RocketLab Discussion Thread

[tater]

I'm actually really liking this concept. It's nice to see something out of the box vs a F9 clone.

[Beccab]

11 minutes ago, tater said:

I'm actually really liking this concept. It's nice to see something out of the box vs a F9 clone.

I like it too, but honestly I was expecting more after all the hyping about "rocket from the 2050s". Still cool

[tater]

7 minutes ago, Beccab said:

I like it too, but honestly I was expecting more after all the hyping about "rocket from the 2050s". Still cool

Fair enough, ideally in the 2050s a LEO vehicle is fully reusable. Still, it seems like a good starting point that they can actually accomplish in a timely way. Who knows, maybe they can make fiber in a cost effective way.

[Silavite]

Also, I'm guessing that the Isp of 320 seconds is an average between sea level and vacuum. If my fiddlings with RPA are correct, you'd need around a ~20 MPa chamber pressure to make that happen at sea level (accounting for a combustion efficiency of 99%, a nozzle efficiency of 98%, and sending 2% of the propellants to the gas generator) which seems a bit silly for an open cycle.

[sh1pman]

Neutron looks more like a rocket from 2030s. Up to date, with minor improvements over competitors - but nothing revolutionary like full reusability, large scale orbital prop transfer, OP engines (nuclear or bimodal), SSTO capability, etc.

[Beccab]

16 minutes ago, sh1pman said:

Neutron looks more like a rocket from 2030s. Up to date, with minor improvements over competitors - but nothing revolutionary like full reusability, large scale orbital prop transfer, OP engines (nuclear or bimodal), SSTO capability, etc.

Agreed, but I guess "a rocket 10 years away, built in the next 5 years" isn't a great slogan

[sevenperforce]

57 minutes ago, Silavite said:

Also, I'm guessing that the Isp of 320 seconds is an average between sea level and vacuum. If my fiddlings with RPA are correct, you'd need around a ~20 MPa chamber pressure to make that happen at sea level (accounting for a combustion efficiency of 99%, a nozzle efficiency of 98%, and sending 2% of the propellants to the gas generator) which seems a bit silly for an open cycle.

The Merlin 1D clocks in at just under 10 MPa; Raptor is 30+ MPa. What is typical thermodynamic efficiency in gas generators?

[sevenperforce]

2 hours ago, tater said:

Fair enough, ideally in the 2050s a LEO vehicle is fully reusable. Still, it seems like a good starting point that they can actually accomplish in a timely way. Who knows, maybe they can make fiber in a cost effective way.

Visually, it’s pretty cool. Makes me think of some of the early speculative BFR designs.

I wonder if they are going with lined or unlined carbon composite.

[tater]

50 minutes ago, sevenperforce said:

I wonder if they are going with lined or unlined carbon composite.

What do they use for Electron? I don't even know, tbh.

This is what we want to see, though. Serious attempts to compete. Starship vs Neutron, maybe Relativity gets going and Terran R is a thing. Who knows, maybe even Blue Origin becomes a real company and flies real rockets (anything could happen)?

[SpaceFace545]

Neutron is pretty rad looking and the concept is neat. It really is a rocket built entirely to be reusable in the most efficient manner and the design is so unconventional. A breath of fresh air from the numerous falcon 9 knockoffs.

[Silavite]

2 hours ago, sevenperforce said:

The Merlin 1D clocks in at just under 10 MPa; Raptor is 30+ MPa. What is typical thermodynamic efficiency in gas generators?

I honestly couldn't tell you for the gas generators themselves. Gas generators are basically small rocket engines, so I'd assume that the combustion efficiency isn't that different? That said, the highly off-stoichiometric mixture ratios may muck that assumption up somewhat...

For supersonic impulse turbines, nozzle efficiency into the first rotor is on the order of 80% - 96% according to Huzel & Huang.

Turbine efficiency seems to be on the order of 60% - 80% as indicated by Sutton as well as Huzel & Huang. (This can be increased if a gearbox is used, but that adds mass.)

Edited December 3, 2021 by Silavite

[RyanRising]

10 hours ago, CatastrophicFailure said:

Beck has officially replaced Musk as "Billionaire most likely to become a Bond Villain."

Have you seen Rocket Lab's headquarters? He was already way ahead in that respect.

7 hours ago, Silavite said:

Also, I'm guessing that the Isp of 320 seconds is an average between sea level and vacuum. If my fiddlings with RPA are correct, you'd need around a ~20 MPa chamber pressure to make that happen at sea level (accounting for a combustion efficiency of 99%, a nozzle efficiency of 98%, and sending 2% of the propellants to the gas generator) which seems a bit silly for an open cycle.

I suspect it's just the sea level engine running in a vacuum. The Merlin 1D (sea-level) should be roughly comparable, same cycle, modern tech, and that has ~310 s in a vacuum. That means between equivalent engines, you gain ~10, 15 seconds of specific impulse by going with methane over kerosene. Raptor is such a stupidly high-pressure engine, and is positioned so early on in the timeline of methalox launch vehicles, that it makes the performance benefit of methane over kerosene seem a lot higher than it actually is. I tend to think Rocket Lab went for methalox not for I_sp, but for the fact that methane is cleaner-burning than kerosene, and so will leave a lot less nasty deposits in the engine.
...not none, methane still can be made to coke, just a lot less than kerosene which has the long chains of carbons all ready to go before they get jumbled around.

Edited December 3, 2021 by RyanRising

[tater]

https://www.cnbc.com/2021/12/02/rocket-lab-reusable-neutron-rocket-update-competing-with-spacex.html

Quote

Beck, in an interview with CNBC on Thursday, said that Rocket Lab is still targeting to get Neutron on the launchpad by 2024, and hopes to launch a commercial customer on the rocket by 2025.

