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What Starhopper achieved

Starhopper in flight
Click for full image.

Captalism in space: While most news reports (including mine yesterday) have focused on the spectacular 150-meter flight of Starhopper, the real story here is the Raptor engine. As one of my readers said most succinctly in a comment:

As impressive as the flight was, there is so much more going on here. This is the most efficient rocket engine ever, with all fuel and LOX running through the combustion chamber – including exhaust from the turbopumps. The Russians tried it, and NASA tried it, but this is the first time such a design has flown. It’s also the first major engine using methane, so SpaceX is learning all the ground support processes for storing, fueling, and detanking methane (mostly) safely. (Still causing grass fires at launch…) They’re aiming for production cost below $2M per Raptor, and they’re about ready to go full production on the engines, around 500 engines per year.

In fact, Musk himself reveals the truth of Diane Wilson’s comment in a tweet, found in this news story about yesterday’s flight:

Starhopper’s flying days may be done, but the stubby prototype will be retasked rather than put out to pasture.

“Yes, last flight for Hopper. If all goes well, it will become a vertical test stand for Raptor,” Musk said via Twitter on Saturday.

In a sense, yesterday’s flight was no different. Starhopper was essentially a flying test stand for Raptor, which is in itself an incredible concept, when you think about it. Now it will continue to be used as a test stand, but will no longer fly.

I have been told by rocket engineers more than once that you need to build and test your engine before you can really start your rocket design. Once you know its capabilities you can then design and construct the rocket.

This is why Virgin Galactic’s SpaceShipTwo has generally been a failure. They built the ship before the engine, and when the engine had issues they had to improvise redesigns that have limited the ship’s capability and seriously delayed its launch.

SpaceX now has its engine ready. Construction on its two prototype Starships, in Boca Chica and Florida, will now proceed quickly. Based on how quickly it took SpaceX to do the first Starhopper test flights (announced in late 2018 and flying in about eight months), expect test flights within six to eight months. (Note that in this last link I expressed doubt they could get those Starhopper flights off in 2019. SpaceX proved me wrong.)

Finally, a minor news note: SpaceX today successfully brought a Dragon cargo capsule back to Earth after a month at ISS, completing its third flight in space. That this multi-use flight is hardly mentioned in the news illustrates how far SpaceX has reshaped space engineering in only a few years.

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