does seem to measure against the maxSpeed value by the way..!

Help???

The envelope command controls the lift vs speed allowing you to define stall speed etc.

Another direct quote from a recent PM chat with Suma:

Quote[/b] ]The speeds are determined by the envelope array and maxSpeed. The entries stallSpeed and landingSpeed are then used to indicate the speeds for AI and autopilot, so that it knows how to fly the airplane.

The envelope is defined like this:

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Code Sample </td></tr><tr><td id="CODE">    /// 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 1.2 1.3 1.4  // rel. speed

     0.0,0.2,0.9,2.1,2.5,3.3,3.5,3.2,2.5,2.0,1.5,1.0,0.9,0.7,0.5 // lift

   };

[flaber 0]

Hi again, I have made a test, i have set up the mass of the helicopter to 25000 kg, (to much I know), and top speed has about 330km/h and no vibrations.

The only thing i have seen, is that when you go to fast to the ground, or turn in a very high angle, the chopper needs more time to recover... have a lot of inertia. (like the cobra)

[Guest RKSL-Rock]

Hi again, I have made a test, i have set up the mass of the helicopter to 25000 kg, (to much I know), and top speed has about 330km/h and no vibrations.

The only thing i have seen, is that when you go to fast to the ground, or turn in a very high angle, the chopper needs more time to recover... have a lot of inertia. (like the cobra)

The total mass really only affects top speed and the sink rate as you say just like the cobra. The AI will fly it the same either way.

You are lucky that you don’t get the wobble then. Every helicopter where I’ve had mass on the blade tips wobbles at higher speeds. No I only add a few kgs to the tips and it works fine for me. Maybe it’s because you only have two blades?

[flaber 0]

I will post a picture, but i remember have this vibrations, but the were produced by the lack of weight in the nose of the chopper.

if you put to much weight in the rotor zone (motor, blades....) and not in the nose, then, when you run so fast, seems that the nose has no strength to face the friction with the air, and start, how you say, wobbles ? and the only thing that prevents the helicopter to make a 180º turn, is the tail.

about having two blades.. well, in the geometry lod, is only a cilinder, no really blades... (look the picture)

I have to try the envelop...