MWH 8 Posted January 28, 2016 Share Posted January 28, 2016 Please can someone explain the flap and trim setting. I have been through the step by Step guide but remain confused. My Flight this afternoon according to the Aerosoft Airbus X Fuel Planner gives a TOW %MAC of 29% with a trim of UP 0.4 https://www.dropbox.com/s/x3sr2bfqreyixzn/Airbus%20Fuel%20Planner.jpg?dl=0 I was flying the Airbus A321 so I referred to the CG/THS chart in section 59 of the Step by Step Guide. https://www.dropbox.com/s/g9t3l42pn2pblo7/Screenshot%202016-01-28%2017.43.30.png?dl=0 As I was flying the A321 reading the chart for 29% gives a reading of UP 0.4. My interpretation was no Flaps with a trim up of 0.4. However on pressing the T.O. config button with Flaps 0 and trim at 0.4 I receive a Take Off Warning which only resolves if I set Flap 1. I would be grateful if someone could explain this or make it more understandable. Thank-you. Michael Houghton Link to comment Share on other sites More sharing options...
Tom Stian 11 Posted January 29, 2016 Share Posted January 29, 2016 What flaps and trim settings did you program in the PERF page on the FMC? Link to comment Share on other sites More sharing options...
skelsey 103 Posted January 29, 2016 Share Posted January 29, 2016 Hi Michael, Config 0 is not an approved configuration for takeoff, hence the config warning. I can't see your documents at the moment (on my phone) but will take a closer look when I am at a PC later. Simon Sent from my GT-I9505 using Tapatalk Link to comment Share on other sites More sharing options...
Emi 5161 Posted January 29, 2016 Share Posted January 29, 2016 Good evening, the trim scale gives no information about the flapsetting. The numbers 0, 1, etc. are for the units of trim, not for the flapsetting (else you'd run into difficoulties from 4 on, would you? Link to comment Share on other sites More sharing options...
MWH 8 Posted January 30, 2016 Author Share Posted January 30, 2016 What I find confusing is the Aerosoft Airbus Fuel Planner does not give a setting for flaps so how do you decide if it is Flaps 1 or Flaps 2?. I did set the Flap setting to of 0/UP 0.4 on the Perf Page which was accepted but as I said I received an aural and visual warning with the TO config with this. If you look at the CG/THS chart a TOW %MAC of 29 on the A321 which is just to the right of Flaps 0 at about 0.4 hence I presume the reading of UP0.4. As a result of Emanuel's reply i am beginning to understand part of my confusion that the CG/THS setting is not showing Flaps but units of trim. I had been reading the units along the bottom as Flaps. As you say I note it goes up to 5 so it cannot be Flaps. So I am beginning to wonder if the trim setting has nothing to do with th Flaps setting and one decides depending on the length of the runway whether you chose Flaps 1 or Flaps 2. So whatever the Trim setting does it matter whether you choose Flaps 1 or Flaps 2? I would be grateful for clarification on this point Thank-you Michael Houghton Link to comment Share on other sites More sharing options...
skelsey 103 Posted January 30, 2016 Share Posted January 30, 2016 Hi Michael, The value on the chart is not 'just to the right of Flaps 0" - as Emmanuel says, those values are units of trim, with 0 being 'neutral' and values either side of that referring to nose-up or nose-down settings on the horizontal stabiliser. You are right in saying that this is unconnected to the flap setting. Runway length and airline SOP are the main factors driving takeoff flap selection. More flap will increase lift, giving a shorter takeoff run, but also increase drag, resulting in poorer climb performance (until the flaps are retracted, of course). As a result, one would generally use the least amount of flap possible for the length of the runway (as mentioned, config 0 is not allowed so the minimum is config 1). In fact, config 3 is also an approved takeoff setting and can be used on very short runways. Config Full is for landing only, though. You can either use an external tool such as Topcat, or there is an Airbus takeoff performance calculator available somewhere - or else when you put a flap setting in to the MCDU it should generate a flex temp and V speeds. If the runway is too short for the flap setting you enter, it won't do the calculation. Hope that helps! Sent from my GT-I9505 using Tapatalk Link to comment Share on other sites More sharing options...
Deputy Sheriffs Hanse 216 Posted January 30, 2016 Deputy Sheriffs Share Posted January 30, 2016 "or there is an Airbus takeoff performance calculator available somewhere" = http://www.avsimrus.com/files.phtml?fileid=36340 Regards, Hanse Link to comment Share on other sites More sharing options...
MWH 8 Posted January 30, 2016 Author Share Posted January 30, 2016 Thank-you for these comments. I now have a good understanding. I did try and look at the performance calculator but could not work out how to download it. In any event it appears the MCDU performance page will calculate the V speeds for you as long as you put in the Flap and the trim setting. I do actually have TopCat so for the aircraft which it supports it will give the V speeds as you say. Interestingly I watched a youtube video this morning of a real Airbus A320 taking off from Skiathos with Flaps 3 Regards, Michael Houghton Link to comment Share on other sites More sharing options...
musefan 363 Posted February 1, 2016 Share Posted February 1, 2016 I always tend to go with "flaps 1" on the left MCDU. If it turns out that it won't calculate, due to the runway being too short, I'll go with "flaps 2". I've never had to use "flaps 3" yet. Link to comment Share on other sites More sharing options...
jmorvay1971 11 Posted May 12, 2016 Share Posted May 12, 2016 Quite honestly, no matter the weather or conditions, I always use flaps 1 as the de facto settings. I then use the pitch value from the fuel planner to manually set the pitch trim via the trim wheel/lower ECAM. Works like a charm every time. Link to comment Share on other sites More sharing options...
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