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Skylon

By Skylon
in Science & Spaceflight

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michal.don

michal.don

Posted
Posted
1 hour ago, Streetwind said:

The launch window opens at 19:30 my time. This is literally the best launch window they could have chosen.

Yup, nice to know Elon is considering his European fans, too :D One small problem though - I moved to another house a few days ago, and I'm still not connected to the internet. So I have to "invite" myself to watch the launch at one of my friend's place. And I'll have to explain what is happening and why this thing is so unbelievably awesome :confused:

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NSEP

NSEP

Posted
Posted

The hype is high. My Dad is going to watch too.

Is this going to be the most action packed launch ever in the history of spaceflight? There are like 8 exciting events during the launch, all of wich can go terribly wrong.

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StrandedonEarth

StrandedonEarth

Posted
Posted

So I'll be at work, but I don't think I'll be doing much work from 10:25-10:45. Which I can get away with because it's my slow season right now. Or I suppose I could take an early launch lunch. It'll be a launch break not a lunch break today. I wonder if my boss will let me use his computer. If not, it'll be a worthy use of cell data.

1xca9f.jpg

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rudi1291

rudi1291

Posted
Posted
10 minutes ago, Streetwind said:

That fairing is going to fly halfway to Africa, considering that it'll be jettisoned only after center core burnout and separation...

OCISLY is something like ~350km downrange to catch the falling core... the fairing probably won´t fall that much further downrange. 

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Technical Ben

Technical Ben

Posted
Posted
13 hours ago, sevenperforce said:

Bingo. Though throttling the MVac for landing in 0.16 gees is a bit iffy. Better to strip down a Dragon 2 and put the payload in the trunk. Burn the MVac to depletion for zero velocity at 100 m altitude, separate, and use the SuperDracos to hover-land and drop the payload wherever you want it. 

SuperDracos on the moon?!?! Would you not be better off with some easy cold gas thrusters? Am I not right (from playing KSP) that at that gravity/payload/TWR you could use the tiniest little thing to "land" the last 100m? SuperDracos seem massively overkill for it? (Though I guess they are designed for Earth, they were also planned for Mars, which is closer/comparable to the moon?).

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CatastrophicFailure

CatastrophicFailure

Posted
Posted

This thread needs one of those interactive maps showing everyone’s location. :D

6 minutes ago, rudi1291 said:

OCISLY is something like ~350km downrange to catch the falling core... the fairing probably won´t fall that much further downrange. 

Et al, re: fairing recovery: we still don’t know the fate of the GovSat booster, it may not be back yet, and that’s possibly where the Steve-O is. Like OCISLY, no time to get there & back again to recover from both missions. 

5 minutes ago, Technical Ben said:

SuperDracos on the moon?!?! Would you not be better off with some easy cold gas thrusters? Am I not right (from playing KSP) that at that gravity/payload/TWR you could use the tiniest little thing to "land" the last 100m? SuperDracos seem massively overkill for it? (Though I guess they are designed for Earth, they were also planned for Mars, which is closer/comparable to the moon?).

Cold gas thrusters also have horrid ISP,  you’d need a LOT of pressurized nitrogen to land several tons on the moon. You’d need a lot of UDMH/NTO too with SuperDrakes, but at least there’s quite the precedent for landing huge payloads on the moon with big hypergolic engines. :wink:

 

And now, back to bed for another few hours!:confused:

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Ringkeeper

Ringkeeper

Posted
Posted
1 minute ago, Frozen_Heart said:

Just pointing out that every launch I've ever watched of a rocket live has gone wrong.

 

Reckon I should skip this one?

yes .. please :D

 

Or ... define "gone wrong" ... if "gone wrong" equals big kerbal style launch explosion, please watch^^

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Technical Ben

Technical Ben

Posted
Posted
1 minute ago, Frozen_Heart said:

Just pointing out that every launch I've ever watched of a rocket live has gone wrong.

 

Reckon I should skip this one?

No? It will either succeed spectacularly, of fail such like. As others have said, this technically may not be needed. As falcon alone can do most launches, and BFG is there for the personal (Mars project) or larger commercial jobs.

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sevenperforce

sevenperforce

Posted
Posted
7 hours ago, insert_name said:

Am i the only one who has class during the launch and is hoping it gets delayed like govsat 1 was?

and on another note, isn't this the first reuse of a GTO core or in this case two?

Curses upon you!

(not really)

But yes, it's the first reuse of a GTO core, Thiacom-8. The other side-core was an LEO launch, though.

2 hours ago, Ringkeeper said:

7000+ already on the live stream..... lets see if it gets above 100k :D

Over 13,000 now, and including me.

1 hour ago, DAL59 said:

7 hours to go!  

Have they said anything about the fairing recovery?

The press kit didn't say anything about it, but one of the diagrams created by a Chris (can't remember which one) from NSF showed a fairing boat for recovery.

1 hour ago, rudi1291 said:
1 hour ago, Streetwind said:

That fairing is going to fly halfway to Africa, considering that it'll be jettisoned only after center core burnout and separation...

OCISLY is something like ~350km downrange to catch the falling core... the fairing probably won´t fall that much further downrange. 

