JF Mezei wrote:

On 2018-02-10 08:16, Jeff Findley wrote:

No. SpaceX found that it is much harder to do parallel loading,
parallel ignition, parallel aerodynamics, and parallel staging than it
was to do a "single stick" vehicle.

Was this a necessary "growing up" step needed for SpaceX to realize this
and reset it plans, going for the single bigger stick *BFR) ?

In other words, had they not had the difficulties with Falcon Heavy,
would BFR have been conceived ?


BFR was 'conceived' long before Falcon Heavy had any difficulties. The
actual timeline answers your question.


How in the hell is it ever going to make back that R&D investment with
those numbers? My guess is that it simply won't. It's a technological
dead end, just like Falcon 9.

Didn't SpaceX develop many skills in terms of structures, load handling
etc that would have value for future projects such as BFR?


Not really, no.


And even that first flight, the data from the (attempted) landings of
the stages is bound to be of use in terms of comparing performance of
the heavy "tubes" with the 9 "tubes". (Musk mentioned that the cone atop
boosters made a big difference in terms of aerodynamic authority of
paddles, greatly increasing difficulty).


All data is of use, even if it's data that tells you something can't
work.



BFR/BFS, a fully reusable TSTO, is
planned to eventually replace them both.


I have my doubts that BFR will replace Falcon 9. I get the impression
that the 9 is the right size for vast majority of payloads and BFR is
overblown.


But when you look at costs BFR is *A LOT* cheaper.


Just as there are complaints about the shuttle being too heavy for what
it carried, I suspect BFR will be way too heavy if it only goes to ISS
to carry 3 or 4 crewmembers. Like a 747 being used to carry just a
handful of people.


So why would you even have that mission? You'd bring 3 astronauts
plus however many tons of cargo you might want to launch. Fewer
bigger resupply missions. Again, BFR is *MUCH CHEAPER* than Falcon 9
launches to do even an approximately equivalent mission. Musk thinks
BFR Spaceship can compete at the high end of high speed air transport.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn