Su-27 - breaking vertcal stabilisers

[winchesterdelta1]

Broken my stabs 3 times in the last two weeks with no intentional rudder input. Thanks ED, twist stick users either stop using rudder, assign it to buttons, buy pedals or fly F-15.

Good job ED thanks.:thumbup:

 

 

Ahhh that is what's going on lately when i fly SU-27. I break it more then the time everybody was complaining about it when structural damage was introduced and it was very easy to break the wings. So the rudder input is the culprit?

[DarkFire]

Ahhh that is what's going on lately when i fly SU-27. I break it more then the time everybody was complaining about it when structural damage was introduced and it was very easy to break the wings. So the rudder input is the culprit?

 

Yes. In the real Su-27 at speeds above 600 Km/h the rudder is limited to 33% deflection by the flight control system. This doesn't appear to be modelled in DCS yet, hence the ability to break the vertical stabilisers at higher speeds.

[JazonXD]

Chiming in a bit late, but I remember when the SU-27 wing break thing was happening and people discussing about pulling 13 something Gs on the F-15 in real life and not breaking the wings, apparently when pulling really high Gs like that actually has a tendency to bend the vertical stabilizers too, to quite a large extent. I don't have documentation to back it up, but the person who mentioned this did.

[Pocket Sized]

He might have been talking about

 

A) During high AoA, high G pulls, the turbulence coming from the wings creates lots of buffeting and flexing in the vertical stabilizers.

 

B) Pulling lots of G while rolling puts huge amounts of lateral stress on the stabilizers, apparently this is where asymmetric G limits come from, but I'm not 100% sure on that.

[GGTharos]

Yes, but it isn't relevant to a flanker. Different airframes, different limits.

 

Chiming in a bit late, but I remember when the SU-27 wing break thing was happening and people discussing about pulling 13 something Gs on the F-15 in real life and not breaking the wings, apparently when pulling really high Gs like that actually has a tendency to bend the vertical stabilizers too, to quite a large extent. I don't have documentation to back it up, but the person who mentioned this did.

[Gruja]

I guess, you would be in court martial in RL for the actions you performed. You INTENTIONALLY pulled the plane in extremal sideslip at high speed swinging it resonantly... The plane did not want to let you break the fins for the first time, but you were full of vim to complete the deal.

 

 

Let's refresh this topic...

[Teknetinium]

I hope ED implement the safe system for lateral-Gs soon.

In RL Su-27 have a safe-system as for the G-limits.

Broke my tailfins by using rudders to hard in order to get a faster roll.

Hard to catch you self in stressed situation.

Edited April 30, 2017 by Teknetinium

[VZ_342]

Activating an 18 kg resistance mechanism to the rudder pedals just makes it more difficult for the pilot to achieve the 1/3rd deflection limit.

 

This can be simulated by adjusting the curves of the rudder axis in the game. I would set it to 30% deflection when 80% pedal travel has occured, and then a gradual increase to 50% rudder at 100% pedal deflection.

 

Of course, ideally this scaling should be automatic depending on airspeed...at 300 km/h 100% deflection is survivable, but at 1000 km/h one would want minimal or no rudder deflection.

 

That's my 2 rubles...incidentally I flew the 27 for the first time yesterday, and noticed I could fly with my feet off the pedals entirely, it was that easy to operate. Never lost control, unlike my first few F-15 flights.

[Esac_mirmidon]

Gruja you are pulling FULL RIGHT PEDAL at 960 Km/h. Well OVER the maximum allowed on the real manual.

 

Watch your ball fully displaced to one side.

 

And also you dont need pedals for air combat on the Su-27.

[DarkFire]

That's my 2 rubles...incidentally I flew the 27 for the first time yesterday, and noticed I could fly with my feet off the pedals entirely, it was that easy to operate. Never lost control, unlike my first few F-15 flights.

 

Indeed you can. The flight control system will perform ~90% co-ordinated turns for you so using the rudder in normal flight simply isn't necessary. The only times you need to touch the rudder at all are:

 

1. To increase roll authority in high-AOA conditions.

2. Cross-wind landings.

3. Ground movement with significant wind conditions.

[DarkFire]

Let's refresh this topic...

 

FEET. OFF. THE. RUDDER!!!!

 

None of what you did in that recording needed any rudder input whatsoever. If you're going to command full rudder deflection at that sort of airspeed then expect the stabs to break. The actual Su-27S manual says exactly that.

 

ED deliberately degrading the Su-27? Remove the tin foil hat, suggesting such irrational conspiracy theories does nobody any credit.

[Axion]

Why are you suggesting the everybody operates the rudder with their .FEET!? That's a pretty short sighted view in my opinion.

[rrohde]

ED deliberately degrading the Su-27? Remove the tin foil hat, suggesting such irrational conspiracy theories does nobody any credit.

 

+1

[Falcon_S]

...If you're going to command full rudder deflection at that sort of airspeed then expect the stabs to break. The actual Su-27S manual says exactly that.

