"Pitch Up"

[Thumper1606688436]

1) An upside down aircraft = NO LIFT.

2) An aircraft without lift + afterburner = Ballistic rocket.

3) An aircraft in a spin + afterburner = Catherine wheel = accelerated time to impact.

4) A ballistic rocket without gyroscope controlled engine = BOOM.

[CoBlue]

About this AB thingie!

Where is all this AB energy going to? Energy will never be lost. The engine is at the plane, the engines producing thrust, thust is energy, but there is no reaction. This is against all physically behaviors I know.

If the engine is running and you put energy out there, there must be a reaction! But the Su27 does nothing. No spin, no acceleration, nothing.. even the stall was not really flat, most of the time the nose shows +20° to the ground.

Yes you can get out of this stall, but the AB behavior is very strange for me.

Where is all this energy going?

Flat stalls are mostly a energy problem after an stall (blow out) but the Su27 has two engines with full AB running and nothing happened. This can't be right!

Action -> reaction! A simple physic law!

The Su27 behaves like she is in her own physic bubble.

I agree :thumbup:

[Ironhand]

That is why I said that it is the relative position of where your plane wants to go ^.^

Does this mean we're saying the same thing, only I'm using a lot more words? :)

 

Here are the promised TRKs. Two for each of your 2 A2A stall TRKs. You'll know when I'm about to take control because I switch to an external view, come back into the cockpit, and bring up the Controls Indicator panel. I actually take control a few seconds later, when the controls snap to neutral. The exception is: 2-IronhandRecovery2.trk. I waited a long time to take over on this one and was in hurry up mode because there wasn't much altitude left. I took control almost immediately after bringing up the Control Panel.

 

I had missed it the first time but in one of your tracks (2.trk, I think), you had entered such a deep stall that your engines shut down because they weren't getting the airflow they needed which I found to be an interesting wrinkle.

 

As far as being in afterburner is concerned, I found that there is a difference in what happens if you are in a simple stall. Haven't had an opportunity to see what the difference is in a spin, if there is one. Part of my problem is that I'm having a hard time forcing it into a spin that isn't easy to recover. I've tried twice and, each time I powered back and let the controls go to neutral, the aircraft recovered itself. And, now, I'm out of time.

[Shadow KT]

Yea we are pretty much talking about the same thing. I'll watch the tracks.

 

The Flame out happend in the one I was upside down. Pretty sure the engines couldn't get the fuel they needed and I was so frustraited at that points I didn't react fast enough on the power idle. I was trying so hard to get my self out of that stall that at some points I have no more hydro pressure to move my elerons. Still no reaction of the plane in the inital try to recover after the flame out

[Svend_Dellepude]

I had missed it the first time but in one of your tracks (2.trk, I think), you had entered such a deep stall that your engines shut down because they weren't getting the airflow they needed which I found to be an interesting wrinkle.

 

More likely fuel starvation from negative G's.

[Ironhand]

Yea we are pretty much talking about the same thing. I'll watch the tracks.

 

The Flame out happend in the one I was upside down. Pretty sure the engines couldn't get the fuel they needed and I was so frustraited at that points I didn't react fast enough on the power idle. I was trying so hard to get my self out of that stall that at some points I have no more hydro pressure to move my elerons. Still no reaction of the plane in the inital try to recover after the flame out

I'm not certain what actually caused this particular flameout (I had assumed lack of airflow but...) but the engines had been spun down for quite awhile (2-IronhandRecovery2.trk) before I took control and exited the stall--with a few feet to spare. :)

 

The more I play with this, the more I'm beginning to suspect that light control inputs are better than extreme and forceful ones. And that seems to coincide with the the Su-27 flight manual (assuming I'm interpreting it correctly). But that's more of an impression on my part than anything else.

 

More likely fuel starvation from negative G's.

Possibly, though I've been inverted for quite awhile at other times without this happening. But, then again, I don't recall if my experience was before or after the flight model update.

 

 

Rich

Edited December 12, 2014 by Ironhand

[Shadow KT]

Not good at all.... I just updated to the newest 1.2.12 Version which just came out of Beta and the Tracks don't work anymore..... Completely different stuff happens..... On the level tracks the planes doesn't even take-off.... goess to the grass and crashes into a hangar....

 

P.S. Illuminati confirmed

Edited December 12, 2014 by Shadow KT

[Ironhand]

Not good at all.... I just updated to the newest 1.2.12 Version which just came out of Beta and the Tracks don't work anymore..... Completely different stuff happens..... On the level tracks the planes doesn't even take-off.... goess to the grass and crashes into a hangar....

 

P.S. Illuminati confirmed

That's too bad. And to think that I got up especially early this AM to have time for them. :) Oh well. At least the coffee tasted good.

