NGX Taxi Performance

[G550flyer 1,007]

Such action could destroy the engine by hot gas reingestion, minimum airspeed usually 60 Kt for reverse thrust operation.

In the Gulfstreams(G-5 or better) it's normal during taxi as long as you stay at reverse idle.As far as the NG, this is from the ops manual. During taxi, the momentary use of idle reverse thrust may be needed on slipperysurfaces for airplane control. The use of reverse thrust above reverse idle is notrecommended due to the possibility of foreign object damage and engine surge.Idle reverse thrust may be necessary on slippery surfaces to control speed whiletaxiing. Consider having the airplane towed rather than relying on extended use ofreverse thrust for airplane control.

[MMartinov 48]

It is amazing how many people are giving out their theoretical knowledge when nobody is asking them to.The OP is right and there is something to be adjusted within FSX. The NGX (at average weight) taxies with throttles approx@24%. 1/10th percent less on my throttles and the airplane starts decelerating and stops very quickly (and in my opinion unrealistic). A few notches forward and the acceleration is too much and brakes have to be used. I have very good (and calibrated throttles) and still find it difficult to control the taxi speed. Yes, there is a sweet spot but its margins are extremely narrow IMHO. Something is not right and has to be looked into.

[Cristi_Neagu 134]

It is amazing how many people are giving out their theoretical knowledge when nobody is asking them to.The OP is right and there is something to be adjusted within FSX. The NGX (at average weight) taxies with throttles approx@24%. 1/10th percent less on my throttles and the airplane starts decelerating and stops very quickly (and in my opinion unrealistic). A few notches forward and the acceleration is too much and brakes have to be used. I have very good (and calibrated throttles) and still find it difficult to control the taxi speed. Yes, there is a sweet spot but its margins are extremely narrow IMHO. Something is not right and has to be looked into.

I think there's something wrong with your setup, because for me and others everything works well. I don't have the problems you describe. I usually push the throttles to 30-35% until the plane starts moving, then i drop them a bit and let the plane accelerate to 10-20kts, depending on how straight the taxiway is. When i need to stop i just put the throttles to idle and the plane slowly coasts to a stop. It feels very realistic and smooth.

[Ericd 4]

I think there's something wrong with your setup, because for me and others everything works well. I don't have the problems you describe. I usually push the throttles to 30-35% until the plane starts moving, then i drop them a bit and let the plane accelerate to 10-20kts, depending on how straight the taxiway is. When i need to stop i just put the throttles to idle and the plane slowly coasts to a stop. It feels very realistic and smooth.

What kind op set up are you referring on.I have no idea how the real plane behave, but I notice the same behavior in the PMDG. At 1/3 full (with fuel) the plane starts moving at 24%. If I load it full then it starts moving at 28%. (well that difference feels realistic :-) ).If I use F3 or the throttle to 30% the plane is moving immediately very very fast and I have to heavily brake to get the steering possible.So what should I change in my setup? Regards. Eric

[Cristi_Neagu 134]

What kind op set up are you referring on.I have no idea how the real plane behave, but I notice the same behavior in the PMDG. At 1/3 full (with fuel) the plane starts moving at 24%. If I load it full then it starts moving at 28%. (well that difference feels realistic :-) ).If I use F3 or the throttle to 30% the plane is moving immediately very very fast and I have to heavily brake to get the steering possible.So what should I change in my setup? Regards. Eric

Well... I don't know what your setup is, nor am i that familiar with the NGX's inner workings. If you're using FSUIPC, you might want to try setting up your controls via FSX, rather that FSUIPC. It causes all sorts of unpredictable problems.

[zachlog 18]

I think there's something wrong with your setup, because for me and others everything works well. I don't have the problems you describe. I usually push the throttles to 30-35% until the plane starts moving, then i drop them a bit and let the plane accelerate to 10-20kts, depending on how straight the taxiway is. When i need to stop i just put the throttles to idle and the plane slowly coasts to a stop. It feels very realistic and smooth.

Cristi, I think Martin above is the only person who understood my original question and is staying on point. You say there may be something wrong with the setup. OK, where do I look for remediation ? If 24% N1 makes the A/C behave as if it's made out of paper instead of an A/C with a ZFW of ~100,000 lbs., what tweek do I go after ? Please keep in mind that the performance/realism sliders are 100% to the right per the Introduction. Thanks for any suggestions you may be able to provide since your observations/experience is what I was expecting to see. Zach

[Cristi_Neagu 134]

Cristi, I think Martin above is the only person who understood my original question and is staying on point. You say there may be something wrong with the setup. OK, where do I look for remediation ? If 24% N1 makes the A/C behave as if it's made out of paper instead of an A/C with a ZFW of ~100,000 lbs., what tweek do I go after ? Please keep in mind that the performance/realism sliders are 100% to the right per the Introduction. Thanks for any suggestions you may be able to provide since your observations/experience is what I was expecting to see. Zach

