investigating Thrust to weight ratio: confused

[captain_dalan]

Alas, i've lived to see the day when a GS video will be considered a yard-stick by which airplane performance will be measured.....i dread to think what comes next? Maybe the Nobel prize committee will give me a personal call to tell them who the next recipient should be? 

[WarbossPetross]

02.12.2021 в 01:29, captain_dalan сказал:

Alas, i've lived to see the day when a GS video will be considered a yard-stick by which airplane performance will be measured.....i dread to think what comes next? Maybe the Nobel prize committee will give me a personal call to tell them who the next recipient should be? 

That's how you get people who want to start a shooting war with Russia and Iran because of all the invasions by them in just about every mission and campaign in this game

[captain_dalan]

On 12/3/2021 at 9:53 AM, WarbossPetross said:

That's how you get people who want to start a shooting war with Russia and Iran because of all the invasions by them in just about every mission and campaign in this game

[Top Jockey]

Regarding @sylkhan prevous claims.

 

On the Fulcrum's performance vs the Tomcat, I'll admit some curiosity of my own, as I do not have Tacview installed :

- MiG-29A vs F-14A (TF30 engines) ;

- guns only, no external payload or fuel tanks, for each ;

- internal fuel quantity for roughly 3 - 4 minutes in full afterburner, for each ;

- slightly above sea level.

 

My doubt is purely: what would be each one's absolute maximum Sustained Turn Rate, in degrees per second ?

( I'm not asking about Corner Speed, or Instantaneous Turn Rate, or minimum turn radius, etc... )

 

Does anyone have an aproximate idea ?

Thank you.

[captain_dalan]

5 hours ago, Top Jockey said:

Regarding @sylkhan prevous claims.

 

On the Fulcrum's performance vs the Tomcat, I'll admit some curiosity of my own, as I do not have Tacview installed :

- MiG-29A vs F-14A (TF30 engines) ;

- guns only, no external payload or fuel tanks, for each ;

- internal fuel quantity for roughly 3 - 4 minutes in full afterburner, for each ;

- slightly above sea level.

 

My doubt is purely: what would be each one's absolute maximum Sustained Turn Rate, in degrees per second ?

( I'm not asking about Corner Speed, or Instantaneous Turn Rate, or minimum turn radius, etc... )

 

Does anyone have an aproximate idea ?

Thank you.

1. By time in burner, you mean, time till out of fuel and hit the ground or time till bingo? And if the latter, then what are the bingo states? Maybe a more concise fuel state would be more helpful? 
2. You mean DCS data, right? Not RL?
3. Going STR may not be the best tactic for an "energy" fighter.

[Cmptohocah]

7 hours ago, Top Jockey said:

My doubt is purely: what would be each one's absolute maximum Sustained Turn Rate, in degrees per second ?

 

( I'm not asking about Corner Speed, or Instantaneous Turn Rate, or minimum turn radius, etc... )

 

Does anyone have an aproximate idea ?

Thank you.

Here's a sustained turn rate for the real 29 (you can calculate turn rate from the speed and the G load):

P.S. Max STR at sea level is around 20.5 degrees/s (880km/h @ 9G)

Edited December 5, 2021 by Cmptohocah

[Ironhand]

23 hours ago, Top Jockey said:

Does anyone have an aproximate idea ?

For the F-14A STR in the sim at sea level is around 21.5°, maybe a bit more. Just fly it on rare occasions.

Edited December 5, 2021 by Ironhand

[Top Jockey]

On 12/4/2021 at 10:20 PM, captain_dalan said:

1. By time in burner, you mean, time till out of fuel and hit the ground or time till bingo? And if the latter, then what are the bingo states? Maybe a more concise fuel state would be more helpful? 
2. You mean DCS data, right? Not RL?
3. Going STR may not be the best tactic for an "energy" fighter.

 

Hello @captain_dalan,

1. It would be time till fuel out, as I would prefer to have an idea of performance in very light airframes;

2. Sure - DCS data would be enough for me, as RL data on those very specific conditions might not always be at hand;

(But, if you have RL data on similar conditions, that would be very good also.)

3. It's just a personal curiosity, as the max. degrees per second a given airframe can sustain always caught my attention.

[Top Jockey]

On 12/5/2021 at 12:58 AM, Cmptohocah said:

Here's a sustained turn rate for the real 29 (you can calculate turn rate from the speed and the G load):

P.S. Max STR at sea level is around 20.5 degrees/s (880km/h @ 9G)

 

 

Yes,

Very good already - and as I recall form talking to the Russian forum members, indeed the MiG-29A does have those characteristics; it does needed some speed to be able to maintain a good STR.

