On Sun, 2003-06-08 at 11:36, Norman Vine wrote: > Jon Berndt writes: > > > > > > As for myself I would be very nervous using any altitude > > control system > > > > that didn't return elevator trim to 'neutral'(1) on > > disengagment because > > > > as you say it is a potential killer > > > > Tony wrote: > > > > > Whose to say that neutral trim is better? And aside from that, there > > > really is no such thing as neutral trim for aircraft that trim with > > > the entire stabilizer. > > > > > > Also there is one real practical problem with "resetting" the trim: > > > trim systems tend to be fairly low rate devices, so returning them to > > > some "safe" position could actually take some time, say 10-20 seconds. > > > > > > Tony is exactly right. In the F-16, to the best of my recollection, the > > autopilot and trim commands are summed. This means that when the > > autopilot > > is on, if there has been some trim already put in, the autopilot adds to > > that setting. If the trim is activated during autopiloted flight, the > > autopilot will correct for that in holding altitude (for instance), so the > > net effect is zero. If the autopilot is turned off, the trim is NOT > > returned to any neutral setting - it remains the same. However, there are > > "sumps" (washouts) in the FCS to temper any transients that might be seen. > > I don't doubt that you guys are right, I just am trying to make sure that > we > are talking about the same 'oranges' > > In the FGFS AP model we have an elevator control (EC) and an > elevator_trim (ETC) control. The elevator_trim control is what is > adjusted by the AP in FGFS but I am guessing that there is either > (1) a coupling between the ETC and EC or > (2) that the AP on heavy planes controls the directly EC and not the ETC.
Depends on the aircraft. If you can get the rate from the trim, why not use it? > > But as I have said I could easily be all 'wet' > > Cheers > > Norman > > > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel -- Tony Peden <[EMAIL PROTECTED]> _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
