Airbus Fly By Wire Question
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Airbus Fly By Wire Question
Hi, gents
I've been reading various sources about the FBW behaviour, and still have the question about the FBW on the Bus
OK, it says that it will 'maintain 1.0g in pitch' with sidestick in neutral.
Effectively, 1.0g usually means lack of acceleration, so in this case, this would be lack of vertical acceleration, i.e. constant vertical speed?
On the other hand, some people are saying the Bus will maintain the FPA (flight path).
Now let's consdier a climb scenario.
Say we climb out at 140 kts and 1000 fpm, sidestick neutral.
Then I move the thrust levers to TOGA and accelerate to, let's say, 300 kts.
Will the aircraft pitch down to maintain the 1000 fpm climb, or will it adjust to maintain the same FPA, and hence increase vertical speed to something about 2000 fpm?
I've been reading various sources about the FBW behaviour, and still have the question about the FBW on the Bus
OK, it says that it will 'maintain 1.0g in pitch' with sidestick in neutral.
Effectively, 1.0g usually means lack of acceleration, so in this case, this would be lack of vertical acceleration, i.e. constant vertical speed?
On the other hand, some people are saying the Bus will maintain the FPA (flight path).
Now let's consdier a climb scenario.
Say we climb out at 140 kts and 1000 fpm, sidestick neutral.
Then I move the thrust levers to TOGA and accelerate to, let's say, 300 kts.
Will the aircraft pitch down to maintain the 1000 fpm climb, or will it adjust to maintain the same FPA, and hence increase vertical speed to something about 2000 fpm?
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According to my ATPL notes, C* is a mix between flightpath and roll/pitch rates depending on the speed of the aircraft. It favours the rates at lower speed and hence the crosswind landing issues. No idea about your specific question though
. My gut instinct says that it would hold a flightpath similar to CWS.
. My gut instinct says that it would hold a flightpath similar to CWS.
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Characteristics in pitch
When acting on the stick the pilot commands a constant G load maneuver and the aircraft response is G load/pitch rate.The pilot order is consistent with the aircraft response expected by the pilot,pitch rate at law speed/flight path or G at high speed.
Stick free , the Aircraft maintains the flight path even in case of speed changes.Furthermore , stick free in case of configuration changes or thrust variations..the pitching moment is redused by the feedbacks in the control law and compensated for by precommands.For T/O and flarewhere stable flight path is not what the pilot expects , the computers adapt auto the ctrl laws to the flight phases,GRND LAW(DCT LAW) and FLARE LAW(Smoother DCT law).
Stick free , the Aircraft maintains the flight path even in case of speed changes.Furthermore , stick free in case of configuration changes or thrust variations..the pitching moment is redused by the feedbacks in the control law and compensated for by precommands.For T/O and flarewhere stable flight path is not what the pilot expects , the computers adapt auto the ctrl laws to the flight phases,GRND LAW(DCT LAW) and FLARE LAW(Smoother DCT law).
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Just to make it absolutely clear... Airbus FBW does NOT "maintain the flight path" when stick free, it maintains 1G in pitch. So it corrects for changes in thrust, trim, and atmospheric disturbances etc. but only by maintaining 1G as accurately as possible. The RESULT is a very stable flight path.
Cheers, TP
Cheers, TP
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What happens in a turn then - let's say we are flying straight and level, maintaining 1g, stick free. Now we start a turn - in order to maintain level flight the g's have to be increased. Now - does the pilot have to pull back the stick, or the FBW compensates itself (eg. for 30 deg of bank stick free giving 1.15g?).
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I suggest you search the Tech Log forum for more info - almost every question has been answered already! And you will find out a lot of other stuff as well.
Yes, it's 1G corrected for bank angle.
TP
Yes, it's 1G corrected for bank angle.
TP