(At that time my comparison was between the Fulcrum and the Flanker... which the later supposedly can pull a little more G's at lower speeds).

 

17 hours ago, Ironhand said:

For the F-14A STR in the sim at sea level is around 21.5°, maybe a bit more. Just fly it on rare occasions.

 

 

Thank you @Ironhand, @Cmptohocah and @captain_dalan,

 

So on those light weights and low altitude conditions, is it reasonable to expect in real life conditions that :

 

The MiG-29A's maximum Sustained Turn Rate, could be roughly similar to the F-14A's (with its underpowered engines) ?

- empty weights:  the F-14A is almost twice heavier than the MiG-29A;

- Thrust / Weight ratio:  is better on the MiG-29A;

- Wing loading:  is better on the F-14A;

- Lift coefficients (CL max):  no idea which is better, I've read the MiG-29A's is supposedly 1.5 or something...

 

Several people here have explained to me that I've probably over-valued the Fulcrum's BFM turning capabilities in real life, but I mean... does it at the least have a more advantageous corner speed than the Tomcat, or something ?

 

[Cmptohocah]

3 hours ago, Top Jockey said:

 

Yes,

Very good already - and as I recall form talking to the Russian forum members, indeed the MiG-29A does have those characteristics; it does needed some speed to be able to maintain a good STR.

(At that time my comparison was between the Fulcrum and the Flanker... which the later supposedly can pull a little more G's at lower speeds).

....

Several people here have explained to me that I've probably over-valued the Fulcrum's BFM turning capabilities in real life, but I mean... does it at the least have a more advantageous corner speed than the Tomcat, or something ?

 

Sustained turn rate is a ratio between drag (induced mostly) and thrust. Once these two forces are equalized you get STR.
Flanker is limited to 8G, so there's no way it can match the STR of a 29 - it can't pull as much load.

MiG-29 is hell of a dog fighter and it was built with this in mind.

Please note: in a dogfight corner speed (max instantaneous turn rate) and sustained turn rate, are only advantages in a two-circle fight (2C). In a one-circle fight, the advantage is the turn radius.

Edited December 6, 2021 by Cmptohocah

[Top Jockey]

2 hours ago, Cmptohocah said:

Sustained turn rate is a ratio between drag (induced mostly) and thrust. Once these two forces are equalized you get STR.
Flanker is limited to 8G, so there's no way it can match the STR of a 29 - it can't pull as much load.

MiG-29 is hell of a dog fighter and it was built with this in mind.

Please note: in a dogfight corner speed (max instantaneous turn rate) and sustained turn rate, are only advantages in a two-circle fight (2C). In a one-circle fight, the advantage is the turn radius.

 

 

Regarding the Flanker's G limit I believe so, but then there's another side of the matter, which is :

 

At another thread I've oppened (1 year ago or so) in the Russian ED sub-forum, roughly 90 % of the members said that the Flanker can maintain slightly more Gs than the Fulcrum at slower speeds... essentially because:

" MiG-29 is a stable design, it's elevators acts opposite to wings decreasing it's overall lift, this increases AoA in turn (plane needs higher AoA for given G, thus bigger drag) and cause MiG to lose it's speed in turn faster than modern unstable designs like F-16 or Su-27. "

 (quoting @bies, from another thread)

 

- so this can end up giving the Flanker a better corner speed, or turn rates, at certain speeds ?

(Let's say, it can not pull 9 Gs, but probably at 330 kts it could pull more Gs than the Fulcrum at the same speed ?)

Edited December 6, 2021 by Top Jockey

[Cmptohocah]

2 hours ago, Top Jockey said:

...

- so this can end up giving the Flanker a better corner speed, or turn rates, at certain speeds ?

(Let's say, it can not pull 9 Gs, but probably at 330 kts it could pull more Gs than the Fulcrum at the same speed ?)

 

I don't have any charts for corner speeds for either Flanker nor Fulcrum, but corner speeds are max. Angle of Attack limited and are equal or higher than the max sustained turn speeds, so I would be wiling to bet that the 29's corner speed turn rate is higher to that of the 27.

It might as well be possible that the Flanker can pull out more Gs at 330kts, but this is irrelevant as it will produce much lower turn rate as it's well below the sustained TR of the MiG. So yeah, maybe it performs better at that speed, but keep the MiG at it's STR and that advantage is lost.

