OUTSTANDING PRODUCT...

[Guest BlueRidgeDx]

No, I don't harbour any contempt for any flight crew member. I excercise Joint Operational Control with the PIC's of nearly forty-five Domestic and Flag Air Carrier flights every day. We have the utmost respect for each other, so let's not make accusations now, shall we?You are failing to see the logic in my "argument", apparently. I know its fruitless, but I feel compelled to make my point clear, so I'll try again.If the amount of hydraulic pressure within the NWS system is enough to overcome what you described as "incredible friction" in order to center itself from a non-centered position, then why would there not be enough authority available to overcome that same friction through pilot movement of the tiller? If it can center itself while stationary, it is equally capable of "un-centering" itself. Where is the failure in logic there?Regards,Nick

[Steve Dra 7,579]

>> I personally, have grabbed the lower scissor arm,>>and with my own strength, turned the nose wheels left/right>as>>needed to line up the arms. >>Sorry, gotta call BS on that one! How much weight is resting>on that wheel? You'd have trouble turning it in a car with>steering shaft disconnected, or even the upper and lower arms.>You'd kill yourself trying to do it on a semi. And that's>nowhere close to the weight of the 747. And I am not talking>about any resistance from the steering mechanism, just the>friction alone. Yah....that's gonna happen!>Actually, it is quite possible when you take a good look at what is actually happening when you turn a nosewheel assembly "With the oleo and shock strut centered vertically above a dual wheel assembly" (That is the critical phrase you should have picked up on).Without getting into a long physics lesson, what do you think happens when this assembly is pivoted from a CENTER point? I'll tell you....if you are pivoting it to the right, the right wheel ROLLS in a backward direction (or clockwise as viewed from above), and the left wheel ROLLS forward...both of them AROUND the pivot point! Like Nick states, there is very little scrubbing motion.It helps to visualize it from the top like so:http://forums.avsim.net/user_files/145582.jpgAdd to this that most of the aircraft's weight is centered very far from the nosewheel (We've seen enough airliners.net pics of planes sitting on their tails to understand this :-lol), plus the fact that the scissor arm makes a pretty good "breaker bar" (if you're a mechanic you know exactly what that is), I bet this is very possible.I know just by the sound of it, the feat sounds impossible, but if you really think about the physics, its really not that impossible. ;)(Plus I have no reason to doubt Nick) Regards,Steve Drahttp://img47.photobucket.com/albums/v144/S...Dra/banner1.jpgDownload my planes at Avsim here:http://library.avsim.net/esearch.php?CatID...&Go=Change+View

[Guest BlueRidgeDx]

Thanks Steve, I appreciate the illustration. I had gone so far as to explain about the wheels rolling in opposite directions, and talk about the weight distribution on the gear, but I edited it out since I didn't have a nice illustration to go with it.Anyway, I knew all those hot/cold, rainy/snowy nights as a ramper/loadmaster would eventually bring me fame and fortune!Regards,Nick

[michal 44]

>If it can center itself while stationary, it is equally>capable of "un-centering" itself. Where is the failure in>logic there?Failure is to realize that it very much depends how the whole thing is designed internally. Such self-centering may be done automatically and there may be enough pressure to overcome friction but it does **NOT** imply that the same boost will be avilable to the pilot all the time. Again, it all depends how Boeing did it, I am afraid devil is in the detail as they often say. If you want me I can fire another email to Alan and ask him about your observations. I certainly value his opinion since he is a true 747 pro and doesn't mind answering emails in between his flights and walking his dog. I would only say that you offered very little plausible explanation for his observations apart from ridiculing him that he never "tried" etc. Sorry, but this is BS.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Guest BlueRidgeDx]

