The Motorcade Puzzle

[Joseph McBride]

The part of Vaughan's breakdown that states Secret Service

Agent Rufus Youngblood jumped over the seat to protect LBJ with his body is inaccurate. See my interview

with Sen. Ralph Yarborough in INTO THE NIGHTMARE for the accurate account.

 

 

[Mark Tyler]

20 hours ago, John Butler said:

Mark,

I would like to make a few suggestions to you. 

1.  First, a technical issue or two.  Place the time clock just directly above where it is at and this would put it on Main Street.  Keep the motorcade progress bar active and viewable all the time.  This would separate the two and help stop the simulation for better viewing as a stopped frame.  I know the location of the various photographers, but I would think it would help to briefly show the name of the photographer in the lighted area shown.

Thanks for taking the time to study my work John.  I am thinking about moving the clock and possibly rejigging the map view to be slightly different.  I shall experiment a little over the next week or two and see what works best.  Its a tricky job though, as I want to keep all of the most important actors in view at all times.

I think the best way to watch the Vimeo video is maximised and then to start and stop it using the spacebar.  This way the clock becomes more visible as the progress bar centralises itself.

[Mark Tyler]

20 hours ago, John Butler said:

2.  You need to show the Pilot Car.  You don't show this vehicle ahead of the Advance Motorcycles.  It is not necessary to show the Advance Car this turned from Main St. onto Market St. and left the motorcade.  See AMIPA film.

Just for reference here is the AMIPA film:

It does indeed seem to show the advance car and the pilot car.  However, I'm not sure this is near Dealey Plaza because when the Presidential Limo makes its turn at 0:36-0:40 its not turning onto Houston Street, so I would deduce that its much further back in the motorcade route.

The reason I didn't include the two cars ahead of the 3 advanced bikes is that I couldn't find any photos or films of them in Dealey Plaza.  All of the other bikes, cars and buses, have photographic proof of being in Dealey Plaza so I included them.  If any evidence regarding them being in Dealey Plaza appears then I would be happy to put them into the animation, but I do want to avoid making any assumptions just in case they are wrong.

[Mark Tyler]

20 hours ago, John Butler said:

3.  You mix up the 3 Advance Motorcycles and the 5 Lead Motorcycles.  The 3 Advance Motorcycles do not have two Lead Motorcycles trailing directly behind them.  There is considerable distance between the two units.  If you analyze the time of the Zapruder Gap you will understand this.

I'm not sure I agree with this.  If you check my technical reference handbook here:

https://www.marktyler.org/mc63/mc63_handbook.pdf

If you look at section 4.1.1 you will see some frames from the Muchmore film where the 3 advanced bikes start and end their turn onto Houston St.  Just as the 3 bikes are completing this turn the 2 bikes behind them are starting the turn.  This gap is roughly the same when the 3 advanced bikes come onto Elm Street because when Moorman snaps here Polaroid (see appendix 3) we don't see the 2 trailing bikes so the gap must have been roughly the same.

[Mark Tyler]

20 hours ago, John Butler said:

4.  You don't show Glen McBride stopping to allow Mary Moorman to take a photo of him.  He gets separated from the others briefly. 

I don't think McBride stopped for this photo.  If you look at the Moorman 3 photo McBride is cruising down Elm with no feet on the ground.  Do you have a reference for him stopping?

[Mark Tyler]

20 hours ago, John Butler said:

5.  I would have to check on this, but I believe that not all of the Lead and Advance motorbikes left Dealey Plaza.

If you do find this out please let me know.  If you check the Bell film as the Presidential Limo leaves under the bridge you will see the 3 lead bikes just visible in the distance:

https://www.jfkassassinationgallery.com/displayimage.php?pid=1461&fullsize=1

Then in the McIntire photo (appendix D.11 in the handbook) we see the same 3 bikes turning onto the Stemmons Freeway ramp and there is no sign of any other bikes other than Martin and Chaney under the bridge:

https://www.jfkassassinationgallery.com/displayimage.php?pid=149&fullsize=1

[Mark Tyler]

20 hours ago, John Butler said:

6.  The wide turn onto Elm St. by the P. Limo was witnessed by many as is generally accepted as having happened.

If you can give me references for which witnesses reported this I will have a look.  Roy Truly reported a wide turn, and I mention this in section 8.1 of the handbook but I haven't yet found any other witnesses supporting this.

