FBW sensitivity between Mig-29 / Su-27S

[Fri13]

Just found this video and noticed about the stick radical correction moves the pilot does to stay nicely on the formation after take-off.

 

https://youtu.be/Z3jsJwIH4NM?t=212

 

Isn't that a Mig-29 they are flying?

 

As I was wondering how much different the FBW is to Su-27S?

As right now in the DCS the Su-27 stick controls are very sensitive for everything. I have 28cm extension on the stick (G940 for KA-50) and I can't at all do that kind movements without flipping Su-27 around.

Edited July 2, 2015 by Fri13
Typo 38 > 28

[sobek]

The 4th gen Mig-29 variants have no FBW. When flown to the edge, it supposedly puts a very high workload onto the pilot.

Edited July 1, 2015 by sobek

[Fri13]

The 4th gen Mig-29 variants have no FBW. When flown to the edge, it supposedly puts a very high workload onto the pilot.

 

Interesting to know.

 

But how does that really behave in Su-27, as i have seen in some videos the pilots to do similar "radical" movements without aircraft pulling around instantly. As I find it difficult to believe that any fighter would have so sensitive stick that moving just 1cm to any direction (so +-1cm) gives maximal effect for turning etc?

[Alfa]

Just found this video and noticed about the stick radical correction moves the pilot does to stay nicely on the formation after take-off.

 

https://youtu.be/Z3jsJwIH4NM?t=212

 

Isn't that a Mig-29 they are flying?

 

No its in fact an Su-27S(or a -UB maybe). The footage first shows MiG-29s taking off, but then cuts to in-cockpit view of an Su-27.

 

The sequence showing Russian jets is from a separate video, where the "Russian Knights"(Su-27 display team) fly together with the "Strizhi"(MiG-29 display team) - IIRC the video was recorded with a mix of external(MiG-29 with a Go-pro camera attached to the vertical stabs) and internal(Su-27 cockpit cam) sequences.

 

As I was wondering how much different the FBW is to Su-27S?

 

As Sobek mentioned, the "baseline" MiG-29 has a mechanical flight-control system(no FBW).

[Fri13]

No its in fact an Su-27S(or a -UB maybe). The footage first shows MiG-29s taking off, but then cuts to in-cockpit view of an Su-27.

 

The sequence showing Russian jets is from a separate video, where the "Russian Knights"(Su-27 display team) fly together with the "Strizhi"(MiG-29 display team) - IIRC the video was recorded with a mix of external(MiG-29 with a Go-pro camera attached to the vertical stabs) and internal(Su-27 cockpit cam) sequences.

 

That is interesting, as I felt that cockpit was familiar but didn't really look closely as assumed it was Mig-29 as previous part was just about Mig-29 before jumping to western ones. :)

 

 

As Sobek mentioned, the "baseline" MiG-29 has a mechanical flight-control system(no FBW).

 

That came clear, except that way how "Baseline" is in quotes? :-p

 

But still wondering the main thing, the FBW allows pilot to do more accurate control changes because the computer/hydraulics doesn't allow pilot to pull a dangerous maneuver in flight parameters that isn't smart, and eases the pilot physical workload by allowing to do the heavier control movements when it would be very stressful.

 

But I have the 28cm extension in my G940 stick as I mentioned, and Su-27S in DCS doesn't allow to use any curves etc because otherwise the force feedback is not correct. And yet with that extension I have very much difficulties to fly because I need to make very very carefull and small stick controls (like mentioned) without Su-27S going crazy Ivan, like suddenly push to negative G on takeoff and hit hard on ground etc. I can't at all do the similar movements that the pilot did on that video.

 

I have flied the Su-27S mostly with the extended stick but tried once or twice with factory design (non-extended) and even on the SFM modeling it was very difficult to fly as slightest movement made huge changes. And no when the AFM was out I have only had the extended stick and find it still very "aggressive" to slight movements.

 

So just wondering that how it really should be on Su-27 in real world about as in some videos you can see pilots to do those radical movements and plane doesn't react much to them. And in some documentary you can hear pilot to explain how the FBW makes sure that pilot gets very easy handling and doesn't react to radical movements that would be dangerous. It just doesn't meet at all with my experience on DCS, that I can only place to lack of the curves adjustments?

