6.1 ROCKETS

 Rockets were first developed by the Chinese several hundred years before Christ. They were used for entertainment, in the form of fireworks. They were not usually used for military purposes because they were inaccurate, expensive, and unpredictable. In modern times, however, rockets are used constantly by the military, since they are cheap, reliable, and have no recoil. Perpetrators of violence, fortunately, cannot obtain military rockets, but they can make or buy rocket engines. Model rocketry is a popular hobby of the space age, and to launch a rocket, an engine is required. Estes, a subsidiary of Damon, is the leading manufacturer of model rockets and rocket engines. Their most powerful engine, the "D" engine, can develop almost 12 lbs. of thrust; enough to send a relatively large explosive charge a significant distance. Other companies, such as Centuri, produce even larger rocket engines, which develop up to 30 lbs. of thrust. These model rocket engines are quite reliable, and are designed to be fired electrically. Most model rocket engines have three basic sections. The diagram below will help explain them.

     __________________________________________________________
     |_________________________________________________________| -- cardboard
      \  clay  | - - - - - - - - - - | * * * | . . . .|c|            casing
       \_______|  - - - - - - - - -  | * * * |  . . . |l|
        ______ _ - - - thrust - - -  | smoke | eject  |a|
       / clay  |  - - - - - - - - -  | * * * | . . . .|y|
      /________|_____________________|_______|________|_|_______
     |_________________________________________________________| -- cardboard
                                              casing
The clay nozzle is where the igniter is inserted. When the area labeled "thrust" is ignited, the "thrust" material, usually a large single grain of a propellant such as black powder or pyrodex, burns, forcing large volumes of hot, rapidly expanding gasses out the narrow nozzle, pushing the rocket forward. After the material has been consumed, the smoke section of the engine is ignited. It is usually a slow-burning material, similar to black powder that has had various compounds added to it to produce visible smoke, usually black, white, or yellow in color. This section exists so that the rocket will be seen when it reaches its maximum altitude, or apogee. When it is burned up, it ignites the ejection charge, labeled "eject". The ejection charge is finely powdered black powder. It burns very rapidly, exploding, in effect. The explosion of the ejection charge pushes out the parachute of the model rocket. It could also be used to ignite the fuse of a bomb...

Rocket engines have their own peculiar labeling system. Typical engine labels are: 1/4A-2T, 1/2A-3T, A8-3, B6-4, C6-7, and D12-5. The letter is an indicator of the power of an engine. "B" engines are twice as powerful as "A" engines, and "C" engines are twice as powerful as "B" engines, and so on. The number following the letter is the approximate thrust of the engine, in pounds. the final number and letter is the time delay, from the time that the thrust period of engine burn ends until the ejection charge fires; "3T" indicates a 3 second delay.

NOTE:
an extremely effective rocket propellant can be made by mixing aluminum dust with ammonium perchlorate and a very small amount of iron oxide. The mixture is bound together by an epoxy.

6.11 BASIC ROCKET BOMB

A rocket bomb is simply what the name implies: a bomb that is delivered to its target by means of a rocket. Most people who would make such a device would use a model rocket engine to power the device. By cutting fins from balsa wood and gluing them to a large rocket engine, such as the Estes "C" engine, a basic rocket could be constructed. Then, by attaching a "crater maker", or CO2 cartridge bomb to the rocket, a bomb would be added. To insure that the fuse of the "crater maker" (see section 4.42) ignited, the clay over the ejection charge of the engine should be scraped off with a plastic tool. The fuse of the bomb should be touching the ejection charge, as shown below.

          ____________ rocket engine
          |                         _________ crater maker
          |                         |
          |                         |
          V                         |
     _______________________________V_
     |_______________________________|  ______________________
      \   | - - - - - -|***|::::|      /# # # # # # # # # # # \
       \__| - - - - - -|***|::::|  ___/  # # # # # # # # # # # \
        __  - - - - - -|***|::::|---fuse--- # #  explosive  # # )
       /  | - - - - - -|***|::::|  ___   # # # # # # # # # # # /
      /___|____________|___|____|____ \_______________________/
     |_______________________________|

     thrust> - - - - - -
     smoke>  ***
     ejection charge> ::::
Duct tape is the best way to attach the crater maker to the rocket engine. Note in the diagram the absence of the clay over the ejection charge Many different types of explosive payloads can be attached to the rocket, such as a high explosive, an incendiary device, or a chemical fire bottle.

Either four or three fins must be glued to the rocket engine to insure that the rocket flies straight. The fins should look like the following diagram:

          |\
          | \
          |  \
          |   \  <--------- glue this to rocket engine
          |    \
          |     \
          |      \
          |       |
          |       |
          |       |
  leading edge    |
   ------->       |
          |       |
          |       |  trailing edge
          |       |    <--------
          |       |
          |       |
          |       |
          |       |
           \_____/
The leading edge and trailing edge should be sanded with sandpaper so that they are rounded. This will help make the rocket fly straight. A two inch long section of a plastic straw can be attached to the rocket to launch it from. A clothes hanger can be cut and made into a launch rod. The segment of a plastic straw should be glued to the rocket engine adjacent to one of the fins of the rocket. A front view of a completed rocket bomb is shown below.