Well, the core will boostback after staging so as to not go quite so far downrange. Fairings will definitely outpace it. Then again, the fairings are super fluffy, so drag is going to cut down on how far they fly.

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cubinator

cubinator

Posted
Posted

Last night I dreamt that the launch had been scrubbed for the day due to some pesky fire or something. I'm quite glad to be reading this thread and seeing it's still go at breakfast-time. Going to watch on my laptop at school, this deserves a bigger screen than my phone.

Packing my launch for the day!

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sevenperforce

sevenperforce

Posted
Posted
1 hour ago, Technical Ben said:

SuperDracos on the moon?!?! Would you not be better off with some easy cold gas thrusters? Am I not right (from playing KSP) that at that gravity/payload/TWR you could use the tiniest little thing to "land" the last 100m? SuperDracos seem massively overkill for it? (Though I guess they are designed for Earth, they were also planned for Mars, which is closer/comparable to the moon?).

The SuperDracos are definitely very thrusty, but no, cold-gas thrusters won't do it. The Draco thrusters themselves only produce 400N; you would need over 70 of them to soft-land an 8-tonne payload on the moon. Cold-gas thrusters would be even worse. Lunar gravity is low, but this isn't Minmus we're talking about.

Of course, you would only need 2 or maybe 4 SuperDracos rather than the 8 that come standard with the Dragon 2. With an 8-tonne vehicle, each SuperDraco gives you 0.91 gees of acceleration on Earth; all 8 firing together will accelerate you away from an RUD at over seven gees. They can, however, throttle down to 14% of their full throttle setting, or lower. With two SuperDracos at 14% throttle, an 8-tonne vehicle would have a net upward acceleration of just 0.095 gees (earth reference), which is perfect for a nice hovering landing.

1 hour ago, CatastrophicFailure said:

Cold gas thrusters also have horrid ISP,  you’d need a LOT of pressurized nitrogen to land several tons on the moon. You’d need a lot of UDMH/NTO too with SuperDrakes, but at least there’s quite the precedent for landing huge payloads on the moon with big hypergolic engines. :wink:

In my proposal, you'd only need the onboard propellant already carried by Dragon 2, because the Falcon 9 upper stage does the suicide burn and the SuperDracos are only used for the last 100-200 m/s of descent.

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tomf

tomf

Posted
Posted

I feel that staging while plummeting towards the moon might be considered a high risk maneuver. Of course I do it all the time when I have been a bit too conservative with delta-v and don't want to waste it. I'm pretty sure that in real life that would be frowned upon, let along my usual alternative of just landing on the engines of the transfer stage and having the astronauts jet-pack up and down from the capsule.

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Technical Ben

Technical Ben

Posted
Posted (edited)
15 minutes ago, sevenperforce said:

The SuperDracos are definitely very thrusty, but no, cold-gas thrusters won't do it. The Draco thrusters themselves only produce 400N; you would need over 70 of them to soft-land an 8-tonne payload on the moon. Cold-gas thrusters would be even worse. Lunar gravity is low, but this isn't Minmus we're talking about.

Of course, you would only need 2 or maybe 4 SuperDracos rather than the 8 that come standard with the Dragon 2. With an 8-tonne vehicle, each SuperDraco gives you 0.91 gees of acceleration on Earth; all 8 firing together will accelerate you away from an RUD at over seven gees. They can, however, throttle down to 14% of their full throttle setting, or lower. With two SuperDracos at 14% throttle, an 8-tonne vehicle would have a net upward acceleration of just 0.095 gees (earth reference), which is perfect for a nice hovering landing.

In my proposal, you'd only need the onboard propellant already carried by Dragon 2, because the Falcon 9 upper stage does the suicide burn and the SuperDracos are only used for the last 100-200 m/s of descent.

Ah thanks. As said, I often forget how strong the gravity is in comparison, as the Moon is rather large in comparison to Earth (say for a comparison of Mars to Phobos). So SuperDracos are a good choice then. :)

I'll have to remember for when I'm making Muna Landers too. :wink:

I'm still of the opinion that if they ever want to do it "proper" for the moon, a cycler for both Luna transfer and Luna take off is going to be required. Else you get a LOT of scrap lying around on the Moon. A refuel/reland/relaunch just has the servicing + fuel to worry about. Though of cause a little loss in efficiency as you cannot drop lots of stages. But depending on how it is setup, you could leave a "stage" that is built into your cargo/habitat etc. To reuse empty fuel tanks as structure.

But as the current falcon shows, sending the empty fuel tanks "back" is not really much of a worry.

Edited by Technical Ben
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tater

tater

Posted
Posted
14 hours ago, Canopus said:

This is why i don‘t get the whole hype around this thing. This Launcher, composed of essentially flight proven components will mostly launch some Comsats and at best a discovery class probe, and people behave like its the second coming of christ.

Because it's going to be awesome to watch. It also drops the cost of large GEO sats (least for SpaceX), since they will not have to expend the booster for even the largest sats that can fit in the fairing.

4 minutes ago, Ultimate Steve said:

The one day I have to go to school...

Sorry about that... I'm picking my son up, we will watch the launch, then I will take him back to school (he doesn't want to miss it live). I figure it's more educational than the fractions of art and Spanish class he'll miss.

Already 19,000+ watching...

 

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