My aircraft is going up and down and up and down and up...

[polartiger]

Hi,I've got a problem with some of my FS2002-aircraft. When I'm flying pretty high (above FL250) some of my aircraft start acting really weird while the're maintaining a flightlevel. For example: I'm flying with an Air France 777-200ER from POSKY at FL350 and it's making some kind of sinus-movement(going up and down and up and down and up....). It's flying between FL347 and FL352 instead of just maintaining FL350. Can someone tell me what to do with this problem 'cause it doesn't appear at all my aircraft. Thanks in advance!

Greetings from The Netherlands,Paul

[Ivaneck]

Hello Paul,

In this link you will find help about this problem: http://www.fsgateway.com/tips_read.asp?id=88

You can also search for help in the Posky website & forum.

And finally, I played with this aircraft.cfg value, increasing it, with good results:

[big][tt]{Flight_Tuning}
pitch_stability=[/tt][/big]increase the current value, and test

Hope this helps,

Joan Coll
Barcelona, Catalonia

[polartiger]

Thanks a lot,it helped:)

cYa! greetz from freezy Amsterdam

[NightEye]

This might be a built-in feature of Flight Simulator. Newer airliners like the 777 can have PIO, or Pilot Induced Oscillation, which is caused from the fly-by-wire flight controls temporarly losing control between what the pilots wants to do and what is actually being done.

[DELTA07]

Hi:

I have the same problem with a 737-800 in my Delta fleet and I think I fixed it but I'm not sure about some other aircraft. I know there is a setting in the aircraft.config file called Oswald Efficiency and usually it's number is between 0.1 and 1.0. I have several aircraft; one such is my MD-88. It's setting is 16.499. How is this possible since in the editor you are required to choose between 0.1 and 1.0.

As far as the flight tuning. I used the list you had on here as a guide to try to fix the up/down effect with my MD-90 but it didn't work. It flies ok but when it banks to make a left or right turn in flight, it starts bouncing again.

In a nutshell, do you have any other suggestions or know anyone I can email and ask about these kinds of problems/questions. Any help you can give me would be greatly appreciated :-)

DELTA 07

[Ivaneck]

[font size="1" color="#FF0000"]LAST EDITED ON Dec-12-02 AT 06:10PM (EST)[/font][p]Let me to tell the story, at least all I can remember.

I began a world tour, months ago. The plane I used originally was the Conceptual Boeing B-575 from Nick Pike, a plane I beloved from FS2000 times. Not sure if I detected the issue in FS2000 or already in FS2002, but in this last sim, when the plane was flying at cruise altitude, it rocks like a dauphin.

I tried different cruise altitudes, different cruise speeds, thinking that the problem is due to my inexperience (perhaps a plane rocks if it's flied at inappropriate altitudes or speeds, I thought). But no success. Then, with my limited experience, I began to investigate and tweak a bit.

The plane is a FS2000 plane. The original aircraft.cfg file supplied in the zip file only had the sections {fltsim.0} and {forcefeedback}. This is usual in FS2000 planes. When this planes are started for first time, the rest of values are created automatically, originated from the .air file.

But not all the possible aircraft.cfg values are automatically created. The section {flight_tuning} wasn't created, at least in the B575.

A inexistent {flight_tunning} section implies a section with all this parameters set at default values. That is, a plane without {flight_tunning} section is really a plane with this implicit section:

[big][tt]{Flight_Tuning}
pitch_stability             = 1.0
aileron_effectiveness       = 1.0
cruise_lift_scalar          = 1.0
parasite_drag_scalar        = 1.0
induced_drag_scalar         = 1.0
elevator_effectiveness      = 1.0
aileron_effectiveness       = 1.0
rudder_effectiveness        = 1.0
pitch_stability             = 1.0
roll_stability              = 1.0
yaw_stability               = 1.0
elevator_trim_effectiveness = 1.0
aileron_trim_effectiveness  = 1.0
rudder_trim_effectiveness   = 1.0[/tt][/big]

Well, to avoid rocking with the B575 I needed to do this:

[big][tt]// JCO Add Section (From Boeing 737-400)----------------------------------------##
{Flight_Tuning}
// JCO ChgStr - Curing rocking problem -----------
pitch_stability                     = 10.0
// JCO OldVal pitch_stability       = 1.0
// JCO ChgEnd - Curing rocking problem -----------
// JCO ChgStr - Adjust behaviour -----------------
aileron_effectiveness               = 1.2
// JCO OldVal aileron_effectiveness = 1.0
// JCO ChgEnd - Adjust behaviour -----------------
cruise_lift_scalar                  = 1.0
parasite_drag_scalar                = 1.0
induced_drag_scalar                 = 1.0
elevator_effectiveness              = 1.0
aileron_effectiveness               = 1.0
rudder_effectiveness                = 1.0
pitch_stability                     = 1.0
roll_stability                      = 1.0
yaw_stability                       = 1.0
elevator_trim_effectiveness         = 1.0
aileron_trim_effectiveness          = 1.0
rudder_trim_effectiveness           = 1.0
// JCO Add Section (From Boeing 737-400)----------------------------------------##[/tt][/big]

Sorry for the remarks preceeded by "//". I document all my changes in all my files, or keep duplicates of the old versions of uneditable files. Good policy, IMHO, although a bit tedious. JCO are my initials (Joan Coll i Ossul, my full name).

Look, pitch_stability from 1.0 to 10.0. Is increased in a 1000% (Edit: See SDK, Aircraft Container System). Exaggerated? Excessive? A Folly? Perhaps. But in this plane, it works.

Try it in your 737-800. Increase pitch_stability in a 1000 percent. Save a flight while the plane is rocking, change the value, and restart. Then, good luck, and tell us the results, eh?

Hope this helps,

Joan Coll
Barcelona, Catalonia

[Ivaneck]

Mike, thanks for the remark. Where can I find some info about PIO?

Anyhow, is PIO a logical thing in a FS2002 plane commanded by autopilot and stabilized at, for instance, FL350, and with no turbulences in the air? I'm think is a design mistake, IMHO.

Kind regards,

Joan Coll
Barcelona, Catalonia