Dassault Mirage 2000 weird behavior

[tiopilotos 2,519]

Hi guys. I realized that some Mirages 2000 (Mirage 2000C, Mirage 2000C FAB, RoCAF Mirage 200-5) have an important problem when you pull many G. Aircraft's behavior is normal until 5-6 G but if you make manuevers with higher G (7+) the aircraft is not moving correctly. For example if you make a loop pulling 7+ G the mirage rolls and you have to use ailerons so that the aircraft can move in the direction you want. That's a problem in general but it is very important when you are dogfighting. Can someone help?

[ShrikeHawk 384]

Hey Tio,

 

I see you got no replies, so I'm mostly replying to bump this back to the top of queue.

 

Still, I wonder if what you're experiencing isn't a very normal stall effect. Remember, delta-winged aircraft don't perform as well at low speed so you can encounter stalls earlier than you might expect.

 

Perhaps some other folks will some better thoughts about it, though.

 

Good luck!

[+Cliff7600 1,148]

Hi guys!

 

I'm not skilled to answer that, but i guess, as ShrikeHawk said, that it's normal stalling effect.

If you increase G-level you will decrease lift level (I've read that in a real aeronautics book)

 

Have you fly the F-106?

;)

[tiopilotos 2,519]

Remember, delta-winged aircraft don't perform as well at low speed so you can encounter stalls earlier than you might expect.

 

I know that delta winged aircraft stall at higher speeds, that's the reason they need higher speed to land but I'm not talking about this. I used many delta winged aircrafts such as Mirage 2000N/D, Mirage III, Mirage 5, Kfir, Atlas Cheetah etc and I realized that only these 3 aircrafts (Mirage 2000C, Mirage 2000C FAB, RoCAF Mirage 200-5) had this weird behavior at performing high G manuevers.

If someone has used one of these 3 can easily understand what I'm talking about.

 

 

[New Guy 1]

Maybe because of the FM is not final? The Mirage 2000 is getting a remake by the Insky AFAIK (not including the TMF version)...

[+NeverEnough 78]

I found this problem when I converted the Mirage 2000-5 for use in SF2. The Ymac value for the Right Wing in the data.ini file for these models was originally Ymac=-0.90, and it should be Ymac=0.90 instead. The negative Ymac value on the right wing caused the plane to flop to one side when pulling over the top. Correcting it to the Ymac=0.90 eliminated the problem.

 

Take a look at the Mirage2000-5_Data.ini in the Mirage 2000-5_SF2 download package for where the changes should be located.

[ShrikeHawk 384]

Yup, I see what neverenough is saying about the data.ini file in my RoCAF Mirage 2000-5. But it seems to have no effect in WoE (SFG1). I pulled lots of high-gee loops with no troubles.

 

It may only cause problems in SF2:E

[FastCargo 412]

Did you check if you were in Hard FM vs Normal FM?

 

FC

[tiopilotos 2,519]

Did you check if you were in Hard FM vs Normal FM?

 

What is Normal FM and what is Hard FM ?

 

 

 

[tiopilotos 2,519]

The negative Ymac value on the right wing caused the plane to flop to one side when pulling over the top. Correcting it to the Ymac=0.90 eliminated the problem.

 

Thank you! I changed the Ymac and now the aircraft can perform high G manuevers normal. Can I ask something elese? I realized also that these 3 aircrafts (Mirage 2000C, Mirage 2000C FAB, RoCAF Mirage 2000-5) have slow roll rate. Older delta winged aircrafts such as Nesher for example have faster roll rate. How can I make them rolling faster?

 

 

 

[+Dave 2,322]

What is Normal FM and what is Hard FM ?

 

 

 

 

You set it in the option area when you start the sim. You either have easy, normal or hard FM's.

[tiopilotos 2,519]

You set it in the option area when you start the sim. You either have easy, normal or hard FM's.

 

You mean the flight model level. I selected normal FM

 

 

 

[Squiffy 1]

Does FM difficulty level effect taxiing performance? I want a good nosewheel! Or am I foolish because everybody knows you can't taxi over 7kts without getting killed?

