Su-27 in 1.5.5

[Belphe]

Anyone else is excited about the announced changes to the Su-27 in 1.5.5?

 

From the Newsletter:

- Incorrect indication of fuel quantity when start in air has been fixed

- Flight control system with AOA and G-limiter has been adjusted

- Autopilot has been adjusted

- Tires strength has been adjusted

 

The second interests me the most..

[Schmidtfire]

Yeah... I wonder if the G limiter will prevent the wings from snapping? And in case of a really tight dogfight, we could override the limiter for a few seconds with the wheel brake button...

[Belphe]

That's what I hope for too..

[Ironhand]

:) Ahhh...hope springs eternal...

 

Guess we'll just have to wait and see what it brings.

[DarkFire]

OK, some very early initial impressions:

 

1. The autopilot is now much more effective at much lower IAS values. Where it used to have to be engaged at above or equal to 560 Km/h, that figure now is significantly lower, somewhere between 320 and 340 Km/h IAS. At around 330 Km/h IAS a slow but significant yaw & roll sets in, particularly at very high altitude, but if IAS increased above ~340 then it damps out.

 

THEY FIXED THE AUTOPILOT!!!! WOOOHOOO!!!!!!!!!!!! :sorcerer:

 

This has opened up the region between 10,000m and say 12,500 - 13,000m to autopilot use for high-altitude cruise. If you're going up there then I'd advise very gradual rates of climb and to keep your IAS as high as possible. This will make flights beyond 1,500Km in range much, much easier now than they were before where the autopilot could only really be used up to 10,000m for safe cruise at 85-87% RPM.

 

 

2. The AOA limited / stick pusher is now significantly more proactive in limiting AOA and hence G values to safe levels. Essentially the limiter will now save you under any weight / speed conditions, as it did before, but now with a much wider margin of safety. For example, I was in a descending turn at around 5,000m, ~1.3M with full stick back. G was limited to roughly 5.5-6. Weight was 27,720Kg.

 

3. The effect of turning off the limiter with the "W" key is now much more pronounced. If you turn off the limiter the ACS will (obviously) allow you to go to maximum aerodynamic G values which can and will destroy your airframe. Changing the ACS to manual mode with the "S" key still does what it does. Use above ~450Km/h is not advised unless you know exactly what will happen when you switch to manual mode and are ready for it. Otherwise, instant G lock and pilot death and/or airframe destruction.

 

All in all the Su-27 has become much more care-free, but with the ability to push beyond what the ACS wants to allow you to do, if you're prepared and are able to fly manually within the safety limits of the airframe.

 

Awesome work ED!!

 

Edited to add: This is it! This is the ACS update I've wanted for months. The only things that are ever going to prise me out of the cockpit of my Su-27 are the Spitfire and the Typhoon...

Edited November 4, 2016 by DarkFire

[bolek]

I have done some very limited testing on the autopilot (item 3 on the list) and it does seem to have changed. It now "works" at much lower IAS than before. However, it seems that the level flight mode (LAlt-3) is no longer level flight. It seems to gradually descend, even if the aircraft was trimmed level or even slightly up before engaging. This is a regression, I believe.

 

EDIT: sniped, but DarkFire can you try level flight mode? Does it maintain altitude?

[probad]

the wings still snap at the same load values, it's just harder to "accidentally" exceed it. you now have to do some serious stick slamming to break the wings. it's also less authoritative at lower airspeed, kind of feels like heavy curves got applied, but then again thats what the override buttons are for.

Edited November 4, 2016 by probad

[Ironhand]

OK, some very early initial impressions:

 

1. The autopilot is now much more effective at much lower IAS values. Where it used to have to be engaged at above or equal to 560 Km/h, that figure now is significantly lower, somewhere between 320 and 340 Km/h IAS. At around 330 Km/h IAS a slow but significant yaw & roll sets in, particularly at very high altitude, but if IAS increased above ~340 then it damps out.

