cannot produce and mssing track file F-18 C Erratic Vertical Trim Behavior

[HvanE]

When operating at speeds above 250 kts IAS, the vertical trim works as expected (although somewhat slow). However, when the IAS drops below 240 kts. a slight touch of the vertical trim button (Chinese Hat) causes a large elevator deviation resulting in either an excessive nose up or down attitude (Gear and/or flaps down or not).

Any thoughts?

[razo+r]

1 hour ago, HvanE said:

When operating at speeds above 250 kts IAS, the vertical trim works as expected (although somewhat slow). However, when the IAS drops below 240 kts. a slight touch of the vertical trim button (Chinese Hat) causes a large elevator deviation resulting in either an excessive nose up or down attitude (Gear and/or flaps down or not).

Any thoughts?

What are your gameplay settings? What are the mission specific settings?

Is arcade flight turned off in both cases?

[HvanE]

Thanks for your quick response, razo+r, but having run several different missions it appears to be inherent to a couple of missions I downloaded Now deleted). All good now.

 

Regards,

 

Henk.

[HvanE]

No, celebrated too early. Still happening…Will do some further investigating..

[rob10]

Post a track rather than a video.  It's likely something simple that will show up on a track.  You realize you really shouldn't need to touch vertical trim if you're >250 kts anyway?

[HvanE]

Thanks, but irrespective of that, this shouldn’t be happening. Further “testing” shows it’s the result of flap selection, either half or full..

[Polo]

Doesn't the Hornet FCS change at low speed with gear down from straight trim to setting the requested AoA? Seem to remember using up/down trim to align the FPM with the AoA bracket. Admittedly haven't flown it for a while so might be off position entirely...

[Phantom711]

@Polo

Yes absolutely. 
With gear down and flaps half or full the FCS behavior changes so that you can now trim to „on speed AOA“. 

Edited December 22, 2024 by Phantom711

[CBStu]

If you have used the Auto Pilot during the flight make sure you have turned it off.

[niru27]

On 12/25/2024 at 12:30 AM, CBStu said:

If you have used the Auto Pilot during the flight make sure you have turned it off.

This is the answer. If you had any AP mode active and did not disable it with a short press of the Paddle (yanking the stick doesn't work either), then when you drop flaps and try to trim, this happens.

[Tholozor]

To expand on the above post: de-selecting an autopilot relief mode (BALT, RALT, etc) from the UFC option select buttons does not fully disengage autopilot (the system drops into Control Stick Steering (CSS) autopilot mode, denoted by an 'A/P' advisory). Actuation of the paddle switch is the recommended method to ensure all autopilot modes are disengaged.