Re: Re: [Paparazzi-de =?ISO-8859-1?Q?vel] Reply to "How to?= =?ISO-8859-1?Q? descent faster? (Fam?= ille Chateauvieux-Hellwig)"

[martin]

Hi,

this spiral was used for two things. First thing is to get down fast in
case the air traffic control tells you to (e.g. if the rescue helicopter
on Svalbard would have to take off). The other thing was to get the
aircraft down in a controlled way if the IR sensors would have failed.

This procedure is intended for flying wings only (the Funjet). A
"regular" aircraft like the Twinstar will go into rolls. Most important:
make sure that you go through the "down_end" block if you want to leave
and fly normal again. Otherwise the control loop will stay off even if
leaving the block! There are gcs icons downdown and downdownend
available.

Martin

Am 30.08.2009 um  Uhr haben Sie geschrieben:
> Hi,
>
> this kind of procedure is available in
> conf/flight_plans/grosslobke_demo.xml (from Martin):
>
>     <block NAME="down" strip_button="Down">
>      <set var="lateral_mode" value="LATERAL_MODE_ROLL"/>
>      <set var="v_ctl_mode" value="V_CTL_MODE_MANUAL"/>
>      <set value="TRUE" var="h_ctl_disabled"/>
>      <set value="(-0.6*MAX_PPRZ)" var="h_ctl_aileron_setpoint"/>
>      <set value="(0.9*MAX_PPRZ)" var="h_ctl_elevator_setpoint"/>
>      <while cond="estimator_z > ground_alt + 220"/>
>      <set value="0" var="h_ctl_aileron_setpoint"/>
>      <set value="0" var="h_ctl_elevator_setpoint"/>
>      <!--deroute block="down_end"/-->
>     </block>
>     <block NAME="down_end" strip_button="DownEnd">
>      <set value="0" var="h_ctl_aileron_setpoint"/>
>      <set value="0" var="h_ctl_elevator_setpoint"/>
>      <while cond="1.> stage_time"/>
>      <set value="FALSE" var="h_ctl_disabled"/>
>      <deroute block="wait"/>
>     </block>
>
> The trick is to set the h_ctl_disabled variable to disable
> stabilization, put the aircraft in a spiral ... and
> restart the autopilot high enough from the ground. Of course, your
> airframe has to handle it (it was the cause of one of the first crash
> with Paparazzi: switching from a manual dive to auto1; Twinstar's
wings
> did not support the strong resulting pull)
>
> --Pascal
>
>
>
> Famille Chateauvieux-Hellwig wrote:
> > Le dimanche 30 août 2009 01:42:16 chris, vous avez écrit :
> >
> >> That looks very interesting i will try it.
> >> You mean that during the full rudder the IR stabilization should be
off
> >> if i understood correctly.
> >>
> >
> > Yes, do not try to stablize anything during the descent. The model
will
> > probably do wild figures. That's ok. The point is that it will fly
very
> > inefficiently.
> >
> > My be you should expect a loss of GPS fix. It might be clever to
keep this
> > configuration olny for a fixed time (30-60s), then check where you
are
> again.
> >
> >
> >> How can i do this in the flight plan?
> >> Chris
> >>
> >
> > No clue. You'll probably have to define somtething new for
paparazzi. I used
>
> > this method on regular gliders. My Horus
(http://www.horus-uav-systems.de) is
>
> > not good enough that I've had this kind of problems before...
> >
> > Another technique that works well for planes with elevators is to
fly on the
>
> > back. It works if you have an asymetrical airfoil (Twinstar,
easyglider,
> > Cularis...). On a paparazzi system this sould be only a question of
> exchanging
> > what is up and what is down... Here again, expect to loose GPS
signal if you
>
> > use a patch Antenna...
> >
> > Martial
> >
> >>
> >>
> >> _______________________________________________
> >> Paparazzi-devel mailing list
> >> address@hidden
> >> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
> >>
> >
> >
> >
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> >
>
>
>
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