RocketLab Discussion Thread

[tater]

(intentional test to failure)

[darthgently]

I'm not fully convinced, given the paucity of physical evidence and data available after all electrical power is lost while suborbitally doomed, that RL is fully convinced that they reconstructed what actually happened.

But I do think they did their due diligence and honestly arrived at their best estimate of what may have happened

[Spaceception]

Is this the first image of the Archimedes engine? In any case, it's a small Neutron update! Always good to see hardware take shape.

[AckSed]

That is a highly unusual combustion chamber, with seemingly no space for a powerhead. Other oddities:

That 'frilled' flange with all the bolts - injector face?

The top part with the exaggerated buttresses, brackets (for swivel joints?) and the pointy parts (hose connections, maybe).

The second picture, where its being mated to a nozzle? I spot two cutouts on opposite edges of the lower combustion chamber, exposing fin-like protrusions. Film cooling?

Speculation: it would be very cool if they managed to 3D-print some/all the hoses that normally stick out of a rocket engine into that top part.

[tater]

 

[tater]

 

[AckSed]

Takeaways, part the first:

RE: the second stage failure in the last launch: it was caused by the very specific circumstances of that flight. The low-pressure mix of helium and nitrogen, the 500V DC, the pressure at that specific height, the AC 'ripple' of the DC synchronous motor when it starts up, all increased the ability of an arc to extend through a pinhole for a few centimetres to a metre or more. They had to stick a second stage in the vacuum chamber to find this out, as it's buried deep in the literature. They show a graph titled "1.6 seconds of anomaly data" where they recorded the fault and the loss of power 1.6 seconds later. Their solution was simple: pressurise the battery pack underneath a flexible 'boot'.

22 Electron launches planned for 2024, 9 of them slated for 12st stage recovery. 2 slated for HASTE.

[sevenperforce]

On 11/10/2023 at 4:33 PM, tater said:

 

The top of the engine looks like the SM-6A Service Module from the Making History DLC:

Maybe they plan on putting the turbopumps on those attachment nodes? /s

In more serious review, it looks like there are gimbal mounting points on the nozzle extension and the nozzle extension seam is fluted, so this could be a true throat-gimbaled engine! Those are fairly rare. I don't think those bits up top are a gimbal, although they might be.

[AckSed]

Takeaway the second:

Production is a pain but they're scaling just have to hold the rate;
1 Electron rocket every 15-17 days;

Have 3 cleanrooms for integration;

Why electric motor on 2nd stage?
Propellant residuals on small stage can be 30kg;
You risk cavitation on other methods of powering the engine;
1st stage can be completely sucked dry, and so can 2nd stage;
Constantly monitoring mixture ratio which is easy with electric motors;
Electron's a relatively tiny vehicle for the payload it can lift.

Little launch vehicles more sensitive to added mass - 100 grammes on Electron is significant.

Wallops a "key site".

Certified for automated FTS at Wallops.

Rapid-response good capability to have, but it's just how they roll anyway.

Launch sites are "money hoovers"; they'll build a site if they feel there's a market opportunity, but not until then.

Ocean recovery of Electron 1st stage: discovered not that much they need to do to make them waterproof and marinised.
Cost of refurbishment vs. cost of helicopter pretty well neutral.
Able to bring it down on last recovery within 400m of predicted landing, which is pretty good for a passive recovery.
They don't do a braking burn.
Now focusing on recovering in different weather conditions without damaging it.
Not just about recovering and reusing, but doing so economically. Next step recovering and reflying all 9 first stage engines, then whole vehicle.
Reuse on Electron a 'nice to have' not a must-have, as they're focusing on production.

[AckSed]

Third part:

First stage to splashdown was there for an hour; they found barnacles on the engine. Once you gift it to the sea, the ocean "instantly starts consuming it". Marine assets still suck because they dissolve in front of your eyes, but they're a necessary evil.

RE: Electron recovery on the manifest: Performance is always maximised over recovery

Launch manifest a giant game of whack-a-mole; always changing, so recovery may end up added or taken away to missions

Tank reuse relatively low-risk, but it's a small part of the rocket compared to the engines.

Have been reusing previously-flown pressurisation and vent-relief systems.

Priority is getting customers to orbit on time.

Venus probe
A "nights and weekends project" for them and the other teams working on it.
NASA provided heatshield for reentry probe.
Biggest question: "Are we the only life in the universe?"
Descent probe passing through the semi-habitable zone 50km up will essentially have a "go/no-go gauge for life".
It will have 120 seconds before it is crushed and melted.
If yes, chances are life is all around the universe, if no it means we have to be a bit more careful with ourselves. Either way, a super-important and exciting thing to do.
They've reached the point on Photon and Electron they can do this for a tiny amount of money.
Wary of scope creep, but with Photon they can go anywhere in the near Earth regime, notably the Escapade missions for NASA.