 

Master, we know that. We know too that DCS Su-27 have simulated load/force on the stabilizers and adequate result/consequence of that force called disaster - breaking vertical stabilisers. But in same time DCS Su-27 have no simulated/modeled limiter that prevent this disaster.

...The actual Su-27S manual says exactly that.

 

Su-27S manual says that there is limiter with 17kg force on pedals too.

 

Why? Answer are persistently ignored here and offered alternatives by various thinkers and philosophers. The fact is that we have a problem with DCS Su-27 because is simply incomplete. Here we are trying to point out exactly that.

 

FEET. OFF. THE. RUDDER!!!!

 

 

THAT. WILL. NOT. HELP. US. TO. HAVE. "COMPLETED". DCS SU-27!!!!

 

 

I don`t know why is hard to agree that here is defect/fault/failure (call it however) on DCS Su-27. No conspiracy theory here. Just the facts.

Edited May 1, 2017 by Falcon_S

[Gruja]

Why are you suggesting the everybody operates the rudder with their .FEET!? That's a pretty short sighted view in my opinion.

 

+1

 

 

I have X-52pro and my rudder is on stick.

In the moment of breaking i didn't do full left twist of stick but just slight one because i was banking left. It is simple natural to do that slight twist because of angle of stick in my hand....

Esac.... ball was fully displaced to one side after first vertical was broken as you can see if you compare first and second video and then after that second vertical was off...

Point of this is to not do full rudder but not rudder at all....

Edited May 1, 2017 by Gruja

[Esac_mirmidon]

I know It could be hard for people to not move the twist grip rudder while flying. I have a X-55 with the twist cancelled because i have pedals.

 

And i agree that the Su-27 need the rudder límiter be modelled.

 

But understand also that breaking the stabs at such speeds because pushing the rudder, only x2 ball diameter is enough over 650 km/h, is what you must expect.

[Dehuman]

+1

 

 

I have X-52pro and my rudder is on stick.

In the moment of breaking i didn't do full left twist of stick but just slight one because i was banking left. It is simple natural to do that slight twist because of angle of stick in my hand....

Esac.... ball was fully displaced to one side after first vertical was broken as you can see if you compare first and second video and then after that second vertical was off...

Point of this is to not do full rudder but not rudder at all....

 

I am also using a twist rudder, however that is what a deadzone is for. Few seconds to set and unintentional rudder inputs are gone.

[DarkFire]

Master, we know that. We know too that DCS Su-27 have simulated load/force on the stabilizers and adequate result/consequence of that force called disaster - breaking vertical stabilisers. But in same time DCS Su-27 have no simulated/modeled limiter that prevent this disaster.

 

Su-27S manual says that there is limiter with 17kg force on pedals too.

 

Why? Answer are persistently ignored here and offered alternatives by various thinkers and philosophers. The fact is that we have a problem with DCS Su-27 because is simply incomplete. Here we are trying to point out exactly that.

 

THAT. WILL. NOT. HELP. US. TO. HAVE. "COMPLETED". DCS SU-27!!!

 

I don`t know why is hard to agree that here is defect/fault/failure (call it however) on DCS Su-27. No conspiracy theory here. Just the facts.

 

Actually I agree completely with you: our Su-27 absolutely should have the deflection limiter modelled so as to be as accurate as possible. "Feet off the rudder" is a metaphorical phrase, since actual pilots typically use their feet to control the rudders. We as virtual pilots can of course can use hands, feet or whatever appendages are useful.

 

My comment about conspiracy theories was not aimed at the fact that our Su-27 isn't complete. Watch the video that Gruja posted: in it he states that the DCS Su-27 has been deliberately constrained. If this is true then so has every other aircraft in DCS! The F-15C is missing half its radar modes, the A-10C is missing a bunch of stuff compared to the modern tranche of that aircraft, the list goes on.

 

There are any number of reasons why ED or a partner dev team might not be able to model each and every feature of a particular aircraft, and we have also seen many times that development continues after an aircraft becomes available to us. Finally, anyone who's been around ED products for a while will be aware that they strive for maximum accuracy where possible, and that notional "balance" is not a consideration for them.

 

Missing features are common for many reasons, but to suggest that one aircraft has been deliberately downgraded compared to others is totally illogical, hence the term conspiracy theory. And yes, in this case I do use the term as a pejorative. This particular conspiracy theory is not supported by facts, logic or the history of the development team behind DCS. DCS isn't a MOBA, first person shooter or a PVP RPG where balance is critical for the success of the game. DCS is about strict realism as far as is possible.

 

Anyway, apologies for the wall of text. We agree entirely on the ideal of a fully modelled Su-27, but this notion that ED have deliberately crippled it is a conspiracy theory and an entirely irrational one.

Edited May 1, 2017 by DarkFire

[captain_dalan]

+1

 

 

I have X-52pro and my rudder is on stick.

