investigating Thrust to weight ratio: confused

[Yo-Yo]

I just want to remind few graphs from the article issued by ED some times ago.

etc...

 

[bkthunder]

@Yo-Yo can you confirm what is the installed engine thrust of the DCS MiG-29A? 

level acceleration and turn performance don't necessarily mean that thrust to weight ratio is correct.
Thrust can be lower than it should be and if drag is also lower, with higher lift, all numbers would match except the thrust to weight ratio, and this seems to be the case according to the various tests presented throughout this thread. 

[Yo-Yo]

11 hours ago, bkthunder said:

@Yo-Yo can you confirm what is the installed engine thrust of the DCS MiG-29A? 

level acceleration and turn performance don't necessarily mean that thrust to weight ratio is correct.
Thrust can be lower than it should be and if drag is also lower, with higher lift, all numbers would match except the thrust to weight ratio, and this seems to be the case according to the various tests presented throughout this thread. 

No, acceleration and turn performance are much more reliable criteria, because thrust/weight ratio is not very useful, as the thrust depends on speed.
Drag polars are well known for MiG-29, so your suggestions are not correct.

[sylkhan]

1 hour ago, Yo-Yo said:

No, acceleration and turn performance are much more reliable criteria, because thrust/weight ratio is not very useful, as the thrust depends on speed.
Drag polars are well known for MiG-29, so your suggestions are not correct.

How do you explain, than in real life Mig29 outclassed F16, f18 in dogfight, and in DCS it's the contrary.
We are not talking about numbers here, but facts.

https://www.16va.be/mig-29_experience.htm

[GGTharos]

4 hours ago, sylkhan said:

How do you explain, than in real life Mig29 outclassed F16, f18 in dogfight, and in DCS it's the contrary.
We are not talking about numbers here, but facts.

https://www.16va.be/mig-29_experience.htm

It's just you posting your own propaganda and falsified record ... you know, exactly the type of explanation you love to give

The advantage granted by the R-73 is undeniable, but the existence of IRCM and counter-HOBS/rmin tactics are also undeniable.  Also, instantaneous turn rates don't necessarily win fights as this is a very transient capability.   The MiG-29 would have had an advantage over F-16s because it could clean up BVR to begin with, have superior numbers at the merge and the HOBS advantage.   This ended when F-16s were equipped with AIM-120.

[Cmptohocah]

7 hours ago, Yo-Yo said:

No, acceleration and turn performance are much more reliable criteria, because thrust/weight ratio is not very useful, as the thrust depends on speed.
Drag polars are well known for MiG-29, so your suggestions are not correct.

Static thrust does not depend on speed and T/W ratios, from what I know, are given for max static thrust and max TO weight.

What @bkthunder was refering to is that static thrust (or near it) might possibly be underperforming. This would manifest it self in straight accel. as lift in this case does not play a big role in drag, where as in turns it does.

[sylkhan]

1 hour ago, GGTharos said:

It's just you posting your own propaganda and falsified record ... you know, exactly the type of explanation you love to give

No falsified record, sorry, you don't like it, i know
If you want falsification, take a look at the documents you are spreading since so many years, to manipulate people, with good succes, i can say :).

1 hour ago, GGTharos said:

The advantage granted by the R-73 is undeniable, but the existence of IRCM and counter-HOBS/rmin tactics are also undeniable.  Also, instantaneous turn rates don't necessarily win fights as this is a very transient capability.   The MiG-29 would have had an advantage over F-16s because it could clean up BVR to begin with, have superior numbers at the merge and the HOBS advantage.   This ended when F-16s were equipped with AIM-120.

And this end up with R27ER/ET and r77, better range and aerodynamic (i mean, in real life)

 

[GGTharos]

3 minutes ago, sylkhan said:

No falsified record, sorry, you don't like it, i know
If you want falsification, take a look at the documents you are spreading since so many years, to manipulate people, with good succes, i can say :).

Oh yeah?  Which ones?   Go ahead point'em out

[Youda]

[bkthunder]

@GGTharos @sylkhan guys I don't wanna play moderator here but please keep it on topic, the thread is very interesting and Yo-yo honoured us with his presence, I don't want to have it locked please. 