[Top Jockey]

19 minutes ago, Cmptohocah said:

I don't have any charts for corner speeds for either Flanker nor Fulcrum, but corner speeds are max. Angle of Attack limited and are equal or higher than the max sustained turn speeds, so I would be wiling to bet that the 29's corner speed turn rate is higher to that of the 27.

It might as well be possible that the Flanker can pull out more Gs at 330kts, but this is irrelevant as it will produce much lower turn rate as it's well below the sustained TR of the MiG. So yeah, maybe it performs better at that speed, but keep the MiG at it's STR and that advantage is lost.

 

I see, but here is where other members tell otherwise...

 

I've found the thread created at the Russian forum last year, see for instance the comment from @Dell_Murrey-RUS I selected on the link (use auto-translator):

https://forums.eagle.ru/topic/242422-sravnenie-manevrov-mig-29-i-su-27/?do=findComment&comment=4383553

 

Edited December 6, 2021 by Top Jockey

[Cmptohocah]

49 minutes ago, Top Jockey said:

 

I see, but here is where other members tell otherwise...

 

I've found the thread created at the Russian forum last year, see for instance the comment from @Dell_Murrey-RUS I selected on the link (use auto-translator):

https://forums.eagle.ru/topic/242422-sravnenie-manevrov-mig-29-i-su-27/?do=findComment&comment=4383553

 

 

You can always show them diagrams. Turn rates and turn radii are pure physics, so it's not something I invented - it's just facts

[Kefa]

 

From the German air force Mig-29  diagram, it can sustain  9G at 460kias.  You then convert from radians to degrees, then Mig-29 at 13,000kg can sustain a 21.2degree per second turn at sea level.  You can do the same with F-14A specific excess power diagrams to sea level.  And then basically add about 1.4 degree per second to the total because you subtracted the 8 air to air missiles and pylons.  

 

Anyways, the Fulcrum has a very good instantaneous turn.   And it also has a better maximum performance turn than even the Mirage 2000 according to this Indian Air Force pilot.

 

https://www.scribd.com/doc/21520658/Mirage-2000-Vs-MiG-29-Rivals-from-the-same-team

 

Even though Mig-29 has less fuel,  in certain cases shouldn't it need less afterburn usage in dogfights? While its other less powerful opponents like F-14,F-15, F-18, and most type of F-16 would need greater afterburn use to compensate.  -just my thoughts here.

 

 

 

 

 

Edited December 6, 2021 by Kefa

[Ironhand]

3 hours ago, Top Jockey said:

 

I see, but here is where other members tell otherwise...

 

I've found the thread created at the Russian forum last year, see for instance the comment from @Dell_Murrey-RUS I selected on the link (use auto-translator):

https://forums.eagle.ru/topic/242422-sravnenie-manevrov-mig-29-i-su-27/?do=findComment&comment=4383553

 

 

Cmptohocah is referring to corner speed (for max instantaneous turn rate), while Dell_Murrey-RUS is referring to sustained turn rate. There’s no contradiction.

[bies]

There is an interview with Ukrainian pilots regularly flying MiG-29s against Su-27s since 1980s.

According to the interview MiG-29 9-12 had better sustained turn rate than Su-27S and more G available in its envelope, but pilot has to be physically strong to make use of that. MiG-29 9-12 had higher thrust to weight than Su-27S which make its advantage more pronounced at higher altitudes.

(Obviously later MiG-29 variants grew in weight, decreased thrust to weight, increased wing loading etc.)

[Cmptohocah]

8 minutes ago, bies said:

There is an interview with Ukrainian pilots regularly flying MiG-29s against Su-27s since 1980s.

According to the interview MiG-29 9-12 had better sustained turn rate than Su-27S and more G available in its envelope, but pilot has to be physically strong to make use of that. MiG-29 9-12 had higher thrust to weight than Su-27S which make its advantage more pronounced at higher altitudes.

(Obviously later MiG-29 variants grew in weight, decreased thrust to weight, increased wing loading etc.)

Yup, Fulcrum has one 1G higher limit (9G) compared to that of a Flanker (8G). Sadly in DCS we have no effects of endlessly pulling high G: you 're not going to be looking around much and flipping switches at 8+ G in a real airplane.

[bies]

33 minutes ago, Cmptohocah said:

Yup, Fulcrum has one 1G higher limit (9G) compared to that of a Flanker (8G). Sadly in DCS we have no effects of endlessly pulling high G: you 're not going to be looking around much and flipping switches at 8+ G in a real airplane.

