"Greg \(Strider\) Moore" wrote:

"Fred J. McCall" wrote in message
.. .

There is no such thing as assembly line production 'spewing out'
rocket engines. It made sense to use Merlin engines because the idea
was to have three identical cores for Falcon Heavy, sort of like what
Delta IV Heavy does. In the event, Musk found they couldn't do that
and that they couldn't just use three Falcon 9 cores for Falcon Heavy.
The side boosters are now different from the central 'core'.


What are the differences? Last I knew the side boosters for the primary
flight are B1023.2 and B1025.2 (i.e 2nd flight for those two boosters)


It's mostly got to do with mechanical loading. The side boosters are
close (but not an exact match) for what they fly on Falcon 9. They're
only slightly modified so as to be able to take structural loading
from the attachment points on the sides rather than straight down
through the center of the core. The center booster requires a lot
more structural work to stand loads, both the side loads from the two
attached boosters and the increased load on the front of the booster
from the second stage and payload. Musk himself has said that he
doesn't necessarily expect the first launch attempt to reach orbit and
would consider it getting far enough away to avoid pad damage a win.
Look at how many Falcon 9 launches failed before they got a success.
According to Musk, Falcon Heavy was "shockingly difficult" to develop.
It was originally supposed to use fuel cross-feed among the three
cores, but that proved too difficult and was dropped. It was
originally supposed to be three 'standard' Falcon 9 cores (with Falcon
9 eating the additional structure) but now the center booster is
different from the side boosters. Yes, it really is rocket science...


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw