Airbus A320 Family Development

[Octal450]

Roger.

VS0 is still nose down, should be nose up...

Roll seems more stable.

[jwocky]

Why do you have nose down and I have nose up? Does your joystick center clean when you let it go?

[jwocky]

And how is the pitch bounce on your end now?

[Octal450]

Hello A319!


@jwocky, affirm, the difference is I use with load, you did it empty. Try adding in left and right inner tanks 2500pnds, and leaving standard passenger weight. You see the problem.
Pitch bounce did not change. It is still way to delayed in reaction time.

[jwocky]

Delayed but not bouncing. The trick is, you want her first balanced, then you can work out the rest. If you try to calibrate on an unbalanced plane, you have always to deal with five or six factors at the same time. It works in Yasim because there is a lot not simulated there, but JSB is another kind of beast in that.

[Octal450]

Yup
can we aim flyable by 1 month?

Josh

[IAHM-COL]

patience is a virtue. Its better to monitor progress than to despair on a deadline.
FDM is not simple bussiness...

[jwocky]

Well, she is almost flyable already. Did you check on the tank positions? Here is the fun part: If you take up a blueprint of an A320-200 on your screen and measure the whole length (I did it in cm) you get some interesting relations:

whole plane 17cm long (on my screen), in reality 1479.1339 inches
center of inner wing section (where the tanks sit, measured on my screen) at 8cm.

In the JSB file, we find ...
left inner tank at x 630 inches, left outer tank at x 737 inches ...

1479.1339 in: 17.0 cm and 8 cm comes down to 696 inches for the middle oif the inner wing section. So ... uhhhh ... you main wing tanks sit significantly in front of the wings out in the fresh air while your outer wing tanks sit behind the wing also out in the fresh air ...
The center tank sits at 580 inches and that is supposed to be the middle of the cneter tank already. So currently it overlaps with your forward cargo compartment. Well, at least, it is still inside the plane, so I guess, it's better than the other tanks which aren't anywhere inside the wings. So, first thing to do is to check on those positions. Of course, you can bring the plane out of the allowed MAC range by just fueling those tanks hanging forward of the wings and far forward in the fuselage. That pushes the CG forward and makes her nose heavy and since they are so far from the CG, they have of course a lot of leverage.

The next thing to look for is, where are your passengers? Because actually, whoever built the original stashed them away in the forward cargo compartment (currently flooded with kerosine by the center tank) and the aft cargo compartment. So, the weight points need also some help here. Now, I have no docu where all of this stuff is really positioned, I could only do some backward engineering, but maybe you have something?

To make my point clear here: I can do it later today, maybe during the night, but it would be better if you take at least a look first so that you get a little bit more insight in the whys and hows.

[Octal450]

what a joke FDM

Is the 3D model wrong?

[jwocky]

I think, the 3D model is correct. It looks correct to me, but then, my eyes miss sometimes details.
The thing is, the FDM uses the tank positions defined in the JSB file (any FDM, so Yasim does the same thing), not the positions from the 3D model. Theoretically, I can take a big box without anything and have it fly like a plane because the FDM doesn't even know the model has no wings. So as long as I tell the FDM, he has wings, he believes me and simulates them. And if I tell him, he has engines 1 mile ahead of my box and some tank two miles behind, he takes it.