Engines too slow to spool up?

[jgoggi 65]

Hi, it's the first time I use the 777, but I have the impression that, when pushing the throttles to the takeoff thrust or when pushing the TOGA, it takes too long to the engines to reach the takeoff value, most of the times when I get to V1 they are still spooling towards that value. I know the engines are big and I was used to the 737 NGX, but I have seen some takeoff videos on Youtube and it definately takes quite less to achieve the takeoff power.

[BigAl.TM 0]

Do you push the levers forward to let the engines spool to around 55% before you engage TO/GA? If memory serves, the Tutorial #1 which comes with the 777 covers correct take off procedures...

Not being a pilot with experience in jets like this bad boy, i can't comment on the actual spool time. But given PMDG's expertise, I would be confident to say it's accurately modelled.

[AzN1337c0d3r 3]

On my sim, the engines are 100% spooled within seconds of applying full throttle. If your engines are still spooling at V1, there is definitely something wrong with your configuration.

[remcoso 7]

It takes too much time to reach 40 or 55%.

 

This is an limitation of fsx.

 

My solution is set manual the thrust around 80% and when it reach 55% press toga.

 

Spool up time depens on how much thrust is set.

 

0-55 spool up slow

0-100 and you reach much faster 55%

[jgoggi 65]

I did a test with an N1 of 93.0 and idle at 22.0. From idle to 55% it takes about 35 seconds, then I press TOGA and it takes about 35 more seconds to get to 93.0. This with the keyboard, without any throttle. Is it normal or not?

Thanks.

[FLEX1978 373]

Spool up time should take around 8 seconds  (Real aircraft & the sim).  In my experience the T7 seemed a little too quick. definitely something wrong with your setup.

[jgoggi 65]

But where could be the problem? What are the settings I should look into? It's not a throttle problem, the throttles move as fast as I tell them to move, but the engines response is slow.

Thanks

[jgoggi 65]

Rob (and all), could you please check that your aircraft.cfg file has the same lines as those reported below, in particular with regard to the fuel_flow_gain parameter?

I am getting crazy, I found out that also the NGX is too slow. After searching I have found that the fuel_flow_gain parameter might be responsible for that, therefore a quick check is much appreciated. 

Thank you!

 

[GeneralEngineData]

engine_type = 1

Engine.0 = -4.224, -31.140, -3.350

Engine.1 = -4.224,  31.140, -3.350

fuel_flow_scalar = 0.85361

min_throttle_limit = -0.31

max_contrail_temperature = -30

 

[TurbineEngineData]

fuel_flow_gain = 0.0017

inlet_area=82.516 // 123in fan diameter

rated_N2_rpm=9345.79

static_thrust=110000.0 // GE90-110B1 (TMCF regulated in code)

afterburner_available=0

reverser_available=1

AfterBurnThrustSpecificFuelConsumption = 0

[jgoggi 65]

Wow, sorted it out!

I tried to erase the fsx.cfg and let FS rebuild it. With the new default fsx.cfg the problem was gone, but of course I had terrible graphics, low fps, etc. So I started replacing each section of the new fsx.cfg with the old one, testing after each replacement. At the end I found out that the problem was in these lines:

 

 [sIM]

SYSCLOCK=1

min_user_sim_fps=16

max_user_sim_fps=120

 

I removed the last two lines and everything now works perfectly, the simulator also looks slightly more fluid.

Who knows where those two min/max fps lines come from...