Anywhere in the world, my 707 lurches up and down while on the ground only.

I posted this: http://www.captainsim.org/yabb2/YaBB.pl?num=1215554144/340#340 in the 757 Captain Forum in regards to the violent rocking and rolling problem. You can try it with the 707 base pack and expansion models. It might help.

Mark

Hi all,

I am a new user of your fine 707 (Fsx).
I am pleased with the aircraft so far but there is one really annoying problem:
When during climb or descend under AP control (with the altitude hold/elevator disconnect switch in the middle position) I use the TRIM WHEEL of the AP  to change the climb/descent rate the plane begins
to PITCH UP AND DOWN , sometimes very lightly only and sometimes very heavily , so that I have to disconnect the elevator completly. (btw manual trim seems also much too sensitive)

Before posting I have made a research in this forum.
The problem has already be signaled by other people, but there is no solution given.
For example in this thread:
http://www.captainsim.org/yabb2/YaBB.pl?num=1294399965/0

Would be grateful to have a solution for this annoying problem.

Guy

Hi,

I followed your advice and disabled the joystick. That changed nothing.
The pitch oscillations are still there.
So it's not a joystick noise problem.
It is also not a center of gravity problem as I use ACE for initialisation.

To be absolutly clear: the problem exist's only when the altitude hold/elev.diconnect switch
is in the middle position (use of AP trimwheel).

I tried to follow the problem a bit more closely during three short flights now, climbing
each time to 35000 feet.

1)The pitch oscillations are there each time I use the trimwheel but generally they are
very light only and not disturbing.

2)During the 3 climbs I ended up three times with very heavy up and down shaking. Two times
I had moved the trim wheel and once it started all by itself (without changing wind conditions).

3)the wild pitch oscillations start EACH time when I INITIATE THE DESCENT from cruise altitude (35000 ft) by
positionning the altitude hold switch from the upper to the middle postion (even without touching
the trimwheel). So this is REPRODUCABLE (at least for me)
I cannot use this middle position (trimwheel) as long as I am above 30000 feet during descent.
So I have to move the switch to the lower position (elevator disconnect) and control the descent
manually.
Below 30000 feet I can then use the trimwheels again.

4)during descents I got the wild oscillations also 3 times while moving the trimwheel and once
it started all by itself again (also without changing wind)

By "wild pitch oscillations" I mean that the plane would have run completly out of control.
When I disconnect then the elevator control   it goes into a steep dive or climb .
I  have to stabilise it manually before reconnecting the elevator.

Otherwise I like the beautiful model, the nice VC and the easy manual flying.

Guy

Hi all,

Concerning the heavy PITCHING OSCILLATIONS in flight I had signaled in my previous messages :

I have changed a parameter of the flight_tuning section of the aircraft.cfg of the 707:

PITCH_STABILITY = 1.400  (instead of 1.0)

Now the pitching  oscillations are gone !

Guy

I have read the reports that are on this about the 707  that have the elevator flutter, I have it on the 707 when I engage the alt hold. I have the 727 and have no problems with it. The 707 is my favorite ac. and hope I can get it corrected.  I can however smooth it out a little by slowly adjusting the trim wheel on left side of the yoke.