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Re: A320-family development

Postby legoboyvdlp » Tue Sep 13, 2022 2:03 pm

Devansh_NoBlue wrote in Mon Sep 12, 2022 11:47 am: Because at times, when I try to look into my flightplan and switch to plan mode. ND instead of showing the plan interface get stuck in the ARC mode. It happens usually when I delete any waypoint from the f/p.


A log file would be really useful - all this sounds like your ND Nasal file has stopped running! Thank you

https://wiki.flightgear.org/Commonly_us ... s#fgfs.log
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Re: A320-family development

Postby DeltaSVEN » Fri Sep 16, 2022 4:15 pm

Hey guys,

For some weeks now I have this behaviour:
Climbing through 10K feet the managed speed drops to minimum clean speed. In ALT CRZ, the problem remains. In descend, the managed speed resumes a normal value of about 280 KIAS. It does this at all kinds of cost indexes.
This only appears in the 3D branch, in dev the aircraft accelerates to normal climb speed based on CI and later maintains a nice mach speed.
I dont know how to troubleshoot, I know from one other Linux user who has observed this.

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Re: A320-family development

Postby OE-LML » Fri Sep 16, 2022 10:28 pm

Hallo!

I would like to take off and depart with non-managed vertical and lateral FD-modes. But I am unable to select HDG mode before departure. I think it was possible to pre-select HDG before take off in earlier versions of the plane (about 2 years ago) to get FD guidance for roll axis immediately. Or is it also in the real plane not possible to use HDG mode for departure?

I also got a question about the behaviour of autothrottle/FD when reaching acceleration altitude.
Before passing acceleration altitude, FD commands an attitude to hold V2+1? . But at acceleration altitude and if I am not quick enough to turn the speed bug up to speeds for flap retraction, FD will command an attitude to reduce speed to V2. Is this a bug or will the real plane do the same strange thing?

thx in advance and CU. :wink:

PS: FG 2020.3, dev-version and 3D-version from lego's github
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Re: A320-family development

Postby merspieler » Sat Sep 17, 2022 2:14 pm

lat nav is always in selected (HDG) mode on startup, you've gotta put it into managed mode your self.
There is no managed vertical mode yet.

With speed, it depends if you're managed or selected, if selected, once you've set the THR LVR to CLB it will target the speed you've set, if managed it should go to S-speed.
Tho I'm aware that there are currently issues with managed speed in 3D branch. This behavior I haven't seen reported tho.
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Re: A320-family development

Postby legoboyvdlp » Mon Sep 19, 2022 11:34 am

Thank you I'm slightly busy but I will look at managed speed

I also got a question about the behaviour of autothrottle/FD when reaching acceleration altitude.
Before passing acceleration altitude, FD commands an attitude to hold V2+1? . But at acceleration altitude and if I am not quick enough to turn the speed bug up to speeds for flap retraction, FD will command an attitude to reduce speed to V2. Is this a bug or will the real plane do the same strange thing?


Once it exits SRS mode (which tracks V2 + 10), it should accelerate to the maximum speed which is I believe VFE ... it sounds like you're somehow in approach mode even though you're actually just taking off. I never noticed any of this, and I did extensive testing.
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Re: A320-family development

Postby V12 » Mon Sep 19, 2022 11:43 am

T/O conf FLAPS3, aircraft accelerates to VFE. Then FLAPS1, again accel to VFE 210 KTS, then CLEAN and aircraft doesn't accelerate to 250 KTS.
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Re: A320-family development

Postby merspieler » Mon Sep 19, 2022 11:50 am

hm... only thing that should prevent it from going to 250KIAS on departure in managed mode would be a speed constraint on the SID.
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Re: A320-family development

Postby V12 » Mon Sep 19, 2022 3:55 pm

I uploaded video of Tarija depart with A320family downloaded few minutes ago :

After flaps retract A320 accelerated to 250 KTS, immediately after pass FL100 target speed droped to S - speed at 10:03.
Last edited by V12 on Mon Sep 19, 2022 5:17 pm, edited 1 time in total.
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Re: A320-family development

Postby OE-LML » Mon Sep 19, 2022 4:46 pm

Just to clarify.
I want to do a non-RNAV departure just with selected modes.
But during take-off I get FD guidance for pitch axis only. The flight mode annunciator for HDG/NAV stays blank after lift-off until I pull the HDG knob.
Further I use different thrust reduction and acceleration altitudes, e.g. 2500/3500. In this example I would set climb thrust at 2500 and turn up the speed bug at 3500 for flap retraction or constraints (if there are any).
If I am a little bit late with turning the speed up, FD will command an attitude to decelerate back to V2.
I have not done a lot of airliner flying in the past months, but I am pretty sure the Zibo 738 (in a similar situation withoug LNAV or VNAV) holds V2+?? until the speed bug is turned up.

