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RobbieHe

Flap retraction schedule

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It's great to see that FS9 is still being used by so many!My questions have to do with the flap retraction schedule.My take off reference is the following:V1 = 126Vr = 134V2 = 143The flap retraction schedule says:Vref30 + 20.....set flaps 5Vref30 + 40.....set flaps 1Vref30 + 60.....set flaps 0In reference to flap retraction, what does Vref mean?What specific airspeeds then do I need to use for the above situation?Thanks in advance! Hope all of you (Americans at least) are enjoying a great ThanksGiving! RH

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Hi,Vref30 is your Flap 30 landing speed. If you don't have the luxury of an onboard FMC then you need to calculate your vref from your Take off weight. So for example if your current weight and ambient conditions are giving you Vref30 150 knots you would select flaps 5 at 170 knots etcWhat aircraft do you fly? here's a handy tool for the 747, A320, 767http://www.topcatsim.com/?page=downloadRob

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Thanks for the response. I will not associate the Vref30 with landing speeds and not flap retraction.I am using the Level D 767 and am wanting to know about flap retraction speeds. Based on the information given in my initial post, how would I figure out the flap retraction speeds? With the Level D, is there an easier way? Thanks,RH

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> how would I figure out the flap retraction speeds? Exactly as Rob explained...You need to have a table with Vref30 landing speeds.Vref is used in a lot of calculations and flap retraction speeds is one of them.

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Hi,If you are using the Level D 767 all your speeds are calculated through the FMC and it's all in the Documentation. If for some reason I decided to fly the 747-400 with all automatics and F/D off (and no FMC) as long as I knew the gross weight of the aircraft I could look at the performance charts find vref30 and then calculate my flap retraction speeds from there.But as I stated before 'TOPCAT' will do this all for you. A large number of real world airlines provide there crew with laptops with software providing the Performance Calculation'sYour asking if there is an easier way but I assume if you paid money for a complex sim surely you want to do it the way real crew do?Rob

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Thanks for the table, but what exactly does VREF30 + 80 or the VREF25 stand for? I am trying to get a sense of what it means.Thanks,RH

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On what part (page) of the FMC are the flap retraction speeds listed? Is it the V1 Vr and V2 speeds listed?Thanks,RH

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>Thanks for the table, but what exactly does VREF30 + 80 or>the VREF25 stand for? I am trying to get a sense of what it>means.>>Thanks,>>RHVref30 stands for the reference speed at Flaps 30.Vref is the landing reference speed and is minimum safe landing speed. It is calculated based on the stall speed of the selected flap setting.If I recall correctly Vref = Vs * 1.3For example, you TOW is 360k lbs, Vref30 is 159So Vref30 + 80 = 159 + 80 = 239ktshttp://en.wikipedia.org/wiki/V_speeds#VREF

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>On what part (page) of the FMC are the flap retraction speeds listed? They are not listed in the FMC.You either calculate them, or on most ADI's they are visible on the speed tape as little green numbers (Boeing style)

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OK, I will look for them. I am running a flight right now. Thanks, buddy for your responses.Much appreciated!RH

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The way its calculated in real aviation for landing is for example on the 737 is that you look at the progress page 1 and work out how much fuel you will burn between now (usually done just before top of descent in the arrival brief) and the fuel you will arrive with, then go to the init ref page and write the new landing weight over the current gross weight, this then gives you new VRef speed for flap 15, 30 and 40. you can the adjust the amount you will fly in accrodance with the wind. At my company we always fly at VRef + 5 for landing regardless of which flap setting (usually 30 on the 737's), for the wind its usually half the headwind plus ALL the gust increment up to a maximum of VRef + 20.Hope this helps.

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Well, again from the real world, we have laptops that caculate the real 'v' speeds because as I'm sure your aware they are dtermined by a lot of external factors. However with the 737 take off flap is 'normally' 5 or 1, retraction speeds for flap 5 is based on being above v2 + 20 and accelerating to go to flap 1 and then once your above 190 and again accelerating to go flap up.With bigger a/c like 76 and 74 you have to be aware of flap limiting speeds as high weights can mean you can easily bust through these speeds.Hope this helps!

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Well, again from the real world, we have laptops that caculate the real 'v' speeds because as I'm sure your aware they are dtermined by a lot of external factors. However with the 737 take off flap is 'normally' 5 or 1, retraction speeds for flap 5 is based on being above v2 + 20 and accelerating to go to flap 1 and then once your above 190 and again accelerating to go flap up.With bigger a/c like 76 and 74 you have to be aware of flap limiting speeds as high weights can mean you can easily bust through these speeds.Hope this helps!
Interesting, thanks again!RH

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