Failures and G-Effects Problems (SU-27)

[Worrazen]

I need to take a look at the russian cockpit, since someone said earlier that the FCS Red Light is actually "CDU" in the Russian version ....

 

The game might have it's warnings altogether not as accurate, maybe there's a number of things going on behind those lights, and yes in the practical version you'd have it like, we can't add more ligts to separate things, but we can at least clean up this for testing and editor purposes so there is a valid reason for solving this although yes it may not be anywhere high at the priority list but what the heck as I said, helping anywhere I could still better than nothing.

 

 

I am so upset I deleted that video, I think all the lights except stall were turned on, but maybe I had this "secondary hydraulics" you talk about. And unless we actually debug or let a developer explain this I can't figure out out what are the requirements for those lights to turn on.

 

EDIT:

 

The Russian Cockpit shows сду, which stands for SDU, where the enblish cockpit mod from early 2014 labeled it as FCS, it's the middle on the right side.

 

And after googling, CDU, which appears only in the legend as a moniker for Central Distribution Unit in the english version, whatever that means, apparently also refers stands the Control Display Unit, let me dig deeper.

 

The only place "SDU" is mentioned in english manual is here

The SDU-10 pitchonly

fly-by-wire system controls the pitch of the aircraft to ensure stability and controllability for the

pilot, increase aerodynamic performance, limit overload and angle of attack when needed and

decrease the airframe aerodynamic load.

 

And this is what the Russian version says the SDU stands for literally: (it throws out CDS when you put it together as a worde > google stuff, i did it letter by letter and it throws out correct)

 

Now, finally figured this one out, and this should help others. So, CDU, SDU, FCS, FBW ... are the same thing.

Edited March 15, 2016 by Worrazen

[Ironhand]

And after googling, CDU, which appears only in the legend as a moniker for Central Distribution Unit in the english version, whatever that means, apparently also refers stands the Control Display Unit, let me dig deeper.

 

The only place "SDU" is mentioned in english manual is here

 

 

And this is what the Russian version says the SDU stands for literally: (it throws out CDS when you put it together as a worde > google stuff, i did it letter by letter and it throws out correct)

 

Now, finally figured this one out, and this should help others. So, CDU, SDU, FCS, FBW ... are the same thing.

From the list of abbreviations in the Russian Flight Manual:

• СДУ - система дистанционного управления. Basically it translates to "remote control system" or "remote executive system".
  

 

 

And from elsewhere in the manual:

• 1.1.2. На самолете установлена система дистанционного управления (СДУ), которая наряду с обеспечением нормальной продольной устойчивости самолета на дозвуковых скоростях полета обеспечила также его высокую маневренность при сохранении хорошей устойчивости и управляемости во всем эксплуатационном диапазоне высот и скоростей полета. 1.1.2. The aircraft has a remote control system [sDU] (for some reason, I never seem able to transliterate the Russian "C" as the English "S" in my mind and I end up using CDU), which, along with providing the proper longitudinal stability of aircraft at subsonic flight speeds ensures its high maneuverability while maintaining good stability and controllability in the entire range of altitudes and flight speeds.

 

But it also states elsewhere that, should the СДУ light illuminate, do not engage (ЖЕСТКУЮ СВЯЗЬ) HARD LINK which is what we refer to as the Direct Control Switch (S key in the sim).

Edited March 15, 2016 by Ironhand

[Worrazen]

I guess the black screen in F1 view is the G-Force blackout ? And F1 view not working sometimes without plane blowing up is Pilot dead ?

 

I'm trying to recreate what I was talking about,it's very hard indeed, it probably was super rare. It probably shouldn't be possible imo, now that I gone through this.

 

But I got some interesting findings nonetheless, seems like some stuff has to do with engines, if the engines are dead it kind of makes plane easily go out of control, even tho it had enough momentum and speed.

So may it be that because one engine worked at the time, it kind of made the whole plane "work" to some extent for some reason.

 

The "Eject" voice message pops up when one of the 2 ruders get's blown down and one engine, but I've managed to land so is it really warranting the Eject recommendation ?

Proof:

 

 

Okay it's getting clearer now, so I lose control when the Pilot blacks out, and takes some time to come back, that would explain that nosedive.