 

So, how has the FM changed? Any sense of it yet?

[Nedum]

Only because of lift. I'd like to suggest that, without lift (a stall condition), the aircraft is going nowhere but down.

 

If I take a stone, put a engine at this stone, fire up the engine, let the stone "stall" (falling down), there must and will be always a path change.

The physically laws of forces!

The Su27 now handles like she is in a "stall/cobra bubble". A special bubble made to do the Cobra maneuver and the trigger for this "switch" is bound with the AOA, speed and the S key, but even alone the AOA and the speed are enough to get in this "cobra bubble". Why you can pull more easy more degress at higher AOA, even there are less forces to do so (at the same speed)? Action = Reaction.

If you look at a flat stalled Su27 you can notice a "wire behavior", a rotation point that is never changing even the nose is going up and down and you change the thrust power. This is impossible!

 

This rotation point seems to be at the same place, if you doing a Cobra, a reverse stall, a stall, a flat stall or an inverted flat stall.

It's looks like there is a invisible wire at this point and this wire prevents any thrust behavior.

 

And if you get near an stall, the Stick inputs are much to sensetiv as they should be!

If there is a stall and there is not enough air drag anymore, the Stick input should be less sensible but 2 micrometer up and down and the plane flips 180 degrees. I have never seen any of this extrem sensible DCS Su27 behavior at one of the Su27 Air Show RL crashs.

 

The DCS Su27 handles completely different to all PC planes I have evern flown (even the DCS ac).

 

If you look at the AC (Su27) with the F2 outside view, and switch the flaps back, you can see again this "wire effect" at the same rotation point like after an stall.

The DCS Su27 is the only AC I know, that reduces the nose position if the flaps are getting down.

The flaps producing lift ALWAYS from the leading edge, but the DCS Su27 is producing lift with flaps down from wing trailing edge. Physically not possible!

There is no physically correct explanation for this behavior.

The basic physics are the same for ALL AC.

If someone want to tell me this is correct, than tell me why with less lift (flaps up) the nose is raising up?

Which physic law is responsible for this? The speed incrase and decrase are to low to explain this behavior. And if so, why is the Su27 the only DCS plane acting like this? Full flaps down = DCS A10 A/C nose up, FW-190D nose up, F15C nose up, BF109K nose up, F-86F nose up, P51-D nose up.

So which ac are acting wrong?

It's all about the laws of forces and some of them seem not to work with the DCS Su27.

Edited December 12, 2014 by Nedum

[Shadow KT]

Man I feel really bad for those tracks and as much as I want to make you reproduce them ... I have to reprodue my own too and they might be completely different....

 

Don't know if it is me or the AC but I am kinda getting the hang of it ;d

 

[ATTACH]109328[/ATTACH]

 

 

Yea, I can agree with Nedum about that feeling when about to stall and the controls get so touchy and that the same things happens with all the types of stalls

 

About the flaps, I thought that was somerthing worng too, but I think it is right . Has something to do with the aerodynamics.... Nose Down doesn't mean we are not increasing lift. I think it just pushes the back side of the aircraft up, but still produces lift

[Shadow KT]

So I jumped into e Flanker and wanted to test how hard can I pull. Was doing all kinds of horizontal turn with different Gs. Even did some extreme G turns with the S button. Gave it a bit of vertical gain as well.... Nothing, No problems at all. The moments I tried doing a high g vertical pull that is when I lost control of the aicraft and no further input was helping out

[Ironhand]

Had about 45 minutes this morning before work to watch your SkyScrapers.trk. Nice flying! :) Right up until that building... I'll have to give that mission a try one of these days. Looked like a lot of fun.

 

Played around with a few high-G turns, did some loops but nothing with a particularly high G loading. Also had a lot of fun barrel rolling. Doing it by the book, the AoA stayed well within limits. Don't know if that's due to the update or an improvement in skill.

 

Stalls still appear to be the way they were. I agree with you and Nedum that there are issues with what happens. Just not sure what they can do about it. In researching, I keep finding that it's easy to calculate things right up until the full stall condition. Then significant complexities ensue. From in the cockpit, things like thrust matter in how easily and quickly you can recover. From outside, it all looks the same whether you have power on or off.

 

BTW, it seems that this update now causes drag from weapons to cause a slight yaw either left or right for symmetrical loads. A clean aircraft in a mission with no wind will roll down the runway and fly without a tendency to yaw. Hang weapons off the pylons and there's a continuous slight yaw either left or right.

 

Probably won't be able to get back to the sim until Tuesday, unless the complexion of this weekend changes. I'll be interested in hearing what you discover in the meantime.