[Mark Tyler]

20 hours ago, John Butler said:

7.  You don't show part of the motorcade stopping for a brief time.  Mrs. Earle Cabell and Dave Wiegman indicate the motorcade stopped as Mrs. Cabell's vehicle turned into the intersection.  Mrs. Cabell and the car following her were released, but the Camera Cars were stopped for a longer period of time.

The stopping of the motorcade is visible in the video at about 1:30 in the video.  If you check appendix D.10 of the handbook you will see an animation frame for when the Mayor's car and the National Press Pool car stopped (with the rest of the motorcade behind stopping soon after).  As you say the Camera Cars stopped for a longer period of time causing the rest of the motorcade to back up and come to a standstill.

[Mark Tyler]

21 hours ago, John Butler said:

8.  The Camera Cars stop briefly to pick up Dave Weigman.  Other forum members estimate there is 29 seconds difference between the stop and movement of Mrs. Cabell's vehicle and the starting of the Camera Cars off Houston Street unto Ellm.

Hope this helps.

If you look at appendix D.13 of the handbook there are 2 frames from the Atkins film showing Wiegman running back to the car.  As per the Paschall film I don't think that Camera Car #1 ever stops, it simply moves extremely slowly with the other cars overtaking it, until it reaches the bridge when it speeds up.

Thanks for the detailed points John, keep up the fact checking and we can iron out all of the issues!

[Mark Tyler]

20 hours ago, Robert Burrows said:

At the beginning of the Zapruder film, three motorcycles are seen turning onto Elm Street, two on the left side of the frame, one on the right. The motorcycle on the far left appears to go straight down the dead end street that runs in front of the Texas School Book Depository, while the other two proceed down Elm Street. I've never seen this discussed and, as far as I can see, it is not reflected in the ariel reconstruction. 

Thanks for the tip Robert.  I viewed the Zapruder film again, and it does look like the bike disappears on the left hand frame.  However, I think this may be an optical illusion because if you look at Zapruder frame 131 (just before it cuts) you see the bike starting to reappear from behind the tree.

Here is a link to show you what I mean:

https://www.assassinationresearch.com/zfilm/z131.jpg

Rather like the Algens 6 photo, the Zapruder camera angle of that corner is highly deceptive as it compresses the long distance up Elm Street.  By contrast the shorter distance across the corner looks much longer by visual comparison, but it isn't, so it tricks the eye regarding the speed and angles of the turning bikes and cars.

[Mark Tyler]

15 hours ago, Chris Davidson said:

Mark,

The mayors car apparently would have been just out of view in Altgens 6.

Somewhere between the green arrows. imo

Altgens z255- z180 = 75/18.3 = 4.09 sec.

The distance traveled from the mayors car front end(you can draw a LOS from Z's pedestal touching the circular wall edge and on through Houston & Elm St) that we see in z180 to Wiegman's beginning is approx 57ft (65ft - 1/2 mayors car length=(8ft).

57/4.09sec = 13.93ft per sec = 9.48mph.

If you plot JFK within the limo in Towner (using 18.3fps as a true rate) over the approx same span as the mayors car from z180-z255, the average speed is 8.82mph.

This would indicate the motorcade increased (minimally) the speed through the Elm St turn vs the limo.

 

I agree Chris, the Presidential Limo took the corner slightly more slowly than the other vehicles behind it.  As you say, its fairly minimal, so its good to see that our measurements roughly agree!

[Andrej Stancak]

Mark:

congratulations on your elaborate model, I find it very useful. I have two questions: 1. You do not seem to include slowing down (stopping) of the President's limo? I assume it is hard as there are no accurate data on that part of Zapruder film. Some frames are surely missing in Zapruder film, and this may confound the speed estimates. 2. The other question is something I could perhaps verify myself using your model, anyway, I would be grateful if you would provide an estimate. It refers to the time elapsing between the instant when Hughes filmed the President's limo just in front of the Depository doorway and the time when the doorway first appeared in Wiegman film. Thanks.

