Jeff Bezos' secretive rocket company just revealed its plans to towerover SpaceX

JF Mezei wrote:

On 2016-09-12 13:14, wrote:

http://www.techinsider.io/blue-origi...rockets-2016-9


Is there commercial demand for such a heavy lifter?


It only lifts 70% of what Falcon Heavy will lift.


Or are its hopes
pinned on governmentds funding the assembly of a large mars expedition
ship, at which point a heavy lifter can be of use to bring the large
modules with fewer flights?


It's physically big, but it doesn't have the lift capacity for that
sort of thing.


Secondly, what is the advantage of having a 3rd stage as oppposed to
making a bigger tank for 2nd stage for longer burn with same delta-V ?


More stages means you're lifting less parasitic structure weight.


Since both second and 3rd stages are single engine, I don't see much of
an advantage of having 3 stages since you end up pushing one extra
engine and all extra weight to orbit.


You shed the parasitic mass of the second stage on the way up. By
your logic, we could just build one big stage. Why have a second one?


If LOX/LH2 is so much more efficient than LOX/LNG, why not make second
stage LOX/LH2 ?


LOX/LNG is only mildly cryogenic and thus easier to handle. Note that
the SpaceX Raptor engine currently in development will also be a
LOX/methane engine.


Seems to me like they could produce their 2 variants by simply making
one with larger tanks for second stage. (or even 2 tanks of each on
second stage if having smaller tanks has advantages over single very
large tank).


Ask yourself why we don't just build single stage rockets. The
reasoning is the same.


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