[+Dave 2,322]

Does FM difficulty level effect taxiing performance? I want a good nosewheel! Or am I foolish because everybody knows you can't taxi over 7kts without getting killed?

 

 

Well that is 8.05 MPH. I would think that is a good taxi speed. How fast are you trying to go?

[Squiffy 1]

Well something more like 15kts. But some of this need is bases on my throttle detents which sit between 7 and 15 or so. It's frustrating to have to keep clicking back and forth through the detents although that might be fine for realism. It's been a long time since I was in a military jet. My biggest issue is with the physics and the control reaction in the sim. I can't believe the nosewheel is so slippery, almost as if there is no weight on it at all. That's why the cg point got mentioned earlier. In LOMAC, you get nice strut compression and it's almost TOO grippy. I swear I could ground loop the thing sometimes. I don't think I've been on hard setting yet. Should do it now because the stick is trimmed nicely. My folder structure in XP is SF/objects/aircraft/f-15a/f-15A_data.ini i've also tested sf/objects/f-15A_data.ini unit conversion is not an issue. I think it's the variable itself (max steering speed) or folder structure or even sf2 june 2009 update. I didn't mod until the update was in place.  What does control rate and coefficient actualy do?  I know what the coe shoudl REALLY do but does this effect lateral force?<BR>

Well that is 8.05 MPH. I would think that is a good taxi speed. How fast are you trying to go?

Edited October 29, 2009 by Squiffy

[FastCargo 412]

It's a weakness of the sim. It doesn't have crisp nosewheel steering response above about 10 knots.

 

Most aircraft are affected like that...that's why you'll notice the AI doesn't taxi very fast.

 

Keep the discussion to the Mirage issues if possible.

 

FC

Edited October 29, 2009 by FastCargo

[tiopilotos 2,519]

I 've never seen something like that! I usually taxi with a speed about 20 Kts and nothing happens. Just sometimes when I get close to buildings, the wings get damaged without being crashed in other objects and smoke appears.

 

Can someone help me about rolling rate? There are 3 mirages that I want to improve their roll rate because it is slow.

[Squiffy 1]

OK FC, I've hit revetments too. Tio, your issue is pure FM so I would look at the elevon entries in the data.ini and compare good ones to bad and see if you can see the difference. How do the wing placements compare. Hi vs lo and such. Mirages should be low and more unstable leading to quicker handling. This is without wing tanks of course.

 

Thanks guys.

 

I 've never seen something like that! I usually taxi with a speed about 20 Kts and nothing happens. Just sometimes when I get close to buildings, the wings get damaged without being crashed in other objects and smoke appears.

 

Can someone help me about rolling rate? There are 3 mirages that I want to improve their roll rate because it is slow.

[tiopilotos 2,519]

Tio, your issue is pure FM so I would look at the elevon entries in the data.ini and compare good ones to bad and see if you can see the difference. How do the wing placements compare. Hi vs lo and such. Mirages should be low and more unstable leading to quicker handling. This is without wing tanks of course.

 

I'm using always the FM normal level but I didn't understand very well what you try to say and how this affects roll rate. Anyway check the elevon parameters:

 

 

[LeftElevon]

SystemType=CONTROL_SURFACE

InputName=ROLL_CONTROL

MaxDeflection=20.0

MinDeflection=-20.0

CDdc=0.0034

Cldc=0.0295

Cndc=-0.0003

ControlRate=2.0

ModelNodeName=LeftElevator

RotationAxis=Z-AXIS

MaxControlSpeed=240

ReverseModelOrientation=FALSE

SecondaryInputName=Pitch_CONTROL

SecondaryInputFactor=1

 

[RightElevon]

SystemType=CONTROL_SURFACE

InputName=ROLL_CONTROL

MaxDeflection=20.0

MinDeflection=-20.0

CDdc=0.0034

Cldc=0.0295

Cndc=-0.0003

ControlRate=2.0

ModelNodeName=RightElevator

RotationAxis=Z-AXIS

MaxControlSpeed=240

ReverseModelOrientation=TRUE

SecondaryInputName=Pitch_CONTROL

SecondaryInputFactor=-1

Edited October 30, 2009 by tiopilotos