M2000c FM changes DCS 1.5.5.59744 Update 1

[zerO_crash]

It seems like there have been many good changes, but I did notice some things that I`m either unsure about, or sure are wrong:

 

- At 40 000 feet, or below, when cruising at full mill, with 8 bombs + 2 magics + 1 fuel tank, the aircraft seems to have a pronounced tendency of pitching up all the time, not much, but it`s constantly going up a little. It`s most pronounced for me when at M 0.8-0.9, but it seems like the aircraft wants to pitch often even without my input. Wasn`t the FBW computer supposed to handle this?

 

- At 60 000 feet, the aircraft behaves very weird, pitch oscillations are apparent, even with no input. Is this correct, or is it still being worked on?

 

- The accuracy of the BLG 66 (CCIP) seems off. Using radar for ranging (tried both with radar and radar altimeter), with correct modes selected on PCA, seems just wrong. Only tested it in mountainous regions right now, trying to bomb a hill top, and the results were often miss by a 3-400m. Sometimes hits, other times not. Seems weird considering that CCRP accuracy is so good, even with releasing from further away. Not sure if this is correct?

 

Otherwise, it seems to me like a overall great patch, many fixes :thumbup: Interesting how the FBW seems to interfere much less with inputs now compared to before. I remember the M2000C as being very direct in commands, and FBW computer having much authority, however now it seems like it`s less. The plane starts to remind me slowly of other, non FBW, where you have to hold the stick in place to counter aircraft`s external forces.

[myHelljumper]

For the BLG, they where accurate when I tested them. Please do some tests in flat area so we can see if the problem comes form the mountains.

[red_coreSix]

60.000 feet is above service ceiling so I wouldn't expect it to handle normally. The pitch up tendency has been there for longer, I just trim it out.

 

I believe the mil-power performance is too high in this patch though, I think you shouldn't be able to sustain a 40.00 feet cruise with the load-out you mentioned, at mil-power.

 

I do agree, the patch is perhaps the biggest leap forward for me, concerning the fixes in turn-rate as well as damage model.

[zerO_crash]

For the BLG, they where accurate when I tested them. Please do some tests in flat area so we can see if the problem comes form the mountains.

 

Did, and they sometimes fall way short, or even overshoot their point. What`s worse, is that I get the cross on my hud (outside launch parameters) most of the time. Diving drops seem to be in most cases accurate, but some of them are totally off, while level drops overshoot by 5-1000m, always.

 

60.000 feet is above service ceiling so I wouldn't expect it to handle normally. The pitch up tendency has been there for longer, I just trim it out.

 

I believe the mil-power performance is too high in this patch though, I think you shouldn't be able to sustain a 40.00 feet cruise with the load-out you mentioned, at mil-power.

 

I do agree, the patch is perhaps the biggest leap forward for me, concerning the fixes in turn-rate as well as damage model.

 

Even though outside it`s ceiling, the aircraft has been to greater heights in real life. Also, military aircraft primarily (civilian too) are tested and certified at much higher altitudes than what`s listed in their ceiling limit.

 

As to the pitch, I have never had this problem before. And at takeoff it has become more sensitive too. It`s easy to replicate in that you are at medium speed (M 0.7-0.9, or so) and point the aircraft at 10, maybe 20 degrees pitch up, the aircraft keeps pitching, as if it was tail-heavy and FBW doesn`t correct it.

 

Thx @CptSmiley

Edited December 3, 2016 by zerO_crash

[zerO_crash]

Got it confirmed, after testing more, it`s because of the radar altimeter. The reading from it always screws up the impact point. At this time, I can hit tanks, or any object the size of a tank/truck with CCRP, and from greater distance away, merely because you get to avoid radar altimeter. With CCIP however, unless it`s flat (few places on Caucasus that flat) it just won`t hit.

 

This brings me to the main question, is it an requirement IRL to feed the targeting computer radar altimeter info?

 

I figured the cross out, you had a little more info in the tutorial about CCIP release requirements than you got in the manual :)

[zerO_crash]

That's normal, with zero input in the G command speed range the plane will seek out 1G and thus in a climb, keep pitching up.

 

EDIT: Discard, misread.

Edited December 3, 2016 by zerO_crash

[zerO_crash]

Nope, scan through my post history on how G command is implemented, I can't recall for the life of me where I posted it, if you have trouble finding it let me know and I'll spend some more time searching.

