Mig-29 turn rate

[Cmptohocah]

23 minutes ago, Skysurfer said:

We have data for the 29A (9.12) from the GAF manuals and those match DCS reasonably well. 9.13 (29S) should have only slightly more max AOA and controlability. 

DDR's 29's were export versions and to my knowledge the engines were tuned down (de-rated) to increase service life.

[XPACT]

2 hours ago, stefasaki said:

Here's a video of the 13 seconds turn (4:25 -> 4:38)

 

Looks to me more like 14 - 14.5 seconds and that is possible to accomplish in the sim, anyway even if it was 13 both flight models seem very realistic at subsonic flight.

 

Tho there are debates with IRL videos and even I have my own doubts about transonic and supersonic performance of Su-27, seems a bit underwhelming.

[Skysurfer]

3 hours ago, Cmptohocah said:

DDR's 29's were export versions and to my knowledge the engines were tuned down (de-rated) to increase service life.

 

Not to my knowledge. Just a regular export 9.12 without IFF.

[Top Jockey]

15 minutes ago, Skysurfer said:

 

Not to my knowledge. Just a regular export 9.12 without IFF.

 

If I recal correctly from what I've read somewhere, what Cmptohocah mentions is that the Germans themselves de-tuned the engines a little bit to increase their lifespan, after already having them in service.

 

So it might mean that, they arrived originally with their "full power" as per what is stated on the manuals...

Edited April 1, 2021 by Top Jockey

[Skysurfer]

8 minutes ago, Top Jockey said:

 

If I recal correctly from what I've read somewhere, what Cmptohocah mentions is that the Germans themselves de-tuned the engines a little bit to increase their lifespan, after already having them in service.

 

So it might mean that, they arrived originally with their "full power" as per what is stated on the manuals...

 

 

Seems more plausible but I'd really need a source for that.

[dundun92]

The GAF MiG-29 manuals have turn performance numbers for both full and limited power anyway so it really doesnt matter.

[Top Jockey]

6 minutes ago, dundun92 said:

The GAF MiG-29 manuals have turn performance numbers for both full and limited power anyway so it really doesnt matter.

 

Even better. 

[MiGCap1]

2 hours ago, Skysurfer said:

 

Seems more plausible but I'd really need a source for that.

 

 

The statement of Top Jockey is correct. We curtailed the engine power a little bit to extend the life time after the jets were taken over from the LSK/LV in the Luftwaffe, but in daily flight ops that meant that we used the burner more often so the benefit was, let me say, limited ...

 

If You need more detailed information, I have to look into my notes. It is nearly 17 years ago now that I flew the last time in a FULCRUM and I am no frontseater, only flight crew. But I handled a lot of public affairs work of our FULCRUM squadron.

Edited April 2, 2021 by MiGCap1

[Ironhand]

10 hours ago, XPACT said:

...With better control, lower AOA hence lower maximum G's, you can do perfect circle with minimal speed loss (entry 750km/h and exit at around 650km/h) and do it in 16 seconds...

 

 Well...if you’re dropping speed during the turn, it won’t be a perfect circle. The rate will be dropping and the circle will be getting tighter as the speed slows. Which brings us to the Farnsborough 1988 routine.

 

In watching that 360, he starts that turn rating his nose at 28+  d/s. He’s pulling over 9 Gs. He makes the first 180 in about 6 sec. The next 90 takes 4 (22.5) and the final 90 takes 6 (15). So his is anything but a perfect circle too.

[XPACT]

1 hour ago, Ironhand said:

 Well...if you’re dropping speed during the turn, it won’t be a perfect circle.

 

haha yeah, should've written it like this: "perfect circle" it is close enough at 750km/h - 650km/h to the naked eye atleast heck even that video I posted while flying like a maniac when you switch to ground camera it looks like a circle and mimics the video OP posted perfectly hehe, but tacview well khmmm

 

1 hour ago, Ironhand said:

The rate will be dropping and the circle will be getting tighter as the speed slows.

 

Yup, damn physics hehe, it also shows in the video I posted, since there I entered with around 800km/h and ended up at 480km/h, plane started above runway and ended up on the right side of it by like 50m

[Cmptohocah]

6 hours ago, Ironhand said:

 

 Well...if you’re dropping speed during the turn, it won’t be a perfect circle. The rate will be dropping and the circle will be getting tighter as the speed slows.

Technically speaking, if you can keep the AoA the same as the speed drops the [turn] rate will increase as the lift coeficient is not dependent on speed.

