Engine thrust

[XPMorten]

Hi All,

I'm an engineer and I develop aircraft for a flight simulator
called http://www.x-plane.com/ (X-Plane)

My problem is with the simulator high-bypass Turbofan Jet Engine. I am 110% sure that we are way low on
thrust in the area N1 50-90% which is in the normal
envelope of operation for airliners.
I'm in a deep discussion with the developer of the
sim about this. I have proven it by analyzing B737 FDR
data we have, but those only give us single data points,
and not the big picture.

So, my question is, can anyone help me with some
real world thrust-N1 data? Static or dynamic - everything of interest.

If this is sensitive information, you can also e-mail me at: mmelhuus(at)start.no

Regards,

Morten

[Mad (Flt) Scientist]

Is this a generic engine? It might not even be N1-controlled.

[XPMorten]

It is N1 controlled. It's a fully simulated
engine model with regards to thrust, N1, EPR, EGT, OAT, pressure, speed, drag, altitude etc.

X-Plane is the only flightsim with an atmosphere
and uses blade element theory for airfoil calculations.

Regards,

Morten

[Mad (Flt) Scientist]

Maybe a stupid question, but if it's fully simulated, why do you need inflight data. Personally, I would be reluctant to trust any engine model other than the actual manufacturer's deck - and even that needs some salt at times.

Is it not just as likely that the drag is off as the thrust (since determining them independently and accurately for a given installation is, to say the least, problematic.)

[XPMorten]

The model also models RAM drag, Net and Gross thrust, this part seems pretty good.

The problem is that the model most likely models
an engine with lower bypass ratio than modern
turbofans have - BR 5 -> 6+, giving us less
thrust in low altitude and low speed than we need.
In other words, the thrust curve SHAPE is of.

The thing is the author cant answer what BR he is
basing the model on, and we cant really tell unless
we have som real life numbers to compare with.

To put it in another way, we are trying to determine if its the sim thats wrong or the acf model. We have strong indication it is the sim
judging from real FDR data. But we need better
evidence :D

Cheers,

M

[XPMorten]

OK, got the information I needed:D

Thanks,

M