So do Estes booster engines ( in this case a C6-0 ) have a trditional ejection charge? The only booster experience I have is with D12's and I would have sworn that the booster has a regular ejection charge but in another thread I saw some back & forth that they did and didnt.
So does anyone have the answer to this?
No, they do not have an ejection charge or delay grain. What you see in the front end of the motor when you look inside is the smoothly pressed surface of the propellant grain.
When the engine is lit, it burns outward from the center dimple in the rear of the propellant grain near the nozzle exit hole, and forward deeper into the grain. When the flame front reaches the sidewall of the case, the propellant keeps burning straight forward along a sorta 'hemispherical shaped' flame front for the length of the propellant grain. When the propellant burns forward, the slug of remaining propellant is getting thinner and thinner, until finally there is long a "disk" of unburned propellant in the front of the motor. This disk will eventually burn thin enough to rupture from the internal pressure inside the engine casing behind the burning propellant surface caused by the hot, high temperature combustion gases trapped inside the casing between the flame front on the propellant surface, the casing walls, and the nozzle itself before they are ejected from the nozzle orifice hole. (IIRC the pressure inside the casing of a D12 is around 70-100 psi or so?? Can't recall ATM... I DO know shuttle SRB's have an internal pressure of 700 psi at standard operating pressure). This pressure ruptures the thin disk of propellant and "blows out" like a blown-out tire does, and sends the burning chunks of propellant forward out of the casing where they impact the nozzle of the upper stage motor and by means of (depending upon who you ask) radiant heat from the burning propellant and high temperature gases that blow out the forward end of the motor, direct contact between the burning particles of BP, or direct contact of the flaming high temperature gases, the upper stage motor ignites (hopefully) and comes up to pressure, blowing the lower stage off and continuing in flight.
A regular motor has a delay train composed of slow-burning smoky BP which does not create appreciable thrust, and gives the rocket time to coast to apogee, before it burns through in a similar manner and ignites a charge of fast burning BP particles which then rupture the forward clay cap of the motor and (hopefully) eject the recovery device.
This is the principle difference in the motors.
Now, when the propellant disk bursts on a booster motor, and releases the high-pressure, high temperature gas inside the casing out the front end of the motor, it has a SIMILAR EFFECT to a true ejection charge in a standard delay-type rocket motor... there's a sudden burst of high pressure high temp gases and burning BP particles shot forward, which are adding MORE hot gases as they burn, further pressurizing the tube, and these CAN (theoretically, not going to get into a peeing match with someone on here about the semantics of it and safety code aspects of it) eject a recovery device or jettison the booster-- that's the main reason for having "ports" on long boosters-- to prevent the hot gases from 'ejecting' the sustainer stage of the rocket before the upper stage can ignite... short boosters tape the motors together for the same reason-- to hold them together long enough for the upper stage motor to ignite.
BUT, it's not a "true" ejection charge in the normal sense of the word, even if it functions for all practical purposes virtually identically...
Hope this helps... Later! OL JR
PS. look in some of the old Estes catalogs on the ninfinger site; they have graphics showing the burn process of the motors in flight for both boosters and regular delay-type motors... I think they even have a short animation on the Estes site, or somewhere (can't recall where I saw it online ATM)...