 

IRL Su-27 G limits are way more complicated than that.

According to manual Su-27 is limited to 8G at subsonic speed, limited to 6,5G at transsonic (Mach 0,85-1,25) speed, limited to 7G at supersonic speed. All of that is for so called "design weight" of 21,400 kg which means only 60% of fuel and only four AA missiles - quite lightweight and restricted configuration.

With more than 60% fuel / more weapon Su-27 is even more G limited. That's why all Su-27 fuel above 60% is called "internal external fuel tank" - it was an artificial way to make the Soviet Air Force to accept the aircraft and its G limits acceptable for them only at less than 60% fuel + 4 AA missiles.

(And that's the reason every fighter in DCS has default fuel set at 100%, but Su-27 default fuel is set automatically at 59% and if you want to take more fuel you have to change it manually)

Edited December 6, 2021 by bies

[Seaeagle]

13 hours ago, bies said:

 

IRL Su-27 G limits are way more complicated than that.

According to manual Su-27 is limited to 8G at subsonic speed, limited to 6,5G at transsonic (Mach 0,85-1,25) speed, limited to 7G at supersonic speed. All of that is for so called "design weight" of 21,400 kg which means only 60% of fuel and only four AA missiles - quite lightweight and restricted configuration.

Also known as "normal take-off weight".

13 hours ago, bies said:

With more than 60% fuel / more weapon Su-27 is even more G limited. That's why all Su-27 fuel above 60% is called "internal external fuel tank" - it was an artificial way to make the Soviet Air Force to accept the aircraft and its G limits acceptable for them only at less than 60% fuel + 4 AA missiles.

(And that's the reason every fighter in DCS has default fuel set at 100%, but Su-27 default fuel is set automatically at 59% and if you want to take more fuel you have to change it manually)

 

No it wasn't bies. Its refered to as "internal external fuel" because thats what it is - compare the amount to any other comparable fighter design. It was a design decision in connection with its intended role to take advantage of internal space for extra fuel instead of carrying it externally(no external tanks available for the Su-27) - less drag penalty, while freeing up external pylons for more weapons.

[Top Jockey]

14 hours ago, Kefa said:

 

From the German air force Mig-29  diagram, it can sustain  9G at 460kias.  You then convert from radians to degrees, then Mig-29 at 13,000kg can sustain a 21.2degree per second turn at sea level.  You can do the same with F-14A specific excess power diagrams to sea level.  And then basically add about 1.4 degree per second to the total because you subtracted the 8 air to air missiles and pylons.  

 

Anyways, the Fulcrum has a very good instantaneous turn.   And it also has a better maximum performance turn than even the Mirage 2000 according to this Indian Air Force pilot.

 

https://www.scribd.com/doc/21520658/Mirage-2000-Vs-MiG-29-Rivals-from-the-same-team

 

Even though Mig-29 has less fuel,  in certain cases shouldn't it need less afterburn usage in dogfights? While its other less powerful opponents like F-14,F-15, F-18, and most type of F-16 would need greater afterburn use to compensate.  -just my thoughts here.

 

 

Thank you.

I'm looking at some F-14A EM's I have although they all provide data for 5000 ft altitude and above...

Already knew the Mirage vs Fulcrum article - very interesting, and although the Mirage does have a very good nose pointing capability and outstanding pitch rate, it also does bleed speed fast while turning, no surprise at all.

 

Regarding less afterburner usage, I believe in that case the F-15C should also benefit from it, as its Thrust / Weight ratio is even higher than the MiG-29A's one.

 

14 hours ago, Ironhand said:

Cmptohocah is referring to corner speed (for max instantaneous turn rate), while Dell_Murrey-RUS is referring to sustained turn rate. There’s no contradiction.

 

Oh I see... didn't notice that.

Eitherway, if I've understood more or less correctly @Dell_Murrey-RUS's several inputs from that thread, he and several others eventually tell that in similar circumstances, the Su-27 would probably get into the MiG-29A's six o'clock easier, than the opposite...

 

And they justified it with :

The Su-27's ability to maintain a little bit more G (in sustained turn rate ?) than the MiG-29A, somewhere at speeds below 700 kph - even accounting with the fact that the MiG could achieve / maintain 9 G's at higher speeds ...

Do you agree that in those conditions the Su-27 would have the upper hand, or not at all ?

