Force-Feedback, Fly-By-Wire
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Force-Feedback, Fly-By-Wire
Hello all,
I was wondering whether there is any sort of artificial force-feedback through the sidestick/control column of fly-by-wire aircraft such as Airbuses and the 777? Is there any difference in the force required to deflect the stick at low and high airspeeds?
If not, is this a drawback compared with non-fly-by-wire aircraft?
Do the forces felt through the control column in a non-fly-by-wire airliner help a pilot gain a feel for how the aircraft is flying, like they would in a light aircraft?
Apologies if these questions have been asked before, I have searched to no avail.
Thanks,
DHdragon
I was wondering whether there is any sort of artificial force-feedback through the sidestick/control column of fly-by-wire aircraft such as Airbuses and the 777? Is there any difference in the force required to deflect the stick at low and high airspeeds?
If not, is this a drawback compared with non-fly-by-wire aircraft?
Do the forces felt through the control column in a non-fly-by-wire airliner help a pilot gain a feel for how the aircraft is flying, like they would in a light aircraft?
Apologies if these questions have been asked before, I have searched to no avail.
Thanks,
DHdragon
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yes they do have artifical feel as a factor of airspeed. I have seen the report of a flight that was undertaken after a maintenance input where the elevator feel computer on a 747 was left disconnected - the result? A broken leg from a trolley hitting the passenger cabin ceiling amongst other injuries due to a violent pitch up.
Mistrust in Management
Moo is correct in respect to Boeings, however on the Airbus FBW no feedback is given to the side-stick.
In simple terms the side-stick on the Bus is used to select a pitch/roll rate and the feel of the side-stick remains the same for all regimes of flight.
Regards
Exeng
In simple terms the side-stick on the Bus is used to select a pitch/roll rate and the feel of the side-stick remains the same for all regimes of flight.
Regards
Exeng
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Thanks lads,
Moo, I didn't realise that a 747 (non-fly-by-wire) had a feel computer. I thought the direct feedback through the hydraulic system would provide the required feel (like power steering in a car) - obviously not.
DHdragon
Moo, I didn't realise that a 747 (non-fly-by-wire) had a feel computer. I thought the direct feedback through the hydraulic system would provide the required feel (like power steering in a car) - obviously not.
DHdragon
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NG Airbus is g-load demand in pitch and roll rate demand in roll. The only thing that happens to the side stick, is that during the landing flare you have to exert more force than usual or than compared to flight mode. During a manual landing there's a transition from flight mode (easy to move side stick) to ground mode (more force required by pilot).
But there is never a feed back to the stick, but visual feedback in terms of what the result of your manipulations were.
But there is never a feed back to the stick, but visual feedback in terms of what the result of your manipulations were.
Last edited by square leg; 26th Mar 2004 at 09:17.
B777 has feedback through a complex system of actuators, pushrods and cables under the flightdeck floor. Even though it is full fly by wire, Boeing took a different view on the need for flight control feedback and stuck with a floor mounted control column which artificially mimicks the controls of a conventional system. Much more mechanically complex than Airbus but it makes the drivers happy. 
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F16 FBW
The side stick controller in the F16 is 3 pnds per g out to 9g. So when you are pulling 9g the force on the stick is 27 pnds.
Early aircraft were straight force feel with no movement. This resulted in problem when pulling max. You couldn't tell when you had reached 27 pnds so usually pulled more. Result - overstrained wrist.
Now , with a small movement you can feel the stop at 27 pnds.
Is that similar to Airbus's side stick?
The side stick controller in the F16 is 3 pnds per g out to 9g. So when you are pulling 9g the force on the stick is 27 pnds.
Early aircraft were straight force feel with no movement. This resulted in problem when pulling max. You couldn't tell when you had reached 27 pnds so usually pulled more. Result - overstrained wrist.
Now , with a small movement you can feel the stop at 27 pnds.
Is that similar to Airbus's side stick?
