Flight model

[Aginor]

Ok, that might be the case. I vaguely remember the number being around 95 kg/min.

I will check that again.

[Hummingbird]

I didn't feel like there was a sustained turn rate issue at all, at least not compared to flying the F-15C, an aircraft the Mirage will beat in both sustained & instantanous turn rate in real life.

[Aginor]

Ok, that might be the case. I vaguely remember the number being around 95 kg/min.

I will check that again.

 

Quoting for reference only.

I made a track and attached it. At about seven minutes I am flying around at Mach 1.01 and I am pretty sure that isn't afterburner. I might be wrong though.

supercruise01.trk

[GGTharos]

I didn't feel like there was a sustained turn rate issue at all, at least not compared to flying the F-15C, an aircraft the Mirage will beat in both sustained & instantanous turn rate in real life.

 

Measured to be incorrect for STR, 2dps over IIRC.

[Brisse]

Measured to be incorrect for STR, 2dps over IIRC.

 

Just to be clear, you mean the M-2000C, right? Not the F-15C?

[GGTharos]

I mean the mirage.

[Brisse]

I mean the mirage.

 

Thanks. It makes sense. I haven't done any measurements but the feeling I get from some dogfight sessions in the M2000C is that it easily out-turns anything in the sim right now.

[GGTharos]

It does a bit better than it ought to, at least compared to the charts included in the manual. :-)

 

CptSmiley already knows about these things so I'm confident that the general performance will be accurately reflected after a couple of rounds of corrections :-)

[rrohde]

Just to let you know that we are listening to you and we will review the FM to check on your concerns. Please be aware that it is possible that the aircraft is behaving as it should, as opposed to as how you believe it should behave. But we will check and fix what needs to be fixed, if any.

 

Thank you. But please don't "dumb it down" to appease anyone. :thumbup:

Edited December 26, 2015 by rrohde
Removed a stray "for" in my sentence :)

[jojo]

:mad:

 

THIS AIRCRAFT IS NOT TO BE FLOWN WITHOUT FBW !!!

 

Good review :thumbup:

 

http://forums.eagle.ru/showpost.php?p=2616297&postcount=27

 

Look at 28' :lol:

[Hummingbird]

Measured to be incorrect for STR, 2dps over IIRC.

 

Really? I didn't get that feeling at all.

 

By contrast feel I am able to get a higher STR at around 900 km/h in the F-15C, infact the Eagle just keeps accelerating at 9 G at that speed.

 

Also how about the ITR? I don't seem to be able to pull the same ITR in the Mirage as in the F-15 at all, eventhough I should easily be able to pull more.

 

Infact the Mirage seems a lot more limited in movement than the F-15, and you can't pull those mini cobras that you are able to do in the ingame F-15 either, despite the Mirage being a delta.

[GGTharos]

You're g limited by the FBW so it may be giving you a skewed idea of what's going on. I didn't check ITR yet.

 

I believe the FBW is an AoA/pitch command system while the eagle's is a G command system focusing on high onset, and that's probably what's making the difference with the 'mini cobras'.

 

You could attempt pitch control with relaxed FBW laws, see how that goes ... Personally I haven't tried that :-)

[Moa]

Great job RAZBAM.

 

Just a little note, you may want to use the magic words "Angular Momentum" when talking with CptSmiley, since "Inertia" is resistance to attitude changes (that is, it is the angular equivalent to mass in linear kinematics).

 

The Mirage 2000 has a wing area of 41 square meters. Compare that to the 27.87 meters for the F-16. Since all aerodynamic torques and linear accelerations multiply the dynamic pressure by wing area (and with the torques further multiplied by either span or mean chord) that means the forces are around 47% greater for the Mirage 2000 than the F-16.

 

Given the shorter wingspan of the Mirage to the F-16 (9.13 vs 9.96 m) the roll intertias may be comparable (although I haven't checked). With greater torques and similar roll inertia it means the Mirage 2000 is likely to have a faster roll response rate (faster to start rolling, and faster to slow down) than the F-16.

