SpaceX installed battery packs equal to the batteries used in four Tesla Model X cars to power the movement of wings on the SpaceX Starship. Moving the wings will enable the Starship to generate lift during re-entry to lower the peak temperature. This along with lightweight reusable tile heatshields will prevent damage during re-entry.
Elon Musk will present the new SpaceX orbital Starship design on September 28.
Many powerful electric motors & batteries. Force required is enormous, as entire fin moves. More about this on the 28th.
— Elon Musk (@elonmusk) September 24, 2019
Exactly. For reusable heatshield, minimize peak heating. For ablative/expendable, minimize total heat. Therefore reusable like Starship wants lift during high Mach reentry for lower peak, but higher total heat.
— Elon Musk (@elonmusk) September 24, 2019
Better just to ride your max temp all the way down & let T^4 be your friend. Lower atmosphere cools you down real fast, so not crazy hot after landing.
— Elon Musk (@elonmusk) September 24, 2019
Could do it, but we developed low cost reusable tiles that are much lighter than transpiration cooling & quite robust
— Elon Musk (@elonmusk) September 24, 2019
SOURCES – Elon Musk Twitter, SpaceX
Written By Brian Wang, Nextbigfuture.com
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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Having header tanks and butteries and other equipment in the front of the passenger are will improve radiation protection for the passengers.
No. That would incur a mass penalty in the amount of batteries you need to power the turbopumps.
Remember that Raptor is a Full-Flow rocket engine. The propellants burned in the two turbine preburners to run the fuel pumps are still used in the main combustion chamber to generate thrust, so ALL of the propellant mass are used to push the rocket.
Battery packs on the other hand just sits inside the ship and weighs it down once depleted of charge, unless you eject the spent batteries overboard like Rocket Lab’s Electron does, and even then ejecting the spent batteries doesn’t generate any thrust, unlike the turbine preburner combustion products in an FFSC engine.
The FFSC engine in other words is more mass-efficient than using battery packs to power the turbopumps, and that’s what you want in an interplanetary rocket ship, where you are trying to squeeze every ounce of performance out of the limited amount of propellant you can carry.
2 Tons of Batteries just to move the wings for few minutes? Must be used on board for through out the flight. A use of thermoelectric materials where feasible and useful could mitigate a lot of that. May even save on some of the heat shield.
A diagram of the Raptor on Wikipedia shows the methane pump at 28 MW and the LOX turbo-pump at 34 MW. Way over my SWAG. Among other things I’m sure, I forgot about the high chamber pressure of the Raptor compared to the F-1 (300 bar or more vs 70 bar).
all you need is a giant windup spring to store kinetic energy and a giant turning key to wind it before launch…
If it already has giant batteries… I wonder why they didn’t use electric motor to run rocket turbo prop instead of diverting rocket fuel to run it… like electron rocket…
My SWAG is it would take about 5 & 10 MW for both pumps together. No doubt the oxygen pump takes quite a bit more than the fuel pump.
Turbines improve with size, because the waste heat goes out with the gas. Electric motors get worse with size, because you have a harder and harder time getting the heat out. Some things just don’t scale well, some things do.
Believe me, Musk has good engineers, besides his being involved with Tesla. If electric motors made sense to run any other than the smallest rocket fuel pumps, he’d have done it.
How does it work on the Electron, then? Mass of power source scales with volume no matter whether it’s batteries or fuel.
“Outside the realm of possibility” and “actually would make sense to do” aren’t quite the same thing. The size of the battery you’d need to run those motors, even if you could run them flat out for the whole burn, would be prohibitive.
A single Raptor engine produces 2 MN of thrust rather than 6.8 MN of the F-1, there’s the Isp difference of 350 to 260, and there’s the fact that the Falcon Super Heavy uses 35 engines rather than 5. Just a ballpark figure, but I reckon each pump (separate oxidiser and fuel motors) would need to be sized at 0.9 MW. That’s not outside the realms of possibility at all when dealing with a vehicle the size of a skyscraper, it’s only 3 Model S motors per pump.
So, what you’re saying is the craft will catch fire and explode.
It wouldn’t be feasible. The fuel pumps alone take a huge amount of power to run. At least an order of magnitude more than even the most powerful version of the Tesla Model S. I don’t know the numbers for the Raptor but for example the Rocketdyne F-1 engine (between 3 to 4 times the thrust of a Raptor) used a gas generator (basically a rocket engine) producing 55,000 horsepower (41 MW) to run the fuel pumps.
I don’t think it’d be lighter, since the power density of liquid fuel is higher than in batteries. But it may be more reliable for restarts.
If you’re sticking that much electrical power on board, would it not be worth replacing the fuel pumps with electric motors a la the Rocket Lab Electron? Certainly lighter than full flow staged combustion powering them.