SpaceX Merlin Rocket Engine

Correction: the grid fins on the first stage do not use the kerosene as hydraulic fluid. They run on their own open hydraulic system.

Elon Musk has also tweeted saying the Merlin-1D can throttle down to about 40%, rather than the 70% said in the video.

[playgroundchooser]

The moment the Falcon came home last December will take a long long time if ever to forget. "LZ-1, the Falcon has landed."

[NetRolllerD]

The newer 40% throttle figure probably comes from the engines being uprated several times (first with v1.2, then in the "Even Fuller Thrust" upgrade, and possibly again in the future with Block 5) since their release. The lowest absolute throttle setting remains unchanged, but because full throttle has increased, the minimum now represents a smaller percentage of that.

[saiboogu]

Some remarks in /r/SpaceX have argued that the grid fins do use RP1 -- A separate RP1 reservoir at the interstage area, Helium pressurization, and plumbing down to the main RP1 tank to dump used fluid into the main RP1 tank. Presumably with the fin hydraulics running at slightly higher pressure than the tank ullage system to allow for pump-less drainage from the fins to the fuel tank. I don't know how accurate this is or if there is any supporting evidence for it -- But it does seem to offer the most efficient way to run the fins with the least wasted mass.

[CBaggers]

Great video, please keep making these!

[jakobdippel]

you have an amazing channel going :) keep it up

[iamcreasy]

Did you say 'care lock' engine? I didn't understand, could you please clarify, and talk some more about it.

[grahammckemy]

Why is it called Merlin? Is it an homage to the engine from the spitfires and the mustangs?