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Guest BMI701EGCC

A3XX Hard to maintain V2+10 on climb

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Guest BMI701EGCC

Good evening,Im am having a slight problem with the PSS A320 series...Ive checked all the weight and they're all fine,So ive set the A320 up for a curcit around LFBO.Ive rotated at V1(Vr) and followed the FD to maintain V2+10, this is where it seems to go wrong has it aquires me to have a pitch of 22 degrees, so i engage the AP1 at 700ft (Flap to 1 at this stage), i no it is just going to exceed the norm pitch(around 15-17) and it does again around 20-22 of pitch. ZFW 125,000V1 134VR 134V2 138+10 148FLP/THS 3/UP2.0FLP/THS 2/UP2.0 (This os on the second attempt)This is a related post about my A3XX flap problem...http://forums.avsim.net/dcboard.php?az=sho...2&topic_id=3027Can anyone help?Thanks,Scott WaterworthBMI701EGCC

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Guest vrandar

After rotating at Vr I have often found that the PSS (and ifdg/PSS merge) A320 needs a pitch of about 20 to maintain V2+10, but usually when I am fairly light. This of course is several more degrees than its real world counterpart as you've noticed. At heavier ZFW weights and with fairly heavy fuel it is often a few degrees less, in the iFDG/PSS A320 anyway. I find the iFDG/PSS A319 and A321 are a bit better at holding V2+10 at a lesser pitch due to slightly different flight dynamics.One thing to mention is that I only input the flaps and trim into the MCDU as a reminder. Certainly on the real world A320 the flaps part of the FLP/THS is only there as a memo and I suspect that the trim setting is as well as I've seen no evidence that inputting anything here and at the same time NOT inputting trim on the lower ECAM has any effect whatsoever, but Bob will probably be able to provide correct info about this. The trim should be set on the F/CTRL page of the lower ECAM either by Shift+numpad1 or the End key on some Microsoft keyboards. -2.0UP usually works for me and helps me not to shoot through V2+10.Your flaps from 1+F to 0 seems a bit early. I remain on 1+F until 'S' speed.

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Guest BMI701EGCC

Thanks rob for the reply, a great help, all i need to do now is merge the PSS/iFDG :s .CheersScott WaterworthBMI701EGCC

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Guest vrandar

Go to the BAV Airbus hangar in my address below and you will find a merge tutorial.

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Guest speight

I fixed the prob like this:For a circuit set fuel 43% each wing tank and centre tank empty.Make sure you have the right weights(A320C to pax 150 and bags+cargo to 12120lb and zfw of 132970).Enter a proper circuit plan in the form of an oblong with 4 turning points, the first at at least a couple of miles ahead of the runway and an altitude of say 4000ft. Make sure the dep and arr rwys are entered as well. Also use a long runway (10000ft+) when going for a reduced thrust t/o.enter the zfw into the init page then the fuel(FOB), the go to perf page and set the flex temp to -42 approx(YES-MINUS42). then right click the v-speeds.Next make sure the FD is on and then L-click speed, heading and alt once each.(this puts the values into the auto-pilot.Check signs on, flaps set 3 and trim to 2.4.Check the lower ecam checklist button for correct t/o.Now line up and hit the + key twice to give a reduced thrust setting of around 90%. Rotate at the green mark to 12deg up-with positive climb, gear up and press autopliot no one. Now sit back and you should be climbing at V2+10 around 1300fpm. At 1500ftagl, the flex thrust in the pfd will flash-hit the -key to go into climb thrust and clean flaps on schedule. You should be clean by 3000ft. The a/c should now follow the plan at 250 kts.I am using the cd version patched to fs9 witout any mods and it works perfectly.The flex temp is I think the wrong way round in the pss mcdu, so entering the temp as minus 42 instead of plus 42 which is displayed as default, will reduce the thrust nicely. If you leave it as +42, you will get to much power and climb too fast with light loads.The load editor has a problem in that as soon as you touch the "scheduled" planes, it crashes with a runtime error.If this happens, simply insert the cd and hit the repair button.Use the "chartered" A3xx buttons only-leave the scheds alone. I saved all the chartered with full pax and 80lb of baggage /cargo per pax, then wrote the values into table which I printed so that I need never go back into the load editor again.The default weights are a bit on the light side, which is another reason why people are getting megga climbouts.Hope this helps.

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Guest vrandar

The programming error with flex and what to do about it now seems to be assuming greater importance than certainly I ever gave it previously. I had just assumed that it hadn't really been modelled that accurately. It certainly explains why there is no real thrust difference between different positive flex numbers. It will be very interesting trying it tomorrow with minus numbers and seeing the results.

