Climbing to upper FL's

[OuterMarker]

Hello Guys,

 

while I'm usually a FSX (now P3D) user this project really got me interessted in X-Plane. I've been using it for quite some time now and got some add-ons to fill the gap until you finish your B737. One thing I noticed while climbing to FL370 (A320, medium gross weight) is that the vertical speed at some point gets as low as 100-200 fpm. Is this a problem with the air density model of X-Plane itself and if so, have you found a way to tweak this with your B737?

 

Cheers, Jan

[Litjan]

Performance in our 737 is very close to the real thing. I can´t speak for other addons, but X-Plane is using a very poor large bypass turbofan model that neglects many of the highly dynamic effects of a real jet-engine. That´s why most developers will have a very hard time tuning their model, it will either behave well in the lower atmosphere/lower mach numbers, or at higher levels/speeds. We have found a way to overcome this problem, therefore the climbrates we see are realistic.

 

Jan

[Morten]

As Jan says, the engine model is a major factor.  We have a completely custom engine model that models the CFM56-3 performance in all

aspects of flight, different altitudes, temperatures and Mach and offcourse N1.  Also the drag is modeled (like in idle descent). We also have "flight idle"

and "ground idle".  Austin never really had any good high-bypass engine data and therefore the XP default engine is far from realistic.  But we have the data. The good news for developers is that they can now check out our CFM56-3 engine model just by outputting the data they need to screen

 

Another factor is offcourse the aerodynamics, lift and drag, if they are off that will also have a strong impact on climb performance.

 

A heavy loaded B733 (63T) will climb at less than 500 fpm the last bit up to FL370

Edited November 19, 2015 by Morten

[OuterMarker]

That's great! Thanks for the fast answer, guys!