There has been reporting NG will not fly until 2024.

They could literally have a second LV—and a 7m one like NG—before BO ever reaches orbit.

[DDE]

2 hours ago, tater said:

https://www.cnbc.com/2021/12/02/rocket-lab-reusable-neutron-rocket-update-competing-with-spacex.html

There has been reporting NG will not fly until 2024.

They could literally have a second LV—and a 7m one like NG—before BO ever reaches orbit.

Hot take, but I don't think BO wants to fly. They seem all about joint ventures, and they can settle into the role of an enginemaker a la Energomash + Voronezh plant.

[SunlitZelkova]

14 hours ago, tater said:

 

It also reminds me of the monster from Stranger Things.

Spoiler

 

[Rakaydos]

13 hours ago, sh1pman said:

Neutron looks more like a rocket from 2030s. Up to date, with minor improvements over competitors - but nothing revolutionary like full reusability, large scale orbital prop transfer, OP engines (nuclear or bimodal), SSTO capability, etc.

Note that there's nuthing fundamentally preventing Rocketlab from constructing an upper stage with Starship Quick-Disconnects, that's able to use any Methalox tanker in orbit.

[Beccab]

1 hour ago, Rakaydos said:

Note that there's nuthing fundamentally preventing Rocketlab from constructing an upper stage with Starship Quick-Disconnects, that's able to use any Methalox tanker in orbit.

That makes me wonder, how would they fuel the second stage from this setup before liftoff? I.e. hang inside the fairing and with no external wall

Edited December 3, 2021 by Beccab

[SpaceFace545]

16 minutes ago, Beccab said:

That makes me wonder, how would they fuel the second stage from this setup before liftoff? I.e. hang inside the fairing and with no external wall

I guess their whole infrastructure would be around  shipping  the rocket assembled rocket to the pad already fuels. That works for a a lot of rockets but methalox is not storable. 

Also to note that neutron won’t ever be flipped horizontal. It’s gonna spend its whole life vertical.

[Galileo chiu]

Peter Beck is a James Bond villain confirmed!

[Beccab]

1 hour ago, SpaceFace545 said:

guess their whole infrastructure would be around  shipping  the rocket assembled rocket to the pad already fuels. That works for a a lot of rockets but methalox is not storable

Yeah the methalox part is the problem here, dunno. On Centaur they can fuel it inside the fairing and it's hydrolox, but I imagine that one passes from the base of the fairing attachment? So it's probably not a applicable here

[magnemoe]

2 hours ago, Beccab said:

That makes me wonder, how would they fuel the second stage from this setup before liftoff? I.e. hang inside the fairing and with no external wall

Pretty sure they have an internal piping to the LOX and methane tanks on the first stage and a quick disconnected just below the fairing. 
The internal piping need to be pulled back before release but this can be done between liftoff and separation. 
Piping are mounted to the tank together with the retractable clamps holding the second stage. 

The clamps are not shown as I know.  I wonder if they will extend up into the fairing an bit?  I say the fairing is longer than needed as in before it curves in it could just be interstage? Or it could be so you don't have to open them so much for the second stage to clear. 

Edited December 3, 2021 by magnemoe

[tater]

 

[FleshJeb]

One of the things that's bugging me about this is the bottom-end aerodynamics.

We know that the overall "reverse bullet shape" is designed to keep shockwaves from attaching to the vertical sides and causing heating. We can also expect that the blunt bottom will create a bow shock.

What happens when that bow shock intersects the legs? What about the shocks coming off the tips of the legs? There's going to be some ridiculous constructive interference between these two and it's going to create localized hot spots on the bottom of the rocket. Granted, they'll be changing locations as the Mach number decreases, but still...

I'll be really curious to see if they release any aerodynamic modeling.

[Silavite]

If this upper stage really does have such an incredible mass ratio, then I'd imagine you're looking at some pretty serious accelerations on lighter, higher energy payloads near the end of the 2nd stage burn. Has there been any information released about Archimedes (assuming that they're using a vacuum version of Archimedes for the second stage) having throttling capabilities?

[sevenperforce]

1 hour ago, FleshJeb said:

One of the things that's bugging me about this is the bottom-end aerodynamics.

We know that the overall "reverse bullet shape" is designed to keep shockwaves from attaching to the vertical sides and causing heating. We can also expect that the blunt bottom will create a bow shock.

What happens when that bow shock intersects the legs? What about the shocks coming off the tips of the legs? There's going to be some ridiculous constructive interference between these two and it's going to create localized hot spots on the bottom of the rocket. Granted, they'll be changing locations as the Mach number decreases, but still...

I'll be really curious to see if they release any aerodynamic modeling.

Perhaps it’s phatt enough that the Mach number will change really really rapidly in the high-density regime, rapidly enough that the flow around such sharp protrusions will remain chaotic.

44 minutes ago, Silavite said:

If this upper stage really does have such an incredible mass ratio, then I'd imagine you're looking at some pretty serious accelerations on lighter, higher energy payloads near the end of the 2nd stage burn. Has there been any information released about Archimedes (assuming that they're using a vacuum version of Archimedes for the second stage) having throttling capabilities?

I know he just means that CF is 4X lighter than SS in terms of weight per unit area, not that the mass ratio will be 4X better than Centaur, but still…wow.

I’m sure the upper stage engine will have to have decent throttling. You need that for precision orbital insertion, anyway. Unthrottleable or limited-throttle liquid engines are mostly the regime of disposable first-stage engines. And throttling isn’t too hard to do with a GG engine.