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747 default takeoff help please...


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22 replies to this topic

#1 XWRed5

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Posted 17 May 2008 - 10:11 AM

I'm finding it very difficult to explain this again without repeating myself ... but I'll bite, I think we are talking at cross purposes.The rotate that Vr refers to is the *act* of rotating, the speed at which the pilot first moves the controls. I think you are referring to the actual rotation of the aircraft. Don't confuse the two. Vr marks the start of the *act* of rotating not the movement of the aircraft. To address three of your comments:1) "...aircraft rotation exactly at Vr and the difference between your suggestion of a 747 with no stick movement until Vr". You're talking about the wrong rotate as described above. No stick movement until rotate speed is a correct rotate, anything else is incorrect.2) "...the aircraft is actually ready to rotate right at Vr". The aircraft isn't supposed to move at Vr, it's the pilot who moves (the yoke) and the aircraft responds (all the while it's accelerating to it's optimum lift off speed). Again you're talking about the wrong rotate.3) "...it easy to understand why he advocates loading up the elevators prior to Vr so it will rotate when it is suppose(sic) to." Easy, but wrong. The aircraft is supposed to move sometime after Vr, Vr takes this into account, as do the performance calculations.I do understand where you're coming from, it seems sensible but is actually wrong. You must remember that Vr is calculated taking into account pilots reaction times, pilots speed of movement of the yoke, time for the controls to move and time for the aircraft to react. If you anticipate any of these the aircraft will be in the take off attitude too soon and hence too slow (back to the Sacramento ice cream parlour).I also recognise that we're splitting hairs but at the end of the day there's a right way to do it and a wrong way. Why would any self respecting professional elect to do it the wrong way? They don't make these speeds up, if you rotate too soon you won't take off any quicker, in fact you may never take off at all (Sacramento ice cream parlour ... again) and if you rotate late you'll take off OK but may be taking some of the trees at the end of the runway with you. Vr is calculated for the optimum take off performance of that aircraft on that runway in that weather, ignore it at your peril.The weight of the aircraft doesn't matter, neither does how short the runway is, Vr is calculated (taking all of the above into consideration) to get the most weight off the runway. If you start the rotation early your are reducing the performance of the aircraft and run the risk of having an accident.Reading back over this post I've repeated myself numerous times, I'm not sure I can make it any clearer. If you require any more clarification please ask, I'll see if I can think of another way to say it.Hope this helps,Ian

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#2 Inactive Member_SkullxBones_***

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Posted 17 May 2008 - 02:15 AM

>I'm sorry, that's simply not correct.You're entitled to your opinion.>Vr is the speed at which the rotation is started. Agreed>The speed at which the handling pilot first moves the yoke >or stick to initiate the rotation. >Rotation is the movement of the yoke>or stick to result in the rotation of the aircraft, *not*>the physical movement of aforementioned aircraft, that's the>result, not the act of rotation. You're splitting hairs over some advice that was given to help someone that was having trouble getting off the runway. In normal conditions, no one is going to sweat the difference between an aircraft rotation exactly at Vr and the difference between your suggestion of a 747 with no stick movement until Vr. But at a minimum runway with a heavy load, they will sweat the difference and make sure the aircraft is actually ready to rotate right at Vr. I have read posts where pilots have talked about unloading nose wheel weight before Vr in these conditions.>You're correct that the>handling pilot doesn't simply wait for the co-pilot's call,>it's his responsibility to rotate, the other guy is just>helping out. Nevertheless, there is no anticipatory movements>of the yoke.>Really, then why does Captain Mike Ray say you should? I believe Capt. Ray flew for Untied during his 747 years. Not to mention the many other Boeings he has type ratings in. He has written books that help real life 747 pilots for their 747 checkrides. In one of his books, he states, "At V1, Gently pull back the stick so as to have a small amount of resistance by the time you get to Vr (ROTATE) speed". He is clearly advocating "anticipatory movements of the yoke." If you think about an 800,000lbs+ aircraft rolling along, it easy to understand why he advocates loading up the elevators prior to Vr so it will rotate when it is suppose to.>While I'm sure some people do it, I've seen one guy do it for>real, it is not correct. It is an old wives tale, a myth,>simply poor airmanship. Lots of very clever people sat around>defining, discussing and calculating Vr, to start the rotation>before Vr is arrogant at best, unsafe at worst (need I mention>the Sacramento ice cream parlour?).>In the sim it doesn't matter but please don't spread these>myths and legends as real life truths.The myths and legends seem to be in your mind, since no one here has said to start rotating before Vr.

