Auto trim and HUD displays
@ Galaxy:
The Viper "auto trim" seems identical to that of the Airbus except for the bank angle and pitch attitude corrections. Actually, not a bad idea for a heavy, but a bit clumsy for the fighter plane requirements. So we trimmed for gee as set using a trim wheel or the thumb hat switch on the stick ( HUD showed instantaneous gee to a tenth of a gee). We could trim for zero gee and during a fight let go of the stick and get less induced drag to "extend" or gain energy.
The 'bus computers add to the basic one gee gee command for a bank angle. So in 30 deg of bank it trims for 1.15 gee or so. Same for pitch - a 30 deg climb would be trimmed for about 0.87 gee, otherwise pitch would continue to increase if still trimmed for one gee.
Neither the Viper or the 'bus trim for attitude, best I can tell from the manuals.
Some folks seem to misunderstand the airspeed/altitude displays and such when talking about the HUD.
BARO DATA IS NOT USED FOR THE FLIGHT PATH VECTOR in any application I have looked at except a "poor man's" FPM (flight path marker - that little airplane doofer)
What it is used for is the speed/altitude part of the display - those "thermometer" doofers on each side of the display. Same for vertical velocity, which could be baro or inertial, depending on a switch. Some planes only show baro VV. Some planes can show radar alt versus baro, and the beat goes on.
I read a symposium presentation by some dude about the Airbus HUD installed in some variants. Thing sounded like a poor man's HUD, and I can't understand a modern plane without a cosmic, large field-of-view HUD, especially for landing and takeoff. Ask 'bird about a night cat shot off the boat without a HUD. The FPM showing your vector was above the horizon was very "comfortable". It also helped getting back onboard at the very end of the task, although flying the meatball was as good or better.
In the AF447 situation, an inertial FPM would have been invaluable showing the crew their flight path with respect to local level. After all, you can have the nose up at 16 degrees and still be falling like a rock! Think I saw that number last week.
HUD "pitch lines" are also easy to read and use. So setting a 3 degree glide path or climb is a no-brainer.
PLZ try to watch the shuttle landing in an hour or so, and you can see a real HUD in action.
Otherwise, I'll hunt down some You Tube sequences to show mine. Haven't digitized my LEF failure landing but it is a good one to see how the thing helped me land.