And for the Fire fx animation on the engines, one engine usually "extinguishes" a fire, but either the fire actually keeps burning all the time, since the FIRE is always lit up, is it like this also in reality, for debugging purposes we would actually need to know whether there's still a fire going on or only the animation stopped playing when it should, or kept playing when it shouldn't anymore.

 

I heard somewhere there is actually a mehanic with the burning engines, there is a way to make them stop to not risk overheating fueltank and exploding, but I forgot where I saw this, the Su-27 engine "shuts down" automatically, so there's no point putting the throttle back off or turning it off by pressing buttons.

 

I've also noticed a burning engine doesn't shutdown completley many times and can't be completely shutdown manually since it's not responding and the RPM is still around 2, or is that only wind intake ? But that didn't result in any exploding fuel tanks, or just it takes more than 10 minutes. I do know that fire does make the plane blow up, but I had to speed it up so much to get to that point, that was usually when I crash landed and the whole plane was on fire.

Edited March 15, 2016 by Worrazen

[Worrazen]

And here is when cockpit voice message should say "eject" and it doesn't.

 

If only hydro fluid leaks out, it's all over I guess.

 

 

Now, does the hydro leak out this fast in reality ?

 

 

The left and right hydraulic system model includes models of sources and consumers of hydraulic

pressure.

 

 Each hydraulic system supplies its own group of hydraulic pressure users (landing gear,

aileron actuator, flaps, wing leading edge flaps, adjustable stabilizer, nose wheel steering,

brake system, etc).

 

 Pressure in the left and right hydraulic systems depends on the balance of hydraulic pump

efficiency and operating fluid consumption by hydraulic pressure users (boosters,

actuators, etc). Hydraulic pumps efficiency depends on the right and left engines speed

respectively, operating fluid consumption depends on their work intensity.

 

 Both catastrophic and partial hydraulic actuators failure when pressure drops in a

corresponding hydraulic system is modeled.

 

=============================

=============================

 

The control system includes models of the primary components: trimming mechanism and trimming

effect, hydraulic boosters in roll channel, and yaw dampener.

 

 Pitch trimming, the yawing model and the aileron trimming mechanism model are all based

on a different logics. In particular, the pitch trimming position does not influence rate

controller position at near-zero flight speed. Trimming tab serviceability depends on

electrical power in the aircraft electrical system.

 

 In the event of a pressure drop in the left side of the fuselage, lateral control worsens with

the rise of indicated flight airspeed. Longitudinal control does not depend on fuselage

pressure.

 The extension and retraction speed of high-lift wing and adjustable stabilizer surfaces

depends on fuselage pressure.

 

 The extension of high-lift wing devices for a more maneuverable configuration at a high

indicated airspeed can lead first to partial and then to complete hydraulic actuator blocking.

This causes fuselage pipe damage, hydraulic fluid leakage and fuselage pressure drop.

 

 Landing gear extension at a high indicated airspeed can first lead to partial and then to

complete hydraulic actuator blocking. This causes fuselage pipe damage, hydraulic fluid

leakage and fuselage pressure drop.

 

 

The above is from FC3 Manual and is only indicated for Su-25 and Su-25T.

 

I also heard some people say "Flaming Cliffs" planes are less complex than buying them separately, when someone was commenting on the fact that DCS A10-C is standalone and has clickable cockpit etc, but this may also be old info.

 

Unfortunately because that's meant for the Su-25 and Su-25T, I can't use that to speculate whether or not Su-27 has that double hydraulics system in real life and if it's in the DCS ....

Edited March 15, 2016 by Worrazen

[Ironhand]

...

I've also noticed a burning engine doesn't shutdown completley many times and can't be completely shutdown manually since it's not responding and the RPM is still around 2, or is that only wind intake ?...

 

...I also heard some people say "Flaming Cliffs" planes are less complex than buying them separately, when someone was commenting on the fact that DCS A10-C is standalone and has clickable cockpit etc, but this may also be old info.

Back when I was having fun with deadstick landings, I was purposely running the engines out of fuel. The turbines continued spinning (rpms) until I was stopped on the ground. Your forward motion is still pushing air through the turbines and making them spin.

