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1
Oh, that argument again.
I wonder how many dollars the US taxpayer -as in every single one of them, personally- could have kept in the pocket if US politics just would make them license the M-1D and all their other engines past, present or future. With such low development costs and that many units already build the price should be real low too. Like really low.

But that is not reality.
Reality is still that the BE-4 is the very best bet for ULA to get an usable and somewhat competitive rocket in time. Crucially it is also the only hope for ULA to get an improved engine down the line.
2
The discussions regarding Falcon Heavy, BFR, New Glenn, SLS, etc. got me to wondering.  It would make some sense that satellite (and other) providers have started considering payloads larger than the standard 5,000 to 8,000 kg platforms currently beling launched.  Most of the discussion centering around why do this, that, or the other usually ends up with 'there is no payload large enough to make <blank> do this.'

What has anyone heard of rumors, plans or speculation regarding truly large payloads in planning or development?
3
A table I found (in French, but it is easy to identify the columns) with tabulated data of time, altitude and velocity of Falcon 9/H 1st stages at MECO with comparison of recovery outcome: https://twitter.com/dlxinorbit/status/967574835550449664
4

You could plausibly argue, say, the RD-180's engineering heritage and flight history as besting Merlin-1D in this comparison. But we're talking Vulcan here, and whichever first stage engine they choose, it hasn't made it off the test stand yet.

I would disagree:
- 81(?) RD-180 engines have flown.
- More than 300(!!!) M-1D's have flown. (difficult to know exact number due to reuse) Over 500 ignition events, and I can't even recall when an M-1D failed to light at liftoff, or when one failed to start in-flight that wasn't propellant starved - has it ever?

That's the benefit of multiple engines... engine history builds up very quickly.  :)

You forgot to mention that many more M-1Ds have been subjected to post-flight inspection ;-). Didn't mean to say I bought that argument myself, just that some (particularly those inclined for whatever reason to count missions, and not ignition events) might find it plausible.
5
SpaceX General Section / Re: Falcon Heavy Distributed Lift Concept(s)
« Last post by RyanC on Today at 04:19 AM »
That seems rather high. Where did I go wrong?

I think you didn't "sandbag enough".

http://www.spacelaunchreport.com/falcon9ft.html

Gives an estimate of F9 v1.2 FT Upper stage masses as:

4.5 tonne burnout mass.
116 tonne gross mass.

Assume that only only 80T of propellant is actually available on orbit (various reasons, boil off; manouvering, etc etc).

4.5T Falcon 9 Upper Stage Mass (dry).
75.6T of useable propellant from an utilization factor of 0.945
4.1T of trapped/reserve propellant not used for calculations
0.53T International Docking Adapter
---------------------------
9.2T Europa Clipper
1.5T Manouver Stage for Europa Clipper (mass at docking, weighed more but used up fuel to manouver to dock)

Total Stack Mass: 95.43T
Stack Mass at Burnout: 19.83T
ISP of Merlin 1D Vac: 348
Delta V = 5,364 m/sec
C3 = 52.3 km2/s2

If we lightened up the sandbagging a bit more; so that 84T of propellant was available on orbit and that the utilization factor was 0.965, it would become:

4.5T Falcon 9 Upper Stage Mass (dry).
81.06T of useable propellant from an utilization factor of 0.965
2.94T of trapped/reserve propellant not used for calculations
0.53T International Docking Adapter
---------------------------
9.2T Europa Clipper
1.5T Manouver Stage for Europa Clipper (mass at docking, weighed more but used up fuel to manouver to dock)

Total Stack Mass: 99.73T
Stack Mass at Burnout: 18.67T
ISP of Merlin 1D Vac: 348
Delta V = 5,720 m/sec
C3 =  61.8 km2/s2
6
Other US Launchers / Re: US Launch Schedule
« Last post by mazen hesham on Today at 04:08 AM »
7
Whether it is 1 or 9,  reliable engines that don't failure are bigger selling point.

You could plausibly argue, say, the RD-180's engineering heritage and flight history as besting Merlin-1D in this comparison. But we're talking Vulcan here, and whichever first stage engine they choose, it hasn't made it off the test stand yet.

I would disagree:
- 81(?) RD-180 engines have flown.
- More than 300(!!!) M-1D's have flown. (difficult to know exact number due to reuse) Over 500 ignition events, and I can't even recall when an M-1D failed to light at liftoff, or when one failed to start in-flight that wasn't propellant starved - has it ever?

That's the benefit of multiple engines... engine history builds up very quickly.  :)
8
Small issue of two FH launches within 24-48hrs, having only 1 heavy capable pad on the east coast.

If there was actually demand for dual FH launches, I am sure that SpaceX could modify LC40 to also support FH launches. 
9
I wish ULA had the guts to prepare - 'Skunk Works' style - a ready-to-go SLS replacement, based on the Vulcan-Centaur V concept. A version with 8 or even 10x GEM-63XL solid strap-ons that would equal SLS Block 1 in lifting ability, but in distributed lift would crush SLS Block II both in cost and payload. Bringing in ACES technology to the upper stages would even sweeten the deal...
I think a dual launch Vulcan ACES 564 already beats SLS Block 1B to TLI. No need for crazy mods.
10
This formatting discussion is interesting and all, but c'mon... This is so .. 1994? We are bot limited to 80 chars width, and welcome to the world of HTML and styled tables, everyone!  8)

(And the site's markup language even has table support)
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