9 ms·

Rocket Lab's engine has electric turbos and 3D-printed primary components

52 points by robszumski 12y ago

NortySpock 12y ago
Why electric turbopumps (requiring independent power) rather than ones powered by the RP1 propellant? EDIT: RP-1 now, not methane
- hwillis 12y ago
  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 12y ago
    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.
- Sanddancer 12y ago
  Turbopumps powered by rocket fuel require quite a bit of plumbing and design work; you're essentially building a second rocket motor to drive the bigger one. By using an electric turbopump, you just need a place to put the motor and batteries, which is a lot more simple in comparison.
  - david-given 12y ago
    Here's an article about test firing a Saturn V turbopump power plant: http://arstechnica.com/science/2013/01/saturn-v-moon-rocket-engine-firing-again-after-40-years-sort-of/ http://arstechnica.com/science/2013/01/saturn-v-moon-rocket-... Yes, the turbopump is run off its own rocket engine --- which drove a 40MW turbine, which ran a pump that could push three tonnes of rocket fuel a second. Admittedly, the Saturn V was a little bit bigger than this rocket's going to be, and had special needs, but it goes to show that rocket fuel powered turbopumps are scary. (Incidentally, SpaceX use a rocket fuel powered turbopump for the Falcon 9. I believe the scary-looking plume of flame that comes out sideways is the exhaust. It's a mere 2MW. Per engine.)
- ironchief 12y ago
  Here's a great technical analysis I submitted the other day. Rocket engine with electric pumps: http://www.scienceforums.net/topic/73571-rocket-engine-with-electric-pumps/ http://www.scienceforums.net/topic/73571-rocket-engine-with-...
ericmsimons 12y ago
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.
- trose 12y ago
  I'm just reciting this from memory but I think spaceX launches are currently $50-100 million per launch. If they can achieve reusable rockets it'll be on the order of a few hundred thousand per launch though.
  - x43b 12y ago
    " If they can achieve reusable rockets it'll be on the order of a few hundred thousand per launch though." Do you have any sources I can read on that? I know reusing some of the hardware will have cost savings, but you are more than an order of magnitude cheaper than I have heard claimed. I would be very surprised that even if all of the hardware was 100% free that there would not be a few hundred thousand in labor costs alone for analysis and launch operations.
    - acadien 12y ago
      I think the above comment of it cost only a few hundred thousand dollars is just the cost of the fuel. Ancillary costs like moving the rocket, repairs, refueling, launch planning etc would also cost some money but it is still orders of magnitude cheaper than building new rockets or heavy repairs from crash landings.
      - x43b 12y ago
        Thank you for the response. However, that is exactly my point. Orders of magnitude, plural, means the rocket will be 1% of the current cost. That means a $61 million rocket is on the order of $610,000. I do not believe that raw material procurement and manufacturing account for 99% of current launches or 97% or 90%. Even if it did, I believe there would be significant amount devoted to quality inspections and testing before you could trust a used rocket that not only fired, but impacted the ground to be used again.
chinathrow 12y ago
No, it has not "all 3d printed parts". It has, actual quote "3D printing for all primary components." Big difference.
- robszumski 12y ago
  Agreed. It was hard to fit in the title.
robertandy 12y ago
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.
- lvs 12y ago
  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.
- Gatsky 12y ago
  He's taking the piss, it's an Australian thing.[1] [1] I know he's actually from New Zealand, but since he might end up being famous, I'm going to start the process of pretending he's Australian.
DannoHung 12y ago
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.
- olympus 12y ago
  100 kg is small compared to some of the behemoths floating around up there. The Milstar satellites that provided high reliability communications for the USA were 4,500 kg each. GPS satellites are over 1,500 kg and are in MEO, which is higher than LEO but lower than GEO. But a lot of smaller companies don't need gargantuan satellites like that and can get a lot done with 100 kg. If you only need to put one or two satellites up it is not cost effective to spend lots of money on a large launch vehicle, so you buy space on another launch that has spare capacity and is launching at a compatible time/inclination. When you do that, you are not given priority and will have to wait if the #1 priority delays the launch for any reason. So Rocketlab can capture a market segment by letting small companies have their own launches. It's kind of like getting the individual packets of ketchup from McDonald's vs the family size bottle of ketchup from the grocery store. Sure, the family size gets you more ketchup for your dollar, but you don't normally need that much.
- patrickyeon 12y ago
  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
- pkinsky 12y ago
  They could be attempting to demo their 3d-printing technology with the smallest launch system possible. I imagine their competitive edge is in manufacturing, and they could be looking for an eventual partnership with a bigger player.
patrickyeon 12y ago
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).
tsuraan 12y ago
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.
mrfusion 12y ago
Regarding the pump, why can't the fuel just be pressurized and not use a pump?
- darkmighty 12y ago
  I'm guessing the fuel will be pressurized, and a pump is necessary on top of that to get as much thrust as you can; it's probably cheaper on a weight basis to make a good pump versus a very thick fuel container at some point.
- sbierwagen 12y ago
  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.
- robocat 12y ago
  The pressures are very high (you are pumping the fuel into the combustion chamber of the rocket engine). A tank that could be pressurised that highly would be uneconomically heavy. Edit: this says it better http://www.scienceforums.net/topic/73571-rocket-engine-with-electric-pumps/ http://www.scienceforums.net/topic/73571-rocket-engine-with-...
morbius 12y ago
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)

