Su-27 Flight Model Discussion

[Ironhand]

45 minutes ago, Iriya said:

Not sure about IRL but the flight model of Su-27 makes me feel controlling a brick. I mean, Su-27 loses air speed so quick when I reduce fuel flow which makes easier to stay in formation comparing to other aircraft. If it's correct as it be I'm totally happy with it. On the other hand, the flight model of MiG-29 is excellent thanks to update around 2018. I understand Su-27 is much heavier than MiG-29 and totally different aircraft by any aspect but still.

I haven’t noticed anything unusual in that regard but I guess it depends on how much fuel you have loaded and the payload you’re carrying. I know it seems slow accelerating in the transonic region but that’s a different concern.

[Seaeagle]

19 hours ago, Iriya said:

Not sure about IRL but the flight model of Su-27 makes me feel controlling a brick. I mean, Su-27 loses air speed so quick when I reduce fuel flow which makes easier to stay in formation comparing to other aircraft. If it's correct as it be I'm totally happy with it. On the other hand, the flight model of MiG-29 is excellent thanks to update around 2018. I understand Su-27 is much heavier than MiG-29 and totally different aircraft by any aspect but still.

Well being heavier should by itself cause it to loose airspeed slower(inertia) when cutting power, so it must be down to drag of the much larger airframe.  

[Exorcet]

1 minute ago, Seaeagle said:

Well being heavier should by itself cause it to loose airspeed slower(inertia) when cutting power, so it must be down to drag of the much larger airframe.  

It's not weight that you want to look at, but the ballistic coefficient:

 

https://en.wikipedia.org/wiki/Ballistic_coefficient

[Seaeagle]

2 hours ago, Exorcet said:

It's not weight that you want to look at, but the ballistic coefficient:

 

https://en.wikipedia.org/wiki/Ballistic_coefficient

Yeah thats what I said .

How quickly an aircraft at a certain speed and altitude will slow down when cutting power, is down to its mass versus drag. So if the Su-27 looses airspeed quicker than the MiG-29 despite being heavier, then it must be because the airframe of the Su-27 is proportionally more draggy than that of the MiG-29....no?  . 

[Exorcet]

23 hours ago, Seaeagle said:

Yeah thats what I said .

How quickly an aircraft at a certain speed and altitude will slow down when cutting power, is down to its mass versus drag. So if the Su-27 looses airspeed quicker than the MiG-29 despite being heavier, then it must be because the airframe of the Su-27 is proportionally more draggy than that of the MiG-29....no?  . 

You're correct, I just put what you said together and provided the "official" term for it. I guess I should have added that I was agreeing with you, not disagreeing.

[Seaeagle]

1 hour ago, Exorcet said:

You're correct, I just put what you said together and provided the "official" term for it. I guess I should have added that I was agreeing with you, not disagreeing.

NP.

[Iriya]

I apologise for my post, that concern comes from what I have heard about the handling of drag in the DCS. I've heard someone says missiles in DCS might have too much drag so it might applies the flight model of Su-27 too. I have no data or deep knowledge about fluid mechanics nor aerodynamics so just posted my guess and no meant to comparing flight characteristic Su-27 and MiG-29. 

Edited January 20, 2023 by Iriya

[Lurker]

6 minutes ago, Iriya said:

I apologise for my post, that concern comes from what I have heard about the handling of drag in the DCS. I've heard someone says missiles in DCS might have too much drag so it might applies the flight model of Su-27 too. I have no data or deep knowledge about fluid mechanics nor aerodynamics so just posted my guess and no meant to comparing flight characteristic Su-27 and MiG-29. 

 

Holy necro thread. Are you carrying stores (missiles) on that Su-27 or flying clean? 

[Pavlin_33]

After thinking about it for a while, I realized that the issue of Su-27s performance comes down to its engines:
They provide maximum power very slowly.

If you think about it, the acceleration of an airplane comes down to two forces: drag and thrust (ignoring gravity at the moment). Now I know that in DCS the Flanker can go Mach 2+ even with significant amount of fuel on board, the drag does not change, so it has to be the thrust. It seems that engines are just not quick enough to provide max thrust available.
I can't see anything else causing very slow acceleration of the Su-27 in DCS when its top-speed matches that of an Eagle or Fulcrum.