Author Topic: Sea Dragon class LV thead  (Read 83048 times)

Offline Jim

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Re: Sea Dragon class LV thead
« Reply #180 on: 07/20/2011 08:04 PM »
Will SpaceX borrow half of the Sea Dragon idea?

SpaceX has talked about making their rocket sea-water resistant.  When I was picturing the fully-reusable future SpaceX launcher, I was picturing a first stage which after separation, turns around, re-ignites some or all of its engines with residual fuel, and boosts back to the launch pad for a propulsive landing.  Might SpaceX instead just propulsively slow it down above the ocean enough to slip in without sustaining damage, to be pulled up, perhaps by an amphibious erector tower or tow-cable to be taken back to the pad? 

Is one of the reasons for building a new Texas pad a range rule against boosting your stages back in the direction of a Florida pad?   

See Kistler.   Also, why do you keep reading things into spacex that aren't there?

Offline DLR

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Re: Sea Dragon class LV thead
« Reply #181 on: 07/31/2011 12:37 PM »
Sea Dragon is not needed.

It's $300 per kg to orbit in 1963 is $2160 per kg in 2011 dollars, which means it would be competing with Russian rockets (Zenit) and Falcon Heavy on a cost per kg basis.
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Online Downix

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Re: Sea Dragon class LV thead
« Reply #182 on: 07/31/2011 04:46 PM »
Sea Dragon is not needed.

It's $300 per kg to orbit in 1963 is $2160 per kg in 2011 dollars, which means it would be competing with Russian rockets (Zenit) and Falcon Heavy on a cost per kg basis.
You only measure to LEO.  To BEO, it crushes everything else.
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Offline Jason1701

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Re: Sea Dragon class LV thead
« Reply #183 on: 07/31/2011 08:45 PM »
Why was Sea Dragon so much more efficient at BEO?

Online Downix

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Re: Sea Dragon class LV thead
« Reply #184 on: 07/31/2011 09:08 PM »
Why was Sea Dragon so much more efficient at BEO?

High energy upper stage.  While not as good as the RL-10, it still was over 400.  Using the same launch costs as above, of ~$1 billion per launch in todays dollars with the projected GTO payload of 294 metric tons would give $3593 per kg, which is over $1000 less per kg than the Falcon for the same.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline Prober

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Re: Sea Dragon class LV thead
« Reply #185 on: 07/31/2011 10:05 PM »
Aerojet did some fantastic engine work and doesn't get the credit like the bigger boys LM, Boeing etc.

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Offline clongton

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Re: Sea Dragon class LV thead
« Reply #186 on: 07/31/2011 10:10 PM »
Aerojet did some fantastic engine work and doesn't get the credit like the bigger boys LM, Boeing etc.



Wait till you see the finished performance of the AJ-500.
Chuck

Online robertross

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Re: Sea Dragon class LV thead
« Reply #187 on: 08/01/2011 01:24 AM »
Is someone going to correct the thread title? ;)
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Offline kraisee

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Re: Sea Dragon class LV thread
« Reply #188 on: 08/02/2011 02:25 AM »
I don't know where DLR's $300 figure originates, but it is not a figure from any of the original AeroJet reports into Sea Dragon, nor the TRW (nee STL) independent assessment reports that von Braun ordered.

The AeroJet worst-case estimate was Case #7, which stated $32.80 per pound ($72.31 per kilogram) to LEO.   In today's money that worst-case would be $533.40 per kilogram to LEO.

The best case was Case #5, which stated $8.90 per pound ($19.62 per kilogram) to LEO.   In today's money that best-case would be $144.73 per kilogram to LEO.


TRW's report was able to validate all of AeroJet's claims and even went so far as to say the figures were highly conservative in all cases.


DLR - Perhaps you're thinking of Truax's "Excalibur", which was essentially a 1/10th scale (55mT to LEO!) version (Truax's 'Falcon-1' development system for his operational 'Falcon-9' heh!) ?  That was estimated around $150 per lb to LEO, which would have been much closer to $300/kg to LEO.

Ross.
« Last Edit: 08/02/2011 02:49 AM by kraisee »
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Offline strangequark

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Re: Sea Dragon class LV thead
« Reply #189 on: 08/02/2011 06:16 AM »
Wait till you see the finished performance of the AJ-500.

;D

Such a pretty engine. God bless you Monica Jacinto.


Also, hopefully I'm not necro-posting too badly, but wanted to address these:
SD was proposed before the F-1 got on the test stand and revealed the problems with large engines and combustion instability. The guarantee of combustion instability on a single-bell 80 million pound thrust first stage engine, or a 7 million pound thrust upper stage engine is simply ridiculous.

The diameter on the Sea Dragon was huge. Use an aerospike with modular combustion chambers. Would be good for production as well, because you could mass produce the damn things.

The cost is also prohibitive. How expensive was the 1 million pound thrust RS-84 was going to be? How expensive is the quarter-million pound thrust J-2X? Warp drives would be cheaper to develop than an 80 million pound single-bell engine.

Pressure-fed, with modular combustion chamber design. The worst thing to design is the spike at that point. Not saying it would be cheap, but well below Dr. Cochrane's designs.


That amount of power in the ocean will kill everything within miles. Environment groups will make it illegal long before the first test flight ever came close.

-MP.

Now, this admittedly is delving outside my expertise (not a Marine Biologist). However, there are large swaths of ocean with very little life in them. Cetaceans would be the big concern, and I would suspect there are ways of annoying them away with warning sounds.
« Last Edit: 08/02/2011 07:42 AM by strangequark »
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Offline Jason1701

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Re: Sea Dragon class LV thead
« Reply #190 on: 08/02/2011 02:03 PM »
If you change Sea Dragon to use an aerospike, it's almost Direct P2.

Offline strangequark

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Re: Sea Dragon class LV thead
« Reply #191 on: 08/02/2011 02:56 PM »
If you change Sea Dragon to use an aerospike, it's almost Direct P2.
s

Haha, it looks like I needed to pay more attention to what Ross, Chuck, et al are up to these days. So is this what C-Star is doing?
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Online Downix

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Re: Sea Dragon class LV thead
« Reply #192 on: 08/02/2011 04:27 PM »
If you change Sea Dragon to use an aerospike, it's almost Direct P2.
s

Haha, it looks like I needed to pay more attention to what Ross, Chuck, et al are up to these days. So is this what C-Star is doing?
From my understanding, Ross left cstar earlier this year, and this is a different venture.

And there is at least one version of the Sea Dragon researched which was to use an aerospike.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline go4mars

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Re: Sea Dragon class LV thead
« Reply #193 on: 06/21/2012 07:27 PM »
How likely are reusable cores/stages from SpaceX's BFR (the colonization rocket) to launch and land from the ocean?  0% likelyhood?  5%?  more? 

Will the BFR (whether land launched or water launched) be more potent in terms of kg to trans-mars injection, or less potent, compared to sea dragon?  Guesses please. 

At this point, I would guess 20% and more potent.
« Last Edit: 06/21/2012 07:30 PM by go4mars »
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Offline go4mars

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Re: Sea Dragon class LV thead
« Reply #194 on: 10/22/2012 08:47 PM »
Several people have mentioned their concern over developing a large rocket engine due to combustion instabilities.  With modern software/analytical tools, is combustion instability still considered a practically insurmountable challenge for developing really big engines?
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

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