 

I roughly stated that "G" command and vertical body axis acceleration are not the same which is why as Vladinsky stated you will see a slight pitch up behavior when the aircraft is pitched up significantly above the horizon. Just as a comparison to a similar control system, the VRS F/A-18 and BMS F-16 (other high fidelity modeled FBW systems) you'll notice the same behavior and even to a degree you will notice it in the F-15C's control system when pitched up very high which is using a less complex but very nice stability augmentation. Old version of the M-2000C were controlled via vertical body axis acceleration but was found to be inaccurate in how it really is. Hope that helps!

 

The issue you found is that the stabilization output at very high altitudes was not countering the normal control positions enough when in very low pressure/density conditions as higher amounts of control deflection are necessary to provide equivalent stabilization you see at lower altitudes.

 

EDIT: Just saw edited but will keep for informational purposes :)

 

Okey, that was pretty interesting. I will have to find that post. Thx again for taking your time, awesome stuff :thumbup:

[CrashO]

I will have to find that post. :

 

Pretty sure this is it:

 

Hi all, if you don't care to read below, these behaviors noted have been corrected. Now for more details:

 

Just a bit of history, there are really two different ways to command based on acceleration. The first and the way it appears to be done across all other aircraft (F-16 [bMS], F-18 [VRS], F-15 [DCS] are good known sim examples) is via G-load that is the apparent G on the aircraft, that is, the apparent vertical acceleration in world frame plus body acceleration on the aircraft. The other and more simpler one is command based on only body axis vertical acceleration.

 

In the first, the aircraft always tries to maintain 1 "G" regardless of orientation the second the aircraft always tries to maintain 0 vertical body axis acceleration regardless of orientation. Now what does this mean you might ask? Well in the "G" command version going level and inverted the aircraft will still try to maintain 1G, thus causing you to go toward the ground, in the other the aircraft will stay level will always point in the direction it is going as a change in pitch rate would result in vertical body acceleration therefore it will actually trim at -1G.

 

So early in the M-2000C code base we had it the first way (G-load command) and the known way it is used in other aircraft. However, a few people complained about minor pitch increase when climbing/descending so I changed it to do the second way some time in the March/April time frame. The problem with the second way is exactly what FoxOne discovered, when you aren't perfectly level the aircraft behaves in a non-standard way especially when off the horizon plane and control load is unpredictable with respect to aircraft orientation. On the other hand with the vertical body acceleration way and stick neutral the aircraft will always point where it's going regardless of any orientation, which in many cases is a good thing.

 

In any event, I went back and looked at a bunch of public FBW diagrams for like aircraft, talked with some people in the know, and based on them along with those FBW aircraft tested out in sims and their respective behaviors the G-load behavior described by FoxOne appears to be the correct one.

 

In conclusion, I've reverted the FBW G-load command logic to be more like it originally was and got the thumbs up from testers. The only "negative" thing (that is also experienced with every of the FBW based sim aircraft I could find in public domain) is a very slow and gradual pitch up tendency when climbing or descending in stick neutral and no trim. This is obviously because G-load is not the same as 0 vertical body acceleration on the aircraft.

 

Hope this helps and is a sufficient explanation :)

source

[Xenovia]

i haven't tried it, will do it soon™.

[zerO_crash]

Pretty sure this is it:

 

 

source

 

Nice stuff, saved me some time looking :thumbup:

 

Edit: Holy molly, how did I miss this. Splendid explanation, and what an interesting way to solve FBW logic. Damn ;)

Edited December 3, 2016 by zerO_crash

[Azrayen]

I believe the mil-power performance is too high in this patch though

Didn't test it with loadout, but the MIL power is in fact just fine with a clean aircraft. :thumbup:

[Robin_Hood]

Got it confirmed, after testing more, it`s because of the radar altimeter. The reading from it always screws up the impact point. At this time, I can hit tanks, or any object the size of a tank/truck with CCRP, and from greater distance away, merely because you get to avoid radar altimeter. With CCIP however, unless it`s flat (few places on Caucasus that flat) it just won`t hit.

 

This brings me to the main question, is it an requirement IRL to feed the targeting computer radar altimeter info?

 

I figured the cross out, you had a little more info in the tutorial about CCIP release requirements than you got in the manual :)

 

If you use TAS, then radar altimeter should not be used, IMHO. I think that since the radar altimeter can only measure your own current height, any elevation difference between the target and the ground below you will induce an error in the targeting. I don't think it can be avoided, since it is a limitation of using radar altimeter as a source. Using TAS should solve the issue.

