So, tell me please....

[Hummingbird]

It realy might be due to stifness, or it could be that the mild stalling characteristic may refer to the power-off stall and not the accelerated stall?:book::huh:

 

The former is not the case as I was flying at 310 km/h IAS, the latter is not the case as Skip Holm is specifically talking about an accelerated stall.

[Yo-Yo]

The lateral instability has nothing to do with slats. It was mentioned in the report that both slats normally deploy at the speed (1g stall) far from the stall speed, so the plane was stalled with both slats.

[Hummingbird]

The lateral instability has nothing to do with slats. It was mentioned in the report that both slats normally deploy at the speed (1g stall) far from the stall speed, so the plane was stalled with both slats.

 

I know, I was mainly refering to the snatching part. But incidentally I couldn't find anything on lateral instability in the succeeding models either.

 

The wing dihedral was there to provide lateral stability.

 

Edited October 7, 2015 by Hummingbird

[Crumpp]

But incidentally I couldn't find anything on lateral instability in the succeeding models either.

 

Most aircraft become laterally unstable at the edge of stall. Ailerons are generally one of the first control surfaces to lose effectiveness in determining Vmc (speed of minimum control).

 

As the stall approaches the ailerons become ineffective first.

 

http://www.pilotfriend.com/training/flight_training/fxd_wing/stalls.htm

 

It would be very unusual if the the Bf-109 did not have some lateral instability in the vicinity of the stall.

[NineLine]

For me it just goes to show how little it takes to get a vastly different picture of the aircraft's behaviour in the sim.

Our controllers are a big part of it.

 

Yes! I wish more people accepted how big their controls play in all these discussions.

 

Another thing is I.A.S. (instant ace syndrome), thinking that you can jump into a high performance fighter and fly it like the the legends :)

[Sporg]

You mention constant speed and stick deflection. The way stick stiffening is simulated in this sim, the following will happen: hold the joystick at a fixed / constant deflection and in game stick forces will prevent you from pulling it all the way back. Essentially the virtual stick will stop at one location until the speed bleeds. Then, as a result of lower stick forces, the virtual stick will continue to move further back to match your joystick position - forcing you to exceed critical AOA and enter a stall.

 

But, since you say constant speed, the above shouldn't happen. Do enable control indicator with CTRL + ENTER when recording please.

 

Thanks for your advice.

 

I made a new attempt, and this time kept in mind what you said here.

 

This time I was able to keep a sustained turn for much longer, just below the stall limit.

And this time I could do it both at 1.4 and 1.8 ATA + MW.

 

Left turn I could sustain at 4.0 - 4.5 G at max. power 1.8 ATA + MW.

 

No doubt my centered joystick helped as well.

It's like I experienced less instability this time.

 

I attach track again.

Mind you, I had some weird problems with this track when playing without Lens Effects on. As soon as I enabled Lens Effects it played as it should.

 

Hope it works at your end and hope it is useful.

109 stall test track 2 centered stick.zip

[[DBS]TH0R]

You are welcome. :)

 

I am in the process of DL v1.5 and will examine tracks as soon as I have the opportunity. Back from my testing in v1.2 I found that in order to keep the virtual stick in the same position you need to "juggle" the stick back and forth a lot, I'm talking about very small movements here. Hence the stick precision is required to ride on the edge of the stall for a longer time, and why FF or extension really do help (not that much, but they do).

 

Now this can be done two ways: a) either carefully watching your virtual stick position in the CTRL+ENTER indicator, ensuring it stays still throughout the maneuver or b) by listening to what the plane is telling you, there is plenty of warning before the stall.

 

In other words, physical stick can not be held in the same position throughout the whole maneuver since it doesn't match the virtual stick, i.e. virtual stick moves depending on the stiffness. However, if Hummingbird really was able to maintain constant airspeed, the stick shouldn't move.

 

At least, this how I experienced / understood stick stiffness modeling.

Edited October 7, 2015 by T}{OR

[Sporg]

Back from my testing in v1.2 I found that in order to keep the virtual stick in the same position you need to "juggle" the stick back and forth a lot, I'm talking about very small movements here. Hence the stick precision is required to ride on the edge of the stall for a longer time, and why FF or extension really do help (not that much, but they do).

 

Now this can be done two ways: a) either carefully watching your virtual stick position in the CTRL+ENTER indicator, ensuring it stays still throughout the maneuver or b) by listening to what the plane is telling you, there is plenty of warning before the stall.

 

Actually, this is exactly what I did this time.

Using my vibration chair to feel the buffering, watching the airspeed, trying to keep the plane following the horizon.

But also trying to see how much the virtual stick moved.

 

As you say, this necessitated moving my physical stick back and forth in order to keep the virtual stick pressure approximately the same.

