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Guest BAW470

PSS Trim

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Guest BAW470

Hi all,i was just wondering if anybody knew of where the trim settings are in the PSS Airbus, when ever i fly the A319/20/21 i cannot rotate, this is proberbly due to incorrect takeoff trim settings, i never have a problem with the A330/340 and im not sure a) where the trim settings are and :( what the problem is with the A319/20/21 at takeoff as it may already be a known problem because all my other planes inc. A330/340 rotate perfectly on takeoffThanks

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Guest vrandar

Ok what you need to do is to set the trim to something like -2.0UP. Clcik on the F/CTRL button below the lower ECAM. ION the middle of the screen you will see Pitch Trim. On my keyboard if you press the End key until the Pitch Trim changes to -2.0UP that should be fine for takeoff.

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Guest vrandar

But you probably won't need this if using the iFDG/PSS merge.

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Guest Calum

Hello ,there are no trim tabs in the real airbuses ( except for backup ) , the autotrim function does it all for you.In FS , i believe the autotrim works well , i have never set trim at any stage of flight , and the aircraft stills handles brilliantly on take-off and landing which means there must be autotrim or something similar installed by PSS ( well done ) :)please feel free to post more detail on your take-off problem , and i ( and others i am sure ) will try and help you out :)Calum

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Guest

hmm, the aircraft will have neutral trim always, no autotrim that I noticed.Of course the MCDU takeoff trim setting also defaults to neutral so that may be why you never noticed :)I guess the MCDU in the real thing will trim the aircraft for you, in FS this doesn't happen so you need to trim the aircraft to match the trim you set in the MCDU.I usually set -1/UP for trim. Check the flight control screen on the lower EICAS and you'll notice it still says 0.0, so manual adjustment is needed.

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Guest Calum

Yeah i know ,the MCDU trim setting is purely a reminder , it has no effect on the flight controls or autotrim , it is just to let you know to check the amount of trim wanted is set , which the autotrim will do based on the aircraft config , weight and one or two other things ;)Calum

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Guest

indeed, but I did notice you do need to manually set it to match for takeoff trim (guess the autotrim doesn't engage until the AP is engaged which is only after takeoff).

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Guest Calum

yeah that is correct ,Calum

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Guest bjornhall

Some thoughts on Airbus trim: - Both the PSS and the real thing uses autotrim. I think that is very apparent when handflying, and I really can't understand how you could not have noticed it... Perhaps one can somehow manage to disable it by using various third-party flight dynamics, merges and what-nots? I only ever use the default files, and when browsing these forums I always get a feeling that most of the stranger problems reported here have to do with using various creative third-party files... - Trim has to be set manually on ground, because autotrim only starts working after takeoff (on the real thing it is five seconds after wheels off ground, if my memory serves me). But it has nothing to do with the AP; autotrim will start functioning even if autopilot is off. - The MCDU entry is purely as a reminder, both in the PSS rendition and the real deal. You still have to manually set the takeoff trim, and what you put in the MCDU does not matter at all.- In the real deal, being somewhat out of trim in the air does not matter much, since the flight control system will just use the elevators to make the aircraft 'feel in trim' as far as the pilot is concerned (i.e., centering the stick still gives 1G flight). In the PSS bus this is of course not the case, so the functioning of the autotrim is much more critical. Luckily, manual trim is still available, and I think one of the most helpful 'tricks' to pleasant handflying of the PSS buses is to help the autotrim out with a manual nudge in the right direction if it goes out of trim a bit. - I believe it is still the case that autotrim (on the PSS buses) only functions if the stick is nearly centered. Understanding this is another good hint to use when hand flying; if you find yourself slightly out of trim, so that you are applying forward or back pressure on the stick, the autotrim will not rectify this for you. In that case, add a little manual trim to get back in trim or, if you are just a little bit out, center the stick and let the autotrim get it sorted. - The above points mean that the behavior on takeoff is a little different. Both the PSS and the real thing will have problems rotating if out of trim on takeoff (being so far out of trim that you can't rotate should never happen!!!). The difference occurs after lift-off: In the real thing, the flight control system will 'hold the out of trim' for you using elevators until autotrim will rectify the situation, so the pilot can just center the stick and go merrily on his way. In the PSS bus, if you lift off out of trim, you will be just as badly mistrimmed on initial climb, holding back pressure to keep the nose up, and the autotrim will not fix this since it only operates with the stick centered. If this happens, apply manual trim to relieve the back pressure, then center the stick and let autotrim keep it in trim.Best, - Bj

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