Ракеты в DCS

[Max1mus]

3 hours ago, tavarish palkovnik said:

For all skeptics  to try show how difficult is to calculate kinematic and dynamic trajectory of just single one rocket not having enough inputs. And after that, multiple it with all rocket types in DCS…give those guys huge credit for their work.

 

So, R-27ER in horizontal flight. To do this mathematic easiest is to equalize vector and value of weight with vector and value of lift force. With assumed thrust to time function and with this postulate G=Y , coefficient Cn can be calculated. With having Cn and with assumed Cy function now angle of attack can be calculated. Lifting due to aerodynamic surfaces rotations I haven’t included, even without it job is complicated.

 

With having angle of attack which in this postulate is always present next step is to increase Cx coefficient due to fact of such “nose up” flight. For that again you have to estimate corrective coefficient function, let’s call it Kt f( Alfa ). 
Cx is also estimated, I involved i58 as 1,25 in active and 1,5 in passive respectively. 
And haven’t change it with altitude, as it should be changed, approximately each 5 km makes increase of roughly 5%. By now lot of assumptions, estimations and free will neglecting.

 

Anyway when everything is arranged machine is ready to keep rolling and to calculate trajectories.

 

 

 

This is at 5 and 10km with v0 500 and 600m/s respectively. While second one is quite corresponding to what in that time major Krupennikov gave us, first one is not. Forgot to say, thrust is also in function of altitude what I neglected in this math as well. I expected to be opposite if I matched values at 10km but never mind. Want to say that I think increase of Cx with altitude should take more then what increase of thrust with altitude will give.

 

Machine keeps further, now with 250 and 305m/s at 1-5-10km. These are v-t and D-t diagrams, velocity and travel with time, for v0=300m/s at 1, 5 and 10 km.

 

 

 

 

After for a while and observing results although not matching fully I still found something what I should call pattern. 
Seams that for 1 and 5 km altitudes value of available overload and let’s take it as 3g is limitation. Fun fact is that at 10km according to this math of mine available overload of 3g fits to 60 seconds, means dead this or that way.

Available overload calculated with same assumed Cy f(M) and with assumed 12 deg maximal allowable angle of attack. Assumptions, assumptions and assumptions 

And plus one more, shooting in ZPS should be with +150km/h in favor of fighter to get close to what diagram of launching zones present.

 

 

Easy job? No, it’s not an easy job to get even some kind of results. Easier is to comment and I would be very pleased for comments about this, comments of any kind.

 

 

Its not 150 km/h, its 540 (150 m/s) and additional energy for 3G capability.

Edited June 21, 2021 by Max1mus

[tavarish palkovnik]

@Max1mus
When I said comments of any kind, I still thought on reasonable comments  

 

[FoxAlfa]

2 minutes ago, tavarish palkovnik said:

@Max1mus
When I said comments of any kind, I still thought on reasonable comments  

 

Actually Max is right on this instance, it is 150 m/s

[tavarish palkovnik]

...

 

Edited April 23 by tavarish palkovnik

[Chizh]

Well, here you are also faced with the fact that the well-known R-27 nomograms do not have an accuracy.

[tavarish palkovnik]

Well not exactly, I rather consider this work of mine not close precise to what should be or what nomograms present. Not surprisingly with so much assumptions.

With same principles I tried with R-27R as well. And it is different in way of shooting in PPS. Seams that for R-27R higher available overload margins are given what is reasonable and explainable. In ZPS more or less same principle as in case of ER.

Nomograms about maximal distances of the rockets from the fighters after launching are however still big mistery, at least to me. I don’t get those at all what doesn’t mean they are wrong. 

[Max1mus]

DCS_ER_vs_IRL.trk (Red line is what i shot at in the track, missile falls behind considerably)

Picture is from: https://bte.by/upload/iblock/952/95237499fca0ecba9a6708e29efd37a2.pdf

Proof that its public information:
 

Spoiler

 

Edited June 22, 2021 by Max1mus

[nighthawk2174]

33 minutes ago, Max1mus said:

DCS_ER_vs_IRL.trk (Red line is what i shot at in the track, missile falls behind considerably)

Picture is from: https://bte.by/upload/iblock/952/95237499fca0ecba9a6708e29efd37a2.pdf

Proof that its public information:
 

  Reveal hidden contents

 

 

is the 790 number above the planes speed the targets velocity?  Additionally does the hud give the targets altitude?

[tavarish palkovnik]

1040…Текущая скорость полета приборная

790…Заданная скорость полета приборная

5100…Текущая высота полета барометрическая 

5400…Заданная высота полета барометрическая 

 

Ф-форсаж…in a second would gone

Г-горка…would continue 

 

 

 

Edited June 22, 2021 by tavarish palkovnik

[Max1mus]

The altitude of the target is 3400 Meters. As indicated by the target being significantly below the artificial horizon.

[BlackPixxel]

The target is above the boresight of the plane. Look for the smallest of the circles that indicates the antenna position, it is above the crosshair.

 

The horizontal line in the top of the HUD is not the artificial horizon, it is  the estimated time of flight of the missile until it hits the target (something we don't have in DSC).

