Re: [ATM] question about plop obstruction(s)

["Bob May" <rmay@nethere.com>]

I think that you had a directory crash.  I.e. the directory that
the file is in is the wrong directory.  At least I remember that
somebody had this problem.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net

----- Original Message -----
From: Mark Holm <markholm@verizon.net>
To: ATM <atm@atmlist.net>
Sent: Friday, May 30, 2008 5:27 PM
Subject: Re: [ATM] question about plop obstruction(s)


> waldo kitty wrote:
> > in plop, is the obstruction the secondary mirror?
> >
> Yes.
> > if so, is the measurement that plop wants the long diameter
or the short
> > diameter or does it matter since the secondary is
(apparently??) tilted at an
> > angle to present a uniformly circular obstruction?
> >
> >
> Short, since that is the diameter of the circle you get when
the ellipse
> is tilted.
> > this also brings me to another question about the Automatic
Cell Generation...
> > for some reason, when i attempt an ACG for a 9 point cell,
plop tells me that it
> > cannot find _2_0_0.gr... it says there is no such file or
directory and that
> > automatic cell generation of this type is not yet implemented
in plop... this is
> > for a "standard" 9 point cell and it has worked in the
past...
> >
> > now, if i go into the autocell directory and manually select
the cell_2_0_0.gr
> > file, it loads and seems to operate just find...
>
> I have had that happen too.  It wasn't on the 9 point though.
I can't
> remember what I decided the cause was.  I recall that the fix
was easy,
> but I don't recall what it is!  Look carefully at your file
name for
> extra spaces or underscores.
> Here are the contents of cell_2_0_0.gr  Just copy and paste.
The .gr
> files are plain old ascii text files, no magic sprites coded
in.
>
>
> ;9 point cell with angles fixed
> var r_inner  0.253672
> var r_outer  0.559738
> diameter 406
> thickness 54
> focal-length 5
> n-mesh-rings 12
> rel-support-radii r_inner r_outer r_outer
> num-support 3 3 3
> support-angle 0 30 90
> basis-ring-size 3
> basis-ring-min 0
> obstruction-diam 80
> optimize r_inner 0.01
> optimize r_outer 0.01
> part triangle 3 point 0 0 point 1 0 point 2 2
>
>
>
>
> >  however, i notice that it
> > already has entries for the mirror diameter (406 fixed) and
thickness (54
> > fixed), the focal length (5?) and the obstruction diameter
(80 fixed)...
> >
> > is my cell_2_0_0.gr file goofed up?
> Mine has those entries also, but works just fine.
> >  i'm just trying to work out the factors for
> > a 10 inch, 3/4 inch thick, F6 plate glass mirror with a 2
inch (?) secondary...
> > the actual numbers i'm using for this are...
> >
> > Mirror Diameter: 254 fixed
> > Mirror Thichness: 19.05 fixed
> > Focal Length: 1524 fixed
> > Obstruction: 50.8 fixed
> >
> >
> Skip the 9-point.  6 will give better support and be easier to
build and
> more robust against construction error.
>
> Mark Holm
> markholm@verizon.net
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>

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