correct as is FCS only resets takeoff trim when putting flaps from non-AUTO to AUTO

[Sarix]

This could be tangentially related to https://forum.dcs.world/topic/345045-fcs-wow-mode-after-fm-update

For the Hornet, when taking off, 22 degrees of ANU is commanded mid-takeoff roll, and after weight-off-wheels one can find the stabs being commanded to 19 degrees NU well into 30 degrees of AoA. I did not include further moments of the track, but after 19 degrees of NU STABs is seen, the STABs would be "eased off" to ~11 degrees NU, and is immediately fixed or at least alleviated by (via keybinds) cycling the flaps from AUTO to HALF/FULL and back into AUTO, with a different resulting STAB position. I have the FCS page on my right DDI - those of you watching the track should be able to see it as well. Hornet AUTO takeoff flaps cycled.trk

One should find the stabilators returning to approximately 3 degs NU upon cycling the flaps in the track attached. Throughout the process the gear is not raised nor did the airspeed exceed 250 kts.

To test the reset logic itself:

I have attempted a normal takeoff, STABs are commanded to ~14-15 degs ANU. After WoW I put flaps to AUTO, gear handle up, and then put the gear handle down again. At ~180kts IAS, STAB is at 2-3 degs NU. Hornet normal takeoff 180kts.trk The same occurs without putting the gear handle up in the first place. Hornet normal takeoff no gear-up 180kts.trk

Then - a second takeoff with flaps in AUTO. The aforementioned 22 degrees ANU STABs is observed with aggressive pitch-up tendencies. I used full stick forward to try to counter this tendency but there is not enough authority to counteract this. Cycled flaps from AUTO to FULL and back to AUTO. No gear up, ~180kts, STAB is also at 2-3 degs NU. Hornet AUTO takeoff 180kts.trk

A third takeoff with flaps set to FULL would still have the STABs on 22 degrees ANU, but when flaps is put back into AUTO without gear up, STAB is observed at 2-3 degs NU at ~180kts. Hornet FULL takeoff 180kts.trk

The gear handle appears to have no influence on the trim reset logic. Putting flaps from non-AUTO to AUTO does.

Cheers.

[BIGNEWY]

Hi, 

please check your take off procedure, take off with half flaps. 

push trim take-off button to position stabilators to take off position, then switch to auto flaps and make control check then switch to half flaps again.

The trim settings don't reset on the ground with flaps switch to auto. You also have indications on the MFD "CHECK FLAPS" "CHECK TRIM" if your take-off conditions are wrong.

 

thank you 

 

[Sarix]

Hi BN,

I am aware of the correct take-off procedure - I was told in the forum post linked above that trim reset logic happens when the gear handle is placed up, which is not the case here (trim reset happens when flaps are put from non-AUTO to AUTO after weight-off-wheels), hence the post. Seeing that it is marked correct as-is I'll take the team's word for it.

Cheers.

Edited March 13, 2024 by Sarix