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Guest akhtarw

Turn radius for 747-400

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HiI can't turn around on a normal runway. The turn radius on the 747 should be better than that!?!Anybody else with this problem?In the manuals it says that the plane vil taxi on idle, like real life. That is not working either..Wakas

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I don't know how long you have been flying the Queen for but for what it is worth I first thought there was something wrong with the plane myself. However, after learning the feel of the aircraft I learned to to finesse the throttles and found that this aircraft turns very well. If you apply too much throttle then you will find it hard to turn the aircraft. I hope this helps. It might be good to check the calibration on your joystick. I had to replace mine a month or two back because it simply lost its calibration and could not be fixed.

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The 747 is big and has four main bogie's, so it turns wide! If you want to turn on a dime, so to speak, apply thrust to only two engines on one side of the aircraft, no more than 40% N1 and apply the brakes on the opposite side wheels.This works the best if you have rudder pedals with individual toe brakes and a four engine throttle controller. A single controller and the keyboard might be a challenge.I've never gotten the aircraft to move at idle. You have to apply about 40% N1 to get her moving and then reduce to about 35% N1 to maintain taxi speed.Kim

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>The 747 is big and has four main bogie's, so it turns wide!>If you want to turn on a dime, so to speak, apply thrust to>only two engines on one side of the aircraft, no more than 40%>N1 and apply the brakes on the opposite side wheels.>>This works the best if you have rudder pedals with individual>toe brakes and a four engine throttle controller. A single>controller and the keyboard might be a challenge.>>I've never gotten the aircraft to move at idle. You have to>apply about 40% N1 to get her moving and then reduce to about>35% N1 to maintain taxi speed.>>KimAh ok. Now I know just how much N1 to use. I'm always trying to guess and stuff. What is the taxi speed anyways?

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The runways in FS9 are way too sticky. It's impossible to get your aircraft to taxi normally AND fly normally, so PMDG chose the latter.The real 744 will taxy at idle... depending on the weight, but it's absolutely normal to apply thrust to get the aircraft rolling.I don't believe differential braking (for turning) is recommended on the 744, but I guess it won't hurt in MSFS :(Hope this helps.Cheers.Q>

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>What is the taxi speed anyways?I try to taxi at about 15 knots and take the turns at about 10. Also, you don't want to have the nose wheel follow the taxi line in a turn. You want to overshoot a little then bring it back after the turn. I saw an image of how to take turns but I can't remember where. I'll try and find it and post it if I can. Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

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WakasI taxi with the two outboard engines at idle and use the two inboard engines (around 45%) to taxi, seems to give a more manageable and constant taxi speed. Don't have a throttle quadrant to work with. Still have problems cutting corners - its a big airplane.Hang in there - gets easier with practise.Peter

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I too use about 36-38% N1 to start moving and then back to 34-35% for taxi- dependant on weight. For turns, allow the nose to overshoot until the taxi line approaches the "C" pillar- the A pillar being the centerpost, B being the windshield to side front separation and C being the side front to side rear separation pillar. As it approaches, start steering- if you look out the side, and keep the taxi center-line on that C pillar through the turn you will be perfectly positioned, and stay on the concrete all the way through. This works on either side.I do have the CH quadrant but never use differential throttle unless in REALLY tight quarters.I have recently revisited my 737 800/900 purchase, and in that sim, once you start rolling with about 25-30% N1, the a/c will continue to taxi and even accelerate at idle thrust (also depending on MTOW).Best-Carl F. Avari-Cooper BAW0225http://www.precisionmanuals.com/images/forum/supporter.jpg

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I like to taxi at about 10 to 12 knots in areas that have tight turns and narrow taxiways. Also, I use differential braking only while the aircraft is moving, making sure to only use them only enough to get the turn going, it tends to slow you down too much.As for differential thrust, it's a sim cheat that I use only in REALLY tight taxiways. Some sim pilot wrote about this in Computer Pilot magazine awhile back. Probably not a sanctioned practice in real aircraft operations. Isn't virtual reality fun!I have noticed that the 737 is easier to start moving, but on the down side, you have to monitor your speed more closely, baby the throttles and use the brakes more frequently.I had a Captain Sim 727 that would literally start rolling at idle as soon as you took off the brakes, a hazard only if you accidentally disengaged the parking brakes (a slight movement of the toe brakes on my rudder pedals would do it) and you were still parked at the terminal. Ouch!Kim

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Darn! I looked all through my old copies of Computer Pilot and can't find that article on taxiing large aircraft or I'd give you the issue number.Another tip for taxiing is to use the view keys (num pad) and check your side position to start your turns. The arrow keys on your keyboard are a quicker way to peek out the side views and return forward instead of any panning control or hat switch, in both the 2D and the virtual cockpits.Kim

