RP-1

So coming up in just about 20 seconds from now, we should be hearing the call-out for Stage 2 locks loading completion.

And at that point, the Falcon Heavy will then be fully loaded with nearly 3 million pounds of propellant comprised of RP-1 and locks.

So we should be hearing that call-out for...

Stage 2 locks load complete.

So we had a real treat that he came and talked to our astronaut class about his experiences and the history, and he said, "Look, you know, what the, the genius behind the Saturn V rocket is you need thrust in the first stage.

And so you get a lot of thrust from, um, get, you know, basically, um, uh, what was called RP, RP-1, which is, uh, kerosene.

It's basically kerosene.

You know, it's kinda like jet fuel.

It is a harder proposition at ground level, where sheer thrust and tank volume matter more.

Refined kerosene, known in the American system as RP-1, paired with liquid oxygen, gives what is often called kerolox.

Its specific impulse is lower, in the region of 300 to 340 seconds depending on the engine and altitude.

but it is dense, it can be handled at ordinary temperatures, and its tanks are compact.

For context, a gallon of gasoline stores about 120 megajoules, while gasoline and kerosene are worth around 40-45 megajoules per kilogram.

Kerosene, or refined RP-1, is one of our classic rocket fuels.

Now that ionization cost becomes less important in very high voltage engines, because accelerating each ion through 10 kilovolts, or even a megavolt, dwarfs the few dozen electron volts needed to ionize it, but for practical modern spacecraft engines, especially lower power ones, xenon is a much nicer compromise.

There's also storage.

The engineering angle on Falcon 9 reuse shows how the 23-flight booster divides the fixed material and manufacturing investment across more payloads.

The first principle's limit is the raw material and energy embodied in a single booster through aluminum-lithium tanks, turbopump forgings, avionics boards, and the RP-1 and liquid oxygen loaded for each mission.

Every additional flight divides that fixed material and manufacturing investment across more payloads, driving the effective cost toward the marginal expense of propellant, inspections, and minor refurbishment.

Structural margins on tanks and the thermal protection on the interstage must remain above minimums after repeated pressure cycles and reentry heating, which is why telemetry from grid fin actuators and tank ullage pressures is scrutinized after every flight.

And the missile itself was basically a giant bomb waiting to go off.

It was powered by liquid oxygen and RP-1 kerosene.

Pumping highly cryogenic liquid oxygen into a missile inside an enclosed concrete silo is incredibly dangerous.

But the physical structure of the Atlas is what blows my mind.