Math Made Easy

[Chris Davidson]

If you take a look at CE884, you'll notice Frame number A has no Station number but does have an Elevation of 431.97

Frame 161 has a Station number of 3+29.2 and an Elevation of 429.25.

Compared to each other, 431.97-429.25=2.72 elevation difference.

Look down at the bottom of the column at frames 255 and 313.

The difference in frame count is 58, and the difference in Elevation is 424.46-421.75=2.71 elevation difference

The elevation change is almost exact.

What if the frame difference is the same.

Then, frame 161-58 frames =frame 103.

So, Position A is around frame 103.

Refer back to my partial plat labeling.

Since there was an approx 4 ft adjustment made for (frames 161-166) an educated guess puts Position A as approx frame 100.

In the past, I have posted my conversions for the original WC CE884 document.

If interested, I can repost with explanations, but I believe the previous description is easy to understand.

chris

Edited February 27, 2012 by Chris Davidson

[James R Gordon]

In the past, I have posted my conversions for the original WC CE884 document.

If interested, I can repost with explanations, but I believe the previous description is easy to understand.

chris

Chris,

Speaking for myself that would be helpful. It is clear you fully understand what you are saying, but quite often I have no idea what you are saying.

Earlier, you showed a portion of the Drommer plat with your annotations. If that that plat is completed annotated, posting that would also help. It would provide a reference to refer your figures back to.

I am sure others follow very easily. but I am finding it very difficult and these kinds of support would certainly help.

James.

[Chris Davidson]

James,

This is a link to my converted WC CE884 document.

http://i140.photobucket.com/albums/r25/123steamn/WC884.jpg

My calculations are in red. The original on the left, mine on the right.

The partial plat I supplied is all that I am using at this time.

Everything I have discussed can be applied back to it. It is not fully annotated as I'm only dealing with the space from the TSBD corner to Zframe 161.

Any specific questions please ask.

chris

[Chris Davidson]

If you take a look at CE884, you'll notice Frame number A has no Station number but does have an Elevation of 431.97

Frame 161 has a Station number of 3+29.2 and an Elevation of 429.25.

Compared to each other, 431.97-429.25=2.72 elevation difference.

Look down at the bottom of the column at frames 255 and 313.

The difference in frame count is 58, and the difference in Elevation is 424.46-421.75=2.71 elevation difference

The elevation change is almost exact.

What if the frame difference is the same.

Then, frame 161-58 frames =frame 103.

So, Position A is around frame 103.

Refer back to my partial plat labeling.

Since there was an approx 4 ft adjustment made for (frames 161-166) an educated guess puts Position A as approx frame 100.

In the past, I have posted my conversions for the original WC CE884 document.

If interested, I can repost with explanations, but I believe the previous description is easy to understand.

chris

If you refer back to WC CE884, you'll notice the specs for frame 161-313 are 152 frames @136.1ft traveled @18.3 fps.

And for frames 255-313 they are 58 frames @ 48.9ft @18.3 fps.

I stated previously that I believe Station A, elevation 2+75 and Drommer 99.5 elevation are the same spot. Why?

152 frames @136.1ft traveled @18.3 fps=11.14mph

58 frames @ 48.9ft @18.3 fps = 10.49 mph

These don't quite equal each other but they probably should.

Remember there is an incorrect travel distance stated for frame 161-166.

If you notice the next 2 entries, 166-185=19ft traveled, that works out to a 1ft per frame.

So, if I apply that to the (161-166) frame span, that is 3 frames needed (58-61) at 3ft.

Plugging this back in to the previous equation looks like this:

58frames @ 48.9ft + 3ft =51.9ft @18.3 fps

58/18.3fps =3.169 sec.

51.9 ft/3.169sec =16.377ft per sec.

16.377ft per sec / 1.47ft(1mph) =11.14mph

BINGO

Yes, those 3 positions are very close if not the exact same position.

Interesting how you can smooth things out over long intervals, as opposed to short steps.

chris

[Chris Davidson]

Frame 100 = Drommer 99.5 = 2+75 = Position A (with 161-166 distance correction included)

JFK aligned with the TSBD corner is frame1.

I have added 3 vertical green and 1 vertical red line to the partial plat.

The green lines intersect the TSBD, Drommer 99.5 and 30ft farther down Elm.

The distance between the TSBD green line and Drommer 99.5 is 30ft.

The distance between Drommer 99.5 and "farthest left" green line is 30ft.

So the distance from TSBD green line to "farthest left" green line is 60ft.

The red vertical line is the front of the limo (15ft farther down Elm than "JFK in the limo") =extant Z133.

Frame 1 -100 is 30ft.

Mathtime:

100/18.3fps=5.46 sec

30ft/5.46sec=5.49ft per sec

5.49/1.47ft per sec(mph)=3.737mph

The WC is doing calculations based on the limo between the TSBD corner and Drommer 99.5/2+75elevation/Position A

It is based on the limo traveling 30ft in 100 frames at 18.3fps=3.74mph.

If you look at the chart supplied again in the top column . far right side, you'll find a match.

The reality is, this document reflects calculations done to eliminate a distance of 30ft within the overall span from the "corner of the TSBD to the extant Z133 frame.

Please note that the frame numbers corresponding to the 3.74 mph entry are 168-171.

Just subtract 100 frames and this puts you at frame 68-71 which would land in between frame 1-100 when applied to the span between the TSBD and Drommer 99.5 = 2+75 = Position A (with 161-166 distance correction included)

Which also coincides with the area in which Myer's changes his measuring stick from "JFK in the limo" to the "front of the limo" to accommodate a 30ft distance change.

