SpaceX Reveals Raptor 3 Engine and Specifications

https://nextbigfuture.substack.com/ ^ | Aug 03, 2024 | NextBigFuture

[PIF]

Stainless steel is heavy ( Musk ), composite carbon fiber is light ( everyone else ).

[bert]

Meanwhile, Americans are stranded on the Space Station because Musk is not being allowed to rescue them.

The Boeing space ship has failed and left them stranded.

Boeing was forced to pick up the NASA scraps and weld them into an incompetent amalgamation

[sloanrb]

The reasons Musk went with stainless steel are

1. Cost
2. Melting point

As fast as SpaceX is changing designs they went with steel because carbon fiber is way more expensive. Carbon fiber is about $200 per pound while stainless steel is about $3 per pound.
Stainless steel also melts at about 1500 degrees F whereas carbon fiber melts at 300 F

Maybe after they settle on a final Starship form they will revisit using CF.

[PIF]

Maybe after they settle on a final Starship form they will revisit using CF.

—
My hope also. But I doubt it, as the whole ship would have to be redesigned and tested.

[Robert A Cook PE]

What was the F1 Saturn engine ISP ? The Space Shuttle’s ?

(Yes, Saturn used 5 F1 in the first stage, 1 more above in the second stage. So they cannot be directly compared.)

[Steely Tom]

You're close, but while Saturn V first stage used five F-1 engines, its second stage used five J-2 engines, also made by Rocketdyne. Its third stage used a single J-2 engine.

F-1 had a sea-level I_sp of 263 seconds (304 seconds in vacuum); this was so because it burned kerosene and liquid oxygen.

J-2 had a sea-level I_sp of 200 seconds (421 seconds in vacuum). It burned liquid hydrogen and liquid oxygen. Of course, on Apollo, the J-2 engines always operated in vacuo.

J-2 vacuum thrust was 232,500 lb, a bit more than half that of Raptor 2 engines at sea level.

[Robert A Cook PE]

Thank you for correcting my assumption.

Tremendous accomplishments by SpaceX.

(It was sobering to see the differences in “publicity” (area of exhibit floorspace, volume, nbr of exhibits, number of models, nbr of placards, amount of attention paid, etc.) inside the Kennedy Space Center museums this summer between the original moon missions, the Space Shuttle, and today’s space missions. Some space given to Boeing and Bezos, but the NASA museum is totally ignoring the last 10 years of SpaceX achievements.)

[SunkenCiv]

When SpaceX is museum-appropriate, all that will be left of NASA will be in a single diorama. :^)

https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches

360 launches, F9 and FH, mostly the former.

“Falcon 9 first-stage boosters landed successfully in 335 of 346 attempts (96.8%), with 310 out of 314 (98.7%) for the Falcon 9 Block 5 version. A total of 306 re-flights of first stage boosters have all successfully launched their payloads.”

[Robert A Cook PE]

Note to self:

From the Air & Space Museum F-1 page

“The first stage of the Saturn V was fitted with five F-1’s for a total lift-off thrust of 7.5 million pounds. The fully-fueled Saturn V weighed 6.5 million pounds. The F-1 used RP-1, a type of kerosene, and liquid oxygen as the propellants.”

SpaceX has “considerably” lightened the weight too. And number of parts. While building many times the 6 Saturn 1 launches + ten in unused Saturn first stages.

[Steely Tom]

It's amazing to imagine a device that can squirt a pound of fuel out fast enough to generate a pound of thrust for seven continuous minutes.

It's also amazing that there is a chemical reaction that can generate that much energy.

A pound is what, 454 grams? So it's turning about one gm/sec into a pound of thrust. And a nickel weighs five grams!

I realize that that's only true in vacuum, and that scaling laws would prevent one from obtaining that level of performance for a tiny one-pound-thrust engine. But still.