SpaceX’s Falcon Heavy rocket seems to be a hit with satellite companies | Hacker News Reader

SpaceX’s Falcon Heavy rocket seems to be a hit with satellite companies

arstechnica.com

184 pointsokket59 comments

What’s amazing to me is when companies do things like this that, for the general public, make perfect sense only in retrospect.

Most seemly well-run companies are a total shit-show from the inside. Stupid projects with features that no one wants, that engineering can’t build, destined to never sell.

It’s just plain refreshing when you see a company firing on all cylinders (sorry, couldn’t help myself) to the point where a shrewd move that helps capture the market only becomes apparent, even to industry insiders, months or years later.

It’s particularly satisfying when the CEO maps it all out in public years ahead of time and then executes on that vision relentlessly for a decade, despite the constant hate and doubt.

</Fanboy>

Shout-out to Gwynne Shotwell, who is a massive factor in the company's success.

Gwynne Shotwell :)

Dang it. Fixed.

+1 for that, Elon might have the vision, but without adult supervision SpaceX would have folded a while ago.

I'm not sure I'd put it that strongly, but it is quite clear that Shotwell has been a huge factor in SpaceX and the absence of someone like her is part of why Tesla is comparatively less healthy. She deserves a lot more credit.

What exactly is wrong with Tesla? You are comparing apples to oranges here and Tesla are doing fine regardless. Didn't they just post a profitable quarter after meeting production goals on the model 3 and virtually the entire market betting against them?

Both companies are fine, and Shotwell is an industry veteran who is no doubt valuable to SpaceX, but don't be ridiculous to think either company would be anywhere without Elon at the helm.

At one point SpaceX was down to a single make-it-or-break-it launch. Had that failed the company would've folded. Not true anymore, but was at least at one point in the past. Previous HN discussion:

https://news.ycombinator.com/item?id=18046049

Lol hyperbole much?

I'm all for credit where credit is due but Shotwell is a completely interchangeable and irrelevant piece of the puzzle here. There are many CEO's, men and women, who could have been in her role. All of the top talent at SpaceX could have been at any other company, but it took Elon steering a ship of motivated individuals, cracking the whip, and putting it all on the line for SpaceX to get where it is.

I really don't understand this recent wave of people who until now loved the guy but after he took a page out of President Trumps say whatever you're thinking book, people hate him.

I think it also made sense beforehand. But the main issue is that most companies are extremely risk averse, perhaps even out of necessity. The stock market butchers companies based on their results over 3 month windows. That's really about the most idiotic system imaginable, but it's the one that we have. This is why I think ever more of the companies with big goal driven ideas are staying private. Go public and suddenly everything is about reducing risk and working to min-max on a quarterly cycle, annual in the worst case.

This is really distorting progress in our country because while going public may severely impair any longterm revolutionary goals of a company, it'll also make you [the founders] filthy stinking rich.

> The stock market butchers companies based on their results over 3 month windows

In the "risk-on" phases of the past few cycles, the stock markets have loved risk takers. The problem, I believe, is in management not wanting to ruin a good thing.

I don't think I had an opinion beforehand or anything. I mean I was always down with the idea. But I think the problem is that it's such a long process to get from point A to B, and then the market for putting things into orbit is pretty niche that most people just can't see the potential. And lot of people are living from paycheck to paycheck aren't really planning years down the road. It's completely out of their realm of experience or expertise in every possible way. And they would never attempt it so that's get projected onto the world as, "Anyone who attempts this is foolish."

Hindsight is 20/20 after all. And vision is only lauded in hindsight. Because a vision that ends in failure gets a big "I told you so." from people who usually have none.

> the market for putting things into orbit is pretty niche

It's only niche until the price comes down, like for computers, cars, air travel, aluminum, coffee, etc.

Fun fact: aluminum used to be more valuable than gold.

From here... https://en.wikipedia.org/wiki/Aluminium

"As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. [57]

...

[57] https://en.wikipedia.org/wiki/Aluminium#cite_note-Venetski-6...

Two things:

1. Things can be niche because there just aren't that many people who want them, rather than because you couldn't make them cheaply if there was demand. A good quality Videodisc player for example costs far more now than it did at the height of the format, because only weird retro collectors want one so there's no reason to mass produce them. Videodisc players are niche.

2. We're talking about literal space, it can actually fill up. Some orbits are either so low that everything de-orbits soon enough anyway and needs replacing, or so high that we'd never conceivably fill them, but in between are plenty of useful orbits that are finite, so filling them up with more crap doesn't make any sense even if you could do it for free.

