1.5 - Su-27 Trim

So this is my eternal ball-ache (see attachment)... the insane nose up tendency of the SU-27.

No matter how much I pound or hold in the pitch down trim, nothing happens. The only way I can fly it relatively normally is to hold my force feedback (MS-FF2) joystick with two fingers so as not to engage the force feedback and avoid getting a wrist workout from pushing the nose down constantly. Has anyone else experience this?

I could disable FF but that's like putting trainer wheels on a Ferrari ;)

You sure you're not accidentally disabling the AOA limiter, check your key command settings and see if you're doing that.

Unfortunately, that seems to be an issue with some FFB sticks. For the time being, you have two options: 1) turn it off or 2) fight it like you are now.

Has anyone else experience this?

I use an MSFFBII & No - I don't experience that..

I have the trim mapped to the hat switch, and as I retract the wheels & flaps, I hold the trim forward, and the rate of trim addition is almost exactly the same as the rate of pitch change due to the flaps & gear retracting (or extending & trimming the nose up at landing).

With a bit of practice you shouldn't have to fight the FFB at all..

I had a similar problem using X55. I found once airborne and gear up the SU-27 would 'balloon' nose up. I got round this by trimming nose down slightly before take off roll. Still allows take off at desired speed. After gear up, as speed increases trim accordingly (trim changes with airspeed).

May work for you?

The trim is not working as expected, it is obvious that developers have missed something before the release or just had no time to work it. Everyone knows this trim-of-hell in our Flanker squadron and had to adapt new counter-intuitive techniques to it. Worst is flying in finger tip formation as #4, you have not enough trim nose down to work with. First things first you must trim this beast almost to the max trim nose down setting before taking off.

Flying with TM Warthog, 11% pitch curve, stick is precise.

Autopilot is also unstable because autopilot routines work through trim.

Su-27 Trim in 1.5

Despite experiencing a weird ground texture bug with 1.5, I'm deeply in love with all the new & great changes that 1.5 has brought. This is by far the best version of DCS that we've ever had and I'm very grateful to all the team at ED for their incredible work :thumbup: :punk:

So, I decided to take my Flanker for a spin and see how fast and how far up I could get. I'm pretty sure that even with ECM pods attached I managed to get the thing to 2.5M (previous best was 2.47M) and took it all the way up to over 34,000m altitude.

Seriously, the view from up there is incredible. My meagre screen shots don't do it justice at all. Give it a try!

I remember reading in the change log that the engine characteristics had been adjusted, and happily the thing seems to both accelerate faster and achieve very slightly higher speeds at altitude. I did manage to over-speed the engine doing 2,700 Km/h at just under 5,000m altitude which was interesting as I've never seen it do that before, but I suppose it makes sense that it does behave in that way.

Trim seems to be unaltered and is just as impossible to balance perfectly. By perfectly I mean VS variance <2 m/s per ~30 seconds. I'm not talking about wobbling around the sky but I want to trim it perfectly, and I find it impossible at present. I still think that the rate of change of the trimmer needs to be reduced, unless this would be unrealistic.

I agree with your trimmer remarks, and, of course, the updates to the Su-27 are awesome. Still my fav jet to fly.

I also hope that that autopilot wobble will be fixed; I remember YoYo replying to me in that regard, saying that the fixes were pending work on DCS 1.5 and 2.0... so there's hope that this is still underway. :)

I could go up to 8500m in loaded Su-25T, without even forcing. I did not tried to go higher as i was reaching the combat area, but things have been changed. :music_whistling:

....Trim seems to be unaltered and is just as impossible to balance perfectly. By perfectly I mean VS variance <2 m/s per ~30 seconds. I'm not talking about wobbling around the sky but I want to trim it perfectly, and I find it impossible at present. I still think that the rate of change of the trimmer needs to be reduced, unless this would be unrealistic.

There's a trick to trimming this aircraft. The length of time you press the trimmer keys matters.

I have pitch up and pitch down set up on one of my hat switches. This allows me to easily control the length of the "press". For gross trimming I give the switch a firm bump up or down. To fine tune it, I barely brush the switch--just enough to give it the very slightest of bumps. Once my airspeed is stable and I've trimmed, I can go get a cup of coffee and return to find that I have gained or lost very little altitude.

Not that I normally worry about it that much. Usually I trim just enough that a light touch on the stick holds me level and a momentary distraction doesn't find the aircraft varying much in altitude.

I just wanted to chime in on this too. I have the logitech G940 and even if I trim full nose down, at around 580kph the nose starts to float up and can only be stopped by holding constant forward pressure on the flight stick.

I have adjusted numerous settings with FF in game with no actual resolve. As soon as you disable FF in game the flanker flies like a dream (all be it I had to adjust my curves to lessen the sensitivity of the pitch). It takes only very little trim to get the jet flying straight and level at that point.

From other modules I have flown... the F-15 and P-51 FF trim seems to work correctly. The stick will actually move forward and pressure is re-leaved from the control surfaces.

I actually have noticed that the black shark and huey suffer the similar problem though.

I've noticed increased high altitude performance in the Mig-21Bis too, it may me related. I was able to zoom climb to 29Km, very cool and magnificent view but i doubt the mig should be able to do that.

However i've been unable to get the flanker past 27km, how on earth did you manage 34km?

I've noticed increased high altitude performance in the Mig-21Bis too, it may me related. I was able to zoom climb to 29Km, very cool and magnificent view but i doubt the mig should be able to do that.

 

However i've been unable to get the flanker past 27km, how on earth did you manage 34km?

First you need a clean bird, no weapons loaded but quite a lot of fuel. I usually take 100% fuel. Climb gently under full military power until you reach 11,000m. At that point engage afterburner until true air speed reaches ~1100 Km/h. At that point climb gently to ~13,000m and then level out. Wait until speed reaches 2.5M before pulling in to a 3-4 G climb with a ~50-55 degree nose-up climb. It's usually best to wait until you're down to ~3,000 Kg of fuel before pulling up so the aircraft is nice and light but you'll still have enough fuel to land.

Once you're in a zoom climb keep the nose at ~50 degrees up no matter what your IAS is because the actual true air speed will still likely be above 800 Km/h. Keep climbing until you run out of lift at which point you'll nose over no matter what you do.

The point of not going above ~50 degrees pitch up is that when you do eventually stall and nose-over the thing will deep stall in a stable manner rather than departing.

I've noticed increased high altitude performance in the Mig-21Bis too, it may me related. I was able to zoom climb to 29Km, very cool and magnificent view but i doubt the mig should be able to do that.

 

However i've been unable to get the flanker past 27km, how on earth did you manage 34km?

MIG-21 : " Georgi Mosolov set the new altitude record at 34,714 m " from : https://en.wikipedia.org/wiki/List_of_Mikoyan-Gurevich_MiG-21_variants Ye-6T/1 ("Ye-66A") (1961)

First you need a clean bird, no weapons loaded but quite a lot of fuel. I usually take 100% fuel. Climb gently under full military power until you reach 11,000m. At that point engage afterburner until true air speed reaches ~1100 Km/h. At that point climb gently to ~13,000m and then level out. Wait until speed reaches 2.5M before pulling in to a 3-4 G climb with a ~50-55 degree nose-up climb. It's usually best to wait until you're down to ~3,000 Kg of fuel before pulling up so the aircraft is nice and light but you'll still have enough fuel to land.

 

Once you're in a zoom climb keep the nose at ~50 degrees up no matter what your IAS is because the actual true air speed will still likely be above 800 Km/h. Keep climbing until you run out of lift at which point you'll nose over no matter what you do.

 

The point of not going above ~50 degrees pitch up is that when you do eventually stall and nose-over the thing will deep stall in a stable manner rather than departing.

Thanks a lot, i'll try this as soon as I can!

MIG-21 : " Georgi Mosolov set the new altitude record at 34,714 m " from : https://en.wikipedia.org/wiki/List_of_Mikoyan-Gurevich_MiG-21_variants Ye-6T/1 ("Ye-66A") (1961)

You're right, I didn't remember that one from The Right Stuff, that's the record Chuck Yeager was trying to break when he crashed the NF-104. But my point is, that must have been a specially modified aircraft for the altitude record. Should a normal, clean Mig-21Bis, with 30% fuel and all it's combat equipment onboard, be able to reach 29,400 m?

Edit: It seems the Ye-66A was indeed a highly modified airframe, with increased fuel capacity, more powerful engine, and a rocket booster, among other modifications.

I'm also struggling to control the nose up issue. Trim just doesn't seem to help.

Using a Warthog and trim on a hat.

Will try again.

EDIT: I had FF on in options.. turned this off problem disappeared.

I'm also struggling to control the nose up issue. Trim just doesn't seem to help.

 

Using a Warthog and trim on a hat.

 

Will try again.

 

EDIT: I had FF on in options.. turned this off problem disappeared.

Yep, many people have reported that using force feedback makes it impossible to trim the Su-27. Some people have apparently had success with swapping the roll & pitch axes for the FF but disabling it seems to be a reliable fix until that particular bug is squashed.

For me the Su27 has too much lift after every little speed change. So I must often hold the "trim stick" a long period to get a fast reaction and with this the "search" for the right trim position is a never ending story. To fly the Su27 you must trim this bird all time long, as long as the speed is changing.

Should be not so hard like it is right now!

The problem I have with the trim is that if you have trimmed too much in one direction the bird gets very nervous and "light" around the center of the stick. The Su27 can do crazy things if you trim her very strong out of level flight. It's like the stick has its full working range but with trim you "squeeze" only the direction in which you have trimmed and so the stick becomes much more aggressive. It's like you stretch the arms of a crossbow. There is a special point at which you have as good as no counter force. You can move very easy the stretch stick at this point. But if you get over this point, in one direction you feel a big resistance and on the other side there is no counter force anymore and this is how I feel with Su27. It’s like the center of my stick will be shoved in one direction.

A unbelievable feeling for me. At this "no counter force point" you can swing the nose of the Su27 without any reaction of the physics. It‘s crazy! As if there are no physics in this special area acting with the Su27. In this area the Su27 becomes “floppy”.

I love the 1.5 Beta update, and I find the SU-27 & F-15 smoother to fly slow and land (only planes I've flown so far), however the trim/float issue is still there. I seem to find enabling [Autopilot straight and level flight] helps calm it down, small adjustments needed afterwards. Other option is I forward trim (nose down) as part of final pre-flight check when lined up on runway, take off speed doesn't seem affected. Using Saitek X55.

Well, that's how it should work. In conventional aircraft (or artificially conventional), you have to trim for every speed change. I've never flown a high performance aircraft, but I imagine it would be similar to what we have in game. I imagine it's hard because of lack of FF. In real aircraft stick would be very heavy with like 10 knots out of trim.

Yep, many people have reported that using force feedback makes it impossible to trim the Su-27. Some people have apparently had success with swapping the roll & pitch axes for the FF but disabling it seems to be a reliable fix until that particular bug is squashed.

Well he had FFB turned on with a non-FFB stick. That's going to cause problems as it changes the trimming mechanism. It's not a bug.

With the exception of issues with a specific model of stick, the vast majority of the issues with FFB have been fixed through the GUI, which makes them set up issues rather than 'a bug'.

That said, some of the set up needed for FFB is not all that intuitive or obvious.

Well he had FFB turned on with a non-FFB stick. That's going to cause problems as it changes the trimming mechanism. It's not a bug.

 

With the exception of issues with a specific model of stick, the vast majority of the issues with FFB have been fixed through the GUI, which makes them set up issues rather than 'a bug'.

 

That said, some of the set up needed for FFB is not all that intuitive or obvious.

Fair enough, I've never used a FF stick so can only comment on observations made by others. Good to know most of the gremlins have already been squashed :)

is there a reason you aren't using stick to trimmer mode? i find that you can make much harder trim inputs with it as you can jam the stick forward which trims very quick.

accuracy doesn't matter so much in the initial trim, just have to get rid of the annoyance first.