Now, how many total frames in the Towner movie, I believe that to be 168. So if I wanted to be clear of any timing references to that movie, I might start just as it has ended.

chris

Edited February 28, 2012 by Chris Davidson

[Chris Davidson]

Refer back to the previous greenline plat.

The distance from the "far left" green line to Drommer 99.5(middle green line) is 30ft.

If I wanted this to coincide with the extant Zfilm frame 133 at the appropriate limo speed, and end in the correct position, then this has to be 33 frames traveled in 30ft.

Remember, Drommer 99.5 is frame100.

Mathtime:

33frames/18.3fps=1.80sec

30ft/1.80sec=16.66ft per sec

16.66/1.47ft per sec(1mph)=11.33mph

What was the average speed of the limo reported by the WC from frames 161-313. It was 11.2 mph I believe.

The difference is less than a frame when added back to the 33frames/30ft scenario.

If this is correct, then the "front of the limo" at Z133 should correspond to the red vertical line and "JFK in the limo" 15ft farther back, which is the far left green vertical line. (Z133 Previously supplied)

This is how you hide 30ft in a short span when applying it to an overall larger span.

chris

[Chris Davidson]

By the way, referring to the green line plat, if you want an equation for the total distance from TSBD corner to extant Z133 it would be:

133 frames/18.3fps=7.26sec

60ft/7.26sec=8.26ft per sec

8.26/1.47(1mph)=5.62 mph

Can't have that as part of the scenario.

So it was buried.

chris

Edited February 28, 2012 by Chris Davidson

[Thomas H. Purvis]

By the way, referring to the green line plat, if you want an equation for the total distance from TSBD corner to extant Z133 it would be:

133 frames/18.3fps=7.26sec

60ft/7.26sec=8.26ft per sec

8.26/1.47(1mph)=5.62 mph

Can't have that as part of the scenario.

So it was buried.

chris

Chris!

In event that you would like me to go back and refence the survey notes, I can give the "surveyed in" elevation for each of the Zfilm frames listed on CE884.

Perhaps the "double-check" may serve some purpose.

Tom

P.S. Not unlike much of the "vehicle speed" and other mathmatic calculations, only those who have lived with this stuff will appreciate what you are actually making attempt to demonstrate.

[Chris Davidson]

Hi Tom,

Thank you for the CE884 offer.

I would love to see the "surveyed in" elevations.

You can email them if you prefer.

chris

P.S.

Do you remember who's testimony alluded to "frame 100", I believe it was you who supplied it and commented that someone had almost let the "cat out of the bag".

I thought it was Shaneyfelt, but he only refers to "frame1".

Or am I getting the two confused?

[Chris Davidson]

There is overlap between Zone1 and Zone2. Refer back to my first post about splitting the film into 4 zones.

I'll now start working with Zone2 (frame161-322) in particular frame161-313 as this is the span dealt with on WC CE884, with some overlap info referring back to Zone1.

Remember, 6.5sec x 24fps=156 frames or 156/24=6.5 sec.=splice+5frames =161

If you followed some of the previous zone info, you know at some point Myer's switched his measuring point from "JFK'S position in the limo" to "the front of the limo".

When he did this along with his syncing, he had JFK some 30ft farther back up Elm St than where he should have been, at what he determined to be Z150 which is approx 82ft traveled in 6.5seconds from the TSBD corner to that point without the WC adjustment included.

But there is an adjustment to be made created by the WC. In 5 frames (161-166) they shorten the distance the limo traveled.

The next closest entry to the (161-166) span is (166-185) which is 19frames in 19ft traveled=1ft per frame.

If you apply that to (161-166) it = 5 frames in 5ft.

So Myer's at Z155=82ft-5ft adjustment=77ft

77FT/6.5seconds=11.84/1.47=8.05 mph in 155frames

Remember, 6.5sec x 24fps=156 frames or 156/24=6.5 sec.

If you haven't noticed yet, the two zones at this time, consist of 2 frame totals that are very close.

It's as if we're working with like quantities over 2 zones.

If someone wanted to hide film changes pertaining to distances, elapsed frames and time, in regards to "JFK's position in the limo and the front of the car" having a stabilized landmark such as the Stemmon's sign wouldn't be very helpful.

The gif is a measurement between those 2 points from the extant film.

13 frames in 15ft

18.3fps/13=1.4

1.4x15ft=21.1ft per sec

21.1/1.47=14.35mph

21.1ft x 6.5 sec=137.15ft

CE884 frame 161-313 = 136.1 ft traveled

Frame difference between Myers and extant film = 1 frame

21.1ft x 6.5 sec=137.15ft

CE884 frame 161-313 = 136.1 ft traveled

Foot difference =1ft

From above:

8.05 mph in 155 frames

14.35 mph in 152 frames

Averaged out =

22.4mph/2=11.2mph

11.2 mph =16.46 ft per sec.

14.35mph=21.1ft per sec.

Difference between the two is:

4.64 ft per sec x 6.5 sec = 30.16 ft.

Remember, 6.5sec x 24fps=156 frames or 156/24=6.5 sec.

chris

[Thomas H. Purvis]

Hi Tom,

Thank you for the CE884 offer.

I would love to see the "surveyed in" elevations.

You can email them if you prefer.

chris

P.S.

Do you remember who's testimony alluded to "frame 100", I believe it was you who supplied it and commented that someone had almost let the "cat out of the bag".

I thought it was Shaneyfelt, but he only refers to "frame1".

Or am I getting the two confused?

I will go back and pull the West Survey notes and get to you the street elevation for the actual (correct) frams of the Z-film that Mr. West was directed to survey in.

Tom

P.S. The Z100 comment has nothing to do with the Altgens re-enactment photo.