In the moment of breaking i didn't do full left twist of stick but just slight one because i was banking left. It is simple natural to do that slight twist because of angle of stick in my hand....

Esac.... ball was fully displaced to one side after first vertical was broken as you can see if you compare first and second video and then after that second vertical was off...

Point of this is to not do full rudder but not rudder at all....

 

Ouch! Yeah, i can guess how that feels like. That's why i never use twist axis for rolls ad well. Well....until a full separate Su-27 module with full cockpit systems comes out (if ever) i suggest what some of the others have mentioned. Deadzone and sensitivity curve. I've added a bit of a deadzone even to my pitch/roll axis.

[Falcon_S]

Actually I agree completely with you: our Su-27 absolutely should have the deflection limiter modelled so as to be as accurate as possible. "Feet off the rudder" is a metaphorical phrase, since actual pilots typically use their feet to control the rudders. We as virtual pilots can of course can use hands, feet or whatever appendages are useful.

 

My comment about conspiracy theories was not aimed at the fact that our Su-27 isn't complete. Watch the video that Gruja posted: in it he states that the DCS Su-27 has been deliberately constrained. If this is true then so has every other aircraft in DCS! The F-15C is missing half its radar modes, the A-10C is missing a bunch of stuff compared to the modern tranche of that aircraft, the list goes on.

 

There are any number of reasons why ED or a partner dev team might not be able to model each and every feature of a particular aircraft, and we have also seen many times that development continues after an aircraft becomes available to us. Finally, anyone who's been around ED products for a while will be aware that they strive for maximum accuracy where possible, and that notional "balance" is not a consideration for them.

 

Missing features are common for many reasons, but to suggest that one aircraft has been deliberately downgraded compared to others is totally illogical, hence the term conspiracy theory. And yes, in this case I do use the term as a pejorative. This particular conspiracy theory is not supported by facts, logic or the history of the development team behind DCS. DCS isn't a MOBA, first person shooter or a PVP RPG where balance is critical for the success of the game. DCS is about strict realism as far as is possible.

 

Anyway, apologies for the wall of text. We agree entirely on the ideal of a fully modelled Su-27, but this notion that ED have deliberately crippled it is a conspiracy theory and an entirely irrational one.

 

Agree and understand. :thumbup:

 

Don`t worry about wall of text... my is bigger:)

Anyway, apologies for the wall of text.

[Pocket Sized]

Will the rudder pedal limiter be enough to prevent exceeding the aforementioned ball deflection at high speeds? My haphazard guess is a pretty firm no.

 

This is a bit of a tricky issue to tackle from a piloting perspective. Those massive rudder surfaces are fantastic for swinging the nose around at low speed, but can put extreme loads on the stabilizers at high speed... which most of us seem to have discovered the hard way.

 

Just like the negative AoA departure, I believe this is something that can only be prevented through piloting technique. (AKA don't touch it unless you're trying to maneuver at high AoA)

[Falcon_S]

Will the rudder pedal limiter be enough to prevent exceeding the aforementioned ball deflection at high speeds? My haphazard guess is a pretty firm no.

...

 

Sure, but i think it would be much less accidental rudder spikes and disasters at high speed fights.

[Tello]

But already touching the rudder at "high speed fights" make for a unstable curve. I would say just leave it for the high AoA dogfights. I feel I have all the power I need. being the only limit is me :music_whistling:

 

Sure, but i think it would be much less accidental rudder spikes and disasters at high speed fights.

[Gruja]

I am also using a twist rudder, however that is what a deadzone is for. Few seconds to set and unintentional rudder inputs are gone.

 

Ouch! Yeah, i can guess how that feels like. That's why i never use twist axis for rolls ad well. Well....until a full separate Su-27 module with full cockpit systems comes out (if ever) i suggest what some of the others have mentioned. Deadzone and sensitivity curve. I've added a bit of a deadzone even to my pitch/roll axis.

 

 

 

Yea you are wright but.... One day before Red Flag i reboot my system. After installing FC i forgot to set up curves and saturation for rudder axis as i has before. But even then those slight turns should not break verticals. Point is to not do full twist of stick as i didn't do. So everyone who do even slight rudder turn will be instantly punished witch is sad....

[Ironhand]

Yea you are wright but.... One day before Red Flag i reboot my system. After installing FC i forgot to set up curves and saturation for rudder axis as i has before. But even then those slight turns should not break verticals. Point is to not do full twist of stick as i didn't do. So everyone who do even slight rudder turn will be instantly punished witch is sad....

 

In my limited experimentation with this it seems that it's not necessarily the rudder application alone. You can get away with quite a bit if doing it in straight and level flight. It becomes a far more serious issue, however, when done in the course of maneuvering. In those situations using them becomes far more hazardous to your health. At around 700 km/hr I can swing my nose back and forth all day if flying with little or no Gs. Start maneuvering at the same time, however, and it's a different story.