[Hummingbird]

Most aircraft become laterally unstable at the edge of stall. Ailerons are generally one of the first control surfaces to lose effectiveness in determining Vmc (speed of minimum control).

 

 

 

http://www.pilotfriend.com/training/flight_training/fxd_wing/stalls.htm

 

It would be very unusual if the the Bf-109 did not have some lateral instability in the vicinity of the stall.

 

You are right, but it should be much less on the 109 due to the slats maintaining the effectiveness of the ailerons much closer to the stall. Also it really shouldn't be rocking the wings that much, something which doesn't happen in either the Fw190 or TF-51, thus I find it extremely strange for it to be so pronounced on the 109 which in reality maintained aileron effectiveness near stall much better. The wing drop also seems too quick and sudden.

 

PS: Will start recording a track in a few minutes.

Edited October 7, 2015 by Hummingbird

[NineLine]

You are right, but it should be much less on the 109....

 

But could that difference you feel is there simple be because of us being in a simulated world, with less capable controls and arguably less skill than your normal/average real world 109 test pilot....

[Crumpp]

You are right, but it should be much less on the 109 due to the slats maintaining the effectiveness of the ailerons much closer to the stall. Also it really shouldn't be rocking the wings that much, something which doesn't happen in either the Fw190 or TF-51, thus I find it extremely strange for it to be so pronounced on the 109 which in reality maintained aileron effectiveness near stall much better.

 

PS: Will start recording a track in a few minutes.

 

Cannot argue against or for the amplitude of the oscillations without more data. I can offer my opinion...but it is just that an non-quantifiable opinion.

 

I am sure Yo-Yo has that data and while it would nice if he shared it, it is his prerogative to do so.

 

He is not required as gathering these documents is neither easy nor cheap.

 

Please do share your track. Several posters have seen an improvement by re-calibrating their controllers. You maybe experiencing excessive instability because of some unforeseen issue outside of the FM.

[Hummingbird]

Well it turns out that I actually do have an unforeseen control issue, which is that my stick doesn't center completely upon release and I don't have full left stick available. (You can see that on the track as I enabled CTRL + ENTER) according to the ingame control indicator I am missing perhaps 3-5% in left stick deflection and the stick isn't perfectly centered upon release. I am abit baffled by this as it doesn't show up during calibration outside the game. I tried recalibrating several times, but the issue remains.

 

That having been said I don't think it should really be a problem in terms of causing wing rocking, esp. since there is NO control jitter, and I should easily be able to compensate for such a small deviation in centering.

 

Anyway the track is recorded but I can't locate it anywhere?

[NineLine]

 

Anyway the track is recorded but I can't locate it anywhere?

 

When you save a track, it asks you where you want to save it. Default location is in your Saved Games folder where your DCS folder is, in this case the Open Beta folder I would imagine.

Edited October 7, 2015 by NineLine

[Hummingbird]

When you save a track, it asks you where you want to save it. Default location is in your Saved Games folder where your DCS folder is, in this case the Open Beta folder I would imagine.

 

Thanks, located it by going back and checking the default saving location.

 

Should be a good amount of accelerated stall testing in there, but I'll do some more.

 

Basically I find the aircraft very jittery near the stall, much more than the Fw190 or Mustang, with the odd wing rockíng and rapid wing drop which immediately stops and then starts again even under constant stick and speed it seems.

 

Here it is:

Testtest.trk

Edited October 7, 2015 by Hummingbird

[Hummingbird]

Another track with some more maneuvers (pay attention to the ending):

Testtest2.trk

[Ala13_ManOWar]

Well, after a quick peak I'm sorry but I only see the usual stall buffeting :huh:. Lets other users see the track.

 

Don't underestimate that control flaw, a minor detail can badly change your feeling in game.

 

S!

[Yo-Yo]

Just to show that any anecdotal reports (even Western) about "mild", "pleasant" or even "deeply sexual" kind of stall can not be compared with the in-flight RECORDS... :)

 

Omega X and omega Z are angular velocities for roll and pitch, sigma эл - means ailerons deflection and РВ index means elevator.

 

V and H are IAS and altitude.

 

 

One can see the pilot's tryings of the aileron effectiveness - omegaX follows the aileron deflection.

 

It's interesting that not so much elevator deflection is necessary to stall the plane. Unfortunately the exact CoG position is not specified for this record, but it can be estimated form the power-off trim curves - approx. 27%.

 

The stall itself is caught where both omegaX and omegaZ gave peaks. Rolling velocity reached 13 deg/s, and overall bank angle can be obtained by integrating this peak - approx 16 degrees for sine-like curve.

 

The pilot tried to counteract the roll with active ailerons input and foward the stick immidiately.