Is something about small satellites harder, given the amount of launch services struggling? What makes RL different?
Incredible efficiency and automation; for e.g. flight-safety team, they can't afford to hire 30 people on a $7.5 million sticker-price, they have to do it with 3.
With regard to small launch vehicles: not everything scales. E.g. a pressure transducer only goes so small. If you can pull that off, engineering a large launch vehicle is a piece of cake.
Large vehicles take capital. A launch site for small launch doesn't take that much concrete or steel. The trouble with Neutron is the quanta of capital and the quanta of infrastructure required. It's why nearly all rocket companies start off with a small launcher to gain credibility and thus attract the capital for a large launcher.

Neutron
Tank test bigger milestone than people realise.
Second stage has to be the lightest, highest-performing and also cost the least, because it's disposable. Economics, materials science, manufacturing all have to pass the test.
Second-stage tank is 5 metres across and weighs the same as a Harley-Davidson - 300-something kilograms. Made comparison to Centaur [Note: dry mass of Centaur 2247 kg].
In comparison, the first stage tank has much more margin - thicker walls, made to be reused.
In the honeymoon period where they are figuring out the margins and what works, what doesn't.
It's a hung stage, but the payload load path is spread out over the launch cone to intersect with the sides - "super clean". Designed that first.
Holding the fairings is a parasitic load, so you have to find other ways to save mass. Talks about the spiral of doom. You know you've done your job right when every engineer is unhappy with the compromises.

Image listing achievements this year: 2nd stage tank testing, critical engine components manufactured, combustion device testing, stage lock and pusher, actuator motor controller, power management module, engine/stage controller functional testing, avionics I/O controller testing, TPS testing, canard test rig built.
Still to do: fairing and upper module testing, Archimedes engine build and first hardware-in-the-loop flight to orbit
Next year is a big year.

Archimedes development going well, but it remains the long pole in the tent.
Chose oxidiser-rich staged combustion because if you dial it back a bit from squeezing out every last bit of performance, you end up in really benign operation at the same level of performance as a gas-generator cycle, but "kind of bulletproof". Compared it to an airplane engine.
Ox-rich combustor couldn't be dialed back too much or it would extinguish; had to solve that in the process of building the most boring, unboring engine.

How many launches per year do you hope to get out of Neutron?
Can't put a number on it, because you'll turn out to be wrong. Generally following the Electron beginning cadence.
Customers they're talking to looking to use it as a mega-constellation deployer.
Designed for high flight rate.

Would you ever use drone ships for more intensive launches?
Kind of resigned to it. Return to launch site is 8 tons, while downrange is 13 tons. You just trade out too much payload.

Any hop tests?
No, just try to bring it home, they learned from Electron's recovery.

Fairing design now just two halves. Render not updated because they've been working on the rocket.

No chance right now of reusable second stage, because payload suffers so horrendously if you have the reusable fairing on that. Also have to direct that to where you care. 70% of the cost of the vehicle is in the first stage.

Cleared land to build LC3 for Neutron at Wallops. It's a big pad. Can't launch from NZ, there isn't the industrial base. All the LOX produced in NZ would fill half a Neutron - once. USA can supply multiple tanker-trucks. Wallops gives a good SSO dog-leg corridor, better than the Cape. Also supportive thanks to existing relationships built with Electron.

Designing it to be human-rate*able*, not human-rated out of the gate. No market as of now, as the one customer for it is well-served. Needs more space stations, more destinations before they would try. Would jump on it if it made sense.

Personal

First launch he saw was the last Space Shuttle night launch. Favourite launch is every successful one. Most memorable was the NASA launch "This One's For Pickering" [NZ founder of JPL], as they had Pickering's family in the launch and growing up he always wanted to work for NASA.

No allegiance to NASA 'meatball' or 'worm'. Capstone mission had the 'worm' - "craziest flight ever" - and there was a three hour debate over whether they could afford the mass of the sticker on the side of the vehicle or not. The worm was probably slightly lighter.

Two/thirds of their business is building spacecraft. Escapade, Varda, MDA Global Star... whole goal of Rocket Lab is to be an end-to-end space company. Launch gives you the keys to space but is just one element. If you can put infrastructure into space, it's incredibly hard to compete. Methodically stepping their way through to that ultimate endpoint.

