Vectors (EDR-Momentum)


Overview:  Computes the Resultant vector (Length and Angle) from the Longitudinal and Lateral DeltaV vectors recorded by an Event Data Recorder (EDR).  With additional inputs it can compute V1, V2, V3, and V4.


Entry into Section:


This section of the program is entered by clicking on the REC-TEC block in the upper left of the REC-TEC Window causing the drop-down menu to appear.  Click on Vectors (EDR-Momentum) on the menu to initiate this section.


Data Entry:


This section contains the following data entry blocks within the leftmost frame:


·             Longitudinal DeltaV (X)* - (CDR download)

·             Lateral DeltaV (Y) - (CDR download)

·             PDOF1 (Degrees)* - Computed


·             Angle 2 (Degrees)*

·             V1 Speed* (Checkbox Selected)  - This is available from the EDR.


·             Angle 3 (Degrees)*

·             V3 Speed* (Checkbox Selected) - This is a post-impact computation using either the EDR or other computation.

·             Angle4 (Degrees)* - If V1 or V3 Entry is selected, this becomes

·             Angle Change (A2 to A4) which is the only angular information required if a Speed Entry is made.  The V1/V3 Speed entry


·             Slip Angle (Degrees)* - Angle between the Longitudinal Axis of Vehicle 1 and its Pre-Impact direction of travel

·             Adjustment Angle (Degrees)* (Checkbox Selected) - Does not affect a Speed Entry computation, as they don't use Angles.  If the Speed Entry Checkboxes are both Unchecked, the A3, A3, and A4 information computed by the program appears in the Angle boxes. 


         This Angle information may not be correct and will make the Impact and           Post Impact Speed information for Vehicle 2 incorrect.  The Adjustment                                                                                                         Angle can be used to look at various solutions to the problem as it changes         both A2 and A4 maintaining the input angular difference between the angles.               It is strongly recommended that the angles remain in the Cone of Departure          unless there is a compelling reason to deviate from this.  



·             Weight (1)*

·             Weight (2)*


Longitudinal and Lateral DeltaV inputs compute a Resultant DeltaV and Angle.


Inputs marked with Asterisks (*) compute DV1, DV2, V1, V2, V3, V4 speeds without the need for momentum computations using the Law of Sines, the Law of Cosines and Newton’s Third Law to solve for the resultant DeltaV and then the pre- and post-impact speeds of both vehicles in the collision.




There are several graphical outputs this module can display. Using the Checkboxes next to the DV1 and DV2 answers on the Graphics screen toggles a Graphical display with Data for that computation.  The graphic shows the individual Longitudinal and Lateral velocities along with the resultant DeltaV showing both the angle and length. 


If enough information is supplied, the pre- and post-impact speeds of both vehicles in the collision are computed and a Momentum Diagram is shown on the Screen.  This Diagram is shown in two different formats which can be toggled using the right mouse button which redraws the screen.  This offers a cross check on Linear Momentum computations.




Several Command Buttons appear in a frame located at the lower right corner of the section Window.  The Command Buttons allow the user to engage options including the option to Open and Save the data required to generate the scenario shown on the screen at the time the file was saved. 


·             Open .VEC File – Calls up a Dialog box, which Opens any pre-existing .VEC file and displays the output results.


·             Save .VEC File – Calls up a Dialog box, which Saves data on the screen to files with any user-selectable filenames.  This is independent of the automatic saving as “LastFile.VEC” of the data at the close of this module or the close of the program.


·             Formulae* – Toggles displaying the interactive formulae for computing the unknowns in this module.  In addition to the basic formulae, the frame shows the actual input data shown in the computation.


·             Graphics – Multiple Graphics Displays (See Options supra.



·             N – This button toggles a graphical number pad on the screen that can be used to enter data into the input boxes without using your keyboard number pad.  This may be useful for presentations as data entry can be accomplished using a wired/wireless mouse.


·             Iteration / FDA  – Calls up a frame that permits the user to input the minimum and maximum values for selected input variables along with the interval for Iteration.  If Finite Difference Analysis (FDA) is selected, the resulting analysis computes the uncertainty level for the specified range of the input variables.


For a more in-depth description of Finite Difference Analysis, see the Finite Difference Analysis Section of this Manual – Press [F2] from any Active module of the program.