Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Future SpaceX Rocket Designs

I had an idea. Want to get peoples' opinions on feasibility of the idea.

SpacexProposal.png
 

Doug_G

Lead Moderator
Global Moderator
Apr 2, 2010
17,888
3,416
Ottawa, Canada
Interesting idea, but surely a single large cylinder has a much higher volume to mass ratio then a bunch of smaller cylinders? If you're trying to reduce cost per pound surely that's a factor? Also if you're trying to bring these things back to Earth and land them, it's going to be easier with one big rocket rather than seven small ones...
 

aronth5

Long Time Follower
Supporting Member
May 8, 2010
3,736
3,834
Boston Suburb
Maybe one of the reasons for development of new methane rockets is SpaceX's stated goal to fly to Mars.
Using methane makes sense since it can be manufactured on Mars combining hydrogen and carbon dioxide to create methane and water. This
means the return vehicle would refuel on the Martian surface. One disadvantage is that method is harder to ignite but SpaceX should be able to address that in time.
The new rocket also will do well in the vacuum of space needed for the long flight to Mars with a reported thrust of 300 metric tons, about 4x the thrust of Merlin 1D.
 

Doug_G

Lead Moderator
Global Moderator
Apr 2, 2010
17,888
3,416
Ottawa, Canada
SpaceX's Mars rocket to be methane-fuelled


Musk says that methane fuel has performance, cost and storage advantages over alternatives and could even be extracted from the Martian atmosphere for use in landing and ascent stages.


Although methane is known to be a better fuel for reusable engine operations in not having significant coking (carbon deposit) problems that kerosene has, Musk noted that this was not a main driver for the choice.


“The energy cost of methane is the lowest and it has a slight Isp (specific impulse) advantage over kerosene,” said Musk, adding that “it does not have the pain-in-the-ass factor that hydrogen has”. Hydrogen, another commonly used fuel, has storage and handling difficulties and the problem of hydrogen embrittlement.
 
Interesting idea, but surely a single large cylinder has a much higher volume to mass ratio then a bunch of smaller cylinders? If you're trying to reduce cost per pound surely that's a factor? Also if you're trying to bring these things back to Earth and land them, it's going to be easier with one big rocket rather than seven small ones...
Theoretically "a bunch of smaller cylinders" could be more efficient. Reason for that is a fuel cross feed. So whole rocket is powered by fuel from two cores, then those are detached. Then next two cores are feeding fuel to central core and then detached. Essentially you are getting multistage rocket that do not drag extra mass higher and higher.

That is the idea behind Falcon Heavy. But no one tried it so far and would be interesting to see how cross feed would work in practice. Anyhow, after SpaceX launch FH for a few times they would be in excellent position to develop even more complex schemes of cross feed, like one shown above.
 
It may be possible to do something like this, but I don't see why you wouldn't want to also develop a new engine if you can improve performance.

Complex staging also has its own costs and can increase the chances of total failure of the launch.

The other thing to keep in mind is reusability. If we want to truly become a space fairing civilization, we need all of our rockets, including the boosters to be reusable, that means that after they separate they would need to land successfully and be attached to the next core, refueled, and be ready to go. Ultimately it may be better not to use heavy launch vehicles for the bulk of launches, and only use them when absolutely necessary. It is much easier to land one core and one second stage than it is to land 6 boosters, and a core and a second stage.

It may be better to design systems for long term use in space that can be assembled in orbit, small enough to be carried by a single, smaller, simpler rocket and multiple launches.

For colonization of Mars, it might take one launch of a large vehicle to shuttle people back and forth, but when it comes back, it will need to be refueled, and have passengers carried to it.
 
It is much easier to land one core and one second stage than it is to land 6 boosters, and a core and a second stage.

Never thought of it, but once they go fully reusable it'd be fun to watch a Falcon Heavy launch. First you get a major launch followed by three separate landings of the initial stages ;) Might develop a queue so indeed would be a tougher challenge as you need three separate landing pads.
 
I had an idea. Want to get peoples' opinions on feasibility of the idea.