#3 XWRed5

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Posted 16 May 2008 - 04:56 AM

I'm sorry, that's simply not correct.Vr is the speed at which the rotation is started. The speed at which the handling pilot first moves the yoke (or stick) to initiate the rotation. Rotation is the movement of the yoke (or stick) to result in the rotation of the aircraft, *not* the physical movement of aforementioned aircraft, that's the result, not the act of rotation. You're correct that the handling pilot doesn't simply wait for the co-pilot's call, it's his responsibility to rotate, the other guy is just helping out. Nevertheless, there is no anticipatory movements of the yoke.While I'm sure some people do it, I've seen one guy do it for real, it is not correct. It is an old wives tale, a myth, simply poor airmanship. Lots of very clever people sat around defining, discussing and calculating Vr, to start the rotation before Vr is arrogant at best, unsafe at worst (need I mention the Sacramento ice cream parlour?).In the sim it doesn't matter but please don't spread these myths and legends as real life truths.Hope this helps,Ian

#4 Inactive Member_Teddie_***

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Posted 15 May 2008 - 01:22 PM

>>I don't have the PMDG version yet.>>Until then, try downloading the IFLY 747 in the files section>of this website. It's free, it has a few bugs, but it's much>better than the default 747. It might work with SP2, I don't>know, I'm still using SP1.>>>>Thanks for the advice.I downloaded the IFLY 747 today. I'm looking forward to trying it out tonight!

#5 Inactive Member_SkullxBones_***

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Posted 15 May 2008 - 04:39 AM

>Of course that's in the sim only. In real life you never>"anticipate" rotate speed, it is the speed the rotation should>be started, not the speed at which the aircraft will leave the>ground.>>*At* Vr the non handling pilot calls rotate and the handling>pilot (irrespective of the other guy's call) starts the>rotation *at* Vr.>>Just to "keep it real",>>Ian>All pilots should anticipate Vr. Any competent pilot should know his Vr speed ahead of time and be anticipating and executing the rotation at Vr and not waiting for the co-pilots callout. Note- Anticipating doesn't mean you should rotate before Vr, that's why I said "have the plane rotating RIGHT AT Vr speed". When I said, "Don't wait till Vr to start pulling back or it will extend your takeoff length." The point here is that you should be rotating at Vr, not just starting to pull back the yoke which takes a bit of time in the Sim before the aircraft actually starts to rotate, especially since you you have to pull back so slowly to meet the 3 degrees per second requirement.According to Captain Mike Ray who flew 747's in real life, you should gently pull back the yoke at V1 until you feel the air resistance so it will be ready at Vr.Teddie case is even worse where he is using the default 747 which, unlike the PMDG747, doesn't have any V speeds on the tape, much less a co-pilot to remind him.

#6 Inactive Member_SkullxBones_***

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Posted 15 May 2008 - 03:10 AM

>I don't have the PMDG version yet.Until then, try downloading the IFLY 747 in the files section of this website. It's free, it has a few bugs, but it's much better than the default 747. It might work with SP2, I don't know, I'm still using SP1.

#7 XWRed5

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Posted 15 May 2008 - 02:17 AM

>At Vr rotate to 8 degrees nose up until you are clear of the>ground. This will stop the tail strike you are experiencing.>Anticipate Vr, and have the plane rotating right at Vr speed.>Don't wait till Vr to start pulling back or it will extend>your takeoff length. I hope you are using your flaps>properly?Of course that's in the sim only. In real life you never "anticipate" rotate speed, it is the speed the rotation should be started, not the speed at which the aircraft will leave the ground.*At* Vr the non handling pilot calls rotate and the handling pilot (irrespective of the other guy's call) starts the rotation *at* Vr.Just to "keep it real",Ian

#8 Inactive Member_Teddie_***

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Posted 14 May 2008 - 09:43 PM

Fantastic!Thank you.

