Beachcraft Bonanza terrible autopilot

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41

Tried it again, making sure I did as suggested.

As I said: stabilized climb at 600 fpm and 95 knots with elevator trim at about 5% up - hand flying with almost no pressure on yoke in a steady climb. FLC is set for 93 knots when I engage AP (in outside view so I can easily see % elevator trim) - the trim INSTANTLY goes to 100% UP and VS zooms to about 1800 fpm. AP tries to bring nose back down but speed bleeds off so fast that a stall warning sounds within a few seconds.

This scenario DOES NOT OCCUR when I put the plane in an identical climb profile but first engage the VS at 600 fpm and then engage the AP. As soon as the AP takes control at 95 knots & 600 fpm VS - I SWITCH from AP/VS to AP/FLC (93 knot target) and it works perfectly - the nose goes up a tiny bit to pull the IAS down to 93 knots. After that - FLC works just as I expect it to.

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42

I haven’t had any issues with the default aircraft AP following the GPS except the Bonanza. It does the same for me and it’s frustrating.

Ditto for the Carenado C182. The AP in HDG mode is screen door on a submarine useless. Does exactly the same thing. I regret having wasted my money on that steaming pile of manure “premium” add-on.

43

dont set lvl mode on the ground. only engage any autopilot modes while already in the air, this isn’t how its done irl. this is pilot error. I will make a clip of how it should be done

45

I am flying from KLGB to KMCC in the G36 right now (with the performance improvement mod, but that shouldn’t change the AP behavior that I am aware of). Preset NAV mode and FLC at 100kts, altitude bug to 8000ft before takeoff but did not engage AP.

Took off, got the plane established in a climb at ~110kts, and hand flew a heading with my intersecting GPS NAV course at a shallow angle. Engaged AP just before the intersection. AP captured the NAV heading and pitched up to the 100kt FLC climb speed, then climbed to 8,000 ft and leveled off.

Later I wanted to climb a bit to get some more separation to some mountains. So I set the altitude bug to 10,000, punched in FLC mode again and set it to 100kts. AP pitched to maintain the 100kt speed and leveled off as expected at 10,000 ft.

After clearing the mountains I decided to descend back to 8,000. Set altitude bug to 8,000, selected VS mode, -500 fpm, and decreased throttle a little bit to maintain a constant speed. The AP descended at the requested rate and leveled off at 8,000 ft, at which point I increased throttle back to the original cruise setting.

I planned this flight in LittleNavMap using Victor airways, AP has had no problem following all heading changes at intersections. (Via GPS, not using actual VORs)

I will say I had very poor AP performance in all aircraft back in August immediately after launch. This seemed to be related to having the manual trim mapped to an axis interfering with the AP. I mapped them to 2 buttons instead and the problem went away for me at that point.

It seems like not everyone is having the same experience with the sim, so I’ll admit this is just my experience.

I do think that Asobo should provide a manual explaining the operation of the default avionics and any way that it differs from the actual real-life Garmins - especially since the Garmin implementations are missing a lot of features, which makes it unclear if a given feature is implemented, not implemented, implemented differently from the real thing, or broken and needs a bug report. If anyone else shares this feeling, please consider upvoting this wishlist item that I created asking for official documentation - Add a 'Learning Center' or other official documentation

46

Correct, this seems to be pilot error. I’ve never had this happen.

47

Try this. No autopilot modes should be set on the ground (including LVL) This seems to be pilot error in pretty much all cases from the descriptions I am seeing here.

48

I always set it to NAV and FLC with the climb speed of 100kts on the ground and simply engage once I have a stable climb.
Never had any issue with that, so I don’t understand your general rule.

49

Just what my flight instructor taught me.

50

Yeah, but I don’t think setting up the AP on the ground makes it misbehave, so the bug isn’t originating from when you set it up.

51

I don’t use autopilot until I am in the air and stabilized. It always seems to work good from there.