It’s not so much that there’s not enough room up there, but rather if any odd piece of shit decides to disintegrate the debris field will make a large swath of orbit uninhabitable until the debris falls back to Earth.

So even if getting up there gets cheap the things we put up there will still need to be expensive.

Except that this isn't hindsight being 20/20...this is foresight.

> And lot of people are living from paycheck to paycheck aren't really planning years down the road.

The average joe had and could have had nothing to do with SpaceX's success. I think OP is referring more to people who could have had an impact, like government entities or aerospace company CEOs.

>cylinders

You mean capacitors. Ba dum tshhh.

Actually I’m this case I think he means combustion chambers...

No. I think they're referring to Tesla (and its struggles) seeing that it's a car company and cars classically run on cylinders, but since Tesla's are electric, no cylinders. You know since Elon Musk is a founding member of both SpaceX and Tesla.

I thought they were referring to SpaceX as well seeing as it's 3 cylinders and the topic at hand.

SpaceX, not Tesla.

Do rockets have cylinders?

you mean the white pointy tubes? yes.

Eh, the Falcon 9 Heavy was years later than what the CEO "mapped out" and is missing an major feature of the original design (crossfeed). They may have done better than their competitors but SpaceX have had their share of mishaps along the way like anyone else. A lot of the "hate and doubt" was justified; certainly the people who said there was no way Falcon 9 Heavy would be flying in 2013 like Musk was claiming turned out to be... 100% correct.

If Wikipedia is pointing at the right numbers, the final Falcon Heavy has 20% more payload to LEO than the initial proposal with crossfeed. Late? Yes. More capable than projected? Yes. Low R&D budget? At $500mm, amazingly so, especially for being late.

> the final Falcon Heavy has 20% more payload to LEO than the initial proposal with crossfeed.

They met the payload goals thanks to unanticipated improvements to Falcon 9 performance. But it rather gives the lie to the "the CEO made a plan and they executed that plan" narrative; actually a substantial part of the CEO's plan was a blind alley and they wasted a lot of time chasing it.

There's a really good comment about why reigniting an engine after a long time in space is difficult.

I hadn't even considered that the fuel will just be floating in the tank with no forwards pressure

#ThingsKSPdoesn'tTeachYou

If you're interested in learning more about this kind of thing, you want to look stuff related to "ullage".

Fun fact: it doesn't actually take that much time without forwards acceleration for ullage to become an issue. For example, the Saturn V included solid-fuel rockets on the interstage between the first and second stages to provide enough forwards acceleration for the second stage engines to ignite, even though the gap between the first stage engines shutting down and the second stage engines igniting wasn't more than several seconds [0, page 14]. You can see the exhaust from those motors on the outside of this video of the Apollo 4 first stage separation [1].

Another fun fact: instead of using smaller motors to provide acceleration between stages, (some?) Soviet rockets ignited upper-stage engines while the lower-stage engines were still firing ("hot-staging"). This is why some soviet rockets had a lattice (or lattices) between stages instead of solid metal.

Yet another fun fact: it doesn't take much acceleration to sufficiently settle the fuel for ignition. The Saturn V's S-IVB stage used its equivalent of its RCS system, which is normally used for attitude control, to settle its fuel prior to firing for trans-lunar injection.

If you're interested in installing KSP mods, RealFuels includes ullage simulation, so you'll need to have some method of providing acceleration to get larger rocket motors to ignite reliably.

[0]: http://web.mit.edu/digitalapollo/Documents/Chapter5/saturnas... [1]: https://youtu.be/iJIY4n5oXjc?t=8

Edit: Fix description of hot-staging for Soviet rockets. Some Soviet rockets hot-staged their third stage and not their second stage, making the description incorrect.

Another fun fact: you can replace the need for ullage acceleration with a Propellant Management Device that uses surface tension among other things to hold propellant enough to fuel an impulse that will settle the rest of the tank.

http://www.pmdtechnology.com/Index.html

For very low accelerations, they can even draw propellant "upwards" against the acceleration.

Ha brilliant post, I always wondered about those lattice structures, I figured they were for mass saving, thanks!

This classic clip of the Saturn launch shows three ullage rockets firing before the main (liquid) engine kicks on:

https://youtu.be/jPDkagD50XU?t=95

One thing I don't know if it is correct is that, on KSP, I've managed to deal with ullage using the overpowered reaction wheels (essentially using centripetal force). Pretty sure that would not work properly in real life, with real materials...