 

EDIT: Here's what I mean:

Edited April 5, 2017 by Robin_Hood

[zerO_crash]

If you use TAS, then radar altimeter should not be used, IMHO. I think that since the radar altimeter can only measure your own current height, any elevation difference between the target and the ground below you will induce an error in the targeting. I don't think it can be avoided, since it is a limitation of using radar altimeter as a source. Using TAS should solve the issue.

 

Again, I don`t like to think, I prefer to know for sure. In the training-mission, it was explained that radar altimeter has to be used even with TAS. But why even have TAS at that point goes beyond me as it doesn`t negate the error. I know how measurement of CCIP/CCRP works, nevertheless nice illustration. If you use TAS alone, it doesn`t solve anything, the error gets even greater. Currently it`s only RS, or TAS + RS. That is why I need to know from Razbam whether this is fully implemented or not. If it is correct, then I notice a huge limitation with CCIP in anywhere but flat terrain, which basically means almost everywhere in Caucasus.

Edited December 6, 2016 by zerO_crash

[Robin_Hood]

I am pretty sure Zeus said somewhere that RS is used in addition to TAS as a backup method in case of radar failure or malfunction during the pass. Therefore, if you're in TAS + RS and your radar is working, your radar altitude will not be used.

 

That is my understanding, but I'm sure someone will confirm. Or you could search through Zeus's posts.

 

EDIT: found it for you

The system only uses one method: TAS or RS.

 

When you select both TAS and RS the system will use TAS but if for any reason the radar is not working, it will use the radalt (RS) as a backup.

https://forums.eagle.ru/showpost.php?p=2919828&postcount=6

 

By the way, TAS is currently lacking in accuracy, I know Zeus is investigating the issue

Edited December 6, 2016 by Robin_Hood

[myHelljumper]

I am pretty sure Zeus said somewhere that RS is used in addition to TAS as a backup method in case of radar failure or malfunction during the pass. Therefore, if you're in TAS + RS and your radar is working, your radar altitude will not be used.

 

That is my understanding, but I'm sure someone will confirm. Or you could search through Zeus's posts.

 

It's my understanding too.

[jojo]

You are right guys, TAS has the priority over RS.

[zerO_crash]

I am pretty sure Zeus said somewhere that RS is used in addition to TAS as a backup method in case of radar failure or malfunction during the pass. Therefore, if you're in TAS + RS and your radar is working, your radar altitude will not be used.

 

That is my understanding, but I'm sure someone will confirm. Or you could search through Zeus's posts.

 

EDIT: found it for you

 

https://forums.eagle.ru/showpost.php?p=2919828&postcount=6

 

By the way, TAS is currently lacking in accuracy, I know Zeus is investigating the issue

 

Right, but TAS is working fully for CCRP (besides a small re-alignment of targeting cross, the accuracy is still there, you just need to put the cross slightly above target, but otherwise, I score 100% hits every single time, no misses). That means that something with TAS for CCIP is borked, and that is really problematic. I remember Zeus67 having written that CCIP was not fixed in terms of accuracy in the last patch for Nevada, and neither is it in this patch for Georgia.

 

Nice contribution btw mate

[Rlaxoxo]

Right, but TAS is working fully for CCRP (besides a small re-alignment of targeting cross, the accuracy is still there, you just need to put the cross slightly above target, but otherwise, I score 100% hits every single time, no misses). That means that something with TAS for CCIP is borked, and that is really problematic. I remember Zeus67 having written that CCIP was not fixed in terms of accuracy in the last patch for Nevada, and neither is it in this patch for Georgia.

 

Nice contribution btw mate

 

That was 4 weeks ago this patch fixed that

[ZHeN]

 

vs.

 

1:58

[zerO_crash]

That was 4 weeks ago this patch fixed that

 

Just checked, you`r right, my bad.

 

Well, the problem still persists anyways. TAS accuracy is non existent with CCIP.

[jojo]

 

vs.

 

1:58

 

Please, explain what are you trying to show ?

 

Because in DCS video you're not flying the proper way to perform the low speed fly by.

[ZHeN]

that's not me, that's a guy from russian section

he's showing extremely high AoA capability of new FM

[myHelljumper]

For me the 2 videos look the same, what did you want to show us ?

[ZHeN]

they don't look the same as for me ... the angle is much higher in DCS

[ZHeN]

oh yes, you're absolutely right, I've missed that he's climbing