 

All Flaming Cliffs aircraft, whether bought collectively as Flaming Cliffs or individually as separate modules, contain the same respective complexity. There are not two different versions of those aircraft. The A-10C is not a Flaming Cliffs aircraft, while the A-10A is. While both share the same flight model, the A-10C includes increased systems complexity.

 

Trying to figure all of this out is likely to drive you crazy. It might be best to simply figure out which vocalized warnings might be missing, etc. Leave the rest for after a more complex Su-27 is released.

 

As far as the HYDRO warning is concerned, the sole instruction is to get to a proper altitude, attitude, and airspeed for ejection and, then, eject. You should be able to do that in the allotted time. So once you've left the aircraft, it doesn't really matter whether or not what the elevators and flaps do is scripted or not. :) You're not bringing the aircraft home, anyway. To my mind that's a lot easier to deal with than trying to calculate how long it might take to run out of hydro. :)

Edited March 15, 2016 by Ironhand

[DarkFire]

I guess the black screen in F1 view is the G-Force blackout ? And F1 view not working sometimes without plane blowing up is Pilot dead ?

 

I'm trying to recreate what I was talking about,it's very hard indeed, it probably was super rare. It probably shouldn't be possible imo, now that I gone through this.

 

But I got some interesting findings nonetheless, seems like some stuff has to do with engines, if the engines are dead it kind of makes plane easily go out of control, even tho it had enough momentum and speed.

So may it be that because one engine worked at the time, it kind of made the whole plane "work" to some extent for some reason.

 

The "Eject" voice message pops up when one of the 2 ruders get's blown down and one engine, but I've managed to land so is it really warranting the Eject recommendation ?

Proof:

 

 

Okay it's getting clearer now, so I lose control when the Pilot blacks out, and takes some time to come back, that would explain that nosedive.

And for the Fire fx animation on the engines, one engine usually "extinguishes" a fire, but either the fire actually keeps burning all the time, since the FIRE is always lit up, is it like this also in reality, for debugging purposes we would actually need to know whether there's still a fire going on or only the animation stopped playing when it should, or kept playing when it shouldn't anymore.

 

I heard somewhere there is actually a mehanic with the burning engines, there is a way to make them stop to not risk overheating fueltank and exploding, but I forgot where I saw this, the Su-27 engine "shuts down" automatically, so there's no point putting the throttle back off or turning it off by pressing buttons.

 

I've also noticed a burning engine doesn't shutdown completley many times and can't be completely shutdown manually since it's not responding and the RPM is still around 2, or is that only wind intake ? But that didn't result in any exploding fuel tanks, or just it takes more than 10 minutes. I do know that fire does make the plane blow up, but I had to speed it up so much to get to that point, that was usually when I crash landed and the whole plane was on fire.

 

Watching that I was thinking "I'll be seriously impressed if he manages to land that aircraft in that condition".... Good effort! :thumbup:

 

To be honest I don't generally see the various failure modes that often in the Su-27. Normally being hit by a missile causes an instant change from normal flight to burning wreckage heading towards the ground :D I was surprised to hear Nadia telling you to eject - I've never heard that before in the Su-27!

[Worrazen]

I wasn't really complaining that some functions being scripted overall, I used that term exclusively to indicate difference when using "scripted Failures" in editor versus a failure from actual missile/bullet damage. However this difference was kind of a false alarm, but the text is mislabeled and some sounds don't activate, so those are holding imo.*

 

Yea, but here we go again:

 

Now this, I noticed that if you closely look, there doesn't seem to be big structural damage in this case, the video above, you have to pause the video somewhere in the middle, and once more later when bottom is visible, there doesn't appear to be anything missing, the bullet holes are kind of going through but, did it really hit many pipes or just one?

 

I mean if this doesn't settle at least something's not right having this defacto 45 sec timer, and yes I was mostly wrong with a lot of stuff I suspected as bugs turned out okay and I aplogoize causing alarm in the beginning.

