Author Topic: NASA Studies Scaled-Up Falcon, Merlin  (Read 157546 times)

Offline go4mars

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #480 on: 08/07/2011 03:40 am »
go4mars:
I'm no engineer, but I just have an instinctive dislike for the five-core idea.  It sounds unnecessarily complicated, and greater complexity provides more opportunities for failure.  I think it would be better to develop more powerful engines and stick to three cores.  A third stage could also be added if necessary.

The five core idea reminds me of this monstrosity.  It actually did get airborne...once.
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline go4mars

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #481 on: 08/07/2011 03:44 am »
go4mars:
I'm no engineer, but I just have an instinctive dislike for the five-core idea.  It sounds unnecessarily complicated, and greater complexity provides more opportunities for failure.  I think it would be better to develop more powerful engines and stick to three cores.  A third stage could also be added if necessary. 

Although I also prefer the notion of a new larger diameter core stage, and a third stage, those both require things that might well cost more than an accomodative pad for the inline cross-fed 5. 

Also, it doesn't really add a lot of complexity (relatively) if the cores already exist and can do this. 

Just wondering if this is possible.   Perhaps like the photo you posted.   
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline hop

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #482 on: 08/07/2011 04:28 am »
What am I missing?       
You seem to assume that the only load is carrying the weight of the boosters and payload. In reality, your 5 boosters in a line require a lot of structure to keep them all pointed in the same direction. A square pattern like Soyuz or Energia would be much more efficient structurally. You could still use crossfeed and/or throttling to drop pairs of boosters at different times.

As Jim says, the 5 in a row version is all downsides with no advantages.

Offline krytek

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #483 on: 08/07/2011 02:11 pm »
Some people complain about rocket porn, but some of you may have noticed a lot of what Elon Musk talks about (and likes to do) is exactly that: biggest rocket since the Saturn 5, electric high end sports car.

Although the M1d sounds just amazing, I wouldn't rule out the new development to be announced be another first stage engine. Something like a full flow staged combustion motor will fit the bill: super high efficiency, highly reliable, cheaper, maintains first and upper stage engine commonality and might beat out the NK-33 in every category.

On another note, Spacex will probably need to further strengthen the first stage to be able to withstand reentry anyway, so a 3 core FH might be possible (maybe for something like propellant/water delivery to LEO depot?).

} //Rocket porn end

Offline Rocket Science

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Offline SpacexULA

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #485 on: 08/07/2011 03:07 pm »
   W               X             Y
xxx  x      + then o     x  xxx
xxx  x      + then o     x  xxx
xxx  x      + then o     x  xxx

When W and Y empty and drop off, X is a lot higher and faster than otherwise possible and with more fuel. 

What am I missing?       

Assumeing the load is 50mt plus, and it's weight is being supporting only by the center rocket, how are you going to build a connector strong enough to tranfer list from the outer boosters to the center booster without snapping, be able release quickly, reliably, and not weight tons?

Put a cender block on the end of a broom handle and try to pick it up, that's what your outer rocket is going to be trying to do.
No Bucks no Buck Rogers, but at least Flexible path gets you Twiki.

Offline TrueBlueWitt

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #486 on: 08/07/2011 04:11 pm »
   W               X             Y
xxx  x      + then o     x  xxx
xxx  x      + then o     x  xxx
xxx  x      + then o     x  xxx

When W and Y empty and drop off, X is a lot higher and faster than otherwise possible and with more fuel. 

What am I missing?       

Assumeing the load is 50mt plus, and it's weight is being supporting only by the center rocket, how are you going to build a connector strong enough to tranfer list from the outer boosters to the center booster without snapping, be able release quickly, reliably, and not weight tons?

Put a cender block on the end of a broom handle and try to pick it up, that's what your outer rocket is going to be trying to do.


Going 5 cores wide would mean huge inertia in the roll direction.. Roll accelerations would have to be kept way down to prevent the whole stack from setting up a standing wave across the 5 cores, which could happen anyway. Never mind that any high roll rates would induce huge forces trying to rip the outer cores away from the stack!(try holding your arms all the way out with 20lb dumbells and spinning fast!) First bending frequency across the 5 cores would be quite low and if not controlled create high stress in directions the cores weren't developed to handle.
« Last Edit: 08/07/2011 04:15 pm by TrueBlueWitt »

Offline go4mars

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Re: NASA Studies Scaled-Up Falcon, Merlin
« Reply #487 on: 02/14/2012 05:14 pm »
If the grasshopper program does what is intended to, and first stages can land and be recovered, would a scaled up version of grasshopper be likely for this (in fitting with the thread)?  Or would they have learned enough from the little grasshopper program (about control, etc,) to omit that step in future programs?
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

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