[TotenDead]

2 часа назад, Cmptohocah сказал:

 as the lift coeficient is not dependent on speed.

Cy=S(Ya*pV^2)/2
V stands for speed, so you're wrong, it's dependent

 

[Skysurfer]

2 hours ago, TotenDead said:

Cy=S(Ya*pV^2)/2
V stands for speed, so you're wrong, it's dependent

 

 

CL is coupled with AOA - you can stall or have any AOA at any speed. 

[Ironhand]

10 hours ago, XPACT said:

...should've written it like this: "perfect circle"...

 

I wasn't particularly worried about it. I just didn't want someone stumbling across this thread in the future and thinking they had the formula for a perfect circle. They'd have become very frustrated.

[TotenDead]

2 минуты назад, Skysurfer сказал:

 

CL is coupled with AOA - you can stall or have any AOA at any speed. 

Of course it is, because AOA changes lift (Ya) and lift is part of the equation i wrote

[stefasaki]

16 hours ago, XPACT said:

 

Looks to me more like 14 - 14.5 seconds and that is possible to accomplish in the sim, anyway even if it was 13 both flight models seem very realistic at subsonic flight.

 

Tho there are debates with IRL videos and even I have my own doubts about transonic and supersonic performance of Su-27, seems a bit underwhelming.

The last 1-1.5 seconds you are referring to are needed to align with the runway, the turn is already completed. If anything it looks closer to 13 than 14 seconds. You cannot replicate that time in DCS without over g-ing or disabling the FBW.

 

Yeah, I know about the problems in the transonic region, I hope that will get fixed, as it certainly is a bigger problem than the probably slightly underestimated Cl max.

 

edit: actually the Cl max may be correct, it's just that the FBW in the sim fails to keep max AOA as the speed drops below cornering speed and therefore the Cl decreases. if the aircraft were capable of keeping max AOA for the entire circle then we might see a 13 sec full turn even in DCS

Edited April 2, 2021 by stefasaki

[Skysurfer]

8 minutes ago, TotenDead said:

Of course it is, because AOA changes lift (Ya) and lift is part of the equation i wrote

 

There is a lot more to it than just one equation, buddy. Zero alpha lift coefficient isn't a CL over alpha plot.

[Yo-Yo]

9 minutes ago, TotenDead said:

Of course it is, because AOA changes lift (Ya) and lift is part of the equation i wrote

Nobel Prize...

CL = f(AoA) and does not depend on dynamic pressure within subsonic range of M (M<0.9 generally) for this class of aircraft.

 

[TotenDead]

2 минуты назад, Yo-Yo сказал:

Nobel Prize...

CL = f(AoA) and does not depend on dynamic pressure within subsonic range of M (M<0.9 generally) for this class of aircraft.

 

So, lift coefficient does not depend on lift, did i get it right?

[Skysurfer]

4 minutes ago, TotenDead said:

So, lift coefficient does not depend on lift, did i get it right?

 

You are literally arguing with SME's right now. 

 

Educate yourself first before you start an argument. https://www.aero.sors.fr/aerolinks.html

[Yo-Yo]

23 minutes ago, TotenDead said:

So, lift coefficient does not depend on lift, did i get it right?

Yes. It's just f(AoA, M). 

 

[TotenDead]

23 минуты назад, Skysurfer сказал:

 

You are literally arguing with SME's right now. 

So what?

 

23 минуты назад, Skysurfer сказал:

Educate yourself first before you start an argument. https://www.aero.sors.fr/aerolinks.html

Perhaps you'd better educate yourself

 

Цитата

The lift coefficient (CL) is a dimensionless coefficient that relates the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area.

 

 

 

You might argue as much as you like, but aerodynamics and mathematics clearly shows that if you loose speed you loose CL

[Skysurfer]

Clearly if you reduce the denomintor you'll get a lower value in your book. That's not how fractions work buddy. Don't embarass yourself even more and let's please stay on topic.

Edited April 2, 2021 by Skysurfer

[TotenDead]

1 минуту назад, Skysurfer сказал:

Clearly if you reduce the denomintor you'll get a lower value in your book. That's not how fractions work buddy. Don't embarass yourself even more and let's please stay on topic.

 

So you recognized that you were mistaken? Good for you, chap.

[Yo-Yo]

40 minutes ago, TotenDead said:

So what?

 

Perhaps you'd better educate yourself

 

 

 

You might argue as much as you like, but aerodynamics and mathematics clearly shows that if you loose speed you loose CL