 

Looking at the F-16 FBW models in NASA TP-1538 (where I'm modelling the F-16 for a different simulation) the FBW is not magic. Its purpose is mostly to moderate down pilot input so that they cannot command departures. A second function is to rotate around the stability axes so that angle-of-attack is preserved when rolling (preventing angle-of-attack being converted into sideslip in a simple aileron roll).

 

Anyway, I don't know much about the Mirage, but just thought I'd throw my two centimes worth in. It looks like CptSmiley has done a smashing job, and a few tweaks (in the corners of the control lag simulation) will give us as good as unclassified civilians could hope for.

[Hummingbird]

You're g limited by the FBW so it may be giving you a skewed idea of what's going on. I didn't check ITR yet.

 

I believe the FBW is an AoA/pitch command system while the eagle's is a G command system focusing on high onset, and that's probably what's making the difference with the 'mini cobras'.

 

You could attempt pitch control with relaxed FBW laws, see how that goes ... Personally I haven't tried that :-)

 

The Mirage's STR should in general be 1 deg/sec higher than the F-15C's, and the ITR significantly higher below the 9G mark.

 

At 15,000 ft the ingame Mirage with two R-550 missiles has to be able to:

1) Sustain 6.7 G's at Mach 0.9

2) Pull 9 G's from Mach 0.65 (23.6 deg/sec)

[GGTharos]

I measured with respect to mirage charts, not f15.

 

I didn't measure the entire envelope, but you can find the charts in the in game manual.

[Hummingbird]

I measured with respect to mirage charts, not f15.

 

I didn't measure the entire envelope, but you can find the charts in the in game manual.

 

Will the ingame Mirage 2000C sustain 6.5 G's at Mach 0.6 at SL? That's what the real thing will do.

[Brisse]

I believe the FBW is an AoA/pitch command system while the eagle's is a G command system focusing on high onset

 

IIRC, the M2000 FBW is AoA command system at low speed and G command system at higher speeds.

[jojo]

IIRC, the M2000 FBW is AoA command system at low speed and G command system at higher speeds.

 

Yes, the transition is around 300kt

[GGTharos]

Hi GGTharos, if you've managed to collect any numerical data on your comparisons I would love to see them. Would help me work on the regimes that aren't matching up how they should.

 

I will get you numbers as soon as possible (unfortunately right after a couple of tests life happened ... Not sure when I'll find time next but I'll see what can be done).

 

I know you're aware of the high altitude thrust issue and that one ought to be quite obvious I think.

Edited December 27, 2015 by GGTharos

[Kuky]

The discussion about lack of inertia, I agree with. FBW or not, it is not possible for the FBW to react at the same time as when physics acts on the air frame (if it did, it would have to mean that FBW can predict where aircraft will be moved, in order to counter-react this force, which is not possible). There must always be some time delay when force acts on air frame, and FBW and control surfaces to react. So I think the FM needs tweaking by first, adding time needed to move the control surfaces (right now they are instant) and second, needs to add small time delay for FBW to react on air frame movement adjustments. That I think will add the missing natural flight characteristics that I also feel is missing.

Edited December 27, 2015 by Kuky

[Fab]

There is a lot of debate about the FBW system and the lack of invertia.

 

Fiste of all, you must understand how the FBW system Works. As there is no other plane in DCS that contains FBW, it will fell very odd, and perhaps to "game Acade Stylies".

 

Some one mentioned that F-15 got an early type FBW... It does not, F-15 is flown with CAS, thats more of a "pilot support system" but enough about the F-15.

 

For those not familair with FBW, please consider this...

 

FWB= Flight By Wire, was originale made, because enginers discovered that unstable planes, was cable of much faster turnrate, and other air combat manouvers. Problem was, that an unstable plane, cant be flowen by any human. Therefor the planes was fittet with a computer, that took care of all control surfaces, so the plane could indeed fly.

