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SpaceX launch webcast: Orbcomm-2 Mission [video]

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Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#251

Post by gozur88 »

tempestn wrote: post #168

This is so exciting. Not quite a moon landing, but still feels like watching a significant moment in history. Does anyone know what specifically changed to allow a landing attempt on land as opposed to barge? Was it just that they gained enough confidence with the barges that they would at least be able to hit the target (and not crash into a building or something), or was some regulatory clearance received or someth…

It was three things. They had to get multiple government agencies to approve the landing pad and plan. They had to have a relatively light payload. And they had to "deep freeze" the fuel to squeeze in enough for a return.

I suspect even as this becomes routine most landings will still be on the barge. Every ounce of fuel you use to reverse your direction is an ounce you could have put toward a larger payload.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#252

Post by RonaldRaygun »

extrapickles wrote: post #237
hyperpallium wrote: post #203

Earlier quoted context omitted.

Why don't they put a smaller engine in the centre for landings?

It would make the rocket too heavy. To add another engine, they would have to make the rocket larger in diameter, increasing the weight by a fair amount (they currently have the 9th engine in the middle, so it would have to get moved to the ring with the rest). Reducing the power of the center engine would also reduce the amount of payload to orbit. Rockets that can reach orbit have very bad weight to payload ratios…

It's actually more about complexity. They could simply replace the center engine with a lower power design and still get plenty of mass to orbit. The issue then is that you have to design a completely new engine and have 2 different engines in your first stage. More complexity generally equals more risk, and historically SpaceX has sought to maximize simplicity for the sake of reliability and rapid iteration.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#254

Post by ctdonath »

sixQuarks wrote: post #224
grkvlt wrote: post #124

Earlier quoted context omitted.

OK, explain how the landing of the SpaceX first stage was many times more difficult? They used different mechanisms, yes (suicide burn vs. hover-capable) and the purpose of the overall system was different, but they are both VTOL rockets. Blue Origin was first , and Bezos can quite rightly welcome SpaceX to 'the club' as the second company to achieve this, without being accused of being classless, surely?

Didn't SpaceX go around the entire earth before landing? I don't think Bezos'did

Could someone clarify the stage one path? Where did it launch, and where did it land, and where did it go horizontally in the meantime?

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#255

Post by zardo »

grkvlt wrote: post #130
JshWright wrote: post #117

Earlier quoted context omitted.

New Shepard is able to make several compromises that make landing _much_ easier. New Shepard doesn't have to get anywhere close to orbital velocity, so it can use a far less powerful engine. That means it can throttle down far enough to hover. That is a _huge_ advantage over Falcon 9, which must time the landing burn perfectly to hit 0 velocity at the exact moment it touches the ground. They're in the same club like…

But the F9 first stage doesn't get to orbital velocity, either, remember. The achievements are comparable, despite the fact it makes SpaceX come second. Blue Origin was first with a VTOL rocket stage, as part of a space system.

The huge difference is the Falcon 9 first stage is part of a system that puts a few thousand kilos in orbit, and it flys half a dozen times per year.

Getting to space is just getting high off the ground, its not very useful unless you can achieve orbit.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#257

Post by robotresearcher »

sixQuarks wrote: post #224
grkvlt wrote: post #124

Earlier quoted context omitted.

OK, explain how the landing of the SpaceX first stage was many times more difficult? They used different mechanisms, yes (suicide burn vs. hover-capable) and the purpose of the overall system was different, but they are both VTOL rockets. Blue Origin was first , and Bezos can quite rightly welcome SpaceX to 'the club' as the second company to achieve this, without being accused of being classless, surely?

Didn't SpaceX go around the entire earth before landing? I don't think Bezos'did

No.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#258

Post by [deleted] »

sixQuarks wrote: post #224
grkvlt wrote: post #124

Earlier quoted context omitted.

OK, explain how the landing of the SpaceX first stage was many times more difficult? They used different mechanisms, yes (suicide burn vs. hover-capable) and the purpose of the overall system was different, but they are both VTOL rockets. Blue Origin was first , and Bezos can quite rightly welcome SpaceX to 'the club' as the second company to achieve this, without being accused of being classless, surely?

Didn't SpaceX go around the entire earth before landing? I don't think Bezos'did

[deleted]

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#259

Post by bigdubs »

guelo wrote: post #256

This makes no sense to me. If you want to recover the rockets why not use parachutes? Guiding a parachute down, maybe with the help of some propellers, has got to be easier and more reliable than this.

even with a gigantic chute you're still approaching the ground at ~20mph. not a lot can hit the ground at that speed (and be that big) without either making it prohibitively heavy to fly, or without things breaking seriously enough it would be a write off.

Re: SpaceX launch webcast: Orbcomm-2 Mission [video]

#260

Post by zardo »

sixQuarks wrote: post #224
grkvlt wrote: post #124

Earlier quoted context omitted.

OK, explain how the landing of the SpaceX first stage was many times more difficult? They used different mechanisms, yes (suicide burn vs. hover-capable) and the purpose of the overall system was different, but they are both VTOL rockets. Blue Origin was first , and Bezos can quite rightly welcome SpaceX to 'the club' as the second company to achieve this, without being accused of being classless, surely?

Didn't SpaceX go around the entire earth before landing? I don't think Bezos'did

No, but it lifted a second stage that continued on to orbit, delivering 11 satellites.

https://i.imgur.com/D9BdO86.png

http://www.flightclub.io/results.php?id=eb627cc3-ffab-43a3-9...

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