 

14 hours ago, bies said:

There is an interview with Ukrainian pilots regularly flying MiG-29s against Su-27s since 1980s.

According to the interview MiG-29 9-12 had better sustained turn rate than Su-27S and more G available in its envelope, but pilot has to be physically strong to make use of that. MiG-29 9-12 had higher thrust to weight than Su-27S which make its advantage more pronounced at higher altitudes.

(Obviously later MiG-29 variants grew in weight, decreased thrust to weight, increased wing loading etc.)

 

Yes, I believe they also mentioned something like that in the Russian forum thread.

On Thrust / Weight ratios:

Maybe it's an error on my part; but comparing both airframe's with completely empty weights, both Su and the MiG's T/W ratios seem very similar: 1.52 ?

And if one add's for example 1000 kg fuel to each, the Su-27S T/W ratio will be higher than the MiG-29A... or I'm i mistaken ?

Edited December 7, 2021 by Top Jockey

[Kefa]

@Top Jockey Look in the manual at Specific Excess Power diagrams.  F-14A at 5G down to sea level  translates to about 17.2degree per second, at 6.5G it is 16.8.  So top of PS-0 slope is probably about 17.6dps.  Lose the 8aams/ gun ammo/ all pylons and you are probably at about 19dps.   

 

  

 

Edited December 7, 2021 by Kefa

[Top Jockey]

1 hour ago, Kefa said:

@Top Jockey Look in the manual at Specific Excess Power diagrams.  F-14A at 5G down to sea level  translates to about 17.2degree per second, at 6.56G it is 16.8.  So top of PS-0 slope is probably about 17.6dps.  Lose the 8aams/ gun ammo/ all pylons and you are probably at about 19dps.   

 

  

 

 

 

Hello,

Which manual exactly ?

[Ironhand]

3 hours ago, Top Jockey said:

Eitherway, if I've understood more or less correctly @Dell_Murrey-RUS's several inputs from that thread, he and several others eventually tell that in similar circumstances, the Su-27 would probably get into the MiG-29A's six o'clock easier, than the opposite...

 

And they justified it with :

The Su-27's ability to maintain a little bit more G (in sustained turn rate ?) than the MiG-29A, somewhere at speeds below 700 kph - even accounting with the fact that the MiG could achieve / maintain 9 G's at higher speeds ...

Do you agree that in those conditions the Su-27 would have the upper hand, or not at all ?

Actually, they are not saying that in "similar circumstances"; they are saying in certain circumstances--specifically, lower altitudes and slower speeds--the Su-27 has the rate and radius advantage.

Only had a few minutes to fly this morning but, with 6 quick flights at 300m altitude at similar air speeds, this is what I got. I wasn't being too picky about my flying but the results illustrate what they are saying about slower speeds and lower altitude:

So, sure, in certain situations--flat turns at low altitudes and speeds--the Su-27 will have the advantage. Obviously, I didn't fly at high altitude and compare results. Maybe another day.

[Top Jockey]

1 hour ago, Ironhand said:

Actually, they are not saying that in "similar circumstances"; they are saying in certain circumstances--specifically, lower altitudes and slower speeds--the Su-27 has the rate and radius advantage.

Only had a few minutes to fly this morning but, with 6 quick flights at 300m altitude at similar air speeds, this is what I got. I wasn't being too picky about my flying but the results illustrate what they are saying about slower speeds and lower altitude:

So, sure, in certain situations--flat turns at low altitudes and speeds--the Su-27 will have the advantage. Obviously, I didn't fly at high altitude and compare results. Maybe another day.

 

Outstanding @Ironhand - precisely what I wanted to know !

No need to test at high altitudes; these are already the parameters in which I was most interested at.

 

Yes, I didn't explain myself well: for "similar circumstances" I meant - for both aircraft (clean config, very low fuel states, etc.)

 

... but then studying that chart, some doubts appear on my mind :

- i guess in a 2 circle fight,  the MiG flying at 850 kph doing 20,5 deg/sec, would eventually prevail over the Su-27 at 640 kph doing 19,3 deg/sec ;

- but then, the Su-27 pilot could force a 1 circle fight and use its smaller turn radius ;

- also, the Su-27 flying at 970 kph doing 21,7 deg/sec, would be of little use, because of the big turn radius factor ?

So, in conclusion one can say, that between those 2 airframes there isn't one which might be significantly better than the other in ACM ?

(Not talking about pilot skill.)

 

Edited December 7, 2021 by Top Jockey