 

The pilot input to the flight stick Works much like your flight stick at home, attached to your pc. It sends info from your stick, to a pc, and the pc controls the controlsurfaces on the plane.

 

If you look at the hud og the M-2000, there is a flight parth marker "looks like a small plane". The pilot points the flight parth marker, to where he want the plane to go, and the flight computer, will do this inside the flight envolope of the plane.

 

The first stick for F-16 "first western plane with FBW" coulden´t even move, but only messaured the force from the pilots input. It was removed, because the pilots could not addapt to it, much like a lot of you cant addapt to the feeling for FBW.

 

I planes without FBW, you as a pilot fly the plane, IRL we talk about flying with your pants, as IRL pilots uses a lot of feel, to compute the behaveaure of the plane and steer acording to that. In FBW planes the plane flyes itself, we as pilots mearley tell the plane where to go. That a hell of a lot diffrente, and it will take you a good amount of time to get used to...

 

Planes without FBW, releys on cables, switches, before the hyd systems kick in. Further more, you need to calculate with the hinge of the control surface, and the overall travel "span ratio" of the surface. Because thats = with the movment the pilot got to move his stick, or = to the gearing, tha needs to be forced, between the stick and the control surface. There is a considerble amount of lag in those systems, more that you would think, and the lag gets bigger the more G you pull. The lag also grows, when you make opposit stick input, like stopping a roll.

 

The F-16 got 0.0495 Sec lag from input by pilot, untill a control surface has moved from one full position til the other full postion.

 

I cant find the data on control surfaces movment speed. But it got to be faster than human reactiontime (150/400 mill sec)+movment speed of the stick by human.

 

You CANT control the movment speed, by looking at the plane, while it stands on the ground. Cause the input you make, will be calculated by the flight computer, and to make the movment of the plane, you ask for on the ground wont requere any volient control surface movments.

 

Happy flying....

[Theskyline35]

What an interesting topic !

 

I found something weird...Power idle, air-brakes deployed, diving at 90°, I'm loosing speed ! Is it normal ? because it's the first plane in DCS that can loose speed in dive (or I'm missing something), it's impressive if it's real !

[Brisse]

I found something weird...Power idle, air-brakes deployed, diving at 90°, I'm loosing speed ! Is it normal ? because it's the first plane in DCS that can loose speed in dive (or I'm missing something), it's impressive if it's real !

 

Well, that depends on what the speed was. Every object in free fall in the atmosphere has something called "terminal velocity". The object will accelerate to it's terminal velocity, then the air resistance will be equal to the gravitational pull and the object will stop accelerating. If you are decelerating, then you started out at a speed above your terminal velocity. Of course, the terminal velocity changes if you deploy your airbrake, or do anything to alter the shape (and thus it's drag) of the object.

[Fab]

What an interesting topic !

 

I found something weird...Power idle, air-brakes deployed, diving at 90°, I'm loosing speed ! Is it normal ? because it's the first plane in DCS that can loose speed in dive (or I'm missing something), it's impressive if it's real !

 

You might find it hard to belive, that a plane will Loose airspeed, in a 90 degree dive, just employing dive brakes.

 

What was your speed, hight, how much speed did you Loose, and where did you ende up (speed)?

 

But gravity makes you (all thing) fall with same grayity accrelation witch is 9,81 m/s2. So i other Words the terminal velocity on anything freefalling is 500 km/h without resistence from Wind/drag from fuselag ect.. nothing can fall any faster than that. So this might have been what you exprienced...

Edited December 27, 2015 by Fab

[OnlyforDCS]

So i other Words the terminal velocity on anything freefalling is 500 km/h without resistence from Wind/drag from fuselag ect.. nothing can fall any faster than that.

 

This sentence makes absolutely no sense at all. An object accelerating in free fall will keep on accelerating until it hits the ground. (If there is no atmosphere to slow it down) This is physics 101 guys. Terminal velocity is different for any object falling in the atmosphere you can't assign an arbitrary value of 500km/h and say that's the limit.