#9 Highmike

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Posted 14 May 2008 - 09:03 PM

The fuel requirement listed in the nav log is the total fuel required, you'll have to distribute this total among the tanks listed in the fuel dialogue. I simply take the amount suggested by the flight planner and divide this by the vehicle's total fuel capacity and enter the percentages into each fuel tank. You'll have to add a bit for taxi time and for flying the pattern, but experiment with it and see what sort of milage you get. It's crude but effective.Mike.

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#10 Inactive Member_Teddie_***

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Posted 14 May 2008 - 06:16 PM

Yes, using flaps correctly. Thanks.Guys, I want to thank you very much.It was the weight from the fuel.I looked in the nav log and lowered the fuel accordingly.One thing I'm confused about. The fuel that tne nav log specifies, do I put that number in each of the fuel fields or do I work out all the fuel fields to equal that gallon number? (this is probably a dumb question).Thanks again guys. I just flew out of KDCA in the default 747 and it was a dream.

#11 Inactive Member_SkullxBones_***

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Posted 14 May 2008 - 06:00 PM

At Vr rotate to 8 degrees nose up until you are clear of the ground. This will stop the tail strike you are experiencing. Anticipate Vr, and have the plane rotating right at Vr speed. Don't wait till Vr to start pulling back or it will extend your takeoff length. I hope you are using your flaps properly?

#12 Inactive Member_jshyluk_***

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Posted 14 May 2008 - 01:40 PM

Kind of, sort of, not really. I'm not sure what you mean by "manage the fuel load". In FSX, fuel is treated as another source of weight. As long as the fuel weighs something, the engines will run. If you use "unlimited fuel", then the engines will never shut off if your fuel weight = 0. Also, whatever fuel you are carrying does not get used up, if memory serves me correctly. What you can do is figure out in basic terms how much fuel you will need by looking at the Fuel column in the Flight Planner. It's not very realistic, but give or take 5-10%, you should be okay. Based on that figure, you can enter that fuel value into the Fuel menu at the beginning of your flight session. Be sure you are using the correct units, unless you want to replay the Gimli Glider. After that, FSX will automatically handle how your fuel gets used, although some aircraft have a cross-feed switch that allows the pilot to fine tune where the fuel goes, which helps maintain a good center of gravity. If you are learning systems, there's nothing to stop you from "cheating" a bit, i.e. changing the fuel load while in flight, or turning on unlimited fuel or no crashes. It takes quite a few runs for a rookie pilot to learn the flow of the checkists and procedures during a flight, so you want to make sure you can handle the basics of getting from A to B before you start adding on layers of realism. Jeff ShylukAssistant Managing EditorSenior Staff ReviewerAVSIM

#13 RFields5421

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Posted 14 May 2008 - 01:32 PM

It has been so long that I don't remember what impact unlimited fuel has on the weight.But the flight planner will give you a guess as to how much fuel the flight will take. I always add at least 25% more.

#14 Inactive Member_Teddie_***

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Posted 14 May 2008 - 12:55 PM

You guys are very helpful, thank you!I will try your suggestions tonight.If I uncheck the "unlimited fuel" option, is there a way to have FSX manage the fuel load based on my flight plan?

#15 RFields5421

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Posted 14 May 2008 - 10:42 AM

KDCA's longest runway - 1/19 at around 6,900 feet long - is way too short for a fully load B747-400.You need about 9,900 feet of runway covered to get to an average V2 speed of 144 KIAS for a MTOW B744.Now, I have removed all the cargo and passenger weight, and set the B744 for 1/2 fuel - and can get it off the ground in about 4,800 feet of runway - in FS2004 and FSX.Be sure to hold the parking brake as the engines spool up to 85-90% before releasing the brake.





   
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