A340 problem

[EHM-1883 Matt]

I don't know whether this has already been answered,

Whenever I switch on the engines on the A340, it starts bouncing up and down very quickly. Never had a plane this excited.

The SAAB2000 does the same thing when I turn on the propellers, and it's driving me mad. It doesn't stop until after I take off.

Simiarlarly, the B744 does the same thing, except after I take-off. It happens when overspeeding (like going over 280 IAS under 10,000 feet) which isn't a bad thing, but i'm wondering whether it's part of the bug. I recently did a flight EHAM-RJTT and it was Pro-pilot, it was plane hell because of this problem with it bouncing. Even if I accidentally go over 280 IAS when under 10,000 feet, I have to get down to about 180 IAS to stop it bouncing...which leads to a stall...which leads to a bad pro-pilot score

I'm not so bothered about the 747, as I can stop that by being a better pilot (via doing more Pro-pilot flights) but I want to do a return flight back to EHAM with the A340 parked there, and it's going to drive me mad, or fly me mad if it doesn't stop bouncing!!

It seems to bounce whenever the wheels have contact with the ground.

However, it is fun to watch it landing.

Anyway, is there something I can do to stop this?

[EHM-1821 Javier]

is it bouncing like its shuddering? i had that problem with the SAAB, not sure if its still that way, but not with the A340 other than when changing views and no problem with the 747 at all

[EHM-0654 Murray]

Are we talking "nose wheel bounce", or is it the entire airplane, and it is bouncing up or down? Use outside view to check... Could be diagnostically helpful.

[EHM-1633 José]

I had a similar problem with a Project Open Sky A343: During final approach it started bouncing left and right. It was like some kind of trembling . Anyway, I was always capable to land it safely and to my surprise, now that I have a brand new computer, this strage behaviour has dissapeared, so I reached the conclusion that it was a matter related to the graphic card:%

[EHM-1001 Robert]

Well,

basically I think we are speaking about 2 ... or more problems.

At FL100 when the plane is bouncing, it probably came from an autopilot bug. If you heavily load your plane, or made it too nose/tail heavy with wrong load distribution, it is possible the altitude hold cannot get it leveled, and the plane is oscillating / bouncing up&down in the air. It MUST not happen at landing when your plane is relatively light.

If it is bouncing on the ground while rolling, it can came from 2 reasons: scenery bug (runway surface problem) or again, can happen from a wrongly loaded airplane that is probably tail heavy and not "sitting" correctly on its nosewheel.

Pls, check these, and your dynamics files version out Thx.

[EHM-2144 Terry]

As a matter of interest while we are talking about boncey a/c and fuel loads and C of G.  Until I get a payware a/c that has it's own fuel loading program I will potentially be using freeware a/c, so the fuel will be loaded through fs.  If im correct the c of g is the moving point in fs, as the c of g can move when weight is moved around as in most things relating to weight and mass.  

So is the correct C of G set, when the moving point sits below the half moon symbol or is it when the moving point is set approximately centre of the wings, as it were.  Sorry don't know correct technical name for that part yet.:%

Think I'm getting out of my comfort zone now:o

Terry
EHM-2144

[EHM-2029 Sotiris]

Hi Terry,

on the standard planes loaded via FS you only need to be approximate. i.e. C of G somewhere near the centre of the fuselage and in the middle of the wings.
Especially in terms of sideways movement of the CoG make sure it is centered as any deviation will make your bird roll.
In most cases the longitudinal axis is demarkated and its comfort limits are fairly visible. However, a 'half-way house' approach has served me well till now.

[EHM-1001 Robert]

The CoG should be somewhere at the first third of the wing. Without complex description, because the lift center of the wing is there. So if we speak about that icon in FS at the Payload section then:

From top to bottom, the nose is 0%, the drawn area is 25...50...75% the tail is 100%. The correct CoG point (moving ball) , should be somewhere at the middle of the upper half section: between 25 and 50%. It differs at each plane, and can be slightly forward or backward from that middle point.

The whole plane is designed, so that after takeoff, this point does not move too much. The wings with the fuel in it, an the cabins and cargo areas are designed so the decreasing and static payload does not change the empty CoG too much. It can, but with a balanced distribution it should not

[EHM-2144 Terry]

Thank you Sotiris and Rob.  That has answered and will resolve a few of my problems and queries.

Thanks again guys.

Terry
EHM-2144