 

@Yo-Yo you didn't answer my direct question though: can you confirm what is the installed engine thrust of the DCS MiG-29A? 

 

 

Thanks!

Edited November 8, 2021 by bkthunder

[Yo-Yo]

2 minutes ago, bkthunder said:

@GGTharos @sylkhan guys I don't wanna play moderator here but please keep it on topic, the thread is very interesting and Yo-yo honoured us with his presence, I don't want to have it locked please. 

 

@Yo-Yo you didn't answer my direct question though: can you confirm what is the installed engine thrust of the DCS MiG-29A? 

 

 

Thanks!

 

What Mach number you mean? Static, H=0, M=0? What use will it have for acceleration, for example?

[bkthunder]

On 11/8/2021 at 10:40 AM, Yo-Yo said:

What Mach number you mean? Static, H=0, M=0? What use will it have for acceleration, for example?

Hi Yo-Yo, I mean both static and at M 0.5 at sea level. 

Thanks!

 

 

[Yo-Yo]

36 minutes ago, bkthunder said:

Hi Yo-Yo, I mean both static and at M 0.5 at sea level. 

Thanks!

 

 

 

 It's a bit less than test bench thrusts you can operate

[bkthunder]

Can you give us a number? 

According to user testing it's between 12.5k and 13.5k Kgf in DCS (total thrust with both engines in Full AB). 

According to the chart in ED's own document, it should be around 16k Kgf.

 

15 hours ago, Yo-Yo said:

 It's a bit less than test bench thrusts you can operate

So a bit less is how much? 
13000 is 18.75% less than 16000.

[Spurts]

~15-20% losses from uninstalled bench thrust to installed static thrust are common.

[bkthunder]

1 hour ago, Spurts said:

~15-20% losses from uninstalled bench thrust to installed static thrust are common.

Please read before you post, otherwise you only create confusion. The chart provides installed thrust at different speeds.

 

 

Edited November 11, 2021 by bkthunder

[Yo-Yo]

On 10/6/2021 at 12:23 PM, bkthunder said:

 

So I *think* I tested this correctly. 

 

Mig-29A

total Mass: 13770Kg

Flaps up in all tests to reduce drag.

 

first I tested the ground friction as you suggested. 

 

Initial speed: 35 m/s

final speed after 10 seconds: 31.3 m/s

= -0.38 m/s2 deceleration

13770 x -0.38 = -533.58 kgf

 

 

Acceleration test - measurement started when in full AB and no brakes. 

Initial speed: 39.8 m/s

final speed after 10 seconds: 125.2 m/s

= 8.54 m/s2 acceleration

13770 x 8.54 = 11991.57 kgf + 533.58 = 12525.15 kgf

 

 

So:

 

- 12500 kgf vs 16600 kgf (static thrust)

- 12500 kgf vs 16000 kgf according to the chart below

 

 

 

Conclusion: 

 

The MiG-26A lacks 4000 kgf of thrust. 

Can someone confirm my calculations are correct? 

 

 

Thanks

 

First of all, where do you find INSTALLED THRUST for this graph? Please point directly.

The second mistake is that up to 240 kph (67 m/s) the engines use upper intakes, that are way worse than the main intakes.

The third mistake is that you neglect the drag but conduct the test up to 125 m/s. 
I think that you can calculate non-induced drag for this speed.

The third mistake is how easy you use 16000 kgf (M=0) for comparison to your results, though the final speed for your test is 125 m/s or 0.37 M

 

[bkthunder]

31 minutes ago, Yo-Yo said:

First of all, where do you find INSTALLED THRUST for this graph? Please point directly.

The graph is showing thrust from 0 to >M2.0 at altitudes up to 20Km. I haven't seen an uninstalled engine fly at any altitude and speed other than 0, so I suppose that graph represents installed thrust.

 

Quote

The second mistake is that up to 240 kph (67 m/s) the engines use upper intakes, that are way worse than the main intakes.

Good point, I don't think any of us have considered this in the "ground-roll" test. That said, the in-flight tests I did before are all gear-up and main intakes fully open, definitely not as precise but they do show the MiG-29 has the worst climb performance compared to F-18, F-16, and F-15 in game (see OP), so pointing at something.

