
Rocket Lab's engine has electric turbos and 3D-printed primary components - robszumski
http://www.rocketlabusa.com/index.html
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patrickyeon
Very cool. For people running the numbers about launch costs, there's a lot
more to it than just $/kg. There are very big constants in the cost of a
launch (even though SpaceX can get 13150kg/61M$, I doubt they'll offer
1315kg/6.1M$), and having final say in launch timing and what orbit you get is
worth a fair bit. For now, it's relatively cheap to hitch a ride as a
secondary to the ISS (or ISS orbit), but 500km sun-synchronous is not nearly
as easy to line up.

Comparable prices for small sats: Nanoracks quotes 60,000$/1U (usually ~1kg)
to the ISS. Interorbital quotes 12,500$/kg at a 310km orbit (or 8,000$ to use
their 0.75kg tubesat).

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DannoHung
So... are these guys actually going to be able put up a payload and also is
there anything really unique about what they're doing? 100kg seems like a
pretty small satellite for a $5MM launch, though I must confess my ignorance
of such matters for commercial launch systems.

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patrickyeon
I work for Planet Labs, and our satellites are 5kg[1] each, providing 3-5m
ground-resolution imaging. You can do a lot with relatively little mass these
days.

1:
[http://space.skyrocket.de/doc_sdat/flock-1.htm](http://space.skyrocket.de/doc_sdat/flock-1.htm)

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tsuraan
I'm curious, given the stated figures (total thrust, rocket dimensions,
payload to certain orbits), is it possible to calculate the specific impulse
of this new engine (with the atmo nozzles, I suppose)? I couldn't find it on
their page, and I'm not quite well-enough versed in rocketry to even know if
there's sufficient information to figure it out.

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NortySpock
Why electric turbopumps (requiring independent power) rather than ones powered
by the RP1 propellant?

EDIT: RP-1 now, not methane

~~~
hwillis
Cost, according to another article I found. The article also mentioned that
electric is 95% efficient while turbine-pumps are ~60%, but that is still
definitely not worth the weight penalty.

I suppose it makes sense, as it is very difficult to have a turbo with rocket
exhaust on one side and cryogenic oxygen on the other. Its quite creative if
it is actually cheaper. It might also allow finer control over throttling
back, but thats not useful unless you're spaceX.

~~~
NickNameNick
The other factor with turbo pumps in open cycle designs is you end up burning
a fair amount of your fuel and oxidizer in them, and throwing it overboard at
fairly low pressures/velocities, which hurts your specific impulse.

Staged combustion motors run the exhaust of the turbo-pump into the main
combustion chamber, and have far better specific impulse, but are much harder
to design and build.

The the electric pump design, you can have the simplicity of and reliability
of the open cycle main engine, with the efficiency inherent in not effectively
throwing a percentage of your fuel overboard.

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chinathrow
No, it has not "all 3d printed parts".

It has, actual quote "3D printing for all primary components."

Big difference.

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robszumski
Agreed. It was hard to fit in the title.

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ericmsimons
Does anyone know what SpaceX's target cost per launch is compared to these
guys (4.9M)?

Also, I'd never heard of Rocketlab before but it turns out that they're back
by Khosla Ventures. Pretty cool.

~~~
olympus
SpaceX lists the launch of a Falcon 9 to be $61M. But they can put 13,150 kg
into LEO. Rocketlab's is much smaller, only sending 100 kg into LEO. So a
Falcon 9 is ~12x more expensive, but delivers more than 125x payload to orbit.
Plus you can send stuff into GEO with a Falcon 9, but Rocketlab doesn't have a
chance with one their size.

So Rocketlab comes out sounding like a worse deal in the cost/payload ratio,
but if Rocketlab can deliver on their launch frequencies then they can capture
the market of smaller companies having to buy a secondary spot on a large
rocket, and then wait for the whims of the other people to be ready to launch.
The smaller company can fork over $5M and have the #1 priority and only
payload on the rocket.

SpaceX source:
[http://www.spacex.com/about/capabilities](http://www.spacex.com/about/capabilities)

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agildehaus
Won't that $61M figure get slashed by a tremendous amount once they achieve
re-usability?

~~~
binoyxj
The cost is expected to go down from $56M to just 5-$7M
[http://www.bloomberg.com/news/videos/2015-04-15/how-huch-
doe...](http://www.bloomberg.com/news/videos/2015-04-15/how-huch-does-it-cost-
to-launch-a-falcon-9-rocket-)

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mrfusion
Regarding the pump, why can't the fuel just be pressurized and not use a pump?

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sbierwagen
The Tsiolkovsky rocket equation.
([https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation))

[https://what-if.xkcd.com/7/](https://what-if.xkcd.com/7/)

    
    
      But this is just a minimum. In practice, everything depends 
      on our means of transportation. If we’re using rockets, 
      it’s going to take a lot more. This is because of a 
      fundamental problem with rockets: they have to lift their 
      own fuel.
    
      If we want to launch a 65-kilogram spaceship, we need to 
      burn around 90 kilograms of fuel. (Gasoline has an energy 
      per pound comparable to that of rocket fuel, so we’ll 
      stick with that example). We load that fuel on board—and 
      now our spaceship weighs 155 kilograms. A 155-kilogram 
      spaceship requires 215 kilograms of fuel, so we load 
      another 125 kilograms on board ...
    
      Fortunately, we’re saved from an infinite loop—where we 
      add 1.3 kilograms for every 1 kilogram we add—by the fact 
      that we don’t have to carry that fuel all the way up. We 
      burn it as we go, so we get lighter and lighter, which 
      means we need less and less fuel. But we do have to lift 
      the fuel partway.
    

A rocket is essentially a series of very large tanks stacked on top of each
other. The economics work out in such a way that you make the tanks as
lightweight as possible, and then pressurize the combustion chamber with
turbopumps.

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robertandy
Somehow for a product of rocketry class, a video of its CEO talking about just
photo selfies and video streaming/other solved problems seems downright lame.

Talk about the capabilities of the rocket instead! The rocket looks cool
though.

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lvs
Man, that promo video was tough to watch all the way through. I'm not sure why
they believe they need to hard-sell the concept of cheap rockets.

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morbius
Unless they make their schematics and blueprints open-source, this isn't worth
my time. Space needs to be fundamentally open, driven by visionaries like Musk
and Bolden who care far more about the future of humanity than selling
product. The hackneyed "open for business" commentator for the video and the
seemingly copious patents they've filed for this vehicle don't give me much
hope. A far more interesting venture is Copenhagen Suborbitals -- they've lost
many key people over the years, but their vision is much more altruistic and
deserves much more support than some VC-backed team who decided to apply the
startup cash-grab culture to rocketry. (and yes, I do know that's an
incredibly loaded thing to say on a web forum run by a VC)

