BUG REPORT: Flight Controls, Pitch Control, Normal Law Flight mode implemented incorrectly

[x 0]

The pitch control of normal law flight mode is not implemented correctly. With the side stick neutral the aircraft is supposed to maintain a 1g flight path. E.g., even if the speed changed, the flight control system automatically alters the pitch attitude to maintain a 1g flight path (with stick released). This means that the present vertical speed is maintained with the stick released throughout the whole envelope (even if speed changes). In contradiction to this the aerosoft A320 model seems to maintain pitch attitude with sidestick neutral instead of the flight path. This is incorrect. In the aerosoft model when reducing airspeed, the A/C vertical speed decreases and with increasing speed, the V/S increases. This behaviour, however, is incorrect for the A320 fly-by-wire flight control system. There - in normal law - the side stick deflection in the pitch channel is proportional to a g-load demand. This is not implemented in the aerosoft model.

 

So, once again: The A320 fly-by-wire flight control system normal law pitch control flight mode is not implemented in the aerosoft A320 model.

[Emi 5161]

Sorry, but our Airbus pilots report different.
Do you have any videos to proof your statements?

[x 0]

Hi. I’m an A320 pilot in real life ... So you may believe me ;-) (and reading the appropriate A320 FCOM chapter will give further info). The aerosoft A320 pitch control of normal law is incorrect.

 

Here’s how you can tell:

Prerequisites: you are in normal law, manual flight, constant IAS (say 250 kts), contant altitude, manual thrust, bank 33° or less, stick released. The system maintains altitude (resp. zero vertical speed) and bank angle (i.e. zero roll rate) (in manual flight)

Procedure: Now: set idle thrust.

 

Behaviour of real A320:

According to the normal law, the A/C maintains bank and in essence the present vertical speed (which is zero according to the prerequisites above). It maintains a 1g flight path  corrected for bank and pitch. This is accomplished by the system automatically adjusting the pitch attitude without pilot intervention.

 

Behaviour of aerosoft A320:

The aerosoft A320 model behaviour, however, is substantial different: With the above described procedure, it will create an increasing negative vertical speed (stick released, thrust idle). This is incorrect. Everyone should be able to reproduce this inappropriate behaviour with his aerosoft A320.

 

The side stick deflection in the pitch channel is proportional to a g-load demand. With the stick neutral, the g-load demand is zero. This means the system automatically adjusts the pitch such as to achieve zero vertical acceleration. This results in the fact that the present vertical speed will be maintained. This is, however, not accomplished by the aerosoft A320 model.

[Patrick1246 353]

and we have 5 A320 Pilots in our team...

 

btw, I also have an FCOM, but I'm not a RW Pilot

[The Dude 6537]

As you are a real Airbus pilot; did you really try to fly the profile you mentioned IRL? Where does it state in the FCOM, or RW, that the FBW will correct small 1G flightpath upsets like you get with large thrust fluctuation (decel/acccel) or wind/turb?

 

I concur that the FBW that is supplied with the AS Airbus is not yet perfect. The beta version we fly is almost same same as the FSL FBW and they set a pretty good benchmark. 

[x 0]

Dear fellows,

 

this is not supposed to be a battle.

 

The aerosoft model maintains pitch constant and as a result the flight path varies with varying EAS (i.e. lift). The A320 normal law accomplishes the opposite: It maintains constant lift with varying EAS materialized by adjusting the AOA (auto trim) (noticeable by a pitch attitude change) and as a result the current flight path is maintained. Not more, not less. The aerosoft realized concept might be ONE concept of a control law. But it does not reflect the A320 normal law at any rate.

 

Please refer to the FCOM, DSC, FLIGHT CONTROLS, 

FLIGHT CONTROL SYSTEM, NORMAL LAW, PITCH CONTROL, FLIGHT MODE.

 

Your A320 pilots will confirm this.

[LLL33 5]

Hi X,  you surely know the Airbus statement: "there is no ballooning on airbus planes" (or similar). The reason for this should be the programmed 1g flightpath, you are talking about. And this statement is nothing then a "running joke". In reality the bus balloons as much as any conventional plane. This 1 g flightpath is only theory. BTW, the manual flight behaviour of all P3D planes is not good, and no addon company can´t do anything about it. As the A320 behaviour in "manual flight" is more than questionable in RL, the AS module is at least closer to the real thing, than any conventional plane module. 

Two weeks ago in Manchester, the wind was a bit gusty, and the headloader (PPL pilot) was asking me, why the 737s are approaching stable,  and the 320s are rolling left right the whole way down. I was laughing, when telling him, that the whole electronic stabilization shit must be the reason. A little bit of wind, and you have sick passengers. I guess I had less in 25 years flying the 737 than in one year on the bus.

Regards

[x 0]

Dear LLL33, thank you for your sharing interesting and emotional opinion.