How do you ensure RL survives the next two years?
Small launch suffered from a lot of aspiration and not a lot of execution. RL not immune to that. Rigid on "did you do what you said you would do?" Prefer to execute and then tell rather than pump up. Trying to build a multigenerational, enduring space company; everyone's got a use-by date, so it can't be the Peter Beck show. Going public means you have to be profitable, to deliver - called it a forcing function. Without investment in Neutron, RL's profitable, but they're investing in the future.

Edited November 14, 2023 by AckSed

[darthgently]

24 minutes ago, AckSed said:

Prefer to execute and then tell rather than pump up

Aka Under-promise, over-deliver.  It is almost magical in its effectiveness

[AckSed]

I'm still boggling at the 2nd stage tank being that lightweight. Remember, that almost has to have a common dome inside it for the methane tank, and then bonded to the wall securely enough that it isn't affected by the oxygen.

[Spaceception]

58 minutes ago, AckSed said:

No allegiance to NASA 'meatball' or 'worm'. Capstone mission had the 'worm' - "craziest flight ever" - and there was a three hour debate over whether they could afford the mass of the sticker on the side of the vehicle or not. The worm was probably slightly lighter.

It's crazy that the payload margins are that thin.

Makes sense that they're not shooting for full reuse right now, they can probably get away with mass manufacturing second stages like SpaceX is doing. That said, it would be neat if they could upgrade it to function as a space tug for higher orbit/deep space missions. The industry is starting to get on the reusability train after all, why not the orbital refueling train too?

I like how they're trying to make Archimedes the "most boring-unboring engine," can't wait to see the first tests on it.

[magnemoe]

12 hours ago, Spaceception said:

It's crazy that the payload margins are that thin.

Makes sense that they're not shooting for full reuse right now, they can probably get away with mass manufacturing second stages like SpaceX is doing. That said, it would be neat if they could upgrade it to function as a space tug for higher orbit/deep space missions. The industry is starting to get on the reusability train after all, why not the orbital refueling train too?

I like how they're trying to make Archimedes the "most boring-unboring engine," can't wait to see the first tests on it.

Find it weird they use stickers for logos, I assumed they was painted. Think this might be easier, simply stretch an tarp with an cutout and spray paint. 
Yes I know stickers are common for adds on car and busses but they change adds often, car paint is also expensive to repair.

[tater]

 

[sevenperforce]

On 11/13/2023 at 11:28 PM, AckSed said:

I'm still boggling at the 2nd stage tank being that lightweight. Remember, that almost has to have a common dome inside it for the methane tank, and then bonded to the wall securely enough that it isn't affected by the oxygen.

Yeah that's truly incredible. If they can really get a 5-meter methalox tank in under 400ish kg then...just wow.

[RCgothic]

On 11/13/2023 at 2:50 PM, sevenperforce said:

The top of the engine looks like the SM-6A Service Module from the Making History DLC:

Maybe they plan on putting the turbopumps on those attachment nodes? /s

In more serious review, it looks like there are gimbal mounting points on the nozzle extension and the nozzle extension seam is fluted, so this could be a true throat-gimbaled engine! Those are fairly rare. I don't think those bits up top are a gimbal, although they might be.

If you look closely you'll see that of the two flat portions with the pins through, the left hand pin mount doesn't extend all the way down and the right hand pin mount doesn't extend all the way up. Two axis freedom. I'm 99% certain that's the gimbal mount.

[tater]

21 hours ago, sevenperforce said:

Yeah that's truly incredible. If they can really get a 5-meter methalox tank in under 400ish kg then...just wow.

Is the Centaur on Atlas V the same regardless of position (under or not under the fairing)? The fair it when the loads are too high (more SRBs), so it's clearly load driven at some level. Neutron doesn't face that issue. It might be possible to make an even lighter Centaur for lower mass payloads with high C3 (if said Centaur was faired)—but this being "old space" probably not worth the effort.

The cost/mass incentives for expendable vehicles are quite different than reused or partially reused.

[sevenperforce]

6 hours ago, RCgothic said:

If you look closely you'll see that of the two flat portions with the pins through, the left hand pin mount doesn't extend all the way down and the right hand pin mount doesn't extend all the way up. Two axis freedom. I'm 99% certain that's the gimbal mount.

Ah, good catch. That might well be the gimbal mount, and the mounting brackets on the sides of the engine bell could simply be for the gimbal actuators.

