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. 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