[Alfa]

 

That came clear, except that way how "Baseline" is in quotes? :-p

 

No particular reason except perhaps that the MiG-29SMT retains the mechanical flight-control system, but isn't really "baseline" :)

 

But still wondering the main thing, the FBW allows pilot to do more accurate control changes because the computer/hydraulics doesn't allow pilot to pull a dangerous maneuver in flight parameters that isn't smart, and eases the pilot physical workload by allowing to do the heavier control movements when it would be very stressful.

 

But I have the 28cm extension in my G940 stick as I mentioned, and Su-27S in DCS doesn't allow to use any curves etc because otherwise the force feedback is not correct. And yet with that extension I have very much difficulties to fly because I need to make very very carefull and small stick controls (like mentioned) without Su-27S going crazy Ivan, like suddenly push to negative G on takeoff and hit hard on ground etc. I can't at all do the similar movements that the pilot did on that video.

 

I have flied the Su-27S mostly with the extended stick but tried once or twice with factory design (non-extended) and even on the SFM modeling it was very difficult to fly as slightest movement made huge changes. And no when the AFM was out I have only had the extended stick and find it still very "aggressive" to slight movements.

 

So just wondering that how it really should be on Su-27 in real world about as in some videos you can see pilots to do those radical movements and plane doesn't react much to them. And in some documentary you can hear pilot to explain how the FBW makes sure that pilot gets very easy handling and doesn't react to radical movements that would be dangerous. It just doesn't meet at all with my experience on DCS, that I can only place to lack of the curves adjustments?

 

I don't know mate - I have no experience with the DCS Su-27/PFM(my old PC cannot run DCS world) or the stick in question, so I am afraid I can't help you with that.

[ФрогФут]

The 4th gen Mig-29 variants have no FBW. When flown to the edge, it supposedly puts a very high workload onto the pilot.

Does F-15 do that? Not really. Why should MiG-29 with practically the same flight control system do?:)

[sobek]

Does F-15 do that? Not really. Why should MiG-29 with practically the same flight control system do?:)

 

It's just what i read in a report from a NATO pilot flying one. He mentioned that he found the controls rather sluggish and that he had to work the stick hard to counter the uncommanded movement that it exhibited. I'm not going to claim that it is gospel though. That's why i said "supposedly".

 

Besides, both planes are quite different, aerodynamically.

Edited July 5, 2015 by sobek

[ФрогФут]

It's just what i read in a report from a NATO pilot flying one. He mentioned that he found the controls rather sluggish and that he had to work the stick hard to counter the uncommanded movement that it exhibited. I'm not going to claim that it is gospel though. That's why i said "supposedly".

 

Besides, both planes are quite different, aerodynamically.

 

Big stick moves are made intentionally and if pilot is aware of some features in controls, he can easily control it at AoA much higher, than allowed range. The main difference between such electromechanical control system and analogue FBW, like Su-27 has - how fast and it what range can the CS operate, which is essential, when plane is unstable.

Edited July 5, 2015 by ФрогФут

[Bucic]

Guys, you've just moved to U vs X vs Y without establishing even the very basic features of each of the control systems. I have subscribed to the topic to learn about this myself. I just don't think this kind of discussion gets us anywhere. The report sobek is referring to has been drafted by an experienced pilot and mentions some specifics of the '29 control system design.

 

I hope he don't mind I used his post here)

 

I shouldn't think so, as fulcrumflyer is a member of our forums: :applause:

http://www.f-16.net/index.php?name=PNphpBB2&file=viewtopic&p=155456#155456

Handling

Of the four fighters I have flown, the MiG-29 has by far the worst handling qualities. The hydro-mechanical flight control system uses an artificial feel system of springs and pulleys to simulate control force changes with varying airspeeds and altitudes. There is a stability augmentation system that makes the aircraft easier to fly but also makes the aircraft more sluggish to flight control inputs. It is my opinion that the jet is more responsive with the augmentation system disengaged. Unfortunately, this was allowed for demonstration purposes only as this also disengages the angle-of-attack (AoA) limiter. Stick forces are relatively light but the stick requires a lot of movement to get the desired response. This only adds to sluggish feeling of the aircraft. The entire time you are flying, the stick will move randomly about one-half inch on its own with a corresponding movement of the flight control surface. Flying the Fulcrum requires constant attention...

 

@OP

Do some representative scenario and post your track. If the real vs simulated discrepancy is really evident, this may qualify to be reported as a bug.

Just one more thing. Long stick won't do miracles if you have poor joystick sensors.

On that note:

Wishlist - Smooth movement of aircraft controls

Edited July 5, 2015 by Bucic