747 default takeoff help please...

[Guest SkullxBones]

>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.

[XWRed5 0]

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

[Guest SkullxBones]

>The rotate that Vr refers to is the *act* of rotating, the speed at which the pilot first moves the controls.No it doesn't. Controls may be moved beforehand as I have shown repeatedly, even to the point of unloading weight off the nose wheel in some conditions, but not to the point of actually rotating.Yes I think we are emphasizing two different things things. I was try to point out that pilots do routinely anticipate Vr by pulling back the yoke prior to Vr, not always, and not all pilots, but certainly in conditions where they don't have a lot of runway and they want to make sure the aircraft rotates at or as close to Vr as they can get.You are emphasizing there must be some lag time between Vr and when the aircraft actually rotates. As I said, we are splitting hairs because as Capt. Ray suggests, if you load up the elevators prior to Vr, the moment you pull back at Vr, the aircraft will rotate without lag, whereas your suggestion of grabbing a slack stick will produce more lag. Capt. Rays method which will rotate the aircraft at Vr is not incorrect because it does not have the required amount of lag you suggest. I believe he also states that the SIM responds with lag where the real 747 doesn't.

[XWRed5 0]

>>The rotate that Vr refers to is the *act* of rotating, the>speed at which the pilot first moves the controls.>>No it doesn't.:-) And herein lies the rub. We are disagreeing on a fundamental part of this discussion. I can't find any authoritative definition to quote so we'll have to agree to disagree ... but it kind of makes the discussion moot. >Yes I think we are emphasizing two different things things. I>was try to point out that pilots do routinely anticipate Vr by>pulling back the yoke prior to Vr, not always, and not all>pilots, but certainly in conditions where they don't have a>lot of runway and they want to make sure the aircraft rotates>at or as close to Vr as they can get.It's not routine, I've only seen one guy do it, indeed when we operate from our shortest runway on the network we're reminded *not* to start the (act of) rotation early, despite the end of the runway looming rapidly. It sometimes even comes up in the brief. In fact, our safety monitoring system has picked up some instances of guys doing exactly what you are trying to advocate and being corrected.>You are emphasizing there must be some lag time between Vr and>when the aircraft actually rotates. As I said, we are>splitting hairs because as Capt. Ray suggests, if you load up>the elevators prior to Vr, the moment you pull back at Vr, the>aircraft will rotate without lag, whereas your suggestion of>grabbing a slack stick will produce more lag. Capt. Rays>method which will rotate the aircraft at Vr is not incorrect>because it does not have the required amount of lag you>suggest. I believe he also states that the SIM responds with>lag where the real 747 doesn't. I'm not sure you read all my previous post, Vr is calculated to include these lags, it is designed so that these lags in aircraft response occur, allowing the speed to build up to the optimum lift off speed when the aircraft reaches the optimum pitch. You need the lag, reducing it means you get to the optimum pitch too slow. That's a bad thing. And for the third time, we're not talking about the sim.I'm not sure we can continue this much more, we've established we fundamentally disagree on the main definition of Vr and we've both written the same thing three times to each other. In fairness, we are talking about very minute differences in actual real life performance, I'm just being a pedant who likes to get everything perfectly correct. Hope this helps,Ian

[Guest SkullxBones]

>It's not routine, I've only seen one guy do it, indeed when we>operate from our shortest runway on the network we're reminded>*not* to start the (act of) rotation early, despite the end of>the runway looming rapidly. It sometimes even comes up in the>brief. In fact, our safety monitoring system has picked up>some instances of guys doing exactly what you are trying to>advocate and being corrected.I know you think you must not touch the stick prior to Vr, and in doing so you are convinced that this puts someone in technical violation of rotation before Vr because you feel this starts the ACT of rotation. Whereas I believe it is acceptable and used in the real world as long as the aircraft is not actually rotating prior to Vr.This is something we are not going to agree on becasue I feel you are too strict in your interpretation of Vr and I backed this up by quoting a very well known 747 pilot who has routinely violated your interpretation of Vr, and advocated it to other 747 pilots in training as proper procedure.>You need the lag, reducing it means you get to the optimum pitch too slow. That's a bad thing. And for the third time, we're not talking about the sim.Do you have specific quotes from 747 manuals that backs up your assertion that you need the extra lag from a 'slack stick'? Because I am willing to learn if this can be documented for the 747 and shown that Capt Ray is wrong. But since he is the only expert on 747's that I have read on this exact subject and advocates pulling back on the stick slightly before Vr as normal procedure, then I must side with him. And for the third time, he did this in a real 747's.>I'm not sure we can continue this much more, we've established>we fundamentally disagree on the main definition of Vr and>we've both written the same thing three times to each other.>In fairness, we are talking about very minute differences in>actual real life performance, I'm just being a pedant who>likes to get everything perfectly correct. On this we can agree. I like the argument because it does shed light on interesting technical interpretation differences of Vr.

