738WL does not want to rotate if being empty

[FlyingAxx 2]

Hi all, Most likely the error sits in front of the screen and if so, I need advice. I'm sitting with my 738WL somewhere in the Andes (SA46). By using my own set of airport data, extracted with Pete Dowson's MakeRunways tool, the airport is available in the FMC - so far no problem. RWY01 LEN: 1844 m, ELE: 4999 ft, TAT: 17°C, QNH: 1019 hP, dry Aircraft t/o data (calculated by the FMC)ZFW: 41.4GW: 49.5selected OAT 25°Cselected Flaps 15°N1: 98.7CG 25.0%, TRIM: 2.62 (seems to be at the borderline of the green band)V2: 126 According to the performance table GW is well under the tabled limits. Why the bird does not want to fly? Even at about 150 kn it remains stable on its wheels. I never have had this problem before but now the second time when trying an empty ferry flight with about 1/3 fuel. Comparing the data to the tables everything looks all-right to me. What could have happened???

[kjjj11223344 48]

Hi all, Most likely the error sits in front of the screen and if so, I need advice. I'm sitting with my 738WL somewhere in the Andes (SA46). By using my own set of airport data, extracted with Pete Dowson's MakeRunways tool, the airport is available in the FMC - so far no problem. RWY01 LEN: 1844 m, ELE: 4999 ft, TAT: 17°C, QNH: 1019 hP, dry Aircraft t/o data (calculated by the FMC)ZFW: 41.4GW: 49.5selected OAT 25°Cselected Flaps 15°N1: 98.7CG 25.0%, TRIM: 2.62 (seems to be at the borderline of the green band)V2: 126 According to the performance table GW is well under the tabled limits. Why the bird does not want to fly? Even at about 150 kn it remains stable on its wheels. I never have had this problem before but now the second time when trying an empty ferry flight with about 1/3 fuel. Comparing the data to the tables everything looks all-right to me. What could have happened???

I might be misunderstanding you, but are you waiting for the aircraft to begin to rotate by itself? If this is the case, then this is not correct, you always rotate the airplane yourself at vR.

[FlyingAxx 2]

I might be misunderstanding you, but are you waiting for the aircraft to begin to rotate by itself? If this is the case, then you always rotate the airplane yourself at v1.

Nope, I'm rotating manually (better, I'm trying to but it does not lift off).

[kjjj11223344 48]

Nope, I'm rotating manually (better, I'm trying to but it does not lift off).

Okay. Are you using ASE or any weather program. I know that you posted the TAT, but is this one the reported by the Ngx, or are you using a metar for the airport. Maybe your weather program is injecting excessively high temperatures into FSX.

[Greg4 0]

Are the controls actually working? It might be a calibration problem or something.

[FlyingAxx 2]

Okay. Are you using ASE or any weather program. I know that you posted the TAT, but is this one the reported by the Ngx, or are you using a metar for the airport. Maybe your weather program is injecting excessively high temperatures into FSX.

I'm using ASE but it does not show any abnormal conditions in the vicinity (17.5°C). BTW, why should the PMDG not detect correctly the outside conditions?

Are the controls actually working? It might be a calibration problem or something.

Yes, everything works fine. EDIT: I just made a pure manual attempt by having the trim somewhere at 3.6 or so and the bird did what it should (about 90% N1).

[Paul Deemer 13]

is that kgs or lbs?

[kjjj11223344 48]

BTW, why should the PMDG not detect correctly the outside conditions?

The problem is that ASE has been known to produce excessively high TAT's (I don't know if only with the Ngx, or if this is a problem it regularly has). It's not the plane, it's the program. There is a fix to this, on a bunch of forum posts on this site.

[FlyingAxx 2]

is that kgs or lbs?

It's in kg.

[FlyingAxx 2]

The problem is that ASE has been known to produce excessively high TAT's (I don't know if only with the Ngx, or if this is a problem it regularly has). It's not the plane, it's the program. There is a fix to this, on a bunch of forum posts on this site.

I think you referred to this one http://forum.avsim.net/topic/346862-my-new-weather-config-works-perfect-with-the-ngx/page__hl__weather+settings+work+perfect__fromsearch__1 However, I cannot see ASE doing any harmful things here. In this case the manual flight (no A/T and no calculated trim setting) wouldn't work either - I think.

[kjjj11223344 48]

I think you referred to this one http://forum.avsim.net/topic/346862-my-new-weather-config-works-perfect-with-the-ngx/page__hl__weather+settings+work+perfect__fromsearch__1 However, I cannot see ASE doing any harmful things here. In this case the manual flight (no A/T and no calculated trim setting) wouldn't work either - I think.

Yeah that makes sense. But maybe try without ASE enabled in order to deduce what the problem is, as that is the only thing I can think of that could be causing a problem.

[JC75 22]

Yes sounds like a weather issue, try disabling ase, and clear all weather...then see if same issue occurs

[B777ER 2,484]

The problem is that ASE has been known to produce excessively high TAT's (I don't know if only with the Ngx, or if this is a problem it regularly has). It's not the plane, it's the program. There is a fix to this, on a bunch of forum posts on this site.

The TAT in the NGX goes up after takeoff some 8 to 10 degrees after t/o everytime. It does match on the ground but for some reason the TAT shoots up after takeoff. I have ASE running with sp3. It does go back to normal in the climb.

[xxJohnxx 21]

You know that the TAT is the outisde air temperature + the heat of the drag which the air makes when the plane flys. TAT is in flight normaly higer than OAT.

[falcon999 24]

EDIT: I just made a pure manual attempt by having the trim somewhere at 3.6 or so and the bird did what it should (about 90% N1).

Could you elaborate what a pure manual attempt means?