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Posted 8 Apr 2010

# Vehicle Casualty Recovery Calculation

, 8 Apr 2010
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This software calculates the recovery requirement for a bogged down vehicle.

Figure 1: The input window

## Source of Motivation

Various questions were the source of motivation for development of this project. Among them were:

1. On what factors does the recovery of vehicle depend?
2. When and what all is required to recover any vehicle (tools, accessories, ropes and recovery vehicle)?
3. How are the terms, load resistance, ground factor and terrain dependent on recovery of vehicles?

While addressing the answer to these questions, I was able to develop an application which is capable of solving recovery related problems and propose the user with a suitable solution.

## Introduction

This software enables the very simple and interactive way to calculate the recovery resources required to recover a bogged down vehicle. The factors upon which any recovery calculation depend, include:

1. Rolling Resistance or simply RR, (related to the rolling of tires of the casualty/bogged down vehicle)
2. Gradient Resistance or GR (related to the angle or slope at which the recovery force is to be applied)
It is noteworthy that when the direction of application of force is greater than 45 degrees, the GR will become equal to the weight of the casualty. Or in other words, the lift is in action.
3. Damage Resistance or DR (while the application of force of recovery) - The variety of vehicles capable of recovering the vehicles is also included.
4. Additional Resistance or AR (any other factor that might include the recovery force magnitude)
5. Ground Factor or GF (type of ground where the casualty is bogged down, e.g., more force will be applied to recover a vehicle in muddy surface than a grassy ground and vice versa)

The user or recovery vehicle operator puts in these values and gets the output.

Figure 2: The Output Window

## Various Calculations

Rolling Resistance (RR) = Weight of the casualty/Ground Factor;

1. For Angle (0-45) degrees

(Weight of Casualty x angle )/60;

2. For Angle greater than 45 degrees.

(weight of casualty x 60)/60; (i.e.; GR = weight of Casualty)

Draw Bar Pull (DBP) = Rolling resistance + Gradient Resistance + Damage Resistance + Additional Resistance.

Safety Factor(SF) = DBP/4;

Estimated Pull (EP) = DBP + SF;

Mechanical Advantage (MA) = EP/Applied Pull or Recovery force available.

Figure 3: Tackle Layout (Pictorial Representation)

Tackle Layout shows the pictorial representation of recovery operation, i.e.; how the layout is to be made while performing the required recovery.

Figure 4: List of some notable recovery appliances used in the field.

There are a number of tools which are required in successful completion of recovery operation. I have just included a few (just to develop an understanding of how and when the requisite tool is required) in my application.