It's physically possible, but it almost certainly wouldn't be practical. The mass needed for a reaction wheel of the right size would probably make it too expensive, never mind the control and mechanical issues of dealing with an accelerating spinning rocket.

Yeah, I don't think a rocket would like this lateral acceleration at all, even if we replaced the reaction wheels with something less far-fetched.

Oh, but KSP does teach you this. It just requires a mod: "Engine Ignitor". Then you have to care about the fuel sloshing about, ullage, limited number of ignitions depending on engine type, things like that.

https://forum.kerbalspaceprogram.com/index.php?/topic/168424...

If you watch some of the old webcasts you can see shots of the LOX tank in 0g transitioning to firing. The trick is to use another source of thrust (e.g. cold gas thrusters) to accelerate the rocket slightly and settle the fuel.

I've always wondered if you couldn't do the same thing by spinning the rocket, and a spiral in the tank. Advantage: doesn't require any reaction mass. Disadvantages: requires a reaction wheel (might be complicated engineering), and spiral in the tank might impact fuel pumping/flowing performance.

Spinning rockets are extremely hard to control due to precession/conservation of angular momentum. Any change in attitude would introduce a wobble. Unless you make your tanks spherical and rotating independently of the rocket motors on a gimbal you will have trouble with changing orientation and compensating for minor offsets of thrust.

Ah, you're right. You'd need to spin until just the moment when you start the engines, and then stop pretty much instantaneously, which in practice would cause all kinds of instabilities and problems...

Spinning the rocket sends the liquid to the sides, not the bottom where the pumps are.

That's why you have the spiral inside the tank, so that it "scoops" the fuel to the bottom.

Not if you spin the rocket end-over-end

But then the rocket isn't consistently pointing the engines in the right direction.

Depends on how fast you need to spin it. If you had a reasonably long period, the lighting of the engines and the cancellation of the angular velocity could occur fast enough that the engines would act like they were consistently pointed in one direction.

I think a bigger issue might be that all the mass is at the engines, so the engines would stay nearly fixed with the other end of the rocket rotating rapidly, and pretty much all the propellant would go to the wrong end of the rocket.

That doesn't sound right. I would expect that the centripetal force will send the fuel to the end of the rocket (or ends, depending on where the pivot point is).

And how do you spin up the rocket?

Using a reaction wheel.

https://en.wikipedia.org/wiki/Reaction_wheel

Basically, an heavy enclosed wheel that you use a motor to spin. Because of the conservation of angular momentum, the rocket will spin in the opposite direction (more slowly, because it's (probably) heavier).

Not going to work at that scale.

SpaceX is using the RCS (Reaction Control System, https://en.wikipedia.org/wiki/Reaction_control_system) of their rockets for this job (i.e. as Ullage motor, https://en.wikipedia.org/wiki/Ullage_motor).

This shows the contents of a tank (I think it's the oxygen tank as there's no transfer tube in the middle of the tank as it would be in the RP-1 tank (that's short for "rocket propellant-1" a sort of refined kerosine - and yeah, very imaginative name!)) sloshing around during SECO-1 (Second Engine Cut-off 1) during the CRS-4 mission.

https://youtu.be/7YkCh7uOw1Y?t=1442

It does, just not the vanilla version. If you want realistic fuel and engine behavior, you should try with RealismOverhaul mod, where ullage and engine restarts are critical parameters during vehicle design and mission planning.

Anyone else enjoy the PDF-like presentation of the webpage? This design is so clean. I initially thought OP submitted a document.

> This design is so clean.

Does that include the giant video ad at the top? https://imgur.com/a/4QvQO3W

That is a pretty big advantage if you save all of that fuel on the satellite. It translates directly into extra years on station and so longer payoff period.

Sure, if you have already built the satellite, and it shares fuel between orbit raising and station keeping, it can be a big win. ULA convinced the US to do that with GOES-16, recently.

But if you're designing from scratch, building a bigger satellite and staging earlier gets more mass to GEO. That's called a "subsync" orbit and SpaceX has talked 2 customers into doing that with 3 satellites so far: Telstar 19V, Telstar 18V, and Hispasat 30W-6.

https://www.reddit.com/r/spacex/wiki/launches/gto_performanc...

In these latter 3 examples, the customer saved ~ $30mm on the launch by staying within the reusable F9 mass limit.

Elon Musk's biography is no less than a thriller :)

Short Story :

He once took Tesla Model S (not fully developed) to his home from tesla HQ. The next morning, he came back with more 40 changes to be made. And yes, he remembered all those changes after more than 12+ hrs.

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