Edited October 7, 2015 by Yo-Yo

[Sporg]

Well it turns out that I actually do have an unforeseen control issue, which is that my stick doesn't center completely upon release and I don't have full left stick available. (You can see that on the track as I enabled CTRL + ENTER) according to the ingame control indicator I am missing perhaps 3-5% in left stick deflection and the stick isn't perfectly centered upon release. I am abit baffled by this as it doesn't show up during calibration outside the game. I tried recalibrating several times, but the issue remains.

 

That having been said I don't think it should really be a problem in terms of causing wing rocking, esp. since there is NO control jitter, and I should easily be able to compensate for such a small deviation in centering.

 

Well, It seems to be exactly the issue I encountered.

Mine was displaced slightly to the right of center.

 

One shouldn't underestimate how much we rely on our feeling of center on the physical stick.

For me the aircraft changed character in a pleasant way after I calibrated the stick properly.

Maybe one should see it as the aircraft feeling extra out of trim, when the controller is not properly calibrated.

 

I don't know which controller you have, I tried HW calibrating mine several times, but it was still off center.

 

Then I went into Windows calibration and chose to reset.

That finally solved the issue.

Edited October 7, 2015 by Sporg

[Foul Ole Ron]

I've been having the same issue as Hummingbird. I'm using a X-55 myself. When the 109 is on the ground the stick is perfectly calibrated and when I release the stick it goes back to the centre. However once I'm in the air it's always slightly deflected to the right.

 

I've tried re-calibrating the stick but that hasn't cleared the issue up. Anyway it doesn't make sense that it's a physical stick issue as there's no problems when the 109 is on the ground. Any ideas what could be causing this or could it be a bug of some sort?

 

I've attached some screenshots showing on the ground with engine at idle, on the ground with engine at full power and in the air cruising at 1.1 ATA.

[Hummingbird]

Well, It seems to be exactly the issue I encountered.

Mine was displaced slightly to the right of center.

 

One shouldn't underestimate how much we rely on our feeling of center on the physical stick.

For me the aircraft changed character in a pleasant way after I calibrated the stick properly.

Maybe one should see it as the aircraft feeling extra out of trim, when the controller is not properly calibrated.

 

I don't know which controller you have, I tried HW calibrating mine several times, but it was still off center.

 

Then I went into Windows calibration and chose to reset.

That finally solved the issue.

 

I'll try to reset instead Sporg and see what happens.

 

Regarding the wing rocking and drop, it still doesn't seem right at all, and it's completely unlike any account of the aircraft I've read or heard.

 

Btw thanks to Yo-Yo for the Russian document, I know the Finnish did similar testing - I wonder if that could shed some light on the issue?

[Hummingbird]

Well, after a quick peak I'm sorry but I only see the usual stall buffeting :huh:. Lets other users see the track.

 

Don't underestimate that control flaw, a minor detail can badly change your feeling in game.

 

S!

 

Did you watch the second one?

[Yo-Yo]

I've been having the same issue as Hummingbird. I'm using a X-55 myself. When the 109 is on the ground the stick is perfectly calibrated and when I release the stick it goes back to the centre. However once I'm in the air it's always slightly deflected to the right.

 

I've tried re-calibrating the stick but that hasn't cleared the issue up. Anyway it doesn't make sense that it's a physical stick issue as there's no problems when the 109 is on the ground. Any ideas what could be causing this or could it be a bug of some sort?

 

I've attached some screenshots showing on the ground with engine at idle, on the ground with engine at full power and in the air cruising at 1.1 ATA.

 

Trimmers? :D

[Sporg]

I've been having the same issue as Hummingbird. I'm using a X-55 myself. When the 109 is on the ground the stick is perfectly calibrated and when I release the stick it goes back to the centre. However once I'm in the air it's always slightly deflected to the right.

 

I've tried re-calibrating the stick but that hasn't cleared the issue up. Anyway it doesn't make sense that it's a physical stick issue as there's no problems when the 109 is on the ground. Any ideas what could be causing this or could it be a bug of some sort?

 

I've attached some screenshots showing on the ground with engine at idle, on the ground with engine at full power and in the air cruising at 1.1 ATA.

 

 

I have the same problem after calibrating.

Centered on the ground, slightly to the right in the air.

I don't know if it is the result of the trim tabs on the ailerons?

Edit: Sniped by Yo-Yo. :)

 

Anyway, the tool I use to test my stick is JoyTester2.

It can be found here: https://drive.google.com/file/d/0ByygDcuGFHYPZ1pWQ0ZZZ3kwdTg

[Foul Ole Ron]

Trimmers? :D

 

Aha.. yep that was it thanks!

 

I have to set my aileron trim in the UI to be -30 for the stick to be centred in flight and remove that unwanted aileron roll to the right.

[Ala13_ManOWar]

Did you watch the second one?

Yes. there I don't even see buffeting, I don't understand quite well what were you trying there. Or may be tracks don't play correctly in 1.5, dunno.

 

S!