On Wed, 2002-09-18 at 06:29, David Megginson wrote:
> Tony Peden writes:
>
> > I didn't look at everything, but the nose wheel was in NONE and the
> > mains CASTERED as far back as I looked (which went back to the beginning
> > of time for the configurable gear). I can't explain the CASTERED mains,
> > but I understood what you call steer groups to be brake groups. It
> > never occurred to me that that would affect the steering control.
>
> Here's an excerpt from FGLGear.cpp:
>
> case bgNose:
> SteerGain = -0.50;
> BrakeFCoeff = rollingFCoeff;
> break;
> case bgTail:
> SteerGain = -0.10;
> BrakeFCoeff = rollingFCoeff;
> break;
> case bgNone:
> SteerGain = 0.0;
> BrakeFCoeff = rollingFCoeff;
> break;
Is there some reasoning behind setting the steering gains according to
the brake selection? This makes no sense to me. It looks to me like
their needs to be a separate steering selection (or just specify the
gain in the config file).
>
> and, a little further down:
>
> switch (eSteerType) {
> case stSteer:
> SteerAngle = SteerGain*FCS->GetDrPos();
> break;
>
> In other words, if gear belongs to bgNone, it gets SteerGain=0.0, so
> SteerAngle is always 0. Perhaps it's a recent C++ change that caused
> this problem.
>
> Note a second problem with this code: it uses getDrPos (the actual
> rudder position) and ignores maxSteerAngle from the config file. A
> better option would probably be
>
> SteerAngle = SteerGain*FCS->GetDrCmd()*maxSteerAngle*RADTODEG;
Agreed. Steering angle should not be a function of rudder position, but
of pedal (or tiller) position. I tend to think this really ought to be
done as an FCS component.
>
> It would also be nice to be able to specify SteerGain in the XML
> config file rather than hard-coding it in FGLGear.cpp.
Indeed.
>
> > (and maybe it didn't, changing the mains from CASTERED to fixed could
> > have a significant effect). I need to experiment with it some more.
>
> The castoring doesn't make a difference (yet), because FGLGear.cpp
> still treats castoring gear as fixed anyway:
>
> case stFixed:
> SteerAngle = 0.0;
> break;
> case stCaster:
> // Note to Jon: This is not correct for castering gear. I'll fix it later.
> SteerAngle = 0.0;
> break;
>
> > > * Usable fuel:
> > > 38in (c172.xml has 56in)
> >
> > Hmm, I got my numbers from a POH as well. I'll have to double check.
>
> That's from the C172R POH. The C172P POH puts usable fuel at 48in,
> probably because of the different wing shape, but it's still not as
> far as c172.xml.
The 48 in number checks with my copy of the POH (from which many other
numbers have been derived, so we should probably stick with that)
>
>
> All the best,
>
>
> David
>
> --
> David Megginson, [EMAIL PROTECTED], http://www.megginson.com/
>
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--
Tony Peden
[EMAIL PROTECTED]
We all know Linux is great ... it does infinite loops in 5 seconds.
-- attributed to Linus Torvalds
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