That exaggerated lip between the nozzle and nozzle extension is kind of weird, though. This is ORSC so I'm not sure why there would be any boundary; it's not like they need an exhaust injection manifold a la F-1 or MVac. Maybe that's part of the regenerative cooling manifold and they're cooling part of the system with LOX and part of the system with CH₄? If I was putting hot oxygen anywhere I would put it as far down the nozzle as possible so that there wouldn't be as much corrosion or risk of failure at burn-through.

Now you've also got me wanting to speculate about what kind of ORSC they're doing, whether they are doing a single-shaft turbine with a helium purge or some other design, whether they have boost pumps, and so forth. It would be cool to do, say, an expander-cycle boost pump. There's not any visible detail on that image. I wonder if they are going to try test firing it from pressurized tanks without the preburner?

1 hour ago, tater said:

23 hours ago, sevenperforce said:

Yeah that's truly incredible. If they can really get a 5-meter methalox tank in under 400ish kg then...just wow.

Is the Centaur on Atlas V the same regardless of position (under or not under the fairing)? The fair it when the loads are too high (more SRBs), so it's clearly load driven at some level. Neutron doesn't face that issue. It might be possible to make an even lighter Centaur for lower mass payloads with high C3 (if said Centaur was faired)—but this being "old space" probably not worth the effort.

Centaur uses the same tanks whether or not they use the fairing. And the fairing isn't just for bigger loads; the Atlas V 501 (5-meter fairing, no SRBs) has been launched a total of seven times. It does like like the 4-meter fairing has never been launched with more than three SRBs, though, so maybe that's where the aero loads get dicey for Centaur.

But the comparison is really something. Centaur has a dry mass of 2,316 kg, which less the 190-kg RL10C-1 comes to 2,126 kg. That, for an external cylindrical volume of 77.15 cubic meters and a total prop load of 20.83 tonnes. Pixel counting is always rough, of course, but based on a 5-meter outer diameter for the Neutron second stage I'm estimating an external cylindrical volume of 119 cubic meters. Even if the more rotund design means lower volumetric utilization -- let's say around 105 cubic meters -- that's 36% more propellant volume than Centaur and 3.02 times more propellant mass given the higher bulk density of methalox over hydrolox. Looking at 63 tonnes of propellant for a 300-400 kg tank is just utterly shocking...that's, like, a propellant mass fraction a little over 99%.

Trying to sanity check this. Assuming typical T/W ratio on the order of 150 for the 890 kN vacuum version, I would expect the weight of a single vacuum-optimized Archimedes engine to be around 600 kg, which still leaves us with a 98.4% stage propellant fraction. They advertise 13 tonnes to LEO and 1.5 tonnes to either Mars or Venus. You need about 3.9 km/s to get a transfer orbit to Venus out of LEO which is lower than typical transfer orbit requirements for Mars so let's go with that. Back-calculating with the expected 365 seconds of specific impulse gives us 6.1 km/s of Δv on the ascent stage with a 13-tonne payload, meaning that the first stage has very little work to do other than getting out of the atmosphere. Back-calculating for a 1.5-tonne payload gives us 11.6 km/s of Δv, which is 5.5 km/s of extra: higher than needed for the Venus transfer, but not entirely out of the ballpark. And we're working with dicey numbers here anyway because we don't really know what a Mars or Venus transfer looks like, or whether that's even reusable.

[AckSed]

A key part of the light weight of the 2nd stage tank is, I think, Rosie. Back in 2019, this carbon-fibre-laying and drilling robot reduced the production time of the carbon composite components for the whole Electron from 400 hours down to 12 hours. The razor-edged mass requirements of Electron mean that it has to be consistent enough to make those, and I think I saw it laying curved pieces in the first Neutron presentation so... All in all, seems like a fast way to prototype and iterate.

Another part of it is the hung stage, with the payload cone transmitting the thrust of the payload into the body of the first stage, leaving the tank and engine free to dangle. So it only has to take the strain of the mass of propellant and the compressive load of whatever a vacuum Archimedes can supply. And they've carefully designed it so that the mounting point for the tank to hang is a ring around the sides, not the neck, spreading the load. It's ingenious.

[tater]

 

[tater]

 

[tater]

Live, T=0 is the top of the hour

[AckSed]

Good launch, though the camera on the second stage wasn't enjoying it. For a moment, I thought the rays from the sun were hot-spots on the engine bell, but no.

[Geonovast]

9 hours ago, AckSed said:

Good launch, though the camera on the second stage wasn't enjoying it. For a moment, I thought the rays from the sun were hot-spots on the engine bell, but no.

I thought the same, too.

I spent pretty much the entire second stage burn chanting in my head: "It's just the camera, it's just the camera, it's just the camera, it means nothing, it's just the camera"