John Denker
> Sent: 05 December 2007 16:43 > To: FlightGear developers discussions > Subject: Re: [Flightgear-devel] control trim reset > > > On 12/04/2007 11:26 PM, Syd&Sandy wrote: > > Hi all , I've added the elevator, aileron and rudder trim to the > > control-centering function - keypad ( 5 ). Should this be added > > before the release ? Or is there a particular reason that the trims > > aren't reset ? > > There is _some_ merit to this idea, but it needs refinement; > see below for details. > > > developed the habit of hitting the 5 key before releasing the brakes > > As Curt pointed out, simply zeroing the trims is a Bad Idea. > In most airplanes -- simulated and real-life -- zeroing the > trim is not the right answer. > > In the C182 for instance -- FG and RL -- you would be well > advised to apply significantly nonzero elevator and rudder > trim before takeoff. A certain nonpilot on this list dismissed > this as "probably not that much help" but every RL pilot I > know does it anyway. > > The general problem of setting the trim to the "desired" > value is ESP-complete; that is, it requires reading the > pilot's mind to ascertain his intentions. As an extreme > example of this, suppose I am buzzing along upside down in my > Decathlon, trimmed for straight-and-level inverted flight. > If I push "5" to center the primary flight controls, I definitely do > not want the trim set to zero, nor set to the level-flight > values. > > So, all evidence suggests that there is a need for a "5" > command that does /not/ mess with the trim. > > You could *also* implement something that does set the > trim automagically. I know a simple way to do this, if > anybody is interested. However, I don't recommend it, > because it is both unnecessary and unrealistic. > This sort of automation appeals to people who drive cars, > and expect to be able to jump in and drive away. It is, > alas, highly unrealistic in present-day general-aviation > aircraft, where the pilot expects to spend quite a long time > running the preflight checklists, including setting the trim. > > One problem is that many aircraft in the FG fleet lack > usable trim-position indicators. That is why the Sport > Model contains a popup that provides the necessary > information. (The popup is only a workaround, it is > not meant as a long-term replacement for a proper > realistic trim-position indicator.) > > http://www.av8n.com/fly/fgfs/README.sport.model > http://www.av8n.com/fly/fgfs/git-overview I use t to autotrim the Buccaneer, and T to remove all trims when I get it wrong and need to retrim. No need to touch 5 - it centres the controls, that's enough (not that I use it very often). Autotrim is quite a handy function. I don't think it's used much. It kind of simulates the way trim can be used to remove stick pressure. Vivian ------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
