[silence]
So you went to the range with your Labradar unit and you recorded
two shot series. The first one was using a projectile weight of 60 grains and the
second one was for a projectile weight of 160 grains. So you finished, you packed
everything up, you came home, you downloaded the files to your computer
and you started looking at them. You then realize, that for the second shot series
you forgot to change the projectile weight from 60 to 160. So your entire
second series was recorded using the incorrect projectile weight. Does this mean
you need to go back out to the range and rerecord that series? No. In this video
we're going to show you how to correct the data when you accidentally use the
wrong projectile weight. Here I've got the workbook opened. As a quick review,
this will be your Labradar unit's serial number, this is the shot series ..
number, the total number of shots. This is our unit of measure legend.
All velocities are in feet per second. Distances are in yards. Kinetic energy is
in foot-pounds force. Weight is in grains. Now, for the purpose of this video,
I've added these headings because these velocities are the ones for the
distances we set at Dx 1, these for Dx 2, 3, 4 and 5. Now, what I did
on purpose on this series, I intentionally shot the first 19 shots
using a projectile weight of 60. Then I went into preferences and set the
projectile weight to the correct weight of 160. So, for all 29 shots, the bullet
actually weighed 160 grains. But I wanted to show the differences in these numbers
when it changes over from 60 to 160. If you look at velocities [pause]
you see there's really no difference as you transition from 60 to 160.
That's because velocity is dependent on distance, not bullet weight.
Your velocities are going to be just fine! The other set of numbers we have, is kinetic energy
[silence]
As you can see, kinetic energy is just in the double digits, until we hit the 160s
and then it goes into triple digits. So kinetic energy is dependent on
bullet weight. So all these numbers here ... are incorrect, because the bullet weight
was actually 160. Take a look at the third set of numbers, which is power factor.
[silence]
As you can see, power factor here is in the 40s, when the weight was recorded as 60,
but then it jumps up into the low 100's, when the correct weight was used.
So these numbers here ... are incorrect. So these need to be fixed.
So the kinetic energy numbers need to be fixed.
And the power factor numbers need to be fixed. And we're going to see how
to do that. Well, the first thing we're going to do, is for the incorrect kinetic
energy numbers, we're going to highlight them. Then we're going to set the number
of decimal places to zero. Because when we input a formula, it's going to
calculate out however many decimal places there are, and we really don't
need to see that many. So we highlight it > right click it > Format Cells [pause] > Number >
Decimal places > zero. Now we're only going to do this to kinetic energy because we're
going to do something different for power factor. Now we're going to enter in
the formula to give us the correct kinetic energy. As you may recall any
formula in Excel begins with the equal sign. So, on the left hand side you see
the formula we're going to use. Its weight times velocity squared divided by
the constant 4 5 0 4 3 6. Now, at the end of this video, I am going to
explain where I came up with that constant. So, to get weight, we're going to ...
highlight the column and cell that contains the projectile weight. And you
can see in this case it's O18. Now, we're going to take this formula, and
we're going to move it all over this place. So as we move it, we want the
reference to .. velocity .. to change. But for projectile weight, as we move the formula,
while we want the row to change, we do not want the column to change. We always
want it to be column O. So, at this point, we're going to press F4,
and you can see that Excel put a $ in front of the O and a $
in front of the 18. This made this an absolute reference. It won't change as
you copy this formula around. The problem is, we want the column to be absolute but
not the row. So, let's press F4 again. It's still not what we want. So let's press it again.
Now we have it the way we want it. The column is absolute. The row is not.
So we've got our weight now. The formula is times velocity squared.
So we enter an asterisk for multiplication. This kinetic energy is
at distance 0. So we highlight the velocity under V0. Now we have to
square it. Which on my keyboard, is shift number 6, which gives a caret, and then 2.
Okay, that is telling Excel to square the number in the cell B18. Now, we want
to divide it by the constant. Now the division symbol. Then 4 5 0 4 3 6
and then Enter. Okay, now it still that number
68 because we haven't changed the projectile weight. But we're going to do
that in a little bit. So, what we're going to do now is drag this formula across the row
and before I release the mouse, I'm looking at the numbers, and I could see
that one of them changed, but not by much. And that's okay. And then Click+hold
and drag down. And while still holding, kind of look at the numbers and
let go. And some of the numbers changed here, but not by much. That tells me
my formula is pretty good. Now, before we change the projectile weight, let's fix the
power factor formula. Now the document we're looking at is the USPSA rule book
for 2019. And here it is showing you the formula for power factor.
It's bullet weight in grains, times average velocity in feet per second
divided by a 1000. A very simple formula. It says the final result will
ignore all decimal places. In other words, if it calculates 124.9999,
that's not a power factor of 125. It's a power factor of 124.
So, what we're going to do is use the Excel Integer function that strips
away decimal places and wrap it around this formula. So, you click in the power
factor cell. You type the equal sign. Then i n t. That's the integer function.
Parentheses. Now I want to enter in the power factor formula. Which is projectile
weight times velocity. In the Labradar unit, the velocity that is used for the
calculation of power factor is Dx 1. That's in your preferences. You set five
distances. The first one you set is Dx 1. So this is my Dx 1. I get that
velocity and then it's divided by a 1000, and then I close parenthesis
and Enter. All right, let's see how well the formula works. This is 46.98.
So, per the rule book, this is a power factor of 46, not 47.
So, let's make sure this formula gives us 46. And it does.
So, now we're going to go ahead and just drag it down ... all the way.
And if you want to, you can just drag it for the complete set of power factor
numbers. That way you'll get rid of all these decimal places.
Okay, so now we have the correct formulas in for kinetic energy and power factor.
Now we are ready to correct the projectile weight. Which is 160. So I want to
click .. drag it all the way down. So it changes my projectile weight to 160.
Now we have the corrected kinetic energies and power factors for our workbook.
Now, if you watch the other videos or are familiar with the Labradar files, you
know down in the tracking folder. You have all these individual shots.
Do we need to change anything in here? Well, let's take a look. And again it shows your
serial number, the shot series, the shot, the time it was taken, the velocity,
the distance, and the signal-to-noise ratio.
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As you can see, weight is not in here anywhere. Because velocity is not
dependent on projectile weight. So there's nothing to fix in the individual
tracking workbooks. So, at this point, we're done! And for those of you who want to
know where I got the constant 4 5 0 4 3 6, this explains the process where
I came up with it. I won't go into detail, because most people probably are not
interested in all the detail. But for those that are, I suggest you
pause the video. and read through it. And it should, hopefully, explain to you where
I came up with the constant. For everyone else, I hope this video was useful to you,
and thank you for watching.