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Setting targets< Radar Guns verses Hoops & Stakes

Discussion in 'Shooting Related Threads' started by maka, Jul 4, 2010.

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  1. maka

    maka Member

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    I m from old school and believe targets should be set to proper height using a Hoop, ten yards out. This per existing wind at the time of setting height. Others from new tech. philosophy believe only way is a Radar gun. My questions are: At what point,(at house, at #3 stand, or else where? In addition, are there different make's or Radar guns,(if so) what are the standard deviation for each?
     
  2. Tom Ruble

    Tom Ruble TS Member

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    Using the radar gun does not determine the height of the target. The radar gun reads the velocity of the target which is related to the distance the target should travel. A different device indicates the vertical angle of the trap which relates to the height of the target at the 30 ft. stake. Break 'em all! Tom Ruble
     
  3. Rebsmith

    Rebsmith Member

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    If there is no 50yd stake, none of the squad members can ask to verify the legality of the targets. You can't question what you can't see.

    Jere
     
  4. Neil Winston

    Neil Winston Well-Known Member

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    Rule XIII, E, Flights and angles

    "Where terrain
    allows, a visible stake must be placed on the centerline of the trap on
    the arc of a circle that has a radius of 50 yards and its center is Point
    B (Point F, Diagram II"
     
  5. Hollywood Marine

    Hollywood Marine TS Member

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    A 50 yard stake is only useful if the ground in front of the traphouse neither rises nor falls significantly in that distance. A precision clinometer is used to measure the trap base plate angle from the horizontal to determine the height at ten yards. My club has two different radar guns, only one of which can be calibrated by the user. The positioning of the gun is critical. It must be in such a position that it can "see" the target immediatly upon exit from the trap in order to give an accurate reading of target velocity. The farther away the target is when"seen" by the radar gun, the greater willbe the error in the velocity reading. As for setting where the terain is not level and horizontal, it will be necessary to calculate the angle and velocity which taken together will produc a target that falls through a point 50 yards in front of the trap in a horizontal plane projected from point "b".
     
  6. phirel

    phirel TS Member

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    The 50 yard stake is useful on level ground and when the wind is not blowing. For all other conditions, a radar gun is more accurate.

    Hollywood Marine- The better, or at least more expensive, radar guns will give the same readings directly behind the house, from the 16 yard line or from 30 yards behind the house. Inside of the house both the inexpensive and expensive guns will read a little faster because the target begins to slow down as soon as it leaves the arm.

    Setting target height with an angle gage only works if all the machines are set in exactly the same way inside of the house.

    Target height is measured at 10 yards from point B (26 yards from the singles line), but what we are trying to achieve is the proper target height 30 yards from point B. With a moderate to strong wind, a target set at 9.5 feet at 10 yards may be too high or too low at 30 yards. Nothing will replace careful observation or targets by someone who knows what the targets should look like at 30 yards from point B.

    Pat Ireland
     
  7. Neil Winston

    Neil Winston Well-Known Member

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    Another reason the readings from inside the house are higher may be, Pat, the reduction in cosine error resulting from the fact that the angles of flight and sight are less divergent.

    Neil
     
  8. 320090T

    320090T Well-Known Member

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  9. Neil Winston

    Neil Winston Well-Known Member

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    320090T, there are two ways to read the speed of the target -

    1) The speed the disk is traveling through the air (chronographs read this if they are tipped to match the approximate angle of the flight of the bird, about 20 degrees) and

    2. The speed the bird is traveling away from the setter "across the ground." Radar guns read this.

    The bird is moving through the air faster than it is leaving the setter. Imagining the bird is set to fly straight up will make that clear. It is not moving horizontally from the setter at all, so the radar gun should read zero. In contrast, if it were set completely "flat," the receding speed and the bird speed would be the same and the radar gun's LCD would report bird speed exactly.