 

Nedum, as far as the nose of the aircraft pitching down when flaps are deployed, check out this link: FAA SAFETY: Use of Flaps. It may not be as strange as it seems. There are also numerous other sources suggesting the same downward pitch.

Edited December 13, 2014 by Ironhand
Add flaps link for Nedum

[Nedum]

Had about 45 minutes this morning before work to watch your SkyScrapers.trk. Nice flying! Right up until that building... I'll have to give that mission a try one of these days. Looked like a lot of fun.

 

Played around with a few high-G turns, did some loops but nothing with a particularly high G loading. Also had a lot of fun barrel rolling. Doing it by the book, the AoA stayed well within limits. Don't know if that's due to the update or an improvement in skill.

 

Stalls still appear to be the way they were. I agree with you and Nedum that there are issues with what happens. Just not sure what they can do about it. In researching, I keep finding that it's easy to calculate things right up until the full stall condition. Then significant complexities ensue. From in the cockpit, things like thrust matter in how easily and quickly you can recover. From outside, it all looks the same whether you have power on or off.

 

BTW, it seems that this update now causes drag from weapons to cause a slight yaw either left or right for symmetrical loads. A clean aircraft in a mission with no wind will roll down the runway and fly without a tendency to yaw. Hang weapons off the pylons and there's a continuous slight yaw either left or right.

 

Probably won't be able to get back to the sim until Tuesday, unless the complexion of this weekend changes. I'll be interested in hearing what you discover in the meantime.

 

Nedum, as far as the nose of the aircraft pitching down when flaps are deployed, check out this link: FAA SAFETY: Use of Flaps. It may not be as strange as it seems.

 

Thank your for your answer und the link. Its all about constant airspeed and power. I know this very well but again many thanks.

That's not the problem the DCS Su27 is showing to me. It's about increase and/or decrase power and speed with flaps up and down.

Even you lower the flaps there will be always a time over which such a behavior smooth occurs.

With the Su27 ist always like a sudden punch in the stomach. You make a "snip" and the AC doing things like there is no physic for short time/you enter a new physic space!

Flaps up and "Bang" the nose goes suddenly up, and after flaps down another "Bang" and the nose wents down. No sensetive inputs, it's like with a hammer. It feels like pure digital.. 0 or 1 nothing in between.

 

And it feels like they are using a completely different Wing design, but I know they use a very well known wing design, that helps the Su27 especially at high AOA maneuvers to be stable and that at a very low speeds.

 

Every day I try to fly a shown Su27 display of a Air Show, but the DCS Su27 is a bitch at low speed and it feels there is always not enough power to get out of this maneuvers like they could do in the RL Air Shows.

It feels like I have to get out of this special physic space to get some thruster input.

With the Su27 I got the most stalls over all other AC in DC AND less much Blackouts even at extrem turns, because the Su27 is eating speed/energie like hell. If I feel/see a BO nearing, I pull for a very short time (less a second) much harder and I am out of this BO behavior, because the speed is gone in less a second.. strange for me. It's like there is a invisible parachute as soon as I pull a short time hard at the stick.

I do RC flying a lot (mostly Helis) and the DCS Su27 is sometimes more agil as our RC ACs and not much less agil as our 3D Helis. Till this DCS Su27 our RC birds were the much more agil ACs compared to any RL AC. And we can't see this extrem flaps behavior with our ACs too.

And why is there always this nose up and down at a stall, with the same amplitude the whole stall long, without any thrust input? I would like to see the force diagram for this behavior.

There are no ways for an amplitude without an continuous impulse to hold the amplitude to stay all the time at the same level.

1. If the power is to high, the amplitude will grow untill she collaps (Su27 would flip over).

2. If the power is to low, the amplitude will become smaller and should be stopping if there is no power impulse anymore. (the Su27 nose would show to the ground even she has a small amplitude).

But in DCS she is, even the AC is falling in different air pressure zones, every time at the same level. Who could that be? You can use Full power, full AB, idle power, not a chance for a change! Who is that possible?

But my very last question is and will be, why are all other ACs in DCS are so completely different compared to the Su27 at stall and low speed!?

I read and heard that the Su27 is one of the most stable ACs at low speeds even at high AOA and that she is so good at this because she has enough power to do so even with high AOA, but in DCS I miss this "over power" behavior at low speeds.

For me it's looking like the DCS Su27 is defined solely on the Corba maneuvers.

But that's only my feeling!

Edited December 13, 2014 by Nedum

[Shadow KT]

The more and more I play this mission the more I have the feeling a I am driving a drifting car. The drifts are real with this one. An yeah about the thing which Nedum said about the plane eating the energy: How come I can go with 800+km/h and press S, do a 180 degree turn for less than 2 second get down to 200km/h and not even start to black out ?

