On Wed, 5 Dec 2007 18:21:45 -0000 "Vivian Meazza" <[EMAIL PROTECTED]> wrote:
> 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 > ok that answers my question .... I thought it was more a user option to center joystick , etc... But now I'm really curious how a real autopilot system handles this .... Thanks , guys ... Cheers -- Syd&Sandy <[EMAIL PROTECTED]> ------------------------------------------------------------------------- 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