[XWRed5 0]

>>It's not routine, I've only seen one guy do it, indeed when>we>>operate from our shortest runway on the network we're>reminded>>*not* to start the (act of) rotation early, despite the end>of>>the runway looming rapidly. It sometimes even comes up in>the>>brief. In fact, our safety monitoring system has picked up>>some instances of guys doing exactly what you are trying to>>advocate and being corrected.>>I know you think you must not touch the stick prior to Vr, and>in doing so you are convinced that this puts someone in>technical violation of rotation before Vr because you feel>this starts the ACT of rotation. Whereas I believe it is>acceptable and used in the real world as long as the aircraft>is not actually rotating prior to Vr.Any rearward motion of the yoke during the take off roll is the start of the act of rotation, technical or otherwise. I understand what you are getting at, I've heard these dangerous bit's of advice (usually in sim details and being told not to do them) like :Taking the weight off the nosewheelPressurise the stickTake up the elevator slackI've been categorically trained not to do it, it is incorrect and potentially dangerous. I appreciate the (perceived) problem they are trying to solve but it's based on the faulty definition of "rotate speed" (that and under confidence in the strength of the nosewheel) that you and I have discussed to death :-).I know it is not acceptable in the company I fly for and I've only seen it once on the line. Maybe other companies use a different calculation method for rotate speed that assumes the pilot already has a rearward control input in place. That speed would be a bugger to calculate though, when and how much rearward motion was already in place would be a moveable beast. The only time the state of the aircraft controls is known for sure is when it is at neutral, that's why rotate speed starts at that known point. The trim is used to account for any C of G variations so the aircraft should behave in exactly the same way, given the same control inputs, on pretty much every take off. How could they calculate the time taken to the lift off attitude (and hence the speed the aircraft will be at) if they don't know where the controls are starting from? I appreciate I'm being unnecessarily picky here (I'm arguing with you over fractions of a second and a couple of knots) but there is only one correct way and it's that way for a reason.>This is something we are not going to agree on becasue I feel>you are too strict in your interpretation of Vr and I backed>this up by quoting a very well known 747 pilot who has>routinely violated your interpretation of Vr, and advocated it>to other 747 pilots in training as proper procedure.Correct, I am a pedant of the highest order :-) that doesn't make him right.>>You need the lag, reducing it means you get to the optimum>pitch too slow. That's a bad thing. And for the third time,>we're not talking about the sim.>>Do you have specific quotes from 747 manuals that backs up>your assertion that you need the extra lag from a 'slack>stick'? Because I am willing to learn if this can be>documented for the 747 and shown that Capt Ray is wrong. Yes, our company 747 training manual, unfortunately I would get fired if I started quoting that on a public forum, I understand and accept your scepticism on this point :-).>But since he is the only expert on 747's that I have read on>this exact subject and advocates pulling back on the stick>slightly before Vr as normal procedure, then I must side with>him. And for the third time, he did this in a real 747's.With all due respect a sample size of one is hardly an overwhelming consensus in that method.>On this we can agree. I like the argument because it does shed>light on interesting technical interpretation differences of>Vr. Indeed, I'm always fascinated in the workings of the human mind and how we all see and understand the same information differently. It's a great human factors debate that we will probably never solve. Nevertheless, there is only one correct interpretation, other, admittedly minor, variations may be close, so close they make little difference, that doesn't make them a correct interpretation.I think we've both run out of authoritative information to back up our respective claims. Let's just agree we shouldn't "try and take off" before rotate speed, any minor variations won't make that much difference anyway.Take care,Ian

[Guest Teddie]

Thanks guys for participating in my request for help. Excellent info.Hey, SkullxBones, I think I'm going to go ahead and purchase the PMDG 747 sometime in the next few weeks. I tried the iFly one, but I really don't like the VC...I know the PMDG one is a beauty.But the fuel load advice was the biggest help for me. Thanks again folks!Cheers,Teddie

[Guest SkullxBones]

Yeah, the IFLY747 VC isn't a thing of beauty, but they did an amazing job modeling all the systems considering it's freeware. There aren't many payware planes that have the same level of complexity as the IFLY. It's just to bad they stopped updating it.You'll love the PMDG version. Just make sure you have enough CPU power to fly it. You'll need it considering it's arguably the most complex aircraft you can buy for FSX. Be prepared for a huge learning curve, but it is a fun one.