 

Also, while doing these drifts around the gates my speed hardly drops if it even drops at all even if at 80% RPM. lolz

Edited December 13, 2014 by Shadow KT

[Godzila]

Nedum, I am no expert in anything, but I made a RC pusher prop model of Su27. Once during testing I put COG too far back and experienced some of the things you mentioned. Model is a bit heavy with high wing loading for RC and 3 axis stabilisation.

 

I have to be very careful because of high wing loading and torque roll. That is with front COG. The mistake I made with rear COG was a whole different beast. Every input was 10x exaggerated, with zero or low speed inputs were completely ineffective and after 10 seconds of scary flying I lost sight of the plane and released commands. Plane was falling level (horizontally) and landed without damage. Similar to the spin of death we have in DCS.

 

If you fly RC you surely have a lot of spare equipment laying around. You can quickly make something with front point of lift and rear prop or EDF. Make the COG rear of point of lift and then report back. Do not compare Mustang, Dora or F86 with something completely different.

[RvETito]

Pitch trim seems definitely off in the Su-27. At speed 700km/h and above I need more than half of the stick travel forward to balance. If I let go on the stick the aircraft is pulling up to 5-6G's all by itself (pitch trim in neutral). It can actually perform a perfect loop with hands off. I have no facts to put on the table since I've never even seen a real Su-27 in my life but that definitely seems not right.

[Shadow KT]

Pitch trim seems definitely off in the Su-27. At speed 700km/h and above I need more than half of the stick travel forward to balance. If I let go on the stick the aircraft is pulling up to 5-6G's all by itself (pitch trim in neutral). It can actually perform a perfect loop with hands off. I have no facts to put on the table since I've never even seen a real Su-27 in my life but that definitely seems not right.

 

Well if the original tracks still work u will se exactly that in them ^.^

[Ironhand]

Pitch trim seems definitely off in the Su-27. At speed 700km/h and above I need more than half of the stick travel forward to balance. If I let go on the stick the aircraft is pulling up to 5-6G's all by itself (pitch trim in neutral). It can actually perform a perfect loop with hands off. I have no facts to put on the table since I've never even seen a real Su-27 in my life but that definitely seems not right.

Not sure what the issue is. Are you saying that you can't trim for level flight above 700 k/h? Or is it that, after trimming, you don't have suffiecient control authority to maneuver? If either of those, then the sim and your hardware aren't playing nicely together.

 

I say that because, fortunately, I have neither issue. The amount of stick travel, per say, isn't an issue. I can trim up to and through 1200 k/h for level flight. And, yes, the stick travels quite a bit forward. However, even then, I still have sufficient control authority to do whatever I need to do.

 

EDIT: Attached a track

 

 

Rich

Edited December 15, 2014 by Ironhand

[RvETito]

I have no problem trimming the aircraft hardware wise but it seems odd that it takes so much of the stick travel. The amount of work required with the "trimmer" through the IAS range is the major problem. I kinda doubt how realistic that is hence the example with the "auto loop".

[Kwiatek]

For some reason trim dont work with some FF stick and FF effect on.

 

I got Saitek Evo Force and trim dont work with FF enabled in game options. :(

[Robin_Hood]

I have no problem trimming the aircraft hardware wise but it seems odd that it takes so much of the stick travel. The amount of work required with the "trimmer" through the IAS range is the major problem. I kinda doubt how realistic that is hence the example with the "auto loop".

 

The "auto loop" is perhaps not that strange if you consider that the pitch stability is artificial. The FCS gives you the pitch behaviour vs IAS for a "natural feel" (which, considering all the debate surrounding the issue, doesn't feel natural after all) with a pitch up tendancy when IAS goes up (while naturally the Su-27 doesn't have this behaviour).

 

I would agree that the artificial stability feels overmodelled (not necessarily saying this is due to DCS, maybe it is really like that in the real Su-27). It is true that the aircraft requires a lot of trim, but maybe it's really only a matter of getting used to it.

[karambiatos]

The "auto loop" is perhaps not that strange if you consider that the pitch stability is artificial. The FCS gives you the pitch behaviour vs IAS for a "natural feel" (which, considering all the debate surrounding the issue, doesn't feel natural after all) with a pitch up tendancy when IAS goes up (while naturally the Su-27 doesn't have this behaviour).

 

I would agree that the artificial stability feels overmodelled (not necessarily saying this is due to DCS, maybe it is really like that in the real Su-27). It is true that the aircraft requires a lot of trim, but maybe it's really only a matter of getting used to it.

 

The interesting thing is that aircraft has less of a "pitch up" when you turn the FCS off.