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ULA launch and discussion thread


tater

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14 minutes ago, DDE said:

Wait, Max Q happens before Mach 1? I did not know that.

Not incredibly surprised. AFAIK, the transonic regime results in high aerodynamic stress, and if I did the calculations right, it has a 1.2 launch TWR. Combine that with the high specific impulse of hydrolox, and it gets going quite slowly at first.

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18 minutes ago, .50calBMG said:

... wanna think about that for a sec?

The last Centaur failure was over 11 years ago, right? It's had what, 12 mishaps out of nearly 250 flights, and most of those in the 60s and 70s.

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There ya go ;)

And I would agree with that, more usable volume vs stage size. looks like they learned their lesson on that too, ACES has the common bulkhead and same diameter tanks like Centaur does.

Edited by .50calBMG
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58 minutes ago, .50calBMG said:

There ya go ;)

I spaced it, had your reply been more explicit I would have immediately reacted accordingly, instead, I looked for why Centaur might not be considered reliable. Mea culpa.

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4 minutes ago, DDE said:

Well, they can’t hold a wet candle to NURO, and its ‘red’ cousin GUGI. Literally murky agencies.

Since we're talking about intelligence agencies and not an autonomous vehicle start-up nor a village in Iran, I will ask who those organizations are? Maybe it puts me on some kind of list just for asking or the answer is "those who need to know, already know."

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17 minutes ago, Racescort666 said:

Since we're talking about intelligence agencies and not an autonomous vehicle start-up nor a village in Iran, I will ask who those organizations are? Maybe it puts me on some kind of list just for asking or the answer is "those who need to know, already know."

The National Underwater Research Organization is on the Wiki, it’s just basically an orphan article that doesn’t get a redirect, evidently. Which is ironic for an organization that engages mostly in cable-tapping and illigal salvage of foreign debris and submarine hulks - a permanent form of the old Glomar Explorer slavage mission, it seems.

The Main Directorate for Deepwater Research is similarily engaged in storming the other final frontier with their “deepwater nuclear stations” and their “aquanauts”... when they’re not getting accidental coverage in Top Gear.

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Hmm. I'm of the opinion that at least some of the activities you listed are actually carried out by SUBDEVRON 5, the US Navy's "experimental" and test submarine unit. Said unit is the operator of the U.S.S. Jimmy Carter, which is essentially tailor made to replace the U.S.S. Parche, which is widely held to have taken part in clandestine and intrusive espionage operations throughout it's long and largely classified career. The fact that the Carter was at sea during a recent round of North Korean missile tests and returned to Bremerton a few weeks later flying the Jolly Roger did not go unnoticed by many...

 

On a somewhat more topical note, Blue Origin has broken ground on the factory that will provide first stage engines for Vulcan.

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On 1/19/2019 at 7:21 PM, tater said:

My bad, I forgot it was the DCSS, not Centaur. DCSS would be a better stage if it was just a bigger Centaur.

Every time I look at the DCSS, I can't help but cringe at what all that non-tank metal does to the dry mass. I can't even tell what that ring around the LOX tank is for, other than maybe stabilizing the stage against the inside of the fairing.

On 1/19/2019 at 7:24 PM, .50calBMG said:

There ya go ;)

And I would agree with that, more usable volume vs stage size. looks like they learned their lesson on that too, ACES has the common bulkhead and same diameter tanks like Centaur does.

Not all versions of Centaur had same diameter tanks. The one that flew on Titan IV (Centaur G, IIRC) had multiple-diameter tanks. I agree, though, common bulkhead and same diameter is the way to go.

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57 minutes ago, IncongruousGoat said:

Every time I look at the DCSS, I can't help but cringe at what all that non-tank metal does to the dry mass. I can't even tell what that ring around the LOX tank is for, other than maybe stabilizing the stage against the inside of the fairing.

Most of that looks to me like an instrument ring, wiring, piping, etc.

I somewhat suspect that ring around the LOX tank might be the structural element connecting the second stage to the interstage, and thus has to deal with a fair bit of force.

17 minutes ago, .50calBMG said:

Centaur G still had a common bulkhead though. Makes me wonder what the thought process was for the separate tanks on the DCSS.

Delta and Centaur came from different companies before they merged into ULA. Different companies, different design philosophies, etc.

Common bulkheads for hydrolox stages aren't easy, either; the hydrogen can freeze the LOX, and the LOX can boil the hydrogen.

Edited by Starman4308
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