737NG tendancy to roll back to wings level
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Location: Heideleberg
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@underfire: The specific type is a 738WL.
i am aware of the fact that i never will reach the realism of the real bird Thats simply impossible, because real is real and simulated is simulated.
The simulation platform from Lockhead Martin has also its limitations, so i try to get as close as possible.
The Project is privat and not Commercial, so the possibilities are limited
Lets say the aircraft has a gw of 60 tons and the weather is CAVOK, no wind.
No speedbrakes, no AP.
Intersting would be the following flight circumstances
250 knots FL 200
300 knots FL 300
220 knots FL 100
Minimum Clean Speed 4000 feet
FLAPS 1 with corespondenting maneuvering Speed
Flaps 15 Gear down
Flaps 30 Gear down
Its much apreciated :-) Sorry fot my english, i amware...that it is not the best..
Eveybody is invited to make a sim check::-)
i am aware of the fact that i never will reach the realism of the real bird Thats simply impossible, because real is real and simulated is simulated.
The simulation platform from Lockhead Martin has also its limitations, so i try to get as close as possible.
The Project is privat and not Commercial, so the possibilities are limited
Lets say the aircraft has a gw of 60 tons and the weather is CAVOK, no wind.
No speedbrakes, no AP.
Intersting would be the following flight circumstances
250 knots FL 200
300 knots FL 300
220 knots FL 100
Minimum Clean Speed 4000 feet
FLAPS 1 with corespondenting maneuvering Speed
Flaps 15 Gear down
Flaps 30 Gear down
Its much apreciated :-) Sorry fot my english, i amware...that it is not the best..
Eveybody is invited to make a sim check::-)
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@John
Thats very interesting indeed Its makes sense for me .
Will try your examples in the sim.
I would expect that the ailerons are quite precise and they goes perfect back to zero without active yoke input!?
If not, it makes the whole think much more complicated, because if the ailerons are not going to zero with Hands of the yoke, its clear that may the AOB increases slowly.
But much more interesting is the feel during turning. How long can i left the yoke in neutral position and look into the blue eyes of my stewardess without decreasing or increasing the AOB.
In a car i know very well that i have to rotate the wheel as Long as i want to turn the car. If i take the hand from the wheel the car drives forward.
I know....its a bad example....
Thats very interesting indeed Its makes sense for me .
Will try your examples in the sim.
I would expect that the ailerons are quite precise and they goes perfect back to zero without active yoke input!?
If not, it makes the whole think much more complicated, because if the ailerons are not going to zero with Hands of the yoke, its clear that may the AOB increases slowly.
But much more interesting is the feel during turning. How long can i left the yoke in neutral position and look into the blue eyes of my stewardess without decreasing or increasing the AOB.
In a car i know very well that i have to rotate the wheel as Long as i want to turn the car. If i take the hand from the wheel the car drives forward.
I know....its a bad example....
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Herc, while the controls will return to their trimmed position when "hands off", that doesn't necessarily mean neutral. The primary controls all have trim inputs, and the ailerons and elevator are trimmed by the autopilot when that's engaged, so your trim settings will be altered by the next time you manually control the aircraft. Add that each aircraft rolls of the assembly line with small variations in rigging angles, and how much their control balance is affected by wear and tear on the line and in maintenance, and you soon find that each individual airframe behaves differently. Some need tweaking of the ail/rudder trims for every change in thrust, speed or flap setting, while others need very little. They are not as predictable and uniform as a car model, even when new.
Aluminium shuffler - the NG autopilot does NOT trim the ailerons. In fact any use of aileron trim in conjunction with the AP is forbidden in the limitations section of FCOM 1.
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Yep, don't know why I put that down - put it down to a brain fart. The ailerons are almost always slightly out of trim on AP disconnect due to variations in fuel tank levels and flap selection. The limitation on ail trim with the AP engaged is just because adjusting that trim will cause AP disconnection, just like elevator trim.