52

Ok so are people using the G36 mod and the Working Title G1000 mod? Because I’m using those two and have no serious issues.

53

I am only using the G36 mod. Have not installed the Working Title G1000.

54

I am not using mods

55

So I went to start another flight from the world map after the prior successful flight. Followed the same procedure of presetting the settings but only enabling the AP once I had the aircraft hand trimmed in a climb at a little above the desired FLC speed.

And the thing went nuts and railed the trim and tried to kill me.

Fought with it for about 10 min and eventually managed to get it working by trying various modes.

Either I mis-pressed something, or there may be state variables in the AP code that are not getting properly reset between flights or something like that.

56

Sounds to me like a pretty solid explanation for the bug report. Should be repeatable.

57

Try not presetting or engaging any autopilot modes on the ground. Do the real world flow:

  1. When in a steady climb, in trim, engage AP. Vertical mode defaults to PIT, which holds the pitch at the time of engagement.
  2. Engage FLC. Vertical mode becomes FLC, and speed defaults to the speed at time of engagement.
  3. Change FLC speed if desired. Ensure to do it gradually so the aircraft is never far from the selected speed.

You want to avoid step changes, and you want to avoid the autopilot suddenly having to do something very different from what it is currently doing. Real life autopilots do not like that much, and the flight simulator autopilot hates it even more.

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58

OK, so in my first post I said that the AP works well for me. But I must admit I had not really delved into VS and FLC up to that point. I did not even know how to set the rate of climb/descent for VS or air speed for FLC! Because of this thread I decided it was time to get to know this part of the AP as well.

The first time I tried it I messed up and had a violent pitch down trim change. I was able to recover and sort out the pitch. After that I figured out how these two functions work and I was able to comfortably climb and descend using either of the two functions without any problems whatsoever. I did this several times and also restarted a flight just to confirm all is good and repeatable. I also did an ILS letdown for practice and it worked beautifully
 better than my hand landing!

So after all that: so far it seems that all the AP functions work acceptably for me. For whatever that is worth as I know that is of no comfort to anybody that is experiencing issues.

Configuration:

Asus X570 mobo
Ryzen 7 3700X
32GB 3200 memory
250GB M.2 NVMe for system
500GB M.2 NVMe for data
Evga RTX2060
Benq 32" 4K monitor
All settings high
Getting framerates in the high 20’s but it looks great and no stutters

59

Remember that IRL, the AP comes off well before landing unless you’re flying a Cat III Autoland system. Although back in FS9, I installed an Autopilot in the Ford and did autolands with that one several times! :shushing_face:

60

Indeed I do know that: I just expressed myself poorly. I let the AP fly the approach down to my own arbitrarily selected 250’-ish minimums and then took over manually. It was the subsequent manual landing that I did that was not up to the standard of the approach that the AP flew. It was in good weather and excellent visibility: the next one will have to be in bad weather! :worried:

FWIW runway 26R at Vancouver (where I landed) does have Cat III for aircraft suitably equipped.

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61

When you first enable FLC it defaults to your current speed of 0KIAS, so on the ground the AP CPU is trying to initiate a climb to your desired altitude while maintaining 0KIAS, so it spikes the FD right up to a 90degree nose up climb. Then once you’ve keyed in your desired speed you start taking off almost right away, so it’s going to see it’s below the commanded speed, triggering the FD to start descending, but also that you are rapidly accelerating towards the desired speed, causing it to reduce the rate the FD comes down to prevent it overshooting the target speed. Climbing out at cruise speed of 110KIAS it takes about 2000ft of climbing before the FD stabilizes in a safe range to engage, as opposed to only dialing in your target Altitude on the ground and engaging FLC once already airborne as per the POH.

Long story short, there’s a reason the manufacturer only certifies the AP and sub-modes to be used above 90KIAS, and also only after 400ft AGL after takeoff.

EDIT: After further testing, the massive nose up command only occurs on the ground with a tailwind, on the ground with a headwind or once airborne it works normally.

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