52 points by robszumski 12y ago

Why electric turbopumps (requiring independent power) rather than ones powered by the RP1 propellant? EDIT: RP-1 now, not methane

hwillis 12y ago
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 12y ago
  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.
Sanddancer 12y ago
Turbopumps powered by rocket fuel require quite a bit of plumbing and design work; you're essentially building a second rocket motor to drive the bigger one. By using an electric turbopump, you just need a place to put the motor and batteries, which is a lot more simple in comparison.
- david-given 12y ago
  Here's an article about test firing a Saturn V turbopump power plant: http://arstechnica.com/science/2013/01/saturn-v-moon-rocket-engine-firing-again-after-40-years-sort-of/ http://arstechnica.com/science/2013/01/saturn-v-moon-rocket-... Yes, the turbopump is run off its own rocket engine --- which drove a 40MW turbine, which ran a pump that could push three tonnes of rocket fuel a second. Admittedly, the Saturn V was a little bit bigger than this rocket's going to be, and had special needs, but it goes to show that rocket fuel powered turbopumps are scary. (Incidentally, SpaceX use a rocket fuel powered turbopump for the Falcon 9. I believe the scary-looking plume of flame that comes out sideways is the exhaust. It's a mere 2MW. Per engine.)
ironchief 12y ago
Here's a great technical analysis I submitted the other day. Rocket engine with electric pumps: http://www.scienceforums.net/topic/73571-rocket-engine-with-electric-pumps/ http://www.scienceforums.net/topic/73571-rocket-engine-with-...

ericmsimons 12y ago

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.

trose 12y ago
I'm just reciting this from memory but I think spaceX launches are currently $50-100 million per launch. If they can achieve reusable rockets it'll be on the order of a few hundred thousand per launch though.
- x43b 12y ago
  " If they can achieve reusable rockets it'll be on the order of a few hundred thousand per launch though." Do you have any sources I can read on that? I know reusing some of the hardware will have cost savings, but you are more than an order of magnitude cheaper than I have heard claimed. I would be very surprised that even if all of the hardware was 100% free that there would not be a few hundred thousand in labor costs alone for analysis and launch operations.
  - acadien 12y ago
    I think the above comment of it cost only a few hundred thousand dollars is just the cost of the fuel. Ancillary costs like moving the rocket, repairs, refueling, launch planning etc would also cost some money but it is still orders of magnitude cheaper than building new rockets or heavy repairs from crash landings.
    - x43b 12y ago
      Thank you for the response. However, that is exactly my point. Orders of magnitude, plural, means the rocket will be 1% of the current cost. That means a $61 million rocket is on the order of $610,000. I do not believe that raw material procurement and manufacturing account for 99% of current launches or 97% or 90%. Even if it did, I believe there would be significant amount devoted to quality inspections and testing before you could trust a used rocket that not only fired, but impacted the ground to be used again.

chinathrow 12y ago

No, it has not "all 3d printed parts". It has, actual quote "3D printing for all primary components." Big difference.

robszumski 12y ago
Agreed. It was hard to fit in the title.

robertandy 12y ago

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.

lvs 12y ago
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.
Gatsky 12y ago
He's taking the piss, it's an Australian thing.[1] [1] I know he's actually from New Zealand, but since he might end up being famous, I'm going to start the process of pretending he's Australian.

DannoHung 12y ago

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.

olympus 12y ago
100 kg is small compared to some of the behemoths floating around up there. The Milstar satellites that provided high reliability communications for the USA were 4,500 kg each. GPS satellites are over 1,500 kg and are in MEO, which is higher than LEO but lower than GEO. But a lot of smaller companies don't need gargantuan satellites like that and can get a lot done with 100 kg. If you only need to put one or two satellites up it is not cost effective to spend lots of money on a large launch vehicle, so you buy space on another launch that has spare capacity and is launching at a compatible time/inclination. When you do that, you are not given priority and will have to wait if the #1 priority delays the launch for any reason. So Rocketlab can capture a market segment by letting small companies have their own launches. It's kind of like getting the individual packets of ketchup from McDonald's vs the family size bottle of ketchup from the grocery store. Sure, the family size gets you more ketchup for your dollar, but you don't normally need that much.
patrickyeon 12y ago
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
pkinsky 12y ago
They could be attempting to demo their 3d-printing technology with the smallest launch system possible. I imagine their competitive edge is in manufacturing, and they could be looking for an eventual partnership with a bigger player.

patrickyeon 12y ago

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).

tsuraan 12y ago

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.

mrfusion 12y ago

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

darkmighty 12y ago
I'm guessing the fuel will be pressurized, and a pump is necessary on top of that to get as much thrust as you can; it's probably cheaper on a weight basis to make a good pump versus a very thick fuel container at some point.
sbierwagen 12y ago
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.
robocat 12y ago
The pressures are very high (you are pumping the fuel into the combustion chamber of the rocket engine). A tank that could be pressurised that highly would be uneconomically heavy. Edit: this says it better http://www.scienceforums.net/topic/73571-rocket-engine-with-electric-pumps/ http://www.scienceforums.net/topic/73571-rocket-engine-with-...

morbius 12y ago

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)