Re: altitude loss with autopilot hold during turns

[bobseaman]

I'd be very grafeful for any help with this problem, which only seems to
afflict a few aircraft.
I was flying a very nice CRJ700 and all was well until I went into a 150 turn,
with autopilot hold engaged at 3000. By the time the turn was completed the
aircraft was down to 1500 and then had to start laboriously back to 3000.
The airspeed may have been a factor, as the 150 turn was to intercept an ILS
and so IAS was at about 170 with about 10 degrees of flap (though the flaps on
this model were of the 08, 20, 40 type).
I am reluctant to ditch this aircraft as this is the only problem with an
otherwise beautiful model.
Is there perhaps some alteration that I could make to some file (I have the
"air-ed" programme)in order to effect a cure?
Thank you.
Regards,
Peter; I wouldn't consider editing the .AIR if you're happy with the planes
normal performance. The easy answer is that FS models banking in such a way
that the wings will start to 'spill' after a given amount of bank. For most of
the RJ's, or the big biz jets, I'll turn off the AP during the turn and hold
alt. manually while adding a bit more power to compensate. You may also
consider adding an AOA gauge to your panel or keeping an eye on your trim
settings. If your trim is close to maxxed out while flying the pattern with
wings level and the AP engaged, you can bet that your airspeed isn't high
enough for a banked turn.

[biguglyguy]

Hi Peter,
This is a relatively simple and benign edit, so you might want to try this.
Under section 1203 of AirEd, set bank limit to 25 and bank limit with flaps to
12. You could go to 20 and 10 respectively, but you may need a lot of real
estate to make a turn. These numbers define the max bank angle.
Good flying,
Bob Boudoin



I'd be very grafeful for any help with this problem, which only seems to
afflict a few aircraft.
I was flying a very nice CRJ700 and all was well until I went into a 150 turn,
with autopilot hold engaged at 3000. By the time the turn was completed the
aircraft was down to 1500 and then had to start laboriously back to 3000.
The airspeed may have been a factor, as the 150 turn was to intercept an ILS
and so IAS was at about 170 with about 10 degrees of flap (though the flaps on
this model were of the 08, 20, 40 type).
I am reluctant to ditch this aircraft as this is the only problem with an
otherwise beautiful model.
Is there perhaps some alteration that I could make to some file (I have the
"air-ed" programme)in order to effect a cure?
Thank you.
Regards,
Peter Preston

[manises]

I'd be very grafeful for any help with this problem, which only seems to
afflict a few aircraft.
I was flying a very nice CRJ700 and all was well until I went into a 150 turn,
with autopilot hold engaged at 3000. By the time the turn was completed the
aircraft was down to 1500 and then had to start laboriously back to 3000.
The airspeed may have been a factor, as the 150 turn was to intercept an ILS
and so IAS was at about 170 with about 10 degrees of flap (though the flaps on
this model were of the 08, 20, 40 type).
I am reluctant to ditch this aircraft as this is the only problem with an
otherwise beautiful model.
Is there perhaps some alteration that I could make to some file (I have the
"air-ed" programme)in order to effect a cure?
Thank you.
Regards,
Peter; I wouldn't consider editing the .AIR if you're happy with the planes
normal performance. The easy answer is that FS models banking in such a way
that the wings will start to 'spill' after a given amount of bank. For most of
the RJ's, or the big biz jets, I'll turn off the AP during the turn and hold
alt. manually while adding a bit more power to compensate. You may also
consider adding an AOA gauge to your panel or keeping an eye on your trim
settings. If your trim is close to maxxed out while flying the pattern with
wings level and the AP engaged, you can bet that your airspeed isn't high
enough for a banked turn.

Many thanks, Bob. I'll try what you suggest.
Much obliged.
Peter Preston

[manises]

Hi Peter,
This is a relatively simple and benign edit, so you might want to try this.
Under section 1203 of AirEd, set bank limit to 25 and bank limit with flaps to
12. You could go to 20 and 10 respectively, but you may need a lot of real
estate to make a turn. These numbers define the max bank angle.
Good flying,
Bob Boudoin


Many thanks, Bob. I'll give what you suggest a try. Much obliged.
Peter Preston




I'd be very grafeful for any help with this problem, which only seems to
afflict a few aircraft.
I was flying a very nice CRJ700 and all was well until I went into a 150 turn,
with autopilot hold engaged at 3000. By the time the turn was completed the
aircraft was down to 1500 and then had to start laboriously back to 3000.
The airspeed may have been a factor, as the 150 turn was to intercept an ILS
and so IAS was at about 170 with about 10 degrees of flap (though the flaps on
this model were of the 08, 20, 40 type).
I am reluctant to ditch this aircraft as this is the only problem with an
otherwise beautiful model.
Is there perhaps some alteration that I could make to some file (I have the
"air-ed" programme)in order to effect a cure?
Thank you.
Regards,
Peter Preston

[pvarn]

Something else you might want to try...
I've been playing a lot with the AirEd entry 1202 which is labled something
like "Yaw Damping" in many INI files. In addition to AP mimits in 1203, I
belive 1202 is a trim or elevator limit of travel (probably trim) and thus
mis-labled. When this is set too positive, the trim's ability to pull the nose
down is limited causing the aircraft to rapidly pitch up during a turn and
recover slowly.
When set too negative (or simply lower- most positive and negative values in
the air file are relative) the ability of the aircraft to recover from pitch
loss is affected.

