[TheOtherCliff]

Baro is always in use in Altitude Hold or Altitude Vario.

CruiseControl increases thrust for higher bank angles and at the same time, the baro increases thrust if it sees higher pressure.

Fly a long straight pass at fairly high speed.  If it dips and comes back up while flying, the baro is acting correctly and you can maybe increase CruiseControlFactor (I forget what it is called, default is 100).  If it dips and stays low as long as you are flying forward at speed that implies the baro is seeing lower pressure than it should and it thinks it is too high and so it decreases the altitude.  To fix that, you must determine why the baro is seeing lower pressure.  Maybe a Bernoulli effect or maybe a big hole in the back of the quad causing a suction.  Does it gain altitude when flying backwards?

[DocHardinger]

Thx! I will do some tests tomorrow...just designed a special cover for the revo and printed it... should be better cover the baro from light and airflow...

[TheOtherCliff]

So to be clear, all GPS modes and any non-GPS mode that uses CruiseControl use both CruiseControl and baro all the time.  Of course CruiseControl adds zero thrust when the sticks are centered.

Any mode that uses the baro and has either a loss or gain in altitude as long as you are traveling forward and recovers when you stop either doesn't have enough power to travel constantly at that angle, has bad altitude PIDs, or (usual case) has a baro that is getting blown on.  Higher pressure makes it thing it is lower and so it gains altitude.  Lower pressure (Bernoulli effect or big hole in back) makes it think it is higher and so it looses altitude.

Also, there are more PIDs in VtolPathFollower.  Some for altitude, some for horizontal, and one especially for VR mode horizontal.