I have found a couple of videos where a 737 NG departs withoug LNAV and VNAV, but I hardly find anything where an Airbus takes off with selected modes only. So is this a realistic scenary anyway?

thx.
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Re: A320-family development

Postby V12 » Mon Sep 19, 2022 6:52 pm

OE-LML :
This is video from take off in selected modes :
https://www.youtube.com/watch?v=8en9nQzwRs4
Speed and heading in selected mode, initial OpenClimb. Above FL100 I switched to managed speed, heading and climb, I had both FD axis. Bus is very different from Boeing.
Last edited by V12 on Tue Sep 20, 2022 5:01 am, edited 1 time in total.
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Re: A320-family development

Postby merspieler » Mon Sep 19, 2022 10:12 pm

V12:
It's not S Speed (Slats retraction speed, can't be cause they are already up) it look like green dot speed (bit hard to tell in the grainy details)

OE-LML:
If you fly fully selected, you MUST dial in the speed you want manually too (if it's set to 100, it will decelerate), so before take off you should
* set initial climb ALT
* set HDG
* set speed after ACCL ALT

Also... do you use one of the "Ready for <state>" shortcuts or do you setup everything your self?
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Re: A320-family development

Postby V12 » Tue Sep 20, 2022 4:52 am

merspieler :
Yes, of course it is Green Dot Speed. Sorry.
But the problem exists - in the managed speed open climb (managed climb in A320family is not yet implemented ) You will pass FL100 and the target speed will immediately drop to the GDS, in this case 205 KIAS. There is not reason for this behaviour, SID KOTKI has not any speed restriction.
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Re: A320-family development

Postby Delta5142 » Tue Sep 20, 2022 6:05 am

Wait hold on... isn't it supposed to go into green dot speed? I may be wrong, but green dot speed is the most economical climb speed according to your weight and all, correct?
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Re: A320-family development

Postby legoboyvdlp » Tue Sep 20, 2022 10:02 am

V12 wrote in Mon Sep 19, 2022 11:43 am:T/O conf FLAPS3, aircraft accelerates to VFE. Then FLAPS1, again accel to VFE 210 KTS, then CLEAN and aircraft doesn't accelerate to 250 KTS.


If its targeting clean speed, its targeting the Vmin speed, which suggests you're somehow in approach mode.

Can you confirm this please by checking the PERF page? Does it show CLIMB or APPROACH?


If it's not actually in approach mode, that would be really weird, but more straightforward to fix as it would be a problem in the managed speed loop - just pessimistically assuming that the DECEL logic is broken :mrgreen:

Thank you for the video, it shows the problem really clearly!
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Re: A320-family development

Postby legoboyvdlp » Tue Sep 20, 2022 10:03 am

OE-LML wrote in Mon Sep 19, 2022 4:46 pm:But during take-off I get FD guidance for pitch axis only. The flight mode annunciator for HDG/NAV stays blank after lift-off until I pull the HDG knob.
Further I use different thrust reduction and acceleration altitudes, e.g. 2500/3500. In this example I would set climb thrust at 2500 and turn up the speed bug at 3500 for flap retraction or constraints (if there are any).
If I am a little bit late with turning the speed up, FD will command an attitude to decelerate back to V2.

thx.


You not getting anything on the roll axis is expected because we don't have RWY guidance yet.


Now I see you're saying that you're using selected modes... what I'm wondering is, are you using managed speed or selected speed as well? Is only your pitch and roll selected, or your speed as well?

Because if you use selected speed you have to select your target speed on the FCU. Otherwise, it will go back to the default 100 knots (and it will go to Vmin

Only if you're using managed speed (dashes on the FCU speed display)
If, however, you're using managed speed with selected pitch and roll modes, which is fine by the way, it would not be correct to go back to V2. If that's the case, I'm actually wondering if you've got a different problem to V12. Maybe you have it going into approach mode accidentally. Maybe you could also check the PERF page, and see if you have CLIMB or APPROACH?
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