? for Airbus Drivers

[uavchaser]

are the sidesticks mechanically linked between each other in any way?

thanks!

 

[Skygod]

Short, but complete, answer is: no.

By the by, the inputs are sumed by the computers and the result sent to the flight control computers. A red button on each stick allows override of the other's input. When the autopilot is on, or when the other pilot is 'hand-flying' your stick just stays motionless in the center detent. Hope this answers your question.

 

[U-I pilot]

So, I know it wouldnt normally happen but.....
1) If the pilot moves full nose up and co-pilot full nose down.....it remains neutral?
2) If both pilots push override...does it do nothing? does it default to one side?
3) If auto pilot is on and you move the control....does it move the airplane or disregard?

Just kinda curious about the system....if no one knows i'll understand cause thats not necessarily something you do .....ever.....

 

[Dizel8]

1) If the pilot moves full nose up and co-pilot full nose down.....it remains neutral?
Yes, it would indeed remain neutral. ( Although, as they were moving it, it would have
to be in perfect sync for the controls not to move)

2) If both pilots push override...does it do nothing? does it default to one side?
It has an over ride push button, which also functions as auto pilot disconnect. The push button is
used, in case one stick has a malfunction and will then lock the other stick out. The push button,
could also be used as over ride, to transfer control to one stick only. Whichever pilot pushed the button last
has control.

3) If auto pilot is on and you move the control....does it move the airplane or disregard?
The stick in locked in the center position when the autopilot is flying. If enough force is apllied
to the stick, cannot remember the exact number, but 15 pounds comes to mind, the auto pilot
will disconnect and both sticks will become active.

Hope that helps.

 

[FlyChicaga]

Doesn't seem very pilot-friendly to me. I am one who loves the slack in the cables, giving each airplane in the fleet it's own characteristics. You learn to love and hate each one for how she treats you when hand flying. I dunno, these Airbii don't seem all that fun to me.

 

[uavchaser]

i guess the next question would be with the trim system, if the stick only has one center detent how would the trim work since the stick remains in the same spot.

are the flight computers attitude based? i.e. for a right turn the stick must be held right and/or for a pitch up the stick must be held back.

your answers are much appreciated

 

[Skygod]

The stick commands roll rate (L-R) and g-load (push-pull). So you want to turn left, you move the stick to the left -- a lot for a high roll rate, less for a gentle roll rate -- and as you approach the desired bank angle you center the stick. The fully automatic trim system now holds the attitude -- left bank -- untill you give some right stick to come out of the bank.

From straight and level flight, a climb is a positive g pull up maneuver, so you bring the stick back. At the desired attitude you let the stick center and again the 'bus will automatically trim and hold attitude. Hands off. To then level out push the stick forward to command a slight negative g and thus change in attidude.

There are no trim handles or switchs in normal operation, the trim is fully automatic, all da time. The roll rate and g command feel the same regardless of flap setting, cg, weight, etc.

Despite the long-winded explanations, it all feels very natural pretty quickly.

 

[Dizel8]

​

What Skygod said is correct and better than what I tried to say, below is the long winded part. It may sound fancy-smancy and a bit weird, but within 5 minutes, it becomes quite natural.​

​

Pitch:​

The normal-law flight mode is a load-factor-demand mode with automatic trim and protection throughout the flight envelope.​

Following normal law, the sidestick controllers set the elevator and THS to maintain load factor proportional to stick deflection and independent of speed.

With the sidestick at neutral, wings level, the system maintains 1 g in pitch (corrected for pitch attitude), and there is no need for the pilot to trim by changing speed or configuration.

Pitch trim is automatic both in manual mode and when the autopilot is engaged. In normal turns (up to 33° of bank) the pilot does not have to make any pitch corrections once the turn is established.

Roll:
When the aircraft is in the "in flight" mode, normal law combines control of the ailerons, spoilers (except N° 1 spoilers), and rudder (for turn coordination) in the sidestick. While the system thereby gives the pilot control of the roll and heading, it also limits the roll rate and bank angle, coordinates the turns, and damps the dutch roll.

The roll rate requested by the pilot during flight is proportional to the sidestick deflection, with a maximum rate of 15° per second when the sidestick is at the stop.

 

[Marko Ramius]

Yep, I agree

Trying to explain the Airbus FBW system ultimately makes it sound a zillion times more complicated than it is in actuality. Up is still up, down is still down, and so forth. Like any airplane, it's annoying to fly in the sim, quite natural in the aircraft. The only time in regular line ops that you have to think about what you're doing vis a vis control laws is a x-wind landing and even that is simple once you think about it for a second. Of course like most Bus pilots, I didn't that first time but I think that can be said of the first few crosswind landings in alot of planes!

 

[TWA Dude]

Doesn't seem very pilot-friendly to me. I am one who loves the slack in the cables, giving each airplane in the fleet it's own characteristics.

It's a change, to be sure, but ALL new airliners will be like this. Once the pilot understands the programming FBW really is a huge advancement in safety. The autotrim still freaks me out. As I understand it the 777 does not have autotrim because the launch customer (UAL) pilots didn't want it. I'd love to hear opinions from anyone who's flown both.

Dude

 

[U-I pilot]

There are no trim handles or switchs in normal operation, the trim is fully automatic, all da time. The roll rate and g command feel the same regardless of flap setting, cg, weight, etc.

So is there a control somewhere?......in my training i always seem to find backups
Is there a backup for runaway trim somewhere or a way to know the trim position to know what its doing?

 

[Cat Driver]

The Bus not only has 6 pretty multi colored display screens but it is a neat new concept of you and a bunch of computers working together to fly the airplane.

As well as the three fly-by- wire control laws ( normal law- alternate law and direct law ) we have some other interesting new words to learn like in a case of high angle of attack.

The high angle of attack protection is an " aerodynamic protection " but thrust is required to manintain the desired flight path.

Although not strictly part of angle of attack protection " three energy features enhance " the high AOA protection:

The A/THR if active in speed mode, prevents the speed to drop below VLS regardless of the target speed.

The low- energy aural warning triggers a message "SPEED - SPEED - SPEED " when the energy level of the aircraft drops below a threshold function of speed, deceleration rate, flight path angle and altitude.

The alpha floor, an autothrust function, sends TOGA thrust when the aircraft angle of attack reaches the alfa floor, set between a PROT and a MAX.

How about that from an old washed up ex tanker pilot.

Cat

 

[Marko Ramius]

Yes, there is

So is there a control somewhere?......in my training i always seem to find backups
Is there a backup for runaway trim somewhere or a way to know the trim position to know what its doing?

The Bus has a trim wheel that is pretty much like any other trim wheel. There are wheels on either side of the yoke, with the standard gradations and color markings on them. The wheels move as the plane autotrims, either in handflight or with the A/P. Manual trim wheel movement has priority over automatic trim wheel movement, however once the wheel is released automatic trim control resumes. The only time pitch trim is inhibited is when you enter 'Alpha Prot'. Basically it's a low energy situation and marked on the speed tape, and under this condition additional trim in the up direction is inhibited(duh). While not as complicated, the speed trim system in the 737 follows a similar principle, except that it applies opposite trim.