 

THEY FIXED THE AUTOPILOT!!!! WOOOHOOO!!!!!!!!!!!! :sorcerer:

 

This has opened up the region between 10,000m and say 12,500 - 13,000m to autopilot use for high-altitude cruise. If you're going up there then I'd advise very gradual rates of climb and to keep your IAS as high as possible. This will make flights beyond 1,500Km in range much, much easier now than they were before where the autopilot could only really be used up to 10,000m for safe cruise at 85-87% RPM.

 

 

2. The AOA limited / stick pusher is now significantly more proactive in limiting AOA and hence G values to safe levels. Essentially the limiter will now save you under any weight / speed conditions, as it did before, but now with a much wider margin of safety. For example, I was in a descending turn at around 5,000m, ~1.3M with full stick back. G was limited to roughly 5.5-6. Weight was 27,720Kg.

 

3. The effect of turning off the limiter with the "W" key is now much more pronounced. If you turn off the limiter the ACS will (obviously) allow you to go to maximum aerodynamic G values which can and will destroy your airframe. Changing the ACS to manual mode with the "S" key still does what it does. Use above ~450Km/h is not advised unless you know exactly what will happen when you switch to manual mode and are ready for it. Otherwise, instant G lock and pilot death and/or airframe destruction.

 

All in all the Su-27 has become much more care-free, but with the ability to push beyond what the ACS wants to allow you to do, if you're prepared and are able to fly manually within the safety limits of the airframe.

 

Awesome work ED!!

 

Edited to add: This is it! This is the ACS update I've wanted for months. The only things that are ever going to prise me out of the cockpit of my Su-27 are the Spitfire and the Typhoon...

Thanks for the update! Now I just have to get home and start downloading. Come on, clock, move!

 

But it sounds like you might still be unable to rely on the AP at landing speeds. Or did you only try it in the thin air at high altitudes?

[Pronin]

THE FLANKER IS FIXED!!! I AM SO HAPPY!!!

 

I feel safe when I pull G's! No more wobbling all over the place after rolling. The plane feels extremely stable.

 

Flanker pilots are about to be so happy with this update. We have all been flying with no G-limiter for the last 6 months like ABSOLUTE MAD MEN. Literally hard mode.

[Belphe]

I'm in Flanker Heaven! :D

[Fri13]

I'm in Flanker Heaven! :D

 

Dont You get there only after eating a ASRAAM? :-P

[Belphe]

Dont You get there only after eating a ASRAAM? :-P

 

I wouldn't know.. Never happened... ;P

[DarkFire]

I have done some very limited testing on the autopilot (item 3 on the list) and it does seem to have changed. It now "works" at much lower IAS than before. However, it seems that the level flight mode (LAlt-3) is no longer level flight. It seems to gradually descend, even if the aircraft was trimmed level or even slightly up before engaging. This is a regression, I believe.

 

EDIT: sniped, but DarkFire can you try level flight mode? Does it maintain altitude?

 

It does still work, but as part of the fixes applied to the AP it loses then regains much more altitude than it used to. For example, if you're at 0m/s Vv and engage the autopilot at say 10,000m it'll dip down to maybe 9,960m before gradually climbing back up again. We'll need to be much more careful when turning on the AP at very low altitudes I think, but it's much better than having to fly at high altitude manually.

 

 

Thanks for the update! Now I just have to get home and start downloading. Come on, clock, move!

 

But it sounds like you might still be unable to rely on the AP at landing speeds. Or did you only try it in the thin air at high altitudes?

 

I haven't tried landing with it yet. To be honest I never use the auto-land capability but I'll try it out. The one test I did was rather extreme: all-up weight of 27,720Kg with a full A-A weapons load at 12-13,000m altitude. I wanted to see how low an IAS it could cope with before it went woolly on me. The yaw & roll I experienced could well have been due to being at very high altitude (I was close to 14,000m at that point), at high weight and at very low IAS. Might well perform better at low level and especially at lower weight.

[bolek]

It does still work, but as part of the fixes applied to the AP it loses then regains much more altitude than it used to. For example, if you're at 0m/s Vv and engage the autopilot at say 10,000m it'll dip down to maybe 9,960m before gradually climbing back up again. We'll need to be much more careful when turning on the AP at very low altitudes I think, but it's much better than having to fly at high altitude manually.

