CFM work in progress preview

[pierre]

I don't know how are made the X-Plane flight models.

Increasing weight has no sens because this reduce again the ceiling. Same result decreasing engines power

An aircraft has always a max ceiling depending of weight, thrust and of air density, itself depending of pressure and of temperature.

[pierre]

Here is an interesting document on aerodynamics.
Search "ceiling" into

Document.

Pierre

[pierre]

It is actually impossible to test CFM, as X-Plane real weather doesn't work.
Waiting for fix....

[smati]

Maybe that's what's causing Xplane to crash then. What Gastonreif thinks

[gastonreif]

I have decreased dry engine thrust and increased fuel consumption for the first try and got very decent results at MTOW. 

[pierre]

Thank you Gaston.
I will test it as soon I will have the next Package.

[gastonreif]

Here is CFM report from KJFK-LFPG whole flight at FL520 @ M1.96 with experimental flightmodel. 

[pierre]

Humm, not so bad...

What fuel bias did you use, 100, 95, else ?

[gastonreif]

im not sure what you mean, where do i find it? i put 95 tons of fuel at MTOW

[pierre]

CPS-NG has a parameter into control panel named "Fuel Bias".
It is set to 100 by default (Real aircraft).
Try with it set to 94 or 95 and plan the flight.

[gastonreif]

ok, was set to default

[gastonreif]

Paris to New York with headwind around 50knots, getting closer to the reference, fuel bias default, FL520 M2.0, same experimental flight model

[pierre]

Great,

The Red line under the black curve at the end of the flight is normal, because at FL520 the fuel burn is greater than at FL 550/570/600.
Next time, try to climb at FL550 after 40° longitude...

[gastonreif]

Experimental flight model proves that current flight model is overpowered so i reduced engine power a bit which demands higher fuel flow to match black reference line from CFM and also is not easy to climb directly to FL600 but needs to be done by steps along route. See charts for both trips between JFK and CDG. Western route achieved FL600 at around 800nm before JFK and eastern route only upto FL560 to save some fuel which is clearly visible from the graph.

[pierre]

Hi Gaston,

The curve seems perfect.
Flying FL560 does not save fuel if air temperature is ISA minus, only if ISA plus and depends of aircraft weight.
I would prefer talking about weight and temperature instead of distance to locate the FL600.