[time-nuts] Why .30 cal holes can't be seen at 800 yds...

[David McClain]

How about a "rubber-mirror", adaptive optics? We use this on our  
large telescopes to overcome the atmospheric scintillation, otherwise  
known as speckle-patterns. Works exceedingly well...

Atmospheric turbulence can be described by a Kolmogorov distribution,  
or equivalently as a chaotic attractor basin of fractal dimension  
between 6 and 7. Hence a feedback Perceptron neural network can be  
trained on the speckle sequences and this also works very well.  
That's how we did it on the Steward Observatory 90-inch.

Dr. David McClain
Chief Technical Officer
Refined Audiometrics Laboratory
4391 N. Camino Ferreo
Tucson, AZ  85750

email: dbm at refined-audiometrics.com
phone: 1.520.390.3995
web: http://refined-audiometrics.com



On Nov 3, 2010, at 11:10, Michael Baker wrote:

>    Timenutters--
>    The question was asked-- Why can't a large aperture
>    high-resolution optic be used to locate bullet holes
>    in a target at 800 yards?
>    Consider this--: I often shoot at targets on the
>    600 yard berm at the Manatee Range (near Bradenton,
>    FL).  Typically, by 11AM the atmospheric shimmering
>    mirage distortion makes even the 4" target hard to see.
>    By 1PM the use of any rifle scope magnification
>    greater than around 10X is an exercise in futility.
>    Often, the mirage is severe enough that even the
>    12" steel plates are hard to find through a 10X
>    scope.
>    .30" holes in a target...?  No way.
>    -----------------
>    Other questions that were asked:  To what degree of
>    accuracy can the 800 yard distance be measured?
>    I have a laser range-finder which has been verified
>    to be within +/- 20 inches out to 1000 yards (the
>    U of F college of Engineering has a series of distance
>    marker posts set up for some research they were doing).
>    What kind of accuracy is expected for measuring bullet
>    velocity at the shooting bench and downrange?  I have
>    a set of Oehler Research sky-screen chronographs that
>    use a 10MHz crystal for clocking the counting registers.
>    The projectiles start out at roughly between 2750 FPS and
>    3100 fps and end up downrange not slower than around
>    1800 fps.  Assume sky-screen clocking ambiguities of
>    only a couple of clock pulses.
>    As an aside, projectiles whose velocity drops to
>    sub-sonic at 800 yds are of no interest to me.
>    The transition from super-sonic to sub-sonic generally
>    includes conditions that create inaccuracy.
>    I am VERY grateful for the feedback on this topic!
>    A couple of innovative suggestions from list members
>    have given me food for thought and I am going
>    to pursue looking into them.
>    My first chore is to investigate what kind of pulse
>    rise-times I get from a selection of inexpensive
>    ultrasonic sensors when a supersonic bullet passes
>    within a couple of feet from them.  I have a Tek
>    2252 scope that I can place downrange to look at the
>    sensors with but storing the waveform for examination
>    may be a problem (no one seems to have volunteered to
>    stand downrange monitoring the scope screen!)
>    The Tek 2252 has a Centronix screen-capture printer
>    output but it is  an Epson FX format and I have no
>    idea if any current printers at the local Office Mart
>    are compatible with the Epson FX data format.  Anyone
>    on the TimeNuts list have any thoughts on this?
>    The 2252 scope also has a GPIB port but I don't know
>    if it outputs the printer data.  I have a Sparkfun
>    GPIB/USB dongle but that may not be of any use if
>    there is no printer data on the GPIB port.
>    Mike Baker
>    -------------------
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