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Guest speight

Hi Rob,I find changing the + to - on it's own is just too much and the climb is too sluggish, so I apply the current air temp to it and bingo.Eg:Change Flex+42 to Flex-42 and apply air temp(say 15) to arrive at Flex-27 gives me N1 of 93%.This gives a nice initial climb around 2300fpm, once flaps are clean, it changes to around 3300 unless I intervene and change it to 2500.I have spent some 5 or 6 full days testing all this, so I think it has been worthwhile. I now fly the busses more than the pmdg. Not knocking pmdg tho', it is a superb plane, just that when these busses are up and running, they are soooooperdoooopa!It might be worth producing a table of weight/runway length/flex that would remove all the guesswork, wotdyathink?

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Guest vrandar

What do I think? I think it's something I've wanted to do for a long time and you might have just provided the impetus for me to do it. I looked at the Tomaflex program produced by Jana Kankesan (and provided some input to an early version) which also produces flex temps amongst other things and is available from www.tomaflex.net , but I've never agreed with the resulting flex temp his program gives. It always seems too high for my liking.I like your solution relating to the temps which seems quite a sensible way to produce a good result. I already have a draft chart but will work on it a bit more this week and send you a test version to look over if that's OK.

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Guest BMI701EGCC

Q1.How do you calculate flex?Q2.Can use iFDG airbus with PSS panel + load values ieI copy the load values from PSS load editor(which then are applied to the PSS 320 aircraft.cfg) and then copy them to the iFDG(A320 aircraft.cfg.I.E.pss load values...station_load.0 = 0450, 0.0, 0.0, 0.0 Pilotsstation_load.1 = 3000, 0.0, 0.0, 0.0 Galleysstation_load.2 = 3780, 0.0, 0.0, 0.0 Baggagestation_load.3 = 9760, 0.0, 0.0, 0.0 Cargo station_load.4 = 6300, 0.0, 0.0, 0.0 Firststation_load.5 = 20700, 0.0, 0.0, 0.0 Coachapplied to iFDG A320 .cfg...station_load.0 = 170, 41.91, -2.0, 1.64, "Pilot" station_load.1 = 170, 41.91, 2.0, 1.64, "Co-Pilot" station_load.2 = 6300, 18.9, 0.0, 1.64, "Front cabin" station_load.3 = 6850, 29.17, 0.0, -3.28, "Front cargo" station_load.4 = 6850, -50.45, 0.0, 3.05, "Rear cargo" station_load.5 = 18180, -18.49, 0.0, 1.64, "Rear cabin" (I have modified these values to match PSS ie. from "170.0, to 170. Also baggage/cargo are split into to because of "front/rear cargo", have to balance out the front/rear cargo values to make sure that the aircraft is properly balance for takeoff) Is this all safe? it isnt causing any problems with the iFDG A320.Scott WaterworthBMI701EGCC

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Guest BMI701EGCC

Im just using tomaflex for the PSS/iFDG A320 and ive noticed that FLEX is mostly at 55, why is this? ive tried different weights and temperatures and its still 55, excluding extreme weights I.e. empty fuel(not real!), or empty baggage/cargo, temp at -50 etc...Anybody know if this is the norm?BTW, takeoff is great now due to FLEX being at "-" XX instead of "+", maintains V2+20 alot better, much realistic climb too. How did PSS make a massive mistake like this one?beats meScott WaterworthBMI701EGCC

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Guest speight

Rob, that sounds great, I will have lots of time this week.Have just been testing the minus value flex temps in my Pss/IfdgA320 merge and it is working so incredibly well. eg:With weather set air and pressure 1013, temp 14deg C, a flex of -27 gives exactly 93% N1. My weights are as follows;Pax 150 at 170lb each, bags 80lb per pax, gives ZFW 128.24 like this;pilot and co pilot 170lb eachF & R cabin 12750lb eachF & R cargo 6000lb each.This is as close as possible to the pss version and when tested back to back, there is little difference in performance btween Ifdg and Pss.If I go back to the default plus flex values, it all goes pear shaped, which strengthens my opinion that Pss made a little mistake in the FMGS by getting the flex wrong way round. Put the minus in and you have nice steady climb just like real world. It just needs a simple table, or database to give a flex for whatever runway length, altitude, a/c weight etc. But I do not have the tools or knowledge to do that. However, I have time on my side-being retired, so can test things at leisure and pleasure.There are a very large number of posts in the A3xx forums relating to the abnormal climbout of the Pss A3xx, which leads me to believe we might make a lot of flight simmers a whole lot happier by transforming their scary busses into beautiful graceful birds.Fundamentally, Pss have done a fine job on their creations, and if this little mistake is rectified, either by the end user simply placing a minus sign in front of the flex figure, or by Pss changing some code or something, then we may not after all be destined to die by wire.Let's go for it Sir!Happy flights,Howie

