Amazing detail, as always from you.
I am still a little slow on the draw.
As I understand the design, ALL five first stage motors are "manifolded" to the central core tube.
within this tube is a spool with a hollow center which holds the fuses.
the zero delay first stage booster motors will burn out first, with the breakthrough gases shooting up the manifold to light the fuses, the excess gas is vented through the hollow center of the spool to prevent premature ejection of the spool.
the delay first stage motors will fire three seconds later, and THEIR combined ejection charges forcibly eject the spool.
the kinetic energy from the ejected spool pulls the chute or chutes out of the first stage.
Have I got it right?
If so, there are some assumptions which may or may not be accurate in practice.
1. The force of the zero delay motors burn through, vented through the spool, is INSUFFICIENT to eject the spool.
Maybe. I haven't tested it, but I believe the force from zero delay burn through is less than an ejection charge (
@BEC probably know the answer to this, I dunno, is the powder of the ejection charge different from the propellant?) I know zero delay motors CAN eject chutes, so their blow throw force is not negligible, even if it IS less than a formal ejection charge.
2. The force of the positive delay motors' ejection charges IS sufficient to eject the spool despite the hollow center which vents the zero delay burn through AND will also at least partially vent the positive delay motors.
Again, maybe. I am more a "black or white" person on ejection events, the idea that one set of motors isn't strong enough to do something but the other set IS strong enough to do something makes me edgy. I'm also not nuts about assuming the kinetic energy of the spool will be sufficient to pull the chutes out, but depends on the mass of the spool and how tightly packed the chutes are.
I still remember Major Fujita, my Japanese instructor in college in 1981, telling me, "KISS- Markel-san" (Keep It Simple Stupid). Disconnect the two outboard positive delay motors from the manifold and duct them straight to the chutes (if space is tight for wadding, use a piston). You can keep the mid-line delay motor where it is, its ejection charge won't help but probably won't hurt anything, although you might as well replace it with a zero delay motor to save weight and prevent a late central ejection charge event from peppering the deployed chutes---although I think this unlikely.) And I think, especially without 3D printing, a three to one duct made from paper tubes is going to be much easier to build than five to one.
But you have demonstrated an amazingly consistent tendency to pull rabbits out of hats, so my unrequested input is likely worth exactly what you paid for it
) this could eventually have an impact. I have printed a few fin cans with a built in ejection tube and it got pretty abused after just a few launches. Given the complexity of your design, if you do plan to print these manifolds (you mentioned "traditional material") take the added time to print them at a high resolution out of ABS if you can. That will give you the best chance at heat and flow.