 

So, if the model isn't advanced in the pipe area enough, it may be scripted(no relation to "scripted failures" talk)* to always causes the oil to leak out at that predefined time, if you lose 2 wings you should lose oil pressure much faster than a few bullet holes only at one wing, but I guess I can't take this to court either since under the wing, several cables or pipes might be damaged, which can't be seen normally, and in that video.

 

My biggest fear is if the "HYDRO" is just a few hitboxes and one of them somewhere around cockpit that triggers the light when hit by some bullets going through the panels, and then activates the script which causes the oil to "leak" out.

I guess that shouldn't be the case with Su-27 right ?

 

 

If any of the Professional Flight Model uses advanced pipes and cables and even connectors, if one bullet kind of makes dent at a connector and the pipe starts dripping or spraying some oil thin, it'll take at least like 3-5 minutes to drop pressure too low imo.

 

 

Watching that I was thinking "I'll be seriously impressed if he manages to land that aircraft in that condition".... Good effort! :thumbup:

 

To be honest I don't generally see the various failure modes that often in the Su-27. Normally being hit by a missile causes an instant change from normal flight to burning wreckage heading towards the ground :D I was surprised to hear Nadia telling you to eject - I've never heard that before in the Su-27!

 

Thanks. And in case anyone wonders why the video looks like that, I explained the technicalities in the video description.

 

And let me re-confirm and re-point something very important, the case when I had 1 engine working and all other failures and still had some control and flew for 10 mins, was unfortunately the NONE setting for G-Effects.

 

Everything from the 2 page forward in this thread, including the videos uses SIMULATION G-Effects.

Edited March 16, 2016 by Worrazen

[Worrazen]

PCA - Propulsion Controlled Aircraft

 

Could be used as a cheat/beginner feature in DCS, since it's only research and not in official planes.

 

 

 

 

While it's been looked into for stable frame (or how you call them) aircraft which are the civilian transport ones, NASA actually used F-15 and that's clearly a type of aircraft that normally isn't expected to be remotely landable without hydros.

 

There doesn't seem to be any mention of this around here, PCA stands for something else with weapons/radios or something with M2000, but I have no familiarity.

 

And in summary this quote from a YT comment why PCA didn't took off and isn't that known:

It was the FAA that pissed the PCA research program off the radar. As far as I'm concerned the saving of a single life was worth completing the research and adding what technically amounts to a self-contained controller with minimal software and a couple of extra sensors. It's really not such a big deal to tie the current day flight controls into a PCA system - most modern airliners can be comfortably landed with a few knobs and settings. It was stupid to abandon such a program.

 

http://safetyforum.alpa.org/LinkClick.aspx?fileticket=F7Pm2rIq%2FNM%3D&tabid=2886

Edited March 17, 2016 by Worrazen

[Ironhand]

As far as I know, ED still plans to update the Su-27's damage model which is currently fairly simplistic and incomplete. So it might be worth your while to make some concrete suggestions in th DCS Wish List thread.

[OneBlueSky]

As far as I know, ED still plans to update the Su-27's damage model which is currently fairly simplistic and incomplete. So it might be worth your while to make some concrete suggestions in th DCS Wish List thread.

 

+1. If one has technical knowledge of the plane or how certain things affect it, that's the place to be. They're always open to people who have knowledge about those things in efforts to make the sim better.

[Worrazen]

So, from 1.2 to 1.5 the Su-27 received "only" this technical-type update:

 

Su-27

Engine model update. Introduced RPM calculation based on flight conditions (temperature, velocity, altitude). Core engine temperature and trust envelope was corrected.

Corrected speed indication on HUD when below 80 KPH.

New Su-27 skins added

Su-27 flaps now jam at over-speed.

 

Please correct me if necessary, I may only found the patches to 1.5 thread but not the changes, not sure, I remember reading through a wall of text at the time, but I wasn't into DCS that much at the time, only checking it for 2-3 days per month.

