This node describes how cars are blown up as part of pyrotechnics productions. Despite the correctness of this information, I would strongly encourage you not to try this at home. As a matter of fact, I would also discourage you from trying this anywhere else than your home. Just choose life. Besides, the descriptions here are "how"'s, not "how to"'s.
Preparations to the car
If there is a stuntman driving the car as it blows up, preparations will have to be made so the driver has a better than 50% chance of escaping the burning wreckage alive. If the car will be rolling along without a driver, there is less of a problem, and if it will be standing still while it is being blown up, there is no problem.
However, these things should be sorted out:
- All windows must be removed from the car. This includes the glass in the side mirrors, the windshield and the back window. If the illusion of glass is needed, specially produced sugar glass is used.
- As much as possible of the car's interior is removed.
- If the remaining bits of car interior are flammable, it is drenched in water.
Making a car flip over
The coolest, although probably most common effect done to cars, is to make them flip over because of an explosion. You might be surprised to know that this can be accomplished fairly safely without the use of a ramp, even with a person inside the car.
To make a car flip over, a directional explosive charge is needed. This can be accomplished by using a piston effect. To do this, a large hole is drilled in the car floor, as close to one of the hind wheels as possible, usually on the side diagonal from where the driver is sitting. The piping is welded securely to the car chassis and welded shut on the top. It is then filled with a slow explosive and fitted with an electronic fuse.
It is usually the driver herself who trips the switch so she has a chance to brace herself. The forceful explosion downwards, combined with a snappy turn of the wheel, causes the flipping action. If the car is driving away from you and the driver is in the left front seat, the charge will be near the right rear wheel. When the charge is set off, the driver will turn the wheel all the way to the right, which will give a controlled start to the roll. Depending on the direction of the explosion and the turning of the wheel, the stuntperson driving the car can actually control fairly well what direction and how far the car will be rolling.
Obviously, when doing this, it is a good idea that a rollcage is fitted in the car, although this is not strictly necessary. There are examples where the stuntperson would merely strap themselves to the car seat, and put the car seat all the way back (i.e down). That way, the roof would be squashed in, but the driver would be relatively safe, because the doors and side collision catchers would prevent the driver from being crushed. Obviously, it took a strong set of Jaws of Life to get the stuntperson out of the car, but these stunts do look "real".
Making a car explode completely
This is relatively easy as well. Here, too, all the windows need to be taken out. A large amount of explosive material is placed in the car (usually the engine is removed, and the explosives are placed inside the engine compartment). This, combined with an explosive mixture will create a huge fireball. If some explosives are put under the car (possibly combined with the piston setup explained above), the car will make a nice jump as well.
The explosive mixture varies from explosion to explosion. Myself, I tended to use a mixture of high viscosity motor oil, petrol and diesel. (I am not gonna tell you the ratios, though... Trade secret!). The motor oil and diesel work together to make an insanely huge black cloud of smoke. The petrol makes for a nice fireball / explosion. The setup is usually some plastic explosives near the hinges of doors and hood / trunk, to make the doors etc blow clean off. A larger explosive pod is placed between a steel plate and an arrangement of cardboard pipe and plastic bags. The cardboard pipe gives the explosion some direction (upwards), and the plastic bags contain the explosive mixture.
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. Also, make sure you have read the Pyrotechnics safety tips