Date: 5/04/2019 09:12:43
From: Tau.Neutrino
ID: 1371010
Subject: The Starhops Have Begun!

The Starhops Have Begun!

According to Elon Musk, SpaceX’s Starship Hopper just completed its inaugural hop test at the company’s South Texas Launch Site. As the first of many, this test is intended to validate the sophisticated Raptor engines that will be used aboard the full-scale Starship spacecraft, which is intrinsic to Musks’ long-term vision of providing intercontinental flights and making commercial trips to the Moon and Mars.

more…

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Date: 5/04/2019 09:47:56
From: Peak Warming Man
ID: 1371013
Subject: re: The Starhops Have Begun!

Thanks for that.

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Date: 5/04/2019 10:40:58
From: Ian
ID: 1371037
Subject: re: The Starhops Have Begun!

this was a baby-step along the long road to conducting orbital and interplanetary flights

I reckon Elon can do it on one leg.

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Date: 6/04/2019 03:35:54
From: mollwollfumble
ID: 1371575
Subject: re: The Starhops Have Begun!

Ian said:


this was a baby-step along the long road to conducting orbital and interplanetary flights

I reckon Elon can do it on one leg.

> “tethered hop”

Tethered rocket, shudder, rather you than me mate.

> Not only was the test successful, it set a new record for combustion chamber pressure.

Nice.

> During this test, the propellants were kept at temperatures just low enough for them to remain in a liquid state. Musk has indicated that when the propellant is kept at cryogenic temperatures, it will boost efficiency.

Well, duh.

> 31 Raptor engines

Again, rather you than me, mate. Unless one is kept as a backup in case one of the other 30 fail.

I’m not sure whether anyone (me, for instance) has solved the problem of the most efficient packing of 31 circles.

“Raptor is a staged combustion, methane-fueled rocket engine under development by SpaceX. The engines are powered by cryogenic liquid methane and liquid oxygen (LOX), rather than the RP-1 kerosene and LOX used in all previous SpaceX Falcon rockets which use or used Merlin 1A, 1C, & 1D and Kestrel engines. The earliest concepts for Raptor considered liquid hydrogen as fuel rather than methane. The Raptor engine will have about two times the thrust of the Merlin 1D engine that powers the current Falcon 9 launch vehicle.”

> “highly reusable”

In what sense? Reusable as in restartable many times = good. Reusable as in shuttle = bad.

> “staged-combustion”

They keep saying that, but what do they mean by it? “Full-flow staged combustion (FFSC) is a twin-shaft staged combustion cycle that uses both oxidizer-rich and fuel-rich preburners.”

https://en.wikipedia.org/wiki/Staged_combustion_cycle#Full-flow_staged_combustion_cycle

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