C172 Autopilot

[b1bmsgt 207]

Thanks for all your comments!

Sounds like maybe a complete re-install might be in order. I have been installing the patches on top of the original download, so maybe that is what's messing me up. When I have the time I think I'll do that...

[Will Fly For Cheese 1,710]

10 minutes ago, b1bmsgt said:

Flight controls yes, trim no...

I think that's what he meant.

[fppilot 4,391]

12 hours ago, b1bmsgt said:

Well, I installed the update with a clean Community folder, and took the C172 G1000 out for a spin to try the autopilot to see if they fixed anything. Set it up on the runway to climb to 4000 feet at 700fpm at runway heading. Took off and engaged the AP at 1000 feet in a 600 foot climb. FPM went to the set value OK, but the aircraft started to porpoise a little. I then set the heading to about 20 degrees to the left and clicked the HDG button. The aircraft showed HDG on the PFD and started to turn for a split second then went right back to ROL. Tried several times with the same results. A few seconds later the AP warning tone went off, the AP disconnected, and the aircraft went into a violent pitchover towrd the ground, actually tucking under and going past a 90 degree dive and crashing.

Not exactly realistic behavior I dare say...

Wonder if anything actually did get fixed

Guess I'll keep flying hand flown VFR until the next update, which is actually OK with me. If I want to fly something on AP, X-Plane still works perfectly...

I have experienced this as well.  Only twice, each time in a different aircraft.  Seems random.  Each time it happened I backed out of the sim, rebooted, loaded sim, and flew same flight in same aircraft, without issues.

Edited October 14, 2020 by fppilot

[b1bmsgt 207]

So, I uninstalled the sim and did a complete download and reinstall to a different drive. Took the C172 G1000 out and.......

 

(drumroll)

 

Exactly the same!!!!!!!!!!!!!!! I was dead within 10 minutes! HDG will not engage and the aircraft porpoises to the point that It apparently disconnects the autopilot, which causes the abrupt death dive.

 

On the other hand, the scenery popping seems to be gone and my flight control sensitivity control  is back, as well as the VFR map.

 

The Microsoft (VFR Hand Flown) Flight Simulator is good to go!!  If I want to fly tubeliners, X-Plane is waiting...

 

Until the next patch...

[MrFuzzy 2,123]

I am using the C172 a lot lately and everything works to me (HDG, VS, NAV, APPR for ILS).

Edited October 15, 2020 by MrFuzzy

[wthomas33065 994]

44 minutes ago, b1bmsgt said:

So, I uninstalled the sim and did a complete download and reinstall to a different drive. Took the C172 G1000 out and.......

 

(drumroll)

 

Exactly the same!!!!!!!!!!!!!!! I was dead within 10 minutes! HDG will not engage and the aircraft porpoises to the point that It apparently disconnects the autopilot, which causes the abrupt death dive.

 

On the other hand, the scenery popping seems to be gone and my flight control sensitivity control  is back, as well as the VFR map.

 

The Microsoft (VFR Hand Flown) Flight Simulator is good to go!!  If I want to fly tubeliners, X-Plane is waiting...

 

Until the next patch...

Quick question.  Do you have fuel set to automix, or do your controls include mixture.  If not set to automix, you have to lean the engine as you climb or else you lose power as you climb  And even so, after a certain altitude, you can't maintain the same climb rate at altitude as you do at sea level.  I find that as I get past 7000 to 8000 feet I have a hard time maintaining 200 - 300 fpm.  Don't know if that's realistic or not.  

But as someone else said, not a lot of reserve power in the C172.  By contrast I can set the C208 to climb at 1000 fpm and accelerate during the entire climbout to 8000. 

Just an observation.

[abrams_tank 7,470]

51 minutes ago, b1bmsgt said:

So, I uninstalled the sim and did a complete download and reinstall to a different drive. Took the C172 G1000 out and.......

 

(drumroll)

 

Exactly the same!!!!!!!!!!!!!!! I was dead within 10 minutes! HDG will not engage and the aircraft porpoises to the point that It apparently disconnects the autopilot, which causes the abrupt death dive.

 

On the other hand, the scenery popping seems to be gone and my flight control sensitivity control  is back, as well as the VFR map.

 

The Microsoft (VFR Hand Flown) Flight Simulator is good to go!!  If I want to fly tubeliners, X-Plane is waiting...

 

Until the next patch...

Is it a bug with that particular location you are flying? Have you tried a different location with a different flight route?

[Bert Pieke 7,591]

I just flew the C172 on an approach to R01L at KTPA, and twice, the autopilot simply decided to put me into a spiral dive. I was in ALT hold at 2000 feet.  NAV GPS tracking.

This is random, as best I can tell.

I can recover by grabbing the yoke and correcting.. When I look at the trim, it is full up at this point.  After retrimming and restoring level flight,  I can turn the autopilot back on.

[marsman2020 1,310]

Depending on how hot a day it is, and the loading conditions the C172 can't even climb at 700 fpm at 4000 feet.

How are you controlling mixture?

 

[wthomas33065 994]

13 minutes ago, marsman2020 said:

Depending on how hot a day it is, and the loading conditions the C172 can't even climb at 700 fpm at 4000 feet.

How are you controlling mixture?

 

My CH FS Yoke dedicated Throttle Condition and Mixture axis, so I map the Mixture lever to mixture axis in the sim.  If you don't have a mixture lever, then you can set automixture in the assists section so that you don't need to worry about , or if you want to actually control it, you can map mixture to keyboard commands or you can manipulate the mixture knob in the VC. 

Way more info about mixture can be found here if you are interested in a read.

https://www.aopa.org/training-and-safety/students/solo/special/the-fuel-air-mixture

[LarryD 132]

3 hours ago, Bert Pieke said:

I just flew the C172 on an approach to R01L at KTPA, and twice, the autopilot simply decided to put me into a spiral dive. I was in ALT hold at 2000 feet.  NAV GPS tracking.

HI Bert:

When you enter the autopilot dive, have you ever quickly switched to the exterior chase camera, and took a look at what percentage your trim was at?  Since you dive immediately after entering AP mode, I would love to know what percentage your trim reads.

Next time that happens, take an exterior look and let us know.  Or better yet, take a look before you hit the AP.  Might give you a warning before it happens.

[Bert Pieke 7,591]

52 minutes ago, LarryD said:

HI Bert:

When you enter the autopilot dive, have you ever quickly switched to the exterior chase camera, and took a look at what percentage your trim was at?  Since you dive immediately after entering AP mode, I would love to know what percentage your trim reads.

Next time that happens, take an exterior look and let us know.  Or better yet, take a look before you hit the AP.  Might give you a warning before it happens.

I am definitely going to pay more attention to what the exact circumstances are.  It is not immediately after entering AP mode, however.  It is while I am flying in stable flight, NAV and ALT mode engaged.  Trim is stable.

Without warning, it is as if the autopilot disconnects, but the AP indicator is still lit and the FD bars appear stable, but the airplane kind of falls away and the trim tries to compensate.. I believe it ends up in the full up position.  If I grab the yoke, I can recover, which is strange, because I would expect the autopilot to fight me, but it does not.  If I really move the yoke enough, the AP indicator goes off and I am flying manually.  I can then trim back to neutral and reengage the autopilot.

Next time, I'll hit the Pause button and see if I can figure out what else is going on.. 

[pannellg 17]

I have the same problem as Bert...exactly the same.  Frustrating...