First of all I'd like say that's the new look of the forum is absolutely great! Very fresh for the eyes and also very clean and organized. Just fantastic!Well, my intention with this post is to put all the informations that all of you have about different aircrafts during the taxi phase. This subject is a very tricky thing on flight simming and most aircraft cannot reproduce fairly the real life aircraft behave as most people says. What you know about, let's say, the 737 or A320 in the taxi phase? Does it taxi in idle like people say? The pilot just need to give a little bit of thrust to take it out of inercia and the idle thrust is enough to keep the taxi speed? Anyway, any information is welcome.

You are correct, closed throttles are normally enough to keep a jet aircraft rolling once it has got going. If you've ever seen a jet engine running on a test stand, it is easy to understand why that would be so, as they kick out a frightening amount of power just running on idle setting, it is also really loud when they have no cowlings covering them up! If you get the chance to see that, it's worth doing so.So idle thrust is usually a bit of a misnomer for jet airliners, for example, the Pratt and Whitney JT8Ds on quite a lot of early airliners, including the original 737, 727, 707, Caravelle, Mercure and DC-9 amongst others, puts out about 800lbs of thrust at idle, which is often more than enough to keep those aircraft rolling once they get going, and the average JT8D is not an especially powerful jet engine when compared to more modern ones. It is sort of similar to the way it is easy to push a car once you have got over the inertia of getting it rolling in the first place. You will notice that the engine start checklists for most airliners include checking that the parking brake is set before cranking the engines, because the engines can set a jet rolling even at idle, although if it has been parked for a while, there is less chance of that happening as the tires stick to the ground a bit.However, as when you push a car, heavy jet aeroplanes also may need a bit more 'jip' when they have to turn, so some throttle might be needed then. In the case of the 727, it is usually taxied on only the outboard engines, with the number 2 engine generally left alone until take off thrust is needed. That's nothing to do with potentially using asymmetric thrust to steer though, it is simply that the two outboard engines on a 727 are more than enough to get it rolling. Asymmetric thrust is rarely, if ever recommended for steering jets in the taxi, and probably wouldn't be much use on a 727 anyway.A more modern aircraft, such as the A320 with its high bypass CFM-56 engines (which is the engine you'll also find on the Classic and NG 737 models), requires little or no thrust to keep it rolling, since all that fan-driven air bypassing around the core of the engine and shooting out the back gives high bypass turbofans quite a lot of power even at low thrust settings. The standard operating procedure manual for the Airbus A320 recommends using no more than 40 percent thrust to unstick the thing and get it rolling (and it probably wouldn't need anywhere near that much), whereupon the throttles can be retarded and just the idle thrust will generally be enough to keep it moving. Despite what many FS add-on applications of the kind which monitor how well you are handling your simulated airliner may claim, the standard maximum taxi speed in a straight line for an A320 is actually a surprisingly high 30 knots (that's according to EADS), and an A320 can easily exceed that speed on idle thrust if the surface is good, but, since in reality when you taxi an aeroplane, the first thing you should do is test the brakes, you will see (and hear) airliners throttle up to get rolling, then probably hear them throttle up again to get going once more after the brake test has been completed, whereupon they will be rolling along mostly at idle.A caveat to all this, is the use of engine anti-ice if you select that option when on the ground, because selecting engine anti-ice increases the idle thrust of an engine. Both the use of engine anti-ice and giving the thrust levers a quick blip to get going or make it around a turn have to be exercised with caution, especially on modern jets with their low-slung podded engines that are close to the ground, because it can kick up debris and cause FOD, either to the engines or to the flap canoes and the horizontal stabiliser.Most of this can be taken with a pinch of salt on FSX and FS9 however, since ground handling simulation is not one of those sims strong points. However, some simulated airliners do a pretty good job of it, notably the Ariane FSX 737 and the Captain Sim FSX 727, although the Captain Sim 727 doesn't do a power back like it actually should.Al

The taxi performance really depends on the aircraft being used. For me the default 737 requires around 40% thrust to get it rolling where the default airbus requires nowhere near that, not to mention the KingAir where if you have a swift wind blowing on your throttle it will darn near takeoff. Out of all the aircraft I own, I find the Level D 767 to seem pretty realistic in the taxi department.

AI,Thanks for the detailed reply. Looking in the internet I found an very useful article if you have the enough knowhow about AirEd you can tweak table #1506 which commands the N1 thrust.If someone wants to try, download the AirEd here. If you need any help, post here and we'll see what we can get. :(

None else? l though i'd burn burn this forum up! :(