                              |
           fin                | <------ fin
            |                 |           |
            |                 |           |
            |               __|__         |
            V              /     \        V
           ---------------|       |---------------
                           \_____/
                              |o <----------- segment of plastic straw
                              |
                              |
                              | <------ fin
                              |
                              |
By cutting a coat hanger at the indicated arrows, and bending it, a launch rod can be made. After a fuse is inserted in the engine, the rocket is simply slid down the launch rod, which is put through the segment of plastic straw. The rocket should slide easily along a coathanger, such as the one illustated below:

                        ____
                       /    \
                      |      |
          cut here _____     |
                       |     |
                       |     |
                       |    / \
                       V   /   \
         _________________/     \________________
        /                                        \
       /                                          \
      /____________________________________________\
                                   ^
                                   |
                                   |
                    and here ______|

     Bend wire to this shape:

                         _______ insert into straw
                         |
                         |
                         |
                         V
          ____________________________________________
          \
           \
            \
             \
              \  <--------- bend here to adjust flight angle
               |
               |
               |
               |
               |
               | <---------- put this end in ground
               |

6.12 LONG RANGE ROCKET BOMB

 Long range rockets can be made by using multi-stage rockets. Model rocket engines with an "0" for a time delay are designed for use in multi- stage rockets. An engine such as the D12-0 is an excellent example of such an engine. Immediately after the thrust period is over, the ejection charge explodes. If another engine is placed directly against the back of an "0" engine, the explosion of the ejection charge will send hot gasses and burning particles into the nozzle of the engine above it, and ignite the thrust section. This will push the used "0" engine off of the rocket, causing an overall loss of weight. The main advantage of a multi-stage rocket is that it loses weight as travels, and it gains velocity. A multi-stage rocket must be designed somewhat differently than a single stage rocket, since, in order for a rocket to fly straight, its center of gravity must be ahead of its center of drag. This is accomplished by adding weight to the front of the rocket, or by moving the center of drag back by putting fins on the rocket that are well behind the rocket. A diagram of a multi-stage rocket appears below:

                    ___
                   /   \
                   |   |
                   | C |
                   | M | ------ CM: Crater Maker
                   |   |
                   |   |
                   |___|
                   |   |
                   |   |
                   |   |
                   | C | ------ C6-5 rocket engine
                  /| 6 |\
                 / | | | \
                /  | 5 |  \
               /   |___|   \ ---- fin
              /   /|   |\   \
             /   / |   | \   \
            /   /  |   |  \   \
           /   /   | C |   \   \
          |   /    | 6 |    \   |
          |  /     | | |     \  |
          | /      | 0 |      \ |
          |/       |___|       \|
          |       /     \       |
          \______/   ^   \______/ ------- fin
                     |
                     |
                     |
                     |
                     C6-0 rocket engine
     The fuse is put in the bottom engine.
Two, three, or even four stages can be added to a rocket bomb to give it a longer range. It is important, however, that for each additional stage, the fin area gets larger.

6.13 MULTIPLE WARHEAD ROCKET BOMBS

"M.R.V." is an acronym for Multiple Reentry Vehicle. The concept is simple: put more than one explosive warhead on a single missile. This can be done without too much difficulty by anyone who knows how to make crater-makers and can buy rocket engines. By attaching crater makers with long fuses to a rocket, it is possible that a single rocket could deliver several explosive devices to a target. Such a rocket might look like the diagram on the following page:

              ___
             /   \
             |   |
             | C |
             | M |
             |___|
          ___|   |___
          |  |   |  |
          |  | T |  |
         / \ | U | / \
        /   \| B |/   \
        |   || E ||   |
        | C ||   || C |
        | M ||   || M |
        |   ||___||   |
        \___/| E |\___/
             | N |
            /| G |\
           / | I | \
          /  | N |  \
         /   | E |   \
        /    |___|    \
       / fin/  |  \ fin\
      |    /   |   \    |
       \__/    |    \__/

               ^
               |____ fin
The crater makers are attached to the tube of rolled paper with tape. the paper tube is made by rolling and gluing a 4 inch by 8 inch piece of paper. The tube is glued to the engine, and is filled with gunpowder or black powder. Small holes are punched in it, and the fuses of the crater makers are inserted in these holes. A crater maker is glued to the open end of the tube, so that its fuse is inside the tube. A fuse is inserted in the engine, or in the bottom engine if the rocket bomb is multi stage, and the rocket is launched from the coathanger launcher, if a segment of a plastic straw has been attached to it.

<--Rockets and cannons-->Index<--Cannons-->