Usually remembers to get the pointy end up
- Apr 26, 2010
- Reaction score
The difference between the blackpowder (BP) you use in an ejection charge and that you would use in a motor is actually more about how the motor is prepared. The composition of the powder is - or can be - identical. What enables BP to burn so fast when used as an ejection charge is the space between the grains. When an individual grain ignites, it generates an enormous amount of hot gas, which quickly expands through the interstices between the BP grains, igniting more. This leads to an almost instantaneous chain reaction. When used to prepare a rocket motor, the BP is packed very tightly into the casing, leaving no space between grains. When the first surface is ignited, there are no interstices for the flame front to spread through, and so the burn is much slower and more controlled - leading to propulsion rather than deflagration.My point about Estes motors is that the "black-powder" that Estes is using is not the same thing as the BP that we often use for recovery device deployment charges with our electronic in our Av-bays. Its not the same thing as cramming a bunch of Dupont 2F, 3F, or even 4F into an empty motor case and calling it "propellant." Chemically they have mostly the same ingredients, but in differing proportions thus creating a propellant rather than low explosive. Am I saying that well enough? Or am I completely in left field?