The Electric Future of Rocket Science

Recent advances allow powerful electric pumps to replace traditional turbopumps in some rocket systems... We dive into the solutions Rocket Lab and Astra Rocket company have found to power their rocket systems, and look to the future.
Designing a dependable turbopump is one of the hardest problems for rocket scientists.
The rest of a rocket engine almost seems simple in comparison…
The blades of your turbine and impeller must spin at tens of thousands of times per second.
NASA recently built a 3D printed hydrogen powered turbopump, here it is…
You know I prefer metric, but this is in imperial, so I’ll convert as we go.
This pump was able to move 1,200 gallons of liquid hydrogen per minute or 76 liters per second.
Since hydrogen has a density of about 71 grams per liter this would be a mass fuel flow of 5.4 kg/s.
It generates 2000 horsepower or 1491 kilowatts of power.
This is a small turbopump made for second stage engines.
But it’s producing twice as much horsepower as a race car does,
and allows the rocket engine to produce 35,000 pounds or 156 kilonewtons of thrust.
Now most small thrust rocket engines usually work best with pressure fed systems,
They don’t need a pump at all.
And this is often the best option for small hypergolic engines like the Draco RCS engines on the Dragon capsule
or even the larger SuperDraco engines used for flight about,
but as your tanks get bigger it is extremely hard to keep them pressurized sufficiently
so as to allow adequate fuel and oxidizer flow.
Expander cycle engines, where fuel is running around the nozzle and heated
with the expanded gas used to power a turbine
has only been used with hydrogen fuel in a small or medium sized engine, like the Blue Origin BE-7,
that would be used on the Blue Moon Lunar Lander, if it ever gets to the Moon.
Dr. Marco Leonardi of the Sapienza University of Rome did an analysis
and determined that methane would also be effective in an expander cycle engine to run a turbopump.
The European Space Agency is planning to use methane in an expander cycle engine for use in their second stage vehicle called the VEGA-E…
The engine will be called the M10, and you can see it here.
This would be the world’s first methane expander cycle rocket engine.
The Starship uses heated oxygen to pressurize the oxygen tank
and heated methane to pressurize the methane tank
but this is just to prevent vapor lock and is usually not more than two atmospheres for most rockets.
Generating enough pressure to push the oxygen and methane
out of large tanks would require up to 100 atmospheres of pressure,
and the ability to repressurize a large volume very quickly and accurately.
and you would need very thick tank walls making your rocket too heavy to fly efficiently.
That is why turbopumps are so important for large rockets.
We covered the oxygen and methane turbopumps in depth in the last lecture…
The raptor engines use an innovative fuel rich driven turbopump for methane
and an oxygen rich driven one for the liquid oxygen.
This works great for methane, but I want to make clear that the dual turbopump system on the Raptor
would not work with RP-1 (kerosene).
When RP-1 burns it produces a lot of soot, this is called coking
and would gum up any turbopump that was burning RP-1 fuel rich.
That is why the Soviets invented oxygen rich turbopumps
by creating new alloys that could resist oxidation.
Fuel rich pumps have been used on the space shuttle main engines burning hydrogen,
and of course,
on the Raptor burning methane
because these fuels burn extremely clean
and do not suffer from coking.
But while pressure fed engines work great for small rocket systems,
And turbopumps are unreplaceable necessary for all large rocket systems.
What if you wanted to make a medium sized rocket?
TSA-SOV-TTM-EFRS-21107

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Music credits:
Kevin MacLeod "Lost Frontier"
Credits: C Bass 3D Productions - the rest
are on screen at the end of the video.

Видео The Electric Future of Rocket Science канала Terran Space Academy