undefined | Better HN

0 pointsjlmorton8y ago0 comments

The unspoken point in Musk's comment is that SpaceX doesn't actually care if they get these particular rockets back. They want to prove reusability, of course, but no matter the outcome they never plan to re-fly these cores. They will focus on the not-yet-flown Block 5 cores, and standardize on that going forward.

In this flight, the side boosters and center core were Blocks 3 and 4. So SpaceX definitely wants to recover the boosters, to perfect reusability, but they never intend to re-fly any of these boosters, so better to get back the one with the expensive and reusable titanium grid fins.

0 comments

kens8y ago

> Block 5 cores

Why are rocket versions specified with the word "Block"? The Saturn launchers did the same thing, but it seems like a strange word to use.

joezydeco8y ago

It's a term carried over from the military/aerospace field.

https://www.f35.com/about/life-cycle/software

perl4ever8y ago

I boggle a little at what I read there, such as "With Block 3i, 89 percent of code required for full warfighting capability is flying". That's 89%? Not 88% or 90%?

1 more reply

Eridrus8y ago

Didn't they say these boosters had already flown before?

I'm also a bit surprised the grid find are so pricey, they seem pretty small? Not that I really know how much titanium costs to buy and machine.

quasse8y ago

They measure 4 by 5 feet, so we can estimate they are probably made from a solid chunk of titanium that was at least 20 cubic feet or almost 5,000 pounds. That would be nearly $150,000 in raw material and probably another 5x that in processing (guesstimating cost per cubic inch of titanium removal).

Either that or they were specially made castings, which are similarly expensive in low volume, if not more.

larkeith8y ago

Wouldn't you be able to recover most of the removed titanium, amortizing the majority of that guesstimated materials cost? Processing likely remains expensive, however.

1 more reply

stmfreak8y ago

You are also dealing with low volume fabrication which means setup and tooling costs don't amortize across many components. I wouldn't be surprised if they cost $1M each.

cryptoz8y ago

The side boosters were flown before, and returned to Earth today for the second time. But they won't fly again.

j / k navigate · click thread line to collapse

0 pointsjlmorton8y ago0 comments

0 comments

kens8y ago

> Block 5 cores

Why are rocket versions specified with the word "Block"? The Saturn launchers did the same thing, but it seems like a strange word to use.

joezydeco8y ago

It's a term carried over from the military/aerospace field.

https://www.f35.com/about/life-cycle/software

perl4ever8y ago

I boggle a little at what I read there, such as "With Block 3i, 89 percent of code required for full warfighting capability is flying". That's 89%? Not 88% or 90%?

1 more reply

Eridrus8y ago

Didn't they say these boosters had already flown before?

I'm also a bit surprised the grid find are so pricey, they seem pretty small? Not that I really know how much titanium costs to buy and machine.

quasse8y ago

Either that or they were specially made castings, which are similarly expensive in low volume, if not more.

larkeith8y ago

Wouldn't you be able to recover most of the removed titanium, amortizing the majority of that guesstimated materials cost? Processing likely remains expensive, however.

1 more reply

stmfreak8y ago

You are also dealing with low volume fabrication which means setup and tooling costs don't amortize across many components. I wouldn't be surprised if they cost $1M each.

cryptoz8y ago

The side boosters were flown before, and returned to Earth today for the second time. But they won't fly again.

j / k navigate · click thread line to collapse