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Guest BMI701EGCC

I agree howie, i think we should develop a table which indicates the flex settings for certain temps and weights, How do you calculate FLEX? by your example im leading to believe that its values which includes the rwy length.air temp.weight?I been using tomaflex which is a great tool, im using Ifdg A3XX + Pedros FDE(Exldng A319/21), and ive modified the values in the iFDG aircraft.cfg to match the values form the PSS aircraft.cfg, these values dont need to be changed with the iFDG 319/21 because they have the same values as the PSS values(look in above post). So now i can using the load editor the calculate the weights visually. Then i tranfer these weights to the iFDG values, have to split the cargo weight in two, to fit the front/rear values accordingly.(dont want to mess about with the naming of the stations). In FS2004 you'll find that you will have to configure the front/rear cargo values to make the aircarft balanced. BTW is there any tables which show the correct trim for takeoff, sometimes ive lifted off before V1 due to the trim settings( this happened at LGKR,7000ft rwy mind). Ive been using 2/UP2.0 for takeoff which gives me 12-15 of pitch(this is only possible with the "-" FLEX instead of "+" FLEX,handles like a dream)Cheers,Scott WaterworthBMI701EGCC

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Guest speight

If we can produce a table, then initially it should be as simple as possible. It could be expanded later.I do not know how in real world they calc the flex, but would hazard a guess that it is governed by two main values namely aircraft weight and runway length. After that comes airfield altitude and ambient temperature. So if we start with a simple table for all the airfields at or within a cat's cok hair of QNH and a temp of 15, we have covered quite a large number. A later sub-table of adjustments could provide the correction for other altitudes and temps.It would be first aimed at the A320 with typical full pax and doing a medium range flight say with 10t of fuel.With such values, I don't think we could go far wrong, even if our weight differs a little.Then some practical testing would produce the flex figures to get the bird clear of obstacles for say 3 runway lengths of1. Minimum A320 normal ops(I think it's about 8000 approx, but is specified in the manuals).2.10000ft.3.12000ft.With these 3 figures it doesn't take a genius to interpolate between, it is only a rough guide, but we could soon do the sums to produce a working base.Perhaps Jana who developed Tomaflex might be able to make th allowances in his program. tried -42+15air temp = -27 and got 93%n1 - adequate to get of medium rwys.I tried -42 and got 90% enough to get off heathrow comfortably.Then -60 which left things a bit thin at 87%.The reasons for reduced thrust, are to conserve fuel, extend engine life and to reduce pollution and I don't think that running above that on a pc is going to shorten your system life.I think there may be a trim setting table but not sure where, I use 3/up2.4 for pss and 3/up1.4 for ifdg, then only need a slight adjustment after t/o to maintain v2+10. Flaps 3 is wots in the pss manual, but if you are light, then 2 or 1 would do, but is not simulated in pss I don't think so might result in scary behaviour.For loading, I setup the pss with its pax, cargo and fuel then make the Ifdg something close to that. I do it each time, but ought to save the config somehow for repeat flights.Thing is just experiment yourself, it is good practice and lotsa fun.

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Guest speight

Further to my previous post, we have to allow for a safe rejected take-off

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Guest vrandar

In producing flex temps there will be a certain amount of interpolation of data and the two areas I am battling with at the moment are runway length and the effect of outside air temperature, but I should have that sorted out during tomorrow.For info Flex is calculated as follows (taken from a tutorial I am writing on the subject to go with whatever chart we end up with!"Flex is a reduced thrust setting takeoff (it is not derated thrust which is a bit different) and is used when the runway is not contaminated by being wet or icy, when the runway is not short and the aircraft is not doing a hot and high departure. If any of these conditions do exist then a TOGA thrust setting must be used. Flex is not recommended with a tailwind. Flex assumes a higher outside air temperature than actually exists, therefore you never input a Flex TO Temp lower than the outside air temperature. The computers command the engines into using less thrust for the takeoff than they would otherwise do with a TOGA thrust setting. Why do this? Well a TOGA thrust setting pushes the engines to the limit of their capabilities, and though they are designed to take the strain it will age them more quickly so maintenance and replacement costs will be higher. Using a lower thrust setting prolongs the life of the engines considerably. The thrust that results must not be reduced by more than 25% of the full rated takeoff thrust. The PSS Airbus has a default setting of 42 deg C which means that if you leave it at that the computers will command the engines to provide thrust which would be achieved from a TOGA takeoff with that outside air temperature. However FLEX has not been modelled absolutely accurately and unless you use the attached AirbusFlex spreadsheet which requires inputting MINUS figures to correct PSS' programmming errors you will not experience the same degree of difference between it and TOGA as you would in a real Airbus. One effect of using a FLEX takeoff is that you will need to use more of the runway to take off. This is why you must only use TOGA thrust on a short runway. The takeoff speeds will not be affected by whether you perform a FLEX or TOGA thrust takeoff. But a FLEX takeoff will use more runway. For many airlines the rule is that the FLEX TO TEMP must not be higher than 60 (ISA+45 at msl) even though the MCDU can go to 99 degrees C. The calculation is done as follows: Enter runway analysis with actual weight and wind. If actual weight is not shown, and interpolation is not desired, use the next highest weight shown in the analysis. Read the maximum temperature shown in the box, or else interpolate Apply temperature corrections as appropriate to determine the Corrected Temperature (CT). CT = maximum temperature + correction. If CT is higher than OAT and TREF, use CT as flexible temperature, limit CT to ISA+45

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