I'm not sure of the logic behind not having the AP trim the ailerons, but I suspect it's so that it doesn't hide things like fuel imbalance or high-lift device asymmetry. It did catch out a BA crew who had a big fuel imbalance, and when the AP had enough the aircraft rolled hard. Had the AP trimmed the ailerons, that wouldn't have happened, but maybe something worse would have resulted later.
I'm not sure of the logic behind not having the AP trim the ailerons, but I suspect it's so that it doesn't hide things like fuel imbalance or high-lift device asymmetry. It did catch out a BA crew who had a big fuel imbalance, and when the AP had enough the aircraft rolled hard. Had the AP trimmed the ailerons, that wouldn't have happened, but maybe something worse would have resulted later.
Last edited by Aluminium shuffler; 3rd Mar 2014 at 09:47.
I believe the limitation is to avoid excessive out of trim forces catching a pilot unaware on autopilot disconnection. Control wheel displacement is then a obvious clue that something is not right.
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where is heideleberg?
I like visiting places, so where is it? Only asking... I was never any good at speeling which is why I moved from Sidney to Birsane, Bribsune, stuff it I come from Cairns.
Hat, coat...
Hat, coat...
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Most swept wing aircraft have inherent roll stability.
Secondary effect of roll is sideslip. Sideslip increases the effective span of a swept wing and, therefore, it produces more lift and rolls back towards wings level.
So, yes, you will have to hold a small amount of roll input to maintain X angle of bank.
But bear in mind that in a climbing turn you will require out of turn aileron to maintain X angle of bank.
Welcome to the can of worms that is aerodynamics.
Secondary effect of roll is sideslip. Sideslip increases the effective span of a swept wing and, therefore, it produces more lift and rolls back towards wings level.
So, yes, you will have to hold a small amount of roll input to maintain X angle of bank.
But bear in mind that in a climbing turn you will require out of turn aileron to maintain X angle of bank.
Welcome to the can of worms that is aerodynamics.
John Farley pointed out a small factor that might make you think this is incorrect in real life, but it's because of the residual aileron if the airplane rolls to wings level.
Yaw dampers are fitted to damp dutch roll oscillations which may be greater than that permitted by the certification standard.
If by "coordinated" you mean zero sideslip, then that is the job of the fin.
As John Farley wrote, the spiral mode is weak and may be either positive or negative. It may change sign with configuration or altitude.
A simple way to look at the spiral mode would be if directional stability is dominant, then the sideslip resulting from bank would cause the aircraft to "weathercock" into wind, the outside wing lift increases and the bank angle further increases - spiral dive.
If lateral static stabilty (dihederal effect) dominates then the sideslip caused by bank results in a roll away from the direction of sideslip, reducing the bank angle.
It is a fine tuning job to achieve the required levels of static and oscillatory stability, often poor oscillatory stability is the result and this is fixed with a yaw damper.
Irrespective of entering a coordinated turn, one has to release the controls to view the behavior under the forces resulting from the various stabilities
If by "coordinated" you mean zero sideslip, then that is the job of the fin.
As John Farley wrote, the spiral mode is weak and may be either positive or negative. It may change sign with configuration or altitude.
A simple way to look at the spiral mode would be if directional stability is dominant, then the sideslip resulting from bank would cause the aircraft to "weathercock" into wind, the outside wing lift increases and the bank angle further increases - spiral dive.
If lateral static stabilty (dihederal effect) dominates then the sideslip caused by bank results in a roll away from the direction of sideslip, reducing the bank angle.
It is a fine tuning job to achieve the required levels of static and oscillatory stability, often poor oscillatory stability is the result and this is fixed with a yaw damper.
Irrespective of entering a coordinated turn, one has to release the controls to view the behavior under the forces resulting from the various stabilities
Last edited by zzuf; 13th Mar 2014 at 05:30. Reason: clarify post
Fair enough....
To me rudder is:
1. A means of controlling yaw rate independent of bank angle, and
2. A means of selecting a sideslip angle which is different to current control free sideslip angle.
To me rudder is:
1. A means of controlling yaw rate independent of bank angle, and
2. A means of selecting a sideslip angle which is different to current control free sideslip angle.