 

 

--------------------------

--------------------------

 

Did some more scripted failure tests:

 

TEST01: 3FPS

http://i.imgur.com/RgrkcNz.png

 

------------------------------------------------

------------------------------------------------

 

 

TEST02: 3FPS

http://i.imgur.com/JgfJl8A.png

 

------------------------------------------------

------------------------------------------------

 

 

TEST03: 10FPS

-same 02-

 

Does appear the second and more obviously in third time when I only get rid of the Hydros for some time, that it kinda is less dramatic, but it still feels like it's being pulled down a bit too much without engines having more horizontal effect, and saying that as an opinion only, if that's how it should be then fine, but that's how I feel it just doesn't look right, when I enable full thrust and afterburners it just keeps affecting more into spin on vertial axis but not into the horizontal direction and then yes it probably going up or down and making some weird loops, should be wobbling and loopy, but not being in the area and just spinning imo, it just feels like it has so more drag into the forward direction, like the air is made out of jelly.

 

 

Now it probably should be doing that like it was also in previous videos on the older pages I posted without engine power, but I don't think it should do that with engine power, I might be wrong because of the fact it's not a stable airframe type plane.

 

 

So maybe without engines those stable-airframe planes would have a chance to keep gliding**, but as you guys said definitely not for fighter-type planes. Right, I understand.

 

Then, a fighter type with engines, shouldn't there be at least a difference from what we seen in TEST03, I'm not even remotely saying it should behave good enough for emergency landing like an Airbus 310 even without engines, but it just shouldn't be almost the same with fighter-type with engines as with no engines in a similar hydroleak scenario** right? When the nose goes up, shouldn't there be some of a kick back up or stall for a bit instead of the altitude falling and surface velocity being very small, like the engines aren't there?

 

And when hydros kept leaking out of the DHL Airbus, were the flaps/ruders/elevators wobbly or frozen? I didn't read into the details of that event enough to know if this was mentioned, i might have a look sometime.

And those are mehanical characteristics that probably need to be tested for each aircraft separately, unless someone knows this for sure already. Someone mentioned it in the earlier posts, but was that only an opinion or standard knowledge?

 

**Only for the cases in which controls aren't crossed and frozen shut and airbrakes disabled.

 

Now, what if there really are more than one type of hydro leaks already in the game, the manual does say that you better not use airbrakes as they may jam in the middle, and, what if the scripted failure produces always only the worst type, crossed controls and frozen ... ? I was searching if there's maybe a debug mode of DCS, but wasn't lucky, or maybe some debug stuff in the dev console?

 

 

 

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-----------------------

 

As far as I know, ED still plans to update the Su-27's damage model which is currently fairly simplistic and incomplete. So it might be worth your while to make some concrete suggestions in th DCS Wish List thread.

 

I am unfamiliar with with specifics of kind of systems and events does the damage model go to and affect, I speculate it has to do when weapons hit the plane on different locations of the plane setting off appropirate damage to the components, but it probably goes a bit further than this?

 

So that I don't mix some other stuff, might not be able to just put all kinds of feedback into that, since, most of the confusion in the first 2 pages of this thread was caused by the mislabeling of the scripted failures ACS (FCS) and AUTOPILOT (ACS), which is

probably the editor not the plane's systems. (I'm still not sure if only affect's the Su-27 tho, should test that, but later)

 

Thanks for the heads up.

Edited March 17, 2016 by Worrazen

[Ironhand]

...

 

 

 

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...

The difference in your diagrams is, more or less, what you get. Attached are two tracks. They are identical until 3 minutes and 10 seconds into the flight. At that point they diverge as in the first I set engines to idle and in the second I went into afterburner. The "idle" flight lasted a total of 5 min and 21 sec, while the AB version lasted 13:14. The latter would have been a lot longer but I ran out of fuel (only had 50% onboard). In any case, my "landing" points were on very different portions of the DCS landscape. Note the differences in airspeed and the rate of altitude loss between the two tracks.

 

Interestingly, once I fell into the denser atmosphere at around 3600 meters, the aircraft in full burner is able to hold it's altitude and even starts gaining.

 

Anyway, interesting to watch. If I have time this weekend, I might superimpose one Trackview over the other.

Edited March 18, 2016 by Ironhand

[DarkFire]

The difference in your diagrams is, more or less, what you get. Attached are two tracks. They are identical until 3 minutes and 10 seconds into the flight. At that point they diverge as in the first I set engines to idle and in the second I went into afterburner. The "idle" flight lasted a total of 5 min and 21 sec, while the AB version lasted 13:14. The latter would have been a lot longer but I ran out of fuel (only had 50% onboard). In any case, my "landing" points were on very different portions of the DCS landscape. Note the differences in airspeed and the rate of altitude loss between the two tracks.