Whether this is a pitch CENTERING, or a PITCH TRAVEL LIMIT is not clear, but I
am certain it's a pitch related factor and not a yaw related factor (at least
in FS2K.)
I have noticed MOST aircraft want a value between +1000 to +4000. Try lowering
the value in 100 increments and see it that helps your plane recover more
effectively.

Also, if the pitch trim authority is set too low (usually called "Pitch Moment"
in section 1101- and what I mean by too low is NOT ENOUGH NEGATIVE) the AP
might not have the authority to respond to pitch changes soon enough. Given
too much authority you will get bouncing. Too low (too close to zero) and you
will get porpoising.
-Pv-


Hi Peter,
This is a relatively simple and benign edit, so you might want to try this.
Under section 1203 of AirEd, set bank limit to 25 and bank limit with flaps to
12. You could go to 20 and 10 respectively, but you may need a lot of real
estate to make a turn. These numbers define the max bank angle.
Good flying,
Bob Boudoin



I'd be very grafeful for any help with this problem, which only seems to
afflict a few aircraft.
I was flying a very nice CRJ700 and all was well until I went into a 150 turn,
with autopilot hold engaged at 3000. By the time the turn was completed the
aircraft was down to 1500 and then had to start laboriously back to 3000.
The airspeed may have been a factor, as the 150 turn was to intercept an ILS
and so IAS was at about 170 with about 10 degrees of flap (though the flaps on
this model were of the 08, 20, 40 type).
I am reluctant to ditch this aircraft as this is the only problem with an
otherwise beautiful model.
Is there perhaps some alteration that I could make to some file (I have the
"air-ed" programme)in order to effect a cure?
Thank you.
Regards,
Peter Preston

[manises]

Something else you might want to try...
I've been playing a lot with the AirEd entry 1202 which is labled something
like "Yaw Damping" in many INI files. In addition to AP mimits in 1203, I
belive 1202 is a trim or elevator limit of travel (probably trim) and thus
mis-labled. When this is set too positive, the trim's ability to pull the nose
down is limited causing the aircraft to rapidly pitch up during a turn and
recover slowly.
When set too negative (or simply lower- most positive and negative values in
the air file are relative) the ability of the aircraft to recover from pitch
loss is affected.

Whether this is a pitch CENTERING, or a PITCH TRAVEL LIMIT is not clear, but I
am certain it's a pitch related factor and not a yaw related factor (at least
in FS2K.)
I have noticed MOST aircraft want a value between +1000 to +4000. Try lowering


the value in 100 increments and see it that helps your plane recover more
effectively.

Also, if the pitch trim authority is set too low (usually called "Pitch Moment"


in section 1101- and what I mean by too low is NOT ENOUGH NEGATIVE) the AP
might not have the authority to respond to pitch changes soon enough. Given
too much authority you will get bouncing. Too low (too close to zero) and you
will get porpoising.
-Pv-


Many thanks, Paul. I'll certainly try what you suggest. Good of you to take so
much trouble. I'm much obliged.
Best wishes,
Peter Preston














Hi Peter,
This is a relatively simple and benign edit, so you might want to try this.
Under section 1203 of AirEd, set bank limit to 25 and bank limit with flaps to
12. You could go to 20 and 10 respectively, but you may need a lot of real
estate to make a turn. These numbers define the max bank angle.
Good flying,
Bob Boudoin



I'd be very grafeful for any help with this problem, which only seems to
afflict a few aircraft.
I was flying a very nice CRJ700 and all was well until I went into a 150 turn,
with autopilot hold engaged at 3000. By the time the turn was completed the
aircraft was down to 1500 and then had to start laboriously back to 3000.
The airspeed may have been a factor, as the 150 turn was to intercept an ILS
and so IAS was at about 170 with about 10 degrees of flap (though the flaps on
this model were of the 08, 20, 40 type).
I am reluctant to ditch this aircraft as this is the only problem with an
otherwise beautiful model.
Is there perhaps some alteration that I could make to some file (I have the
"air-ed" programme)in order to effect a cure?
Thank you.
Regards,
Peter Preston