 

Hmm, this is not what I am seeing. See the attached track. I engaged the level-flight mode at around 10,000m and saw it drop continuously to about 8,000m when I gave up. I then disengaged AP and engaged the altitude hold mode (LAlt-4) instead which interestingly did not have this problem. Altitude was maintained perfectly. So, I do think this is a bug. Oh, and this was with a fully loaded plane, so maybe that affects things.

 

But I am not complaining (much :)). All the other fixes are worth it. Great job ED.

 

In fact the tires are now made of steel. In the second track I did a bad landing with a heavy plane in a crosswind, damaged the suspension, applied brakes almost right away (did not use the chute) and the tires are still intact!

level_flight(not).trk

crosswind_landing.trk

[DarkFire]

Hmm, this is not what I am seeing. See the attached track. I engaged the level-flight mode at around 10,000m and saw it drop continuously to about 8,000m when I gave up. I then disengaged AP and engaged the altitude hold mode (LAlt-4) instead which interestingly did not have this problem. Altitude was maintained perfectly. So, I do think this is a bug. Oh, and this was with a fully loaded plane, so maybe that affects things.

 

But I am not complaining (much :)). All the other fixes are worth it. Great job ED.

 

In fact the tires are now made of steel. In the second track I did a bad landing with a heavy plane in a crosswind, damaged the suspension, applied brakes almost right away (did not use the chute) and the tires are still intact!

 

You're right and I was wrong. My mistake. Exactly as you pointed out, altitude hold works as I described, whereas level flight does indeed have a problem as you described. I'd confused myself about what ACS mode I was using. And I agree, we now have solid titanium tires!

 

Another observation on the autopilot - I tried using the route following mode to land, or at least take me to the inner ILS marker. That also suffered serious problems with maintaining altitude, though it was otherwise stable in terms of pitch & yaw, even down to ~300 Km/h.

 

Final observation - the nasty level of cross-talk between yaw & roll that the ACS had is now completely absent! Roll control feels wonderfully crisp, responsive & accurate even at low speeds & high weight.

 

ED really made a massive difference to the Su-27 with this update. :thumbup:

 

I also tried flying with the AOA limiter disengaged - this feels a lot like our old Su-27 did pre-patch, but of course with no AOA limiter at all. Still very nice crisp response but with the ability to go in to and beyond the AOA / G safety margin.

 

I'd recommend binding the AOA limiter disengagement button (W) to a HOTAS key, I think it's going to get some serious use now during WVR combat.

Edited November 5, 2016 by DarkFire

[bolek]

Another observation on the autopilot - I tried using the route following mode to land, or at least take me to the inner ILS marker. That also suffered serious problems with maintaining altitude, though it was otherwise stable in terms of pitch & yaw, even down to ~300 Km/h.

 

From my experience, route following mode only works well if you also engage altitude hold. This is different than Su-25T where route following automatically maintains the programmed altitude. This was true even before this update and it didn't change in this respect. It's like in Su-27 route following mode is a lateral mode only. When altitude hold is engaged while route following is in effect, it maintains programmed altitude (instead of a fixed one when used standalone). Is this what you are seeing too?

 

(Ironically, I think our beloved Su-25T has the best autopilot in the game...)

[Ironhand]

...I engaged the level-flight mode at around 10,000m and saw it drop continuously to about 8,000m when I gave up. I then disengaged AP and engaged the altitude hold mode (LAlt-4) instead which interestingly did not have this problem...

Perhaps this is an indication that LAlt-3 (ПРИВЕД К ГОРИЗ--Towards the Horizon) is actually working properly now. Notice it is a "leveling" mode not an altitude hold mode. It's simply there to get your wings level with the horizon. Then you engage an altitude hold mode.

[bolek]

Perhaps this is an indication that LAlt-3 (ПРИВЕД К ГОРИЗ--Towards the Horizon) is actually working properly now. Notice it is a "leveling" mode not an altitude hold mode. It's simply there to get your wings level with the horizon. Then you engage an altitude hold mode.

 

Yeah, I was thinking the same thing, but I tried that and engaging altitude hold while level flight is engaged seems to have no effect.