    This sort of relationship, unity when the angle is zero and zero when the angle is 90 degrees is matched by the trigonometric function the cosine. The difference between object speed and reading speed is called cosine error. For normal bird angles, the outcome is that radar guns report a speed about 6 percent lower than the speed the bird is traveling through the air.

    When read from inside the traphouse this error drops to about zero, since (guessing at a representative value) the cosine of 5 degrees is 1.00, measured to two decimal places.

    This is also why theory recommends that speed be set first, then angle, since changes in the angle have a direct effect on the speed reading. Practice, however, says that it makes no practical difference at all.

    In any case, the angle effect is much smaller for radar setting than "setting by stake." If you raise the bird a lot it will fall much "shorter;" if you do the same with a radar gun, it will read a little slower. You can only start to measure either effect if you set the bird to be at least ten feet high at 30 feet, so it seldom comes up in practice.

    Neil
     
  10. phirel

    phirel TS Member

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    Neil- Yes, I omitted the cosine error when reading the speed from the 16 yard line. I can type faster than I can think, and I type rather slowly. This error does result in a lower speed reading of the target.

    Pat Ireland
     
  11. 320090T

    320090T Well-Known Member

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    Got it.
     
  12. crk

    crk Member

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    I knew that some day I would need that Trig course. Didn't pay attention anyhow.
     
  13. BAD 303

    BAD 303 Active Member

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    Dang all this to make sure someone runs a 100 straight.
     
  14. setter

    setter Member

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    I would offer that it's a radar gun plus the stake. Your choice, get the Decatur or one of the others. However; use it according to the excerpt below (from the rulebook). In my part of the country, with the near constant wind, the pole at the stake is a reference for how far the target needs to be above or below for that particular wind. The radar gun offers the opportunity to acheive more consistent target speed, from trap to trap, than can be had otherwise. Neal described the science involved, but in practice and as he taught me, you point the yellow Decatur as described below and bring the target up to speed. The trap will vary, in speed, throw to throw (some more than others) and you sometimes have to bracket the speed. Decatur & Stalker to the nearest tenth mph, the low powered to the nearest mph.

    Jim


    F. Rules for the use of Radar Guns and Chronographs
    to set Target Speed


    There are two types of radar guns, high-power and low-power. The
    practical difference between them is that high-power guns work reliably
    from the 16-yard line and low-power guns don’t.


    High-power guns (Decatur, Stalker, most “police radar guns” and similar)
    are to be used at the 16-yard line. The trap oscillation is stopped, and
    the target measured is a straightaway. The gun is pointed horizontally.
    The correct speed for a singles or handicap target is a minimum of 42
    MPH. The correct speed for the right target of a doubles pair must be a
    minimum of 39 MPH.


    Low-power guns (SportRadar, Bushnell, and similar) are to be used at the
    back of the traphouse and at the level of the top of the traphouse. (Holding
    the gun higher than that will lead to a target which is too fast.) The trap
    oscillation is stopped, and the target measured is a straightaway. The gun
    is pointed horizontally. The correct speed for a singles or handicap target
    must be a minimum of 42 MPH. The correct speed for the right target of a
    doubles pair must be a minimum of 39 MPH. When a radar gun is used
    from inside the house, the correct speed for a singles or handicap target
    must be a minimum of 44 MPH. The correct speed for the right target of
    a doubles pair must be a minimum of 41 MPH.


    A chronograph is to be used as close to the trap as practical and tipped
    up at approximately the same angle as the flight of the target. The correct
    speed for a singles or handicap target is 67 ft/sec. To set doubles with a
    chronograph, set a singles target to 76 ft/sec. and then switch the trap
    to throw doubles without changing the spring tension.


    Note: target speed may be set by distance as above or by speed as
    determined by a radar gun or chronograph. Target must be set by
    measured speed or distance.
     
  15. Bob Hawkes

    Bob Hawkes Well-Known Member

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    Jim, You've said it all, and the most important part is the consistancy. It just can't happen without a good radar gun used as you've described. Shoot often while we can, Bob
     
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