## The Code

The code that I have implemented is pretty simple.

```// Main Program Loading
public partial class Form1 : Form
{
double a, b, gf, grad, rr, gr, dr, ar, dbp, sf, ep, ma;// assigning the variables
public Form1()
{
InitializeComponent();
pictureBox1.ImageLocation = Application.StartupPath +
other1.Visible = false;
other1.Text = "";
Other2.Visible = false;
}
//Defining the Type of Casualty
private void Casualty_SelectedIndexChanged(object sender, EventArgs e)
{
if (Casualty.Text == "Jeep")
a = 1;
else if (Casualty.Text == "3/4 Ton Vehicles")
a = 3;
else if (Casualty.Text == "2-1/2 Ton Vehicles")
a = 6;
else if (Casualty.Text == "5 Ton Recovery Vehicles")
a = 18;
else if (Casualty.Text == "Tank M-48A5")
a = 48;
else if (Casualty.Text == "Tank T-59M")
a = 36;
else if (Casualty.Text == "Tank T-69IIM")
a = 36.7;
else if (Casualty.Text == "Tank T-85IIAP")
a = 44;
else if (Casualty.Text == "Tank T-80UD")
a = 46;
else if (Casualty.Text == "Tank Centurion")
a = 52;
else if (Casualty.Text == "SP M-109A2/M 110A2")
a = 46;
else if (Casualty.Text == "Other")
{
other1.Visible = true; //for assigning the user based casualty
}
}
//Defining the Type of Recovery available
private void Recovery_Veh_SelectedIndexChanged(object sender, EventArgs e)
{
if (Recovery_Veh.Text == "Truck Wrecker M-816")
b = 22.5;
else if (Recovery_Veh.Text == "Tatra AV-8")
b = 25;
else if (Recovery_Veh.Text == "Truck Wrecker FIAT 90.17WM")
b = 6;
else if (Recovery_Veh.Text == "ARV M-88A1")
b = 45;
else if (Recovery_Veh.Text == "ARV W-653")
b = 35;
else if (Recovery_Veh.Text == "Towing Tractor T-59")
b = 22.5;
else if (Recovery_Veh.Text == "2-1/2 Ton Vehicle")
b = 5;
else if (Recovery_Veh.Text == "Truck Wrecker IVECO 140E24W")
b = 7.5;
else if (Recovery_Veh.Text == "Other")//for user assignment
Other2.Visible = true;
}
//Defining the Type of Ground Factor
private void comboBox3_SelectedIndexChanged(object sender, EventArgs e)
{
gf = 25;
else if (comboBox3.Text == "Grass")
gf = 7;
else if (comboBox3.Text == "Gravel")
gf = 5;
else if (comboBox3.Text == "Soft Sand")
gf = 4;
else if (comboBox3.Text == "Loose Dry Sand")
gf = 4;
else if (comboBox3.Text == "Shallow Mud")
gf = 3;
else if (comboBox3.Text == "Wet Sand")
gf = 3;
else if (comboBox3.Text == "Mud")
gf = 3;
else if (comboBox3.Text == "Soft Clay and Sand")
gf = 2;
else if (comboBox3.Text == "Clay with Sand")
gf = 2;
else if (comboBox3.Text == "Deep Mud")
gf = 2;
}
//Performing calculations
private void btnCal_Click(object sender, EventArgs e)
{
try
{
{
rr = a / gf; //rolling resistance = weight of casualty/ground factor
textBox1.Text += string.Format("{0:0.0}", rr);

if (textBoxDR.Text == "")
dr = 0; //damage resistance
else
dr = double.Parse(textBoxDR.Text);
if (textBoxAR.Text == "")
else
ar = double.Parse(textBoxAR.Text);
{
MessageBox.Show("Invalid entry for Value of Gradient\n\n
(Enter any value from 0 to 90 Degrees)");
}

else
{
{
}
else
gr = a;
}
textBoxGR.Text += string.Format("{0:0.0}", gr);

dbp = rr + gr + ar + dr; //draw bar pull = rolling resistance +
textBoxDBP.Text += string.Format("{0:0.0}", dbp);

sf = dbp / 4; //safety factor = draw bar pull/4 (formula)
textBoxSF.Text += string.Format("{0:0.0}", sf);

ep = dbp + sf; //estimated pull = draw bar pull + safety factor
textBoxEP.Text += string.Format("{0:0.0}", ep);

ma = ep / b; 	//mechanical advantage =
//estimated pull/recovery vehicle available
double tt = 0;//for selection of tackle layout figure.
for (double ab = 0; ab < 10; ab++)//can support upto 9:1 tackle layout
{
if (ab > ma)
{
tt = ab;
ab = 80;// just to break the loop
textBoxMA.Text += string.Format("{0:0}", tt);
}
}

double t = 0;
for (double ab = 0; ab < 8; ab++)
{
if (ab > ma)
{
t = ab;
textBox2.Text += t + " : 1";//selection of image for
//tackle layout
ab = 8;
pictureBox1.ImageLocation = Application.StartupPath +
"\\" + t + ".jpg";
}
}
}
else
{
Gradient\n \n Help! (From 0 to 90 Degrees)");
}
}
catch (Exception ex)
{
MessageBox.Show("Error: " + ex.Message);
}
}
private void button2_Click(object sender, EventArgs e)//refresh
{
textBox1.Text = "";
textBox2.Text = "";
textBoxAR.Text = "";
textBoxDBP.Text = "";
textBoxDR.Text = "";
textBoxEP.Text = "";
textBoxGR.Text = "";
textBoxMA.Text = "";
textBoxSF.Text = "";
pictureBox1.ImageLocation = Application.StartupPath + "\\as.jpg";
other1.Text = "";
Other2.Text = "";
other1.Visible = false;
Other2.Visible = false;
}
private void other1_TextChanged(object sender, EventArgs e)
{
if (other1.Text != "")//for user input of casualty
a = double.Parse(other1.Text);
}
private void Other2_TextChanged(object sender, EventArgs e)
{
if (Other2.Text != "")//for user input of recovery
b = double.Parse(Other2.Text);
}
{
ab.ShowDialog();
}
(object sender, EventArgs e)
{
Form2 rec_ap = new Form2();//dialog window for recovery appliances.
rec_ap.ShowDialog();
}
private void exitToolStripMenuItem_Click(object sender, EventArgs e)
{
Close();
}
{
OpenFileDialog book = new OpenFileDialog();
book.InitialDirectory = Application.StartupPath;
book.Filter = "(*.jpg) |*.jpg|All files (*.*)|*.*";
String name = book.FileName;
//book.FileName = Application.StartupPath + "\\as";

//book.OpenFile = Application.StartupPath + "\\as";
book.ShowDialog();

//
//

//book.ShowDialog();

//OpenFileDialog book = new OpenFileDialog();
//OpenFileDialog high = new OpenFileDialog();
////high.DefaultExt = "//.jpg";

////book.DefaultExt = Application.StartupPath + "\\.jpg";
//high.FileName = Application.StartupPath + "\\a.xls";
// high.ShowDialog();

//book.OpenFile = Application.StartupPath + "\\as.jpg";

//book.ShowDialog();
}
}
//```

## More to Come

1. I have deliberately ignored a few factors which are often used in recovery operation.
1. Sheeve Resistance (the resistance offered by the pulleys)
2. Fording Resistance
2. Rope Tension Calculation should be made prior to performing the recovery operation.

## History

• Article revised

## Share

 Engineer Pakistan
No Biography provided

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 Australian Army version required, can anyone help Ryan Waldram31-May-12 11:53 Ryan Waldram 31-May-12 11:53
 Re: Australian Army version required, can anyone help Farhat Masood9-Jun-12 21:32 Farhat Masood 9-Jun-12 21:32
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 Jamie, if i may add my two cents. I'm a Recovery Mechanic in the Army, we use these calculations for working out how much winch pressure is required for de-bogging vehicles, bringing them back up cliffs after an accident etc. To sit down and put pen to paper (which in itself can be an issue in the pouring rain) can take anywhere upto an hour per job. For some jobs there are 3 or more of these calculations required (put a vehicle back onto it's wheels, turn it, pull it up a cliff). the 'if' rules that Farhat has created are correct and i don't think that the correct results could've been achieved with any other rules (ie: if the casualty is in mud you need a different formula to if it was in long grass, or on bitumen). As Farhat as mentioned, this application is aimed as a specific trade and i can assure you that the British, New Zealand and Australian Army's all have recovery mechanics that use this type of formula. I'm doing my best to pass the word around of it's existance and am liaising with Farhat to get it tailored to the equipment we use and to also get a smart phone app of it so it can be easily accessible at any time.
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