[bolek]

Actually, it's even more strange. Altitude hold now behaves like level flight used to be. Not only it maintains altitude but also keeps the wings level.

[Ironhand]

After some quick and dirty tests this AM it seems that:

 

1) the limiter now holds you to rough maximum of 120% of max operational Gs

 

2) AP: "A" and "LALT-6" (the 2 Route Following modes) behave differently. "A" follows the route AND assigned altitude. EDIT: "LALT-6" is Route Following Mode with your pitch stabilized to the pitch value at the time you enable the mode. :EDIT ENDS.

 

3) The 3 "Barometric altimeter hold" keys all work the same and hold your current altitude.

 

4) LALT-3 (Wings Level to Horizon) does what it's supposed to do--level your wings.

 

5) "A" will now take you smoothly in for a landing. You need to be landing by the numbers though. No zooming in and expecting to stilll land safely. Darkfire, my landing weight was somewhere around/below 23,000 kg. I was under the impression that the AP was supposed to release at 150 m altitude but it didn't. It brought me right down to touchdown and I had to manually disengage it on the runway.

 

EDIT: I have to admit to rarely using the AP. So it may be that some of what I think of as different really isn't. But the slow speed handling of the AP is definitely fixed.

Edited November 6, 2016 by Ironhand

[DarkFire]

After some quick and dirty tests this AM it seems that:

 

1) the limiter now holds you to rough maximum of 120% of max operational Gs

 

5) "A" will now take you smoothly in for a landing. You need to be landing by the numbers though. No zooming in and expecting to stilll land safely. Darkfire, my landing weight was somewhere around/below 23,000 kg. I was under the impression that the AP was supposed to release at 150 m altitude but it didn't. It brought me right down to touchdown and I had to manually disengage it on the runway.

 

1. Agree. It's a little difficult to calculate as the AOA limiter / stick pusher wavers around a bit but I'd roughly calculated somewhere between 115 & 125% of safe maximum.

 

5. Surprising - I'd always thought that the route following "A" mode when landing took you to the inner marker, or at whatever point the system lost the ILS signal. Still, if it can actually land now then maybe that's a better simulation of the real system. I was much heavier when I tested it - somewhere around 27,000Kg, but in fairness I may have been using Alt-6 instead of "A" mode.

 

I think the ACS still has a few interesting quirks but it's light years ahead of the old version, especially at low speed.

[Ironhand]

1. Agree. It's a little difficult to calculate as the AOA limiter / stick pusher wavers around a bit but I'd roughly calculated somewhere between 115 & 125% of safe maximum.

 

5. Surprising - I'd always thought that the route following "A" mode when landing took you to the inner marker, or at whatever point the system lost the ILS signal. Still, if it can actually land now then maybe that's a better simulation of the real system. I was much heavier when I tested it - somewhere around 27,000Kg, but in fairness I may have been using Alt-6 instead of "A" mode.

 

I think the ACS still has a few interesting quirks but it's light years ahead of the old version, especially at low speed.

:) I only had an hour to test/play with it this morning and, unfortunately, probably won't have another chance soon. So, my testing was limited using the same TRKs I'd been using before the update. The 120% seemed fairly consistent but, then again, I'm rounding to only one place so that actually mimics your results.

 

I didn't think the real AP took you right down to the touchdown. But, anyway, real world max landing weight is around 23,000 kg. If nothing else, you should disengage and use the stick to flare just before touchdown. Otherwise you'll hit hard. This would be especially true if you were coming in heavy. If I get a chance soon, I'll try a heavy landing with it and see what happens.

 

For anyone interested in using the AP for landing, make sure you intercept the start of the glideslope with gear down and flaps set and an airspeed of around 350-380 km/hr (assuming a normal landing weight). Gradually throttle back so that you touch down at 260-270 km/hr. If you find yourself falling a bit below the slope, throttle up slightly until you start to lift and then throttle back slightly again.

[ebabil]

what about the canopy bug?

[DarkFire]

what about the canopy bug?

 

Canopy bug?

[probad]

im fairly sure he's talking about the missing canopy reflectivity

 

no it's not fixed.