So looking at it more closely, when you start applying nose up trim, the nose starts pitching up without any elevator movement, then the FCS kicks in and applies nose down elevator to maintain 1G pitch trim. So the real question is how is the manual trim changing pitch without moving a control surface?
just looking at the F18 after the Maverik upgrade.
The animation of the stab trim is reversed. Elevator controls work correctly bet the stab runs in the wrong direction
There’s a general mismatch: you have to assign nose up/down in reverse and also the animation is wrong for most if not all airplanes. Best to see looking at the elevator of the most “basic” airplane: the C152.
Just to help @MimikriX and @PZL104 sort things out, I’d suggest you review the link below. @MimikriX is describing an antiservo tab (which is frequently just called a trim tab by people using planes equipped with those). @PZL104 is describing a trim tab, which is what’s used on the RL Cessnas (and many others) and those used in the sim.
Everyone needs to be specific about the type of plane being discussed because there are differences in various makes and models.
Regards
Visualize the airflow on that, the air will hit the trim tab deflected down into the airstream. This will created an upwards force on the elevator, which will apply a downwards force on the tail, raising the nose. So the 100% nose up trim indication is correct there. The bug in this thread is specifically for the F/A-18E due to some weird interaction between the manual trim code and the FCS 1G auto trim code.
Ok, sorry if this thread applies to F16 jets. My impression was that it is for trim problems in general.
On the other hand: your explanation is correct till the after the one piece: yes, the trim tab creates an up force to the elevator… but an up force to the elevator creates an upward force to the tail (how should this be different?) resulting in a nose down (NOT nose up) attitude and therefore also the trim indicator on the HUD is wrong.
An upward force TO the elevator is very different than an upward force BY the elevator. An upward force to the elevator will push the elevator up into the oncoming air, which in turn will create a downward force on the tail. But again we’re getting off-topic here and going around in circles.
For an on-topic part of this reply, honestly not sure if this “bug” can be resolved without just programming the sim to ignore manual elevator trim commands while flying the F/A-18E and the FCS is in 1G trim mode. I don’t have the programming knowledge to know how feasible that is.
Trim Tabs
The most common installation on small aircraft is a single
trim tab attached to the trailing edge of the elevator. Most trim
tabs are manually operated by a small, vertically mounted
control wheel. However, a trim crank may be found in some
aircraft. The flight deck control includes a trim tab position
indicator. Placing the trim control in the full nose-down
position moves the trim tab to its full up position. With
the trim tab up and into the airstream, the airflow over the
horizontal tail surface tends to force the trailing edge of the
elevator down. This causes the tail of the aircraft to move
up and the nose to move down. [Figure 6-20]
You are missing the situation we discussed where the elevator is straight and just the trim flap is deflected up or down.
As I said: try the Gotfriends Discus 2C and see what they have simulated.
Also, it is always good to read the full text so please have a look at the text above your reference:
And luckily for those not interested in our OT discussion this will be it. Thanks a lot for your understanding and happy flights for everybody be it irl or in sim.
That unfortunately does not prove your case the way you hoped, as per the text full nose down trim will place the trim tab in full up. Which means full nose up trim will place the trim tab in the full down position, which is the case we have all been presenting. Now go back the screenshot you provided of the Cessna 152 with full nose up trim and look at the position of the trim tab.
