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Short but interesting answer about why "fueldraulic" systems are still used, including on the Boeing 777, and F35: https://aviation.stackexchange.com/questions/24787/why-is-fu...
After the Saturn V was retired, they put one out in the front yard of the Johnson Space Center.

It was kind of sizable, and for years you could see it when you drove by on NASA Road 1.

Laying sideways where the different stages were laid end-to-end, and walk right up and touch it, with outdoor photo ops all over the place.

Eventually they built buildings to enclose it, which you now have to go inside if you want to take a look.

I remember seeing it in Florida when I was young, and when I took my kids to the US for a wedding a few years ago that was one of our stops. We say a Falcon 9 night launch, too.

The Saturn V was so impressive. I hope to take the kids to a Starship launch to instill in them too the awe of rocketry and space exploration.

When you walk under the 130ft or so that is composed of the 5 F-1 engines, the LOX and RP1 tanks and you stop to think they’re emptied in less than 2 minutes you understand what an impressive machine it was.
Yes! Those tanks are unbelievably huge. And they're emptied in the time a child can hold his breath.
And the one time I have ever been to Houston, they were constructing that building and I couldn't see the Saturn V :(
I love those mid-century names: FuelDraulic, Hydra-Glide, PowerGlide, Ultramatic
My personal fave is hydropneumatic suspension, mainly because it’s in the Citroen DS (my favourite MCM car).
Why does the hydraulic system need 2000 psi and the fueldraulic system only needs 50 psi?

Then they needed to double hydraulic pressure to 4000 psi for the new rocket, but never explained the key considerations. Seemed like it would be the same actuator?

Cool article.

The way the article describes that diagram is misleading. The whole diagram is the fueldraulic system, and it's 50 psi on the return side and 2000 psi on the high pressure side like a regular hydraulic system.
Going to higher pressure reduces the weight.

Working on the Boeing 757, increasing the pressure was considered to save weight. It was eventually scrapped because higher pressure meant the spray from a leak would slice up your skin.

I think the Concorde went for the higher pressure anyway, but I'm not sure.

The Merlin engine in the Falcon 9 also uses fuel (RP-1) as hydraulic fluid, I believe.
Indeed it does. It was a notoriously fickle design to get right and for a long time they outsourced some parts of it to a company. One of the few things they outsourced. I remember you could find a listing on the company website for this very specific valve, with wink wink references to SpaceX.

I think they managed to bring it all in-house now.

I wonder how they normalize the flow of RP-1 through the hydraulic actuators. You wouldn't want the mixture ratio in the engine itself to vary depending on the gimbaling. I guess there's a bypass where fluid is just dumped back into the pump inlets without having been used, so the flow is always constant.
I don't know about today, but early Falcon 9 gridfin actuators used an open loop of RP-1 as the working fluid as well. It would drain into the tank, and be burned in the engines on descent.
They had Comic Sans in 1963?
Do you think the diagrams are from 1963?
Wasn't really being serious :)