Was the Followup Car Blocking a Shot at Z313?

[Drew Phipps]

The math equations are pretty simple, once you know the shot angle at the respective distances.

variable "SEP" = separation distance from Ready to JFK. Distances are based on published specs for SS-10-X and Caddy Sedan chase car on wiki.
JFK to back bumper = 78"
bumper to bumper = (varies)
front bumper to Ready = 71"

so SEP = 149" plus anywhere from 60" (a motorcycle length, and also the bumper to bumper distance in the SS report for the chase car at the turn) to 300" (roughly a car length). [Any more than this and there is no way that Ready would be in the line of fire.]

Height difference JFK to Ready: Ready: 74" (measured with pixel counting software from info on Caddy specs, Altgens 6, and this picture:



JFK : 53" (based on prior post this thread)

(Height difference = 21 inches)


Shot Height = 53" + Sin (15.3 degrees) * SEP (This angle 15.3 is the slope of the shot)
Ready Height = 74" + sin (3 degrees) * SEP (This angle 3 is the slope of the road)

Where Ready Height => Shot Height you might have a block, so:

1) At sight line distance 268 feet

53 + (sin (15.3) * SEP) <= 74 + (sin (3) * SEP)
53 + (.26 * SEP) <= 74 + (.05 * SEP)
(.21 * SEP) <= 21
SEP <= 100 inches

100 - 78 - 71 = a negative number, so it just cant be possible for Ready to block the shot at 265 feet.

2. At 307 feet sight line distance, you have a shot angle of 13.8 degrees

53+ (sin(13.8)*SEP) <= 74+(sin(3)* SEP)
53+ (.24* SEP) <= 74+ (.05* SEP)
(.19*SEP) <= 21
SEP = 111 inches

Again, 111 - 78 - 71 is negative, so no way for a block there.

[Chris Davidson]

And here are the two shots location per the SS...

4 feet from 5+00 is either 5+04 or 4+96...

WCD298 tells us that Z313 was 262' versus the last shot at 307'. 307-262=45 feet
The legend and the SS statement creates a 39 foot base (5+04 minus 4+65) or a 31 foot base.

From JFK to the front of the limo was about 15 feet
With the adjustment BACK at the top of Elm and forward at the bottom, we have our 30+ feet of difference related to the location of the final shot... (I think that's right, Chris?)

David,

Disregarding WCD298 for now, I believe this is the direct correlation between CE875 and the SS/FBI plat of Feb64, dealing with the Altgens shot.

It appears the measurement was to the street, not JFK'S head on this plat. And, a 3degree slope was used in the calculation.

It would look like this:

Elevation 429.7 = TSBD at street
Plat élévation for last shot at 416.83
Difference = 12.87ft
TSBD window sill= 60.7ft
60.7ft + 12.87ft = 73.57ft
73.57squared x 285squared =294.34hypotenuse = plat entries for shot #3(Altgens)

The 3 degree slope = 5.238% grade = 1ft vertical/19.09ft horizontal ratio
Elevation change at shot#3 = 12.87ft
12.87 x 19.09 = 245.7ft

TSBD = Station# 2+50
2+50 + 245.7ft =Station# 4+95.7 = CE875

chris

[Chris Davidson]

btw,

The angle for the previous post

chris

[Herbert Blenner]

btw,

The angle for the previous post

chris

You are not calculating the "angle." Instead you have calculated the base of the right triangle given the height and an angle.

[Drew Phipps]

I think this is a lot simpler than you guys are making it out to be...Or perhaps you're discussing something so far over my head I don't get it.

If you put SS Ready at the minimum distance he could be at (since closer is better for shot blocking) that distance is 209".

JFK to back bumper = 78"
back bumper to front bumper = 60" (5 feet, based on the image of the motorcycle in Z313)
front bumper to Ready = 71"

78+60+71 = 209"

The distance the bullet drops in 209 inches is either:

209 * sin (15.3) = 55" (This is the angle for sight distance 268 feet)
or
209 * sin (13.8) = 50" (this is the angle for sight distance 307 feet)

If JFK is 53" above the ground (from previous post this thread by Chris Davidson), then the bullet must be a minimum of either 108" inches off the ground (at impact site) when it passes Agent Ready (at sight 268 feet) or 103" off the ground (at impact site) when it passes Agent Ready (at sight 307 feet).

If we give Agent Ready the benefit of his elevation change 209 * sin (3) = 11" that knocks the required height to 97" (at 268) and 92" (at 307). If we further add a generous 12" for the running board Agent Ready is standing on, that brings us to 85" (at 268), which is 7' 1" tall... and 80" (at 307), which is 6' 8" tall.

I don't know how tall Ready really was, but he wasn't either of those heights.