Falcon Super Heavy (speculation)

[Winter Man]

no they arn't pumping fuel, rather fuel is being drained from the side tanks into the center engines, this requires a system that can switch from outertanks to center tank once the out tank is drained instantaneously (without stopping the center engines), that never been done before.

Dude, think about it. Fuel doesn't just drain into the engine, it's pumped. There isn't just a hole between the combustion chamber and the fuel tanks with a valve, there's pumps powered by smaller solid rocket motors - far more reliable than using an electric motor. That exhaust has to vent somewhere (near cryogenic fuel, at that), the solid motor has to be shaped right to provide the correct thrust profile to pump the correct amount of fuel throughout the ascent, the pump itself has to deal with an extreme temperature gradient between the fuel and motor exhaust and a whole book (literally) worth of other issues. Then you've got to consider that you're feeding two engines now at different rates meaning a separate pump for each, then it needs to be decouple-able (sealing the centre engine off from external atmosphere - or lack thereof) and it starts to get a fair bit more complicated than just clicking on a fuel line. It is rocket science, remember.

Edited December 27, 2013 by Winter Man
spelling and whatnot

[Themohawkninja]

*cough* government's that want to send probes to mars for a comparatively cheap cost *cough*

Hey, there's nothing wrong with cheap, rocket-assisted labor.

[Themohawkninja]

Wow, I've been looking up the Falcon Heavy (I can't find a rocket called the "super heavy", so I'm assuming that they are two different names for the same rocket), and here is a quote from the National Space Society:

The Chinese have said flatly that there is no way they can compete with such a low price.

[Firov]

Dude, think about it. Fuel doesn't just drain into the engine, it's pumped. There isn't just a hole between the combustion chamber and the fuel tanks with a valve, there's pumps powered by smaller solid rocket motors - far more reliable than using an electric motor. That exhaust has to vent somewhere (near cryogenic fuel, at that), the solid motor has to be shaped right to provide the correct thrust profile to pump the correct amount of fuel throughout the ascent, the pump itself has to deal with an extreme temperature gradient between the fuel and motor exhaust and a whole book (literally) worth of other issues. Then you've got to consider that you're feeding two engines now at different rates meaning a separate pump for each, then it needs to be decouple-able (sealing the centre engine off from external atmosphere - or lack thereof) and it starts to get a fair bit more complicated than just clicking on a fuel line. It is rocket science, remember.

You're thinking of turbopumps, but they're not powered by a solid rocket motor. For rockets they're usually gas driven, and this gas is generated by burning some of the rocket's liquid fuel and oxidizer in a combustion chamber.

http://en.wikipedia.org/wiki/Turbopump

[koshelenkovv]

Most of the satellites being launched go into an Earth orbit albeit LEO or geosynchronous. And since technology has the tendency to become smaller as time progresses I reckon the need for super heavy launchers will be sparse in the future. It might be better to develop a launcher that is cheap and can send multiple lightweight payloads in orbit. I think the Antares rocket has a bigger market then a Falcon nine super heavy.

But, quite strangely, GSO satellites tends to be heavier and heavier with time.

[Kryten]

But, quite strangely, GSO satellites tends to be heavier and heavier with time.

Adoption of electric propulsion for orbit-raising is causing that trend to reverse. Boeing has started producing an ion-propelled bus small enough for dual-launch to GTO on Falcon 9, and two companies have already ordered pairs and contracted launches.

[SargeRho]

The biggest client for a rocket like that would probably be the Asteroid Mining industry, and after that, the Government. Using a private rocket instead of a purpose-built rocket to send People to Mars for instance is probably cheaper.

[Nibb31]

Yeah, but there's no such thing as an asteroid mining industry, and there won't be before a very long time. NASA won't be allowed to use a private rocket if they have SLS.

[SargeRho]

I used "would" for a reason. Also I never said anything about NASA. As far as I know, SpaceX isn't exclusive for US-Based companies.

[check]

Not sure where