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markk70

Spins in X-Plane 12

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One aspect I notice in this animations, both in XP11 and apparently also in XP12, is that the location of the Center of Pressure ( CP ) doesn't change with AoA ?

Actually Austin uses the AC - Aerodynamic Center - a conceptual point always at 25 % chord to set the origin of the lift / drag vectors, and the moments on the airfoil.

All very well explained here :

Aerodynamic Centre & Centre of Pressure - GATE AEROSPACE - YouTube

 

 

Edited by jcomm
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1 hour ago, jcomm said:

One aspect I notice in this animations, both in XP11 and apparently also in XP12, is that the location of the Center of Pressure ( CP ) doesn't change with AoA ?

Actually Austin uses the AC - Aerodynamic Center - a conceptual point always at 25 % chord to set the origin of the lift / drag vectors, and the moments on the airfoil.

All very well explained here :

Aerodynamic Centre & Centre of Pressure - GATE AEROSPACE - YouTube

That's just a convention. A change of position of the aerodynamic center is equivalent to adding a pitching moment with respect to a reference point (25% chord, by convention).

So, the change of position of the A.C. near and after stall is modeled with the airfoil pitch moment changing (editable in airfoil maker). So, the fact that the lift force vectors appear to remain fixed at the 25% chord (in the flight model output) is just a convention.

 

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With XP12 simulating the shift of CP toward the Aft of the Chord, with increasing Mach, maybe this will be visually despicted? Or just internal changes to the moment. Anyway, its cool to visualize, but doesnt really matter in the end result, as long as the calculations are correct

 

I also wonder how will Stall for Ailiners, specially T-Tail ones, behave in XP12. Those can become quite interesting, would be very cool to see them unfolding with newer XP12 Flight Model improvements!

 

Edited by Alec
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Alexis Mefano

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Yes, it is, and it's also explained in the other video I linked above.

It would be cool, though, to be able to visualize the Lift / Drag vectors acting at the varying CP, as AoA changes... Just from an FM-Visualization / Didactic  PoV.

Edited by jcomm
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I spot volumetric clouds in Austin's video. Which, however, don't look too different from those in Enhanced Cloud-/Skyscapes, so I'm unsure whether this is XP12's default clouds or EC/ES running in XP12.


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21 minutes ago, Bjoern said:

I spot volumetric clouds in Austin's video. Which, however, don't look too different from those in Enhanced Cloud-/Skyscapes, so I'm unsure whether this is XP12's default clouds or EC/ES running in XP12.

Clouds ?

I only saw Vectors ? 

😁

Edited by jcomm
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Spins, Finally! This is icing on the cake!

Hopefully we get to see a beta before WWIII starts!

I got into a spin by accident practicing stalls. Scariest word not allowed! I thought I was going to die! Lucky my instructor was with me!

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Eric Escobar

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XP11 already did spins... Maybe the "new" spins feel better ...

The problem with spins IRL is that sometimes it's difficult to get into it when we want to... while they can come "out of nothing" when we weren't expecting it to happen 😕

In the whole history of glider / soaring flight in Portugal there were only two casualties ( which is always more than it should ever be ), both caused by spins ...

Edited by jcomm
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6 minutes ago, jcomm said:

XP11 already did spins... Maybe the "new" spins feel better ...

The problem with spins IRL is that sometimes it's difficult to get into it when we want to... while they can come "out of nothing" when we weren't expecting it to happen 😕

In the whole history of glider / soaring flight in Portugal there were only two casualties ( which is always more than it should ever be ), both caused by spins ...

I have never been able to get anything to spin in X11.


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1 hour ago, strider1 said:

I have never been able to get anything to spin in X11.

Yeah, spins in XP were always lacking in some way or another. Not on par with military sims like DCS or IL2, but even some of the old FS9/FSX aircraft (RealAir comes to mind) spun a lot more convincingly.

I know that Austin is working on spins for XP12, so at least they should be improved! 🙂

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1 hour ago, strider1 said:

I have never been able to get anything to spin in X11.

push the plane harder...

The spitfire would regularily kill me with a flat spin before i learnt its limits.


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3 hours ago, mSparks said:

push the plane harder...

The spitfire would regularily kill me with a flat spin before i learnt its limits.

Are you sure? "Final tuning of the flight model math for X-Plane 12... we now have spins as an emergent phenomenon".


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Yeah,

but it's going to get even better in XP12....

So, I envision myself using XP12 as if it was a CFD software, a kind of soft XFLR5 or Flow5 🙂


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