S-Tec 30 Alt autopilot operation

[whiskytango]

I have a general question about operation of the s-Tec 30 autopilot.  I have noticed that in both Low and High Nav modes, the rate of turn is never more than 1/2 the standard rate, i.e., it is less than 1.5 degrees per second, which works out to about a 10 degree angle of bank.  This is the case no matter what the crosstrack error from the course centerline is.  As a result, the plane wanders off course if there is even light turbulence.  Is this typical?  Is there any adjustment for control authority?

 

I have flown with an s-Tec 55x and it will use significantly higher bank angles in order to join course centerline.

[1964-M20E]

I have not really noticed but I'll try to remember to look next time I go flying.

[pirate]

My 30 is pretty solid, will generally always do standard rate. Holds course high and low in turbulence.

[duke]

my s tec 30 is the same thing. ok in flight. bit does't bank much and as a result overshoots turn at waypoints. It is th same wheather in heading or nav mode.

[Cruiser]

For Piston airplanes, S-TEC System 30 Autopilots  Roll Axis Limits are pre set to a turn rate of 90% Stardard Rate turn. This is maximum allowed.

 

I believe the normal tracking setup for both  NAV LO and NAV HI is 50% standard rate. NAV HI selection increases the sensitivity to off course deflection and responds quicker than NAV LO but it does not change the rate of turn during correction.

[Marauder]

The STEC 50, 60 and 55 derivatives will allow for a full standard rate turn. If I fly an intercept, the plane will go into a standard rate if the angle exceeds 30 degrees or so. It will go into a "soft capture" mode if the intercept is less than that.

I always thought the 30s and 40s behaved the same way.

[BigTex]

I have a STEC50... I can't remember, does it go to 1/2 standard rate in Approach mode?

[GeorgePerry]

I have a general question about operation of the s-Tec 30 autopilot.  I have noticed that in both Low and High Nav modes, the rate of turn is never more than 1/2 the standard rate, i.e., it is less than 1.5 degrees per second, which works out to about a 10 degree angle of bank.  This is the case no matter what the crosstrack error from the course centerline is.  As a result, the plane wanders off course if there is even light turbulence.  Is this typical?  Is there any adjustment for control authority?

 

I have flown with an s-Tec 55x and it will use significantly higher bank angles in order to join course centerline.

 

Yes…this is normal for the STEC 30.  It stinks and is basically only good for S&L and very basic functions.  Any kind of instrument approach and it's better to hand fly.  Turbulence is the same.  Wanders all over the place.  

[Marauder]

I have a STEC50... I can't remember, does it go to 1/2 standard rate in Approach mode?

I think the 50 and up units will change to 1/2 rate or somewhere near that depending on CDI deflection. I have a video of a pretty aggressive intercept (something like 80 degrees) on an LPV approach and the AP intercept was standard rate through it.