 

Radial speed of the target is about 60% or so of the own speed, as indicated by the small arrow on the bottom right.

 

You will propably find out that when correctly recreating the scene from the HUD photo the missile in DCS will "overperform", but that is just because the DLZ in the real Su-27 shows less ranges than the charts as additional safety margin. The Su-27 DLZ simulator that Chizh has shows the same behaviour.

[Max1mus]

6 minutes ago, BlackPixxel said:

The target is above the boresight of the plane. Look for the smallest of the circles that indicates the antenna position, it is above the crosshair.

 

The horizontal line in the top of the HUD is not the artificial horizon, it is  the estimated time of flight of the missile until it hits the target (something we don't have in DSC).

 

Radial speed of the target is about 60% or so of the own speed, as indicated by the small arrow on the bottom right.

 

You will propably find out that when correctly recreating the scene from the HUD photo the missile in DCS will "overperform", but that is just because the DLZ in the real Su-27 shows less ranges than the charts as additional safety margin. The Su-27 DLZ simulator that Chizh has shows the same behaviour.

 

That number on the altitude looks like a 3 to me. When you zoom out especially.

 

And the elevation indicator on the right is pointing down significantly.

 

Whats interesting is that the DCS DLZ will show exactly the same number, 20km of range. But the missile will not overshoot with enough energy+provisions above 15-16.

Edited June 22, 2021 by Max1mus

[tavarish palkovnik]

And don’t forget that instrumental speed or indicated speed (приборная скорость) ,doesn’t correspond to the true speed (истинная скорость) which is important in absolute system of the rocket.

 

[tavarish palkovnik]

@Max1mus 

[GGTharos]

33 minutes ago, tavarish palkovnik said:

And don’t forget that instrumental speed or indicated speed (приборная скорость) ,doesn’t correspond to the true speed (истинная скорость) which is important in absolute system of the rocket.

 

If a loft is involved I could see this happening - so you're saying the gorka is in action here.

[Max1mus]

The target is below the aircraft (this is a MiG-29).

Spoiler

Here is the elevation indicator at work:
https://youtu.be/7AmWtMonq-c?t=153

Edited June 22, 2021 by Max1mus

[BlackPixxel]

No, that is not the elevation indicator. It is the closure speed indicator.

 

There are two lines in the lower part. The bottom one is zero closure, the upper one is the own speed.

 

The arrow is pointing at the value of radial closure speed.

 

For example: target in front aspect, the arrow will be above the own speed marker

target notching, the arrow will point at the own speed marker

target cold, the arrow will point below the own speed marker

 

If the target is directly head on with the same speed as the own aircraft, then the arrow will point at a value twice as high as the own speed.

[Max1mus]

Ok. Did not know the russian avionics were this mismodelled in DCS.

But the clouds still prove that the target is lower. And i remind you that in DCS, the DLZ is exactly the same if the target is at 3400. Just the missile is underperforming by at least 20%. Exactly like the DCS ER versus the ER on the well-known graphs, at 1.000m (over 15%) and 5.000m (over 20%).

 

Spoiler

Real:


Track:

DCS_ER_vs_IRL.trk 

DCS 3400m scenario:


DCS 5400m scenario:

Viewdistance is on the maximum setting of 150km.

Edited June 22, 2021 by Max1mus

[BlackPixxel]

Look at the number to the right that shows the elevation angle. It says 1. So the nose is already pointed above the horizon by 1°. The smallest of the three circles shows that the target is above the crosshair, so the elevation angle of the target is even higher.

 

Note that the big circle does not show the location of the target in the real HUD. It instead is to be used like the ILS on landings. It shows the recommended flight path to get into the best position to engage the target. So in the HUD photo it wants the pilot to climb.

[GGTharos]

So is the HUD showing the target travelling at 600kph or so?

[BlackPixxel]

It seems so

 

[GGTharos]

If I get time I'll try to do the test from the HuD shot.

[Max1mus]

New track with target at 5400m and 790 km/h showing as target speed.

DCS_ER_5400m.trk

Falls behind, it has the necessairy speed about 2km from the target (considering the 150 m/s limit). Further behind if you consider provisions.

Still underperforming by at least 10%.


 

Edited June 22, 2021 by Max1mus

[tavarish palkovnik]

I truly belive that speed values on this ILS are not true speed but indicated speed.

Velocity 1040km/h or 290m/s should be 355m/s of true speed and if 790km/h or 220m/s is aimed that could mean that velocity of target is around 640km/h (180m/s). This is again not true speed of target which at 5400m should be 230m/s.

 

With those two values, 355m/s against 230m/s, and with checking trajectory, I'm getting that in second 36th missile will have it's true speed of 390m/s and it will travel for 27900 m.

27900 - 36*230 = 19620m

 

In case 1040km/h is true speed and accordingly 640km/h is true speed of target....after 40 second missile will have speed of 355m/s, will travel 28400m -> 28400 - 40*180 = 21200m 

Edited June 23, 2021 by tavarish palkovnik

[Маэстро]

The velocity on HUD you call "target velocity" is not target velocity IRL. It's called "скорость заданная истинная" as you may see on BlackPixel's screenshot. In english it would be somtehing like commanded TAS or requested TAS.