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ULA launch and discussion thread


tater

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On that note -- I often see discussion of GTO insertions being quoted with a certain "-dV" value, like "-1800 m/s". I assume that is the dV which the payload will have to spend in order to circularize at GEO. For F9 launches, the upper stage sometimes burns to MRS to make that value as low as possible. In those cases, is the burn to MRS intended merely to raise apoapsis a little higher (decreasing the cost of the payload's plane change maneuver) or does it do a little bit of work to directly change inclination?

3 minutes ago, GoSlash27 said:

They said it's running rich and they have an O2 fault. Hope they have the DV to make it.

Shoot! I suppose they can just do two burns but it will really shorten the lifespan of the sat.

What's the oblong thing off-center next to the RL-10? Is that a helium bottle? 

My Centaur clone got the positions of the ullage thrusters and attitude thrusters exactly right, entirely by luck.

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5 minutes ago, GoSlash27 said:

They said it's running rich and they have an O2 fault. Hope they have the DV to make it.

Out of curiosity, where did you see that? I don't see any indication of a problem on the stuff I'm looking at?

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2 minutes ago, sevenperforce said:

What's the oblong thing off-center next to the RL-10? Is that a helium bottle? 

I think so. Not sure

It was during the first burn. You could see the plume coming out of the side of the bell

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38 minutes ago, sevenperforce said:

What's the oblong thing off-center next to the RL-10? Is that a helium bottle?

Yep! Only a single one in this flight, since it is a GTO flight.

@GoSlash27 IIRC that's normal for the RL10, it is a secondary vent but i do not remember it's purpose. It is more pronounced this time because of the relative sun position.

Edit: found the document where i first read about it. It is probably some kind of fuel valve for pressure relief.

Edited by Phineas Freak
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1 hour ago, sevenperforce said:

That would be H2, not O2, anyway, since the RL-10 is an expander cycle that uses fuel as coolant.

RL102-B2 always runs rich, it converts some of its heat into work by heating hydrogen gas, this is effective because hydrogen weighs 1/9th the weight of water and 1/16th the weight of O2, consequently it makes no sense having hot steam coming out of the combustion chamber when its 10 times cheaper to heat hydrogen. But alas you cannot get the heat to heat hydrogen without creating some water from oxygen also present. So there is a trade-off. Ideally one would have a power supply that was so insanely powerful that you had no oxygen at all, and you were cleaving hydrogen into to atomic hydrogen, removing the electrons and ejecting highly repulsive plasma (i.e. 6000K). That would be a different kind of engine the nozzle on the RL10s cannot stand that kind of heat (another reason the rocket is run rich).

Expander cycles are theoretically limited to 300 kN. The RL10b-2 only produces 110 kN and does so with a wacky big bell for a 277 kg rocket. The limiting factor on RL10B-2 use is its low thrust, the huge tanks required to store liquid hydrogen and the fact it cannot be stored very long.

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That was something for sure! Such a beautiful sight with a thunderous melody that kept on for about a minute.

Alas, there was a cloud cell right above the pad at the time of the launch, and it quickly became impossible to see it.

 

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Spoiler

 

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Anyway, this spotting site is incredible, and if it is possible I will go back there for the next Atlas launch with AFSPC-11.

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23 minutes ago, PB666 said:

RL102-B2 always runs rich

As far as I know, all hydrolox engines run rich, that simply optimizes the exhaust velocity and keeps the chamber temperature (and exhaust temperature) down.  I thought that whacky big bell might not be so heavy, but then realized that 110kN is a bit more than ten tons at Earth gravity.  I still expect that most of that force is near the combustion area, and as the bell spreads out it can be much lighter.  Still, expect any vacuum bell to be really, really big (quite the opposite of kerbal graphics).

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1 hour ago, wumpus said:

As far as I know, all hydrolox engines run rich, that simply optimizes the exhaust velocity and keeps the chamber temperature (and exhaust temperature) down.  I thought that whacky big bell might not be so heavy, but then realized that 110kN is a bit more than ten tons at Earth gravity.  I still expect that most of that force is near the combustion area, and as the bell spreads out it can be much lighter.  Still, expect any vacuum bell to be really, really big (quite the opposite of kerbal graphics).

The difference is about 30 units of ISP.

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  • 2 weeks later...
1 hour ago, PB666 said:

lol, ummm, focus on what customers willing to pay 4 times as much?

From the article:

“We should be able to offer them a better deal,” he said. “We’re not trying to do this to make higher profits. We’re trying to do this to be more competitive by offering them a better solution.”

Tory seems to be aware that they cost too much and they’re in the process of doing something about it.

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31 minutes ago, Racescort666 said:

From the article:

“We should be able to offer them a better deal,” he said. “We’re not trying to do this to make higher profits. We’re trying to do this to be more competitive by offering them a better solution.”

Tory seems to be aware that they cost too much and they’re in the process of doing something about it.

I'm really honestly lost as to where the appeal of going with ULA is vs SpaceX, as a commercial customer. Does ULA have less of a backlog?

I love this, though:

Quote

 “To customize the perfect solution for a customer, our engineers sit in a room with their engineers for a couple of weeks and go through all these iterations. That’s very hard to do when we’re working through a third party.”

I WANT THAT JOB

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15 minutes ago, sevenperforce said:

I'm really honestly lost as to where the appeal of going with ULA is vs SpaceX, as a commercial customer. Does ULA have less of a backlog?

I love this, though:

I WANT THAT JOB

Maybe insurance is less because they have better launch history? Is there another cost I'm unaware of that affects how expensive it is to put something into space? SX is catching up quick and BO is still the wild card. 

Also, yes, I agree, I would like that job. It sounds like KSP in real life with real rockets.

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18 minutes ago, Racescort666 said:

Maybe insurance is less because they have better launch history? Is there another cost I'm unaware of that affects how expensive it is to put something into space? SX is catching up quick and BO is still the wild card. 

Also, yes, I agree, I would like that job. It sounds like KSP in real life with real rockets.

Pretty damn sure I could do that job with about a week of training, too...

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17 hours ago, Racescort666 said:

Tory seems to be aware that they cost too much and they’re in the process of doing something about it.

Not just that - since Tory Bruno took over the CEO position, ULA's prices already came down by 30%-40%. Clearly not enough to match SpaceX, but also definitely good progress.

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19 minutes ago, Canopus said:

That’s a good niche for ULA. While the billionaires of new space are trying to build gargantuan rockets for their dream colonies, ULA is quietly moving towards the industrialization of Earth-Moon system. 

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