 

Quote

The third mistake is that you neglect the drag but conduct the test up to 125 m/s. 
I think that you can calculate non-induced drag for this speed.

Correct, in fact Cmptohocah here did the test measuring only up to 100 Km/h. But you make a valid point about the air intakes being closed.

Quote

The third mistake is how easy you use 16000 kgf (M=0) for comparison to your results, though the final speed for your test is 125 m/s or 0.37 M

Again you are right, and at mach 0.37 according to the graph the thrust would be 7700 kgf per engine, which is the lowest peak in the graph happening around that speed.
We should consider that up to that point the thrust is higher, but even if we supposed the thust was 7700*2= 15400 kgf from brakes release, we still end up with a test result of 13500 kgf in the best case, so more than 12% below the thrust stated in the graph. 

 

All great comments form your side that put things more and more into perspective, but at the end this whole discussion revolves around a simple number, as I've asked now already 3 times, could you point directly at the installed thrust of the DCS Mig-29A?

[GGTharos]

41 minutes ago, bkthunder said:

The graph is showing thrust from 0 to >M2.0 at altitudes up to 20Km. I haven't seen an uninstalled engine fly at any altitude and speed other than 0, so I suppose that graph represents installed thrust.

The chart could be from a wind tunnel bench test, so not installed.   But it would be good to know if this is the case or not.

[Yo-Yo]

1 hour ago, GGTharos said:

The chart could be from a wind tunnel bench test, so not installed.   But it would be good to know if this is the case or not.

No, it specified as a test bench with theoretical correction to the TYPICAL intake. What TYPICAL was meant we do not know, but MiG-29 has it's own very special one.
By the way (for bkthunder), the simulated condition for engines do spread up to high altitude and M.

[Yo-Yo]

2 hours ago, bkthunder said:

 

 

All great comments form your side that put things more and more into perspective, but at the end this whole discussion revolves around a simple number, as I've asked now already 3 times, could you point directly at the installed thrust of the DCS Mig-29A?

I think, this value will not be quite useful. As it was shown above the SEP of the MiG-29 is very accurate, so, as the drag is known and correct, you can trust the thrust.
Probably, providing more correct tests you can find this value for yourself.

[bkthunder]

10 hours ago, Yo-Yo said:

I think, this value will not be quite useful. As it was shown above the SEP of the MiG-29 is very accurate, so, as the drag is known and correct, you can trust the thrust.
Probably, providing more correct tests you can find this value for yourself.

Is there a reason why you are so secretive about this value? 

[Ironhand]

12 hours ago, bkthunder said:

Is there a reason why you are so secretive about this value? 

Probably because the simulation isn't designed the way you think it is.

[sylkhan]

A video is better than thousand of words/graphs/test or whatever you want, and confirm what i am saying since a long time "Mig-29 FM is way off reality"

Some viewer's comments :

"Amazing video again. Quite surprised the Mig-29 isn't a lot better. Always thought the 29 would be a lot better then the Tomcat in a dogfight."

"For some reason I would've assumed that in a turn-and-burn within-visual-range dogfight the MiG-29 would be more nimble and dominate the F-14 with its higher thrust-to-weight ratio..."

"I didn't expect that F-14 could beat Mig-29 ! "

"Why is the F14 so dominant in the rate fight ?"

"Currently in DCS the 29 feels kinda underpowered...Also it gets pretty wobbly when slow ... "

" mig-29"

"Dogfight mig29 and f14, mig lose, really?!? ;

[BonerCat]

20 hours ago, sylkhan said:

A video is better than thousand of words/graphs/test or whatever you want, and confirm what i am saying since a long time "Mig-29 FM is way off reality"

Well, not really, no.
A video of a dogfight, which heavily depends on the pilots, and other circumstances, and a few comments has basically close to 0 objective facts in the mix.
Sure, you can maybe get a rough idea of how an aircraft performs if you *know* both pilots are of roughly equal skill, but other than that, it's pretty useless.

In order to change the FM, you *need* facts. How much to adjust each parameter. "FM is way off" or "mig lose, really?!?" gives you exactly none of that data.

Sorry man, but this just does not contribute in a tangible way