All i was providing were my observations with the plane. I do not get the same problems you are getting, and apparently, neither does the lawyer+pilot guy who doesn't sign his posts with his full name, as per the forum rules. Anyways, back to the point: I find the plane behaving just as the real thing should (mind you, i've never flown a 737, or anything larger than a 2 seater). At about 30-40% load, the airplane unsticks at about 35% and is accelerating smoothly. Just after it starts to move, i just pull the throttle back a bit, and everything's well. At idle, the plane slows down to an eventual stop. I don't need to ride the brakes and I don't need to use reverse thrust. In fact, most of the time I can taxi to the runway without touching the brakes, holding a max of 20kts on the straights, and 10kts in the turns.Since others don't complain about this, it must be something on your end, but as to what that is, I couldn't tell you. Submit a ticket to PMDG. If they can't figure it out, no one can. P.S.: I do not have any kind of friction model modifications on my sim (i don't even know if such a thing exits). I also have my sliders to 100%

[sprangerjack 0]

Zach and Martin, i have the same problem. What i've realised is full weight or empty it take the same trust to move the a/c. If it is indeed a setup issue, when u guys figure it out let me know. spranger

[zachlog 18]

Zach and Martin, i have the same problem. What i've realised is full weight or empty it take the same trust to move the a/c. If it is indeed a setup issue, when u guys figure it out let me know. spranger

Honestly, my gut tells me this is not a setup issue. The key here is the 24% N1. At idle (~22%) the A/C is stationary (no brakes), at 24%, reached very carefully and with the lightest possible touch of the throttle, we are off to the races. I had a similar issue with the 400X with lower GWs, it taxied very well with higher ones. I have not tried variable GWs with the NGX yet but the problem seems to be more acute with the NGX. I will let you know if I find anything but in general, this seems to be a problem somewhere between FSX and the NGX model. Zach

[sprangerjack 0]

Thanks Zach. to move from 22-24 is literally millimeters for my trottle. Im a RW dash 8 pilot, flew 737 in the sim. if u figure anything out let me know. and vice versa Spranger

[zachlog 18]

Thanks Zach. to move from 22-24 is literally millimeters for my trottle. Im a RW dash 8 pilot, flew 737 in the sim. if u figure anything out let me know. and vice versa Spranger

Spranger After many tests taxiing, the only way I observe good, i.e., realistic performance where the A/C does not zip around like a toy A/C is with large payloads (A/C 90% full + the required fuel). Moving the throttle millimeters back and forth between 22% and idle is a frustrating experience so I set it to 22% and then use the brakes to modulate speed. Regards,Zach

[N520AT 3]

Such action could destroy the engine by hot gas reingestion, minimum airspeed usually 60 Kt for reverse thrust operation.

Where?

@ :50 http://www.youtube.com/watch?v=bmRKSv73lZg @ :58 On the all of Cessna Citation jets (Citation 500 series, 650, 750, 680, 560XL etc.) it is mandatory that you test the EMER STOW function of the thrust reversers prior to each flight. This involves activating the thrust reversers, selecting the Thurst Reverser EMER STOW switch on the glare shield and making sure that the buckets stow with the actuation of the switch and the TR paddles in the up position. On the Cessna Citation 500 series limitations, there is no limitation on using TR's to control taxi speed other than reverse thurst must be at idle below 60 knots due to FOD considerations. At ExpressJet Airlines, it is an approved procedure to use idle reverse thurst to control taxi speed on the EMB145 jets. Note that all of these aircraft have tail-mounted engines, and the risk of FOD is nearly 0 with the engines at idle thrust.

[martin-w 3,234]

I too have no issues at all with Taxi. Increase power to overcome the aircrafts standing inertia, and then back to a little above idle, momentum does the rest. Or idle if required. Very realistic, no issues. Some add-ons have an issue with FSX and it's inability to correctly model ground friction, well all I can say, is that in my experience, the NGX is spot on in terms of taxi.

[DavidB7237 0]

NGX taxiing is weird.if I push to 30% that would take me over 15 knots pretty quick. 21 gets me to move, I will have to lower that when moving by very little (by 0.3-0.5), that means you eitehr have to quickly press and release the F2 button or keep playing with the throttles to maintain a taxi speed or 5 + brakes. I use real world config, so no carbon pads!

[martin-w 3,234]

I find nothing weird about taxi in the NGX.However... the brakes for me are another thing. Much too grabby. Hit the brakes during taxi and it brakes to hard, dipping the nose considerably.Wish the brakes were more gradual.