I'm not sure to what degree there is a parallel, but the old Russian N1 suffered some serious development problems because it had 30 engines arranged in 5 clusters of 6. At a minimum, the potential for destructive harmonics would seem to still be there. One the positive side, I think the N1 only had one oxidizer & one fuel tank, which probably made feeding the 30 engines more difficult than in the scenario that you've shown - where the you have multiple independent systems.

from Wikipedia -

Complex plumbing was needed to feed fuel and oxidizer into the clustered arrangement of rocket engines. This proved to be extremely fragile, and was a major factor in the design's launch failures. Furthermore, the N1's Baikonur launch complex could not be reached by heavy barge. To allow transport by rail, all the stages had to be broken down and re-assembled. The engines for Block A were only test fired individually and the entire cluster of 30 engines was never static test fired as a unit. Sergei Khrushchev stated that only two out of every batch of six engines were tested.[SUP][17][/SUP] As a result, the complex and destructive vibrational modes (which ripped apart propellant lines and turbines) as well as exhaust plume and fluid dynamic problems (causing vehicle roll, vacuum cavitation, and other problems) in Block A were not discovered and worked out before flight.[SUP][18][/SUP] Blocks B and V were static test fired as complete units.
 

rabar10

Model 3 >> Focus Electric
Moderator
Dec 3, 2010
1,455
190
Indianapolis, IN
Wouldn't it be super much more expensive? If they make the asparagus-config, trying to land all booster-stages would require extra engines on all the stages. More engines=higher cost? Make your arguments why not.
Each booster stage would presumably have all the engines it needs -- just like the Falcon 9 uses 3 of its 9 engines for a braking/reversing burn up high, then a single engine to renter the thick atmosphere and again to finally land. It certainly requires more propellant though.

But I think the plumbing interconnections and valves between so many booster stages, along with mechanical changes on at least the core booster to support the weight/thrust, and detachable structural links to hold them all together, may be more trouble than its worth.
 

Grendal

SpaceX Moderator
Moderator
Jan 31, 2012
6,887
9,759
Santa Fe, New Mexico
Wouldn't it be super much more expensive? If they make the asparagus-config, trying to land all booster-stages would require extra engines on all the stages. More engines=higher cost? Make your arguments why not.

More engines equal more mass production. Another advantage is that is easier for someone to work with because each engine is much smaller. It is much easier to transport. If there is a problem with one engine it would be much easier to replace a single smaller engine than a massive engine. It is probably easier to tweak the specifications of a smaller engine to adjust performance than a much larger engine.

The Russian RD-180 is a really big engine.

Those are just a few reasons off the top of my head...
 

Doug_G

Lead Moderator
Global Moderator
Apr 2, 2010
17,888
3,416
Ottawa, Canada
A four-engine airplane is typically less reliable than a twin engine airplane, simply because there are more engines to fail. They tend to be more expensive to maintain, thus the recent move to really huge twin engine designs.

On the other hand, the loss of one engine in flight is a less serious situation when you have four. For that reason for many years twin engine airliners were not allowed to do long haul cross-ocean flights. The DC-10 had a third engine kludged onto the tail when the designers realized it couldn't get certification for extended range operation over water.

Of course for a rocket the tradeoffs are probably more complicated.
 

HVM

Savolainen
Oct 30, 2012
1,471
2,767
Finland
The Falcon Heavy's second stage is already lacking in delta-v. Example FH needs a kick stage for Solar Probe Plus mission. Your design would need a new Hydrogen or Methane engine and a upper stage to be any helpful.

Asparagus needs multiple staging events, and SpaceX wants minimum number of those as possible. HF will not use the propellant crossfeed in first missions (if ever), and crossfeed would be extra complex with Asparagus design. If you have Methane engine, why not use it also in the first stage? With a single big first stage you get rid of those multiple staging events.

This is moot anyway, we know that next SpaceX launcher is BFR with ten meter core and full flow Methane engine; Raptor.
 
Huh.... :)

Here are four things we learned from Elon Musk before the first Falcon Heavy launch

FALCON SUPER HEAVY
Musk was asked whether SpaceX can increase the Falcon Heavy’s performance over time, much like it has with the Falcon 9. That’s when the CEO suggested the possibility of a Falcon Super Heavy — a Falcon Heavy with extra boosters. “We could really dial it up to as much performance as anyone could ever want. If we wanted to we could actually add two more side boosters and make it Falcon Super Heavy,” Musk said. This five-rocket Falcon Super Heavy would have around 9 million pounds of thrust, Musk said, nearly doubling the rocket’s current capability, and putting it in line with the Saturn V as the most powerful rocket ever built.
 

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top