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Comment by kirrent | Hacker News Reader

The electron is a really cool rocket. It's constructed using carbon composite tanks and uses Rocketlab's Rutherford engine. The engine is constructed using a large amount of 3d printing and uses battery powered electrically driven fuel pumps.

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It's worth mentioning that while electric turbopumps are a lot better that pressure-fed designs, for larger engines they aren't as effective as using pre-burners (due to the weight of the batteries).

It does make the design much simpler, though.

The weight is an issue here too. It's something like 200kg of battery in the first stage. The second stage is designed to use its batteries one by one, and them drop them as they're expended.

That seems... Really bad for the environment? Nobody said launching rockets was environmentally friendly but that sounds particularly egregious.

>The batteries had a low auto-ignition temperature of 150 degrees Celsius, which meant they were highly likely to burn up in the atmosphere before reaching Earth's surface, MfE said. The batteries contained no lead, acid, mercury, cadmium, or other toxic heavy metals.

http://www.stuff.co.nz/technology/83804825/360kg-motor-assem...

One bit I remember from reading about rocket systems design is first stage performance is less critical than second and follow on stages. The cost of lower ISP/Mass ratio on the first stage is linear, you just make the it proportionately bigger. Where with higher stages the cost is exponential.

Which makes me wonder if electric pumps might make sense for larger rockets even though their performance is lower. You'd need a larger first stage, question then is how much bigger vs cost savings from a simpler design. I don't have an out of my keister answer for that though.

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