 

Interestingly, once I fell into the denser atmosphere at around 3600 meters, the aircraft in full burner is able to hold it's altitude and even starts gaining.

 

Anyway, interesting to watch. If I have time this weekend, I might superimpose one Trackview over the other.

 

Very interesting tracks. The question that follows is: is the departure soon after hydraulic failure a scripted event or is it generated as a calculated response to aerodynamic & aircraft system conditions?

[Ironhand]

Very interesting tracks. The question that follows is: is the departure soon after hydraulic failure a scripted event or is it generated as a calculated response to aerodynamic & aircraft system conditions?

The thing about modeling stalls is that, to a degree, they have to be manufactured. You can create tables full of data right up until the stall. After that, all of the equations and tables go out the window because what happens becomes so complex that you have to "manufacture" the result. In a sense a stall is like those blank areas on the old world charts with "There be dragons" inked in.

[DarkFire]

The thing about modeling stalls is that, to a degree, they have to be manufactured. You can create tables full of data right up until the stall. After that, all of the equations and tables go out the window because what happens becomes so complex that you have to "manufacture" the result. In a sense a stall is like those blank areas on the old world charts with "There be dragons" inked in.

 

Good point. Navier-Stokes + large Reynolds number = computationally hard. I suppose one could go all Kolmogorov on it but good luck running that statistical model on a home PC :(

 

Given that the Su-27 is longitudinally unstable I guess the modelled effect at least appears to be fairly realistic.

[Ironhand]

...

 

Given that the Su-27 is longitudinally unstable I guess the modelled effect at least appears to be fairly realistic.

It may or may not be realistic. And it's not something I'm going to lose sleep over. It certainly doesn't behave in a way you would expect of an aircraft with positive static and/or dynamic longitudinal stability.

 

Anyway, had a few minutes to overlay the Full Afterburner and Engine Idle track posted above as viewed in Trackview. Here's the result. Obviously, the one with the shorter flight time is the engine idle sequence.

 

 

You can definitely see the increase in speed and range during the stall period.

[Worrazen]

Wow such a program does exist, I was basically thinking about this a day later when I woke up, wouldn't it be a lot more practical to show paths in full 3D to just make the plane drag a permanent red line behind it in-game, shouldn't the devs already have such a debug feature ?

 

But I guess it's very similar what I had in mind, it's just a top-down view with an external utility.

[Ironhand]

Wow such a program does exist, I was basically thinking about this a day later when I woke up, wouldn't it be a lot more practical to show paths in full 3D to just make the plane drag a permanent red line behind it in-game, shouldn't the devs already have such a debug feature ?

 

But I guess it's very similar what I had in mind, it's just a top-down view with an external utility.

I could just as easily shown a side view. But that would not have shown what I wanted to highlight at this point: horizontal flight paths, relative speeds, and flight time post stall. Those were easier to display with the top down view.

Edited March 19, 2016 by Ironhand

[DarkFire]

It may or may not be realistic. And it's not something I'm going to lose sleep over. It certainly doesn't behave in a way you would expect of an aircraft with positive static and/or dynamic longitudinal stability.

 

Anyway, had a few minutes to overlay the Full Afterburner and Engine Idle track posted above as viewed in Trackview. Here's the result. Obviously, the one with the shorter flight time is the engine idle sequence.

 

You can definitely see the increase in speed and range during the stall period.

 

True. It's good enough so beyond that... Meh :)

 

Wow such a program does exist, I was basically thinking about this a day later when I woke up, wouldn't it be a lot more practical to show paths in full 3D to just make the plane drag a permanent red line behind it in-game, shouldn't the devs already have such a debug feature ?

 

But I guess it's very similar what I had in mind, it's just a top-down view with an external utility.

 

Tacview is the single best tool available for analysing your performance after a flight. The latest version can do amazing things and I'd highly recommend it to anyone who plays DCS.

 

http://tacview.strasoftware.com/product/about/en/