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Kim,With reference to differential thrust...I suspect its use is subject to individual company policy...an excellent example of it's use is shown in the old ITVV Cathay Pacific 744 video by Capt Don Grange as he negotiates the aprons & taxiways at LHR...its worth a view if you can get an old copy...you can see him pull 1 & 2 Throttles back to idle as he applies a small amount of differential thrust on a 90 deg left turn...once into the turn you can see him pull Throttles 3 & 4 back to idle.IMHO as for taxi speeds...dependant on weight I can get her to 'unstick' from the taxiway at between 32-34% N1...she happilly trundles at about 10-15 knts with 32-32.5 N1 set...but I always apply a dab of brake prior to any turn...aiming for 7-9 knts as I turn - Also a useful way to check your brake pressure & action prior to entering the RWY.Much of the feel will depend on the setup of your controls...especially the rudder pedals...mine have quite a generous null zone giving a nice 'spongy' feel.Although not really modelled in FS9 if there is rain or ice/snow/slush around restrict your turns to below 8 knts or she could well slide.RegardsSteve B

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I remember a while back people complained that due to having to use so much thrust to taxi it was throwing out their fuel planning calculations! Whenever I taxi the PMDG 747 it feels like the brakes are binding. I really hope PMDG can fix the taxi thrust problem. The LDS 767 is one example that seems to work well.Paul

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>I remember a while back people complained that due to having>to use so much thrust to taxi it was throwing out their fuel>planning calculations! Whenever I taxi the PMDG 747 it feels>like the brakes are binding. I really hope PMDG can fix the>taxi thrust problem. The LDS 767 is one example that seems to>work well.It isn't PMDG. It's Microsoft's ground handling model (or lack of one, I don't know). The LDS isn't perfect. Notice how quickly you get off the runway during takeoff? LDS gives you more power on the ground which is why you can taxi at idle.Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

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Actually, you are absolutely right. The PMDG 744 does not handle properly on the ground. I'm sure the guys tried to get it as close as possible, but the real aircraft turns much better and tighter. I sent them an e-mail on this issue a long time ago but I never got a reply. Here is some guidance to what we use on the real 744 where I work.Tight turns, where you will be going to full tiller left or right (ninety degrees), no more than 6 kts. If it is a gentle 90 degree turn, then you can go arround at 10kts. If you are turning onto the runway, try not to make a sharp turn on the piano-keys unless it is absolutely necessary. Tight turns make the nose-gear tires loose grip and skid along the slick paint, especially if it is moist. Not only is this not good for the Nose-gear assembly, but you won't believe how loud and obnoxious it is if you are sitting in first class. Normal taxi speed on the ramp is 10 kts and around 20kts once away from the ramp. You definetly have to keep an eye on the GS readout as you taxi arround. Because you are sitting so hi, you have very little sence of motion. So you might think you are slow enough to turn, and then look down to see you are actually doing 30kts. Yikes!As far as overshooting the centerline, you actually overshoot very little, only the distance from the nosegear to the cokpit really.The plane has body-gear steering, so the assend follows you when you turn. It really is a neat system that works great on the real whale. I've ridden up front on our 773, and they have to overshoot turns by quite a bit (it has rear wheel steering but only to reduce tire scrubbing).As far as thrust to taxi. I fly both Rollers and Pratts, and they both handle differently. When you are heavy (375T+), you need thrust to move. More so on the RB211s than on the PW4056. When you are light, you still need thrust to get going on the RR, but the PW takes off as soon as you release the PB. I normally find that shutting one down on the PW after landing works great to control taxi speed on the real airplane. As far as differential thrust, the only time I've needed it is when making a 180 on the runway-node for takeoff or back taxi. I've done this in BOM many times and it works great. The trick is to keep her rolling at 6 to 10 kts, whatever you do, don't let her stop or you might need to get towed out of the runway (how embarrasing that would be)Anyway, I really wish PMDG would fix the turn radius on the 744. I know it is a small thing, but it actually kind of kills the fun when you can't take certain turns without going 4-wheeling on the grass.Mariano

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One thing to keep in mind is that I have noticed that if you turn too much your nose wheel you are actually slipping and not turning much, specially if turning over 10kts.For best results always start your turns in any plane somewhere between 7-9 nots. That seems to work every time for me. and alternating engines throttle control depending on your turns also helps with the big birds.cheers

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Turning around on a runway, forget it! I don't like driving in the grass either so usually I get turned as far as I can and then back up (shift-P key). Not very realistic but it gives you more room and to heck with the guys waiting in line behind you.Kim

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Strange that PMDG team has not done anything about it. Ground realism is very important too.

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As stated before, PMDG has no control over this. The problem is the ground friction model in MSFS. Andrew

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