On Aug 4, 11:05 pm, Pat Flannery wrote:
richard schumacher wrote:
Or something as simple as thrust created by gas exhausting from the
(new) cooling system. Geez Louise. Does Falcon 1 use anything other
than explosive bolts and springs for stage separation? How many more
basic errors can they afford to re-discover?

That's their problem; they are basically rediscovering every problem
that rockets had in the mid-late 1950s.
They should have hunted down retired steely-eyed missile men who worked
on vehicles like Jupiter, Thor, Titan I, and Delta and pooled everything
they learned from those programs as how to do and not do things.
Propellant oscillation was a big problem in the early days, particularly
for Jupiter.

Per the SpaceX website:

"The problem arose due to the longer thrust decay transient of our new
Merlin 1C regeneratively cooled engine, as compared to the prior
flight that used our old Merlin 1A ablatively cooled engine. Unlike
the ablative engine, the regen engine had unburned fuel in the cooling
channels and manifold that combined with a small amount of residual
oxygen to produce a small thrust that was just enough to overcome the
stage separation pusher impulse. "

/dps