Okay chief...I never ridiculed anyone. I queried you as to whether you had asked him if he'd ever actually tried to turn the tiller while stopped. I acknowledged the fact that is is not standard practice to do so, therefore, in all probabability he's never actually tried.If you want to bother the man with further questions, thats up to you. But, I think you've made the mistake of making an ego investment along with your argument, and that makes it hard for you to accept that you're wrong. Thats perfectly normal, and I'm not upset about it.I must be a glutton for punishment, because I'm still trying to get through to you. Think about this for moment:1) We're arguing about whether the 747 has the ability to use NWS while stationary.2) You argued that the "incredible friction" would prevent the wheels from turning.3) I related a story from my experience that illustrated that the NWS can and does turn the nosewheels while stationary. Further, it does so with enough force to break an 8" (hollow) steel towbar.4) Now you're arguing that just because the wheels self-center when the NWS actuators are hydraulically pressurized, that it doesn't necessarily mean the tiller will actuate the NWS.In response, I will offer this:Why wouldn't the tiller move the nosewheels? Without some evidence that NWS operation is specifically inhibited while stationary, the only logical conclusion, given my personal observation of countless aircraft during ground operations, is that the NWS will operate normally. I would readily concede however, that it may take increase control force to do so.Again, I think you're arguing procedure as opposed to capability. The airplane has the capability to use NWS while stationary. However, it is not normal procedure to do so.Regards,NickPS. Your claim of "BS" is really unnecessary. I don't agree with you, but I'm not slinging mud at you, so please try and refrain.

[Guest BlueRidgeDx]

Listen, I'm growing tired of this whole thing, so I'm going to use your own source to seal the deal on this one...Your arguments against the operation of NWS while stationary have consisted of the following:1) Incredible amounts of friction would prevent the wheels from moving.and2) There is some sort of inhibit that will not allow the NWS to be actuated while stationary.In regard to number 1, I've already demonstrated that the hydraulic force available to the NWS is more than an ample to overcome the rolling friction of a canted nose wheel assembly. Since the pilot was not making a tiller input when the bypass pin was removed, the NWS did exactly what it was asked to do: return to center. Similarly, if the crew had made a full left or right steering input, when the pin was removed, the NWS would have immediately moved as commanded. Its that simple. Further, 3000psi (or thereabout) is always available in a normally funtioning hydraulic system. There is neither a boost, nor a limitation on the amount of hydraulic pressure available for tiller actuated NWS. In regard to number 2, your own source has confirmed that there is no such inhibit or interlock. Reference the following quote from your own post: "However, if the tarmac is icy, then yes you would be able to move the nosewheel whilst stationary."When combined, the evidence clearly indicates that the NWS will operate when stationary.Regards,Nick

[rsrandazzo 6,353]

Gents-Okay- i must say that this has become the most pedantic discussion I've seen in some time. :-)We seem to have a vast field of experts who can base an entire operating procedure on single experiences- so let me throw in a bit of The Boeing Company's knowledge....Granted- they are only the manufacturer- so they probably haven't a clue what they are talking about- but hey- it's worth something.....There is nothing to inhibit the turning of the nose castor while sitting still. ie: No mechanical lock out.If the weight of the airplane is light, AND/OR the inflation level of the tyres is high, AND/OR the airplane is sitting on a ramp declination that naturally shifts the weight aft.... Then the nose wheel will turn with normal tiller movement without the airplane moving.If, however, the airplane is heavy, AND/OR the CG is far forward AND/OR the tyre pressures are not optimal AND/OR the ramp has an inclination that causes greater pressure on the nose tyre- it will NOT turn with normal tiller pressure.So... you all can be right.Can someone please forgive us for trying to include some realism? jeez... :-)

[michal 44]

>Can someone please forgive us for trying to include some>realism? jeez... :-)Sure RR, we forgive you. :-hahI was expecting something of the sort - widely varying friction due to surface condition and/or weight of the aircraft can swing things in either direction as far as ease of turn goes. I do appreciate this succinct explanation.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Guest BlueRidgeDx]

Hi Boss,I realize that this discussion was taking place on a PMDG forum, but my argument was never whether PMDG should or shouldn't have included the feature. I'm extremely happy with every PMDG product I own...and I own them all.My only argument was the real jet's capability.Regards,Nick

[Guest bbalfe]

Gracious to the end Michael!!Thanks Captain Razz for the closure...

[Guest gremel]

Gentle with the 'tiller' now. You can sometimes tell a new co-pilot by the way they over-handle the tiller when they are in taxiing. It causes me to shutter thinking about it.jack

[Tabs 2,790]

You know we're nerds where there's a flame war about the intricacies of nosegear steering going on... ;)