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53 minutes ago, RCgothic said:

Is 100kN feasible for hot gas RCS thrusters? Space Shuttle's primary RCS was under 4kN each and the primary OMS engines less than 30kN each.

The primary OMS engines are virtually the same engine on the Apollo Service Module.  100kN is just over the thrust of the engine on the Viking sounding rocket.  I'd say 100kN is way beyond an RCS thruster.

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6 hours ago, Jacke said:

The primary OMS engines are virtually the same engine on the Apollo Service Module.

Not really. They're both variants of the AJ-10, but the Apollo SM engine had something like 90 kN of thrust, while the Shuttle's OMS engines had something more like 25 kN each. The designs were conceptually very similar, but the sheer difference in thrust means that they (very probably) had no components in common.

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9 hours ago, IncongruousGoat said:

Not really. They're both variants of the AJ-10, but the Apollo SM engine had something like 90 kN of thrust, while the Shuttle's OMS engines had something more like 25 kN each. The designs were conceptually very similar, but the sheer difference in thrust means that they (very probably) had no components in common.

Well, that's interesting.  I think the Apollo SPS was different enough from the other AJ-10 variants to really be its own separate design.

Interesting document here from Clay Boyce, the engineer at Aerojet who was the manager of Apollo SPS development.  Reading it sounds like despite the previous AJ-10's, each feature of the Apollo SPS was redesigned, partly due to the scale and due to the change to a pressure-fed throat-gimbled design.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100027319.pdf

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I thought I would post the Elon Musk timeline for BFR dated from the first presentation about it 3 years ago, in September 2016. This will allow people to comment on "Elon time" in a realistic way...

Htngdsv.png

Red Dragon clearly bit it, costing everyone on Earth exactly nothing. Crew Dragon dev is clearly behind by about a year (ditto+ CST-100).

BFR...

2019 has:

Propulsion dev ending towards the beginning of the year. They were firing Raptor full duration by then, but dev continued for maybe 6 months after that, so a few months off schedule from this very "aspirational" 2016 chart.

They have structure dev ending at the same time, early 2019. Interestingly, they abandoned all their work up to that time, and started over a couple months before the end of 2018, and they are clearly quite far along in this dev as of 1 year after that change, with them actually constructing multiple vehicles to test (1 close to done, one right behind that, and 2 in various stages of pre-assembly). Call it 1 year behind. Ship testing? Well, sort of begun with Hopper, and they are absolutely on a path to possibly meet that end of 2020 deadline (early 2020 for the 20 km flight). Orbital testing will require the booster, so the start of booster testing is likely more like mid to late 2020 than their late Spring on the chart. Still not impossible.

So is it behind? Yeah. Is it really far behind this schedule? Not really. Maybe a year behind, maybe 6 months. Much less than I would have expected, honestly.

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Regarding Crew Dragon, Bridenstine really needs to get someone in place where Gerst used to be. He has stated definitively that Gerst's replacement is the person who makes the call on putting crew on Dragon and Starliner. It;s already October, and SpaceX is planning a ground test of the Dragon to mimic the test that resulted in the RUD, then they use the same vehicle for the in flight abort test, and the crew vehicle is also going to be good to go all within 10 weeks. Any Gerst replacement could pull the trigger on crew maybe quickly if they are already in place at NASA doing the same thing, but I would have thought we'd see names floating around if that was the case. I can't imagine someone being named, then literally the first thing they do on the job is make that sort of decision in a short time frame. They need to get their feet under them, etc. In short, if the replacement isn't named pretty soon, any delays are the result of dumping Gerst.

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39 minutes ago, CatastrophicFailure said:

The Martians would be too busy destroying each other over which end of a Martian egg to open... <_<

They'll be destroying each other to eat. Because they are starving to death.

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The year is 2037. Due to insufficient allocation of resources towards psychological screening for Elon Musk's Mars Colony initiative, the 2 beachhead colonies have repurposed their nuclear bombs, meant for terraforming, into makeshift ICBMs  to wage war upon each other over the proper side of bread on which to place the Spreadable fat-BAsed Nutritional Component (S-BANC, also known as margarine). 

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The year is 2137. Due to insufficient allocation of resources towards... anything at all prior to the incident of 2037, one thing led to another and today the surviving members of the Global Congress voted unanimously to accept the surrender terms of the Martian Cockroach Ascendency. :wacko:

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