[Chris Davidson]

4 hours ago, Mark Tyler said:

I agree Chris, the Presidential Limo took the corner slightly more slowly than the other vehicles behind it.  As you say, its fairly minimal, so its good to see that our measurements roughly agree!

Mark,

One of the most important elements in a study such as yours is the inclusion of distance traveled. imo

The following is an example:

I have layered two frames from your study: z133.4 -z161.4 = 28 frames

Your mph designation for this span has the limo travel from 8.5mph (slowest) to 9.6mph (fastest).

This would equal an average of 9.05mph.

I've included Sprague's plotting for Z133 which I confirmed via my own plotting at Station# 2+99.0

WC CE884 plotted Z161 at Station# 3+29.2

The distance for these 28 frames = 329.2 - 299 = 30.2ft

You used 18.3fps as the frame rate for the extant Zfilm.

28/18.3 = 1.53 seconds.

30.2ft/1.53 seconds = 19.738ft per sec /1.47 (1mph-rounded off) = 13.427mph

At 9.05mph x 1.47ft per sec = 13.30ft per sec x 1.53 sec = 20.35ft traveled.

30.2ft - 20.35ft = 9.85ft distance traveled unaccounted for because of the difference in the vehicle speeds.

If you wanted to fix this in terms of a different frame rate for the extant Z film, approx 41.55fps would work.

 

 

 

 

 

[Robert Burrows]

8 hours ago, Mark Tyler said:

Thanks for the tip Robert.  I viewed the Zapruder film again, and it does look like the bike disappears on the left hand frame.  However, I think this may be an optical illusion because if you look at Zapruder frame 131 (just before it cuts) you see the bike starting to reappear from behind the tree.

Here is a link to show you what I mean:

https://www.assassinationresearch.com/zfilm/z131.jpg

Rather like the Algens 6 photo, the Zapruder camera angle of that corner is highly deceptive as it compresses the long distance up Elm Street.  By contrast the shorter distance across the corner looks much longer by visual comparison, but it isn't, so it tricks the eye regarding the speed and angles of the turning bikes and cars.

I've placed an x under the motorcycle that proceeds in front of the T.S.B.D. 

If you study the next few frames you can see the white portion of the motorcycle disappear behind the leaves of the tree that blocks view of the dead end street.

 

[Mark Tyler]

17 hours ago, Andrej Stancak said:

Mark:

congratulations on your elaborate model, I find it very useful. I have two questions: 1. You do not seem to include slowing down (stopping) of the President's limo? I assume it is hard as there are no accurate data on that part of Zapruder film. Some frames are surely missing in Zapruder film, and this may confound the speed estimates. 2. The other question is something I could perhaps verify myself using your model, anyway, I would be grateful if you would provide an estimate. It refers to the time elapsing between the instant when Hughes filmed the President's limo just in front of the Depository doorway and the time when the doorway first appeared in Wiegman film. Thanks.

To answer your two questions Andrej:

1. I have the Limo slowing down from about 13 MPH at Z245 to about 7 MPH at Z313, which is less than 4 seconds later which I presume is the result of gentle braking after the first shot.  As I recall there was a frame or two of the Muchmore film around Z313 that suggests a brake light was lit while Clint Hill was running to the Limo (sadly the brake lights were mostly obscured by people and bikes so we can't be certain of the exact braking times, plus the Muchmore film started around Z280-Z285 so misses the early braking).  You can see the result of the Z313 braking in the Zapruder film as the bikes catch up Z313-Z334 before the Limo accelerates away and the bikes stop.

2. The Presidential Limo passed the front of the TSBD (from the Hughes film view) at around the clock time of 12:29:45, with the Wiegman film start time of 12:29:59, so the gap was about 14 seconds.

On the subject of Zapruder and Wiegman, I did go into some detail in the animation handbook regarding how you can synchronize the two in terms of frame rates.  It is in appendix C here:

https://www.marktyler.org/mc63/mc63_handbook.pdf