Angular Movement of the Rifle

[Gerry Down]

As Oswald shot at JFK, he had to continuously adjust his aim to match the moving limo. I've heard that for the first shot to be at around Z150, the angular movement of Oswalds rifle to match the movement of the limo is about 5 to 6 degrees. For the second shot, it was 1.8 degrees per second. For the third, it was 0.7 degrees per second.

Does anyone have a source for these calculations?

[Dan O'meara]

As Oswald shot at JFK, he had to continuously adjust his aim to match the moving limo. I've heard that for the first shot to be at around Z150, the angular movement of Oswalds rifle to match the movement of the limo is about 5 to 6 degrees. For the second shot, it was 1.8 degrees per second. For the third, it was 0.7 degrees per second.

Does anyone have a source for these calculations?

It doesn't matter as there is overwhelming evidence the first shot was way after z150 (re: "The First Shot" thread)

[John Iacoletti]

“As Oswald shot at JFK”. LOL.

[Joe Elliott]

I believe the source was me. My main writing on this is here:

https://www.jfkassassinationforum.com/index.php/topic,2640.msg93376.html#msg93376

with my initial July 9, 2020 post.

I have modified my earlier estimates a bit, based on my realization that the limousine was moving slower than I thought at z153. My current estimate on the angular velocity for the three shots is:

z-153   4.8 degrees per second
z-222   1.9 degrees per second
z-312   0.58 degrees per second

and for a hypothetical shot from the grassy knoll:

z-312   5.1 degrees per second

I am very confident in my math. I used two methods to make these calculations. Exact trigonometry calculations. And calculations based on seeing the change in the angles after letting the car run for a millisecond, to see how much the angle changed in a millisecond, giving the average angular velocity during that millisecond. And both methods give about the same answer.

However, I’m not an expert at examining film. And the measurements of the angles, both horizontal and vertical, and the speed of the limousine for each shot, are solely base on my estimates from looking at maps and individual frames of the Zapruder film.

[Gerry Down]

I believe the source was me. My main writing on this is here:

https://www.jfkassassinationforum.com/index.php/topic,2640.msg93376.html#msg93376

with my initial July 9, 2020 post.

I have modified my earlier estimates a bit, based on my realization that the limousine was moving slower than I thought at z153. My current estimate on the angular velocity for the three shots is:

z-153   4.8 degrees per second
z-222   1.9 degrees per second
z-312   0.58 degrees per second

and for a hypothetical shot from the grassy knoll:

z-312   5.1 degrees per second

I am very confident in my math. I used two methods to make these calculations. Exact trigonometry calculations. And calculations based on seeing the change in the angles after letting the car run for a millisecond, to see how much the angle changed in a millisecond, giving the average angular velocity during that millisecond. And both methods give about the same answer.

However, I’m not an expert at examining film. And the measurements of the angles, both horizontal and vertical, and the speed of the limousine for each shot, are solely base on my estimates from looking at maps and individual frames of the Zapruder film.

Thanks. How many degrees per second at z133 from the snipers nest does this come out at?

[Joe Elliott]

It would take some work for me to estimate the angles, distances and speed for z133. The speed is particularly difficult. If the camera started filming at z110, I would have a better idea of the speed at z133. Getting an estimate for the very beginning or end of the Zapruder film is a little tricky.

But there was enough distance from the sharp corner that I think the limousine probably got up to 10 mph by z133, the same speed as at z153. Apparently, a good motorcade speed when on a fairly straight road with still a good crowd on either side of the road, and you want to give the people a good look.

The angles and distances I got from some estimate I made about 15 years ago. I think those estimates are off some, but they would be roughly right. So here are my estimates

(theta) difference between the horizontal direction of travel of the limousine and the horizontal bearing from the shooter, I make as 31 degrees.
(delta) the vertical angle the shooter is looking down onto the target, I make as 32 degrees.
(gamma) the vertical angle the limousine is traveling down at, I assume is the average slope of Elm Street, 3 degrees.
V, the velocity of the limousine, I make as 10 mph, or 14.7 feet per second.
R, the 3D distance from the shooter to the limousine, I make as 119 feet.

So, when I plug in these numbers into my formula, I get 4.6 degrees per second.

This estimate makes sense. Certainly, the angular velocity of the target would be at its highest at z133, then would generally get less and less through z345, as the angles get smaller, and the distance gets larger (which lowers the angular velocity of the target).

As a caveat, my estimate at z133 of 4.6 degrees per second, is probably less accurate than my estimates for z153, z222 and z312, where I spent more time making accurate estimates, as much as my ability will allow in a reasonable amount of time. But still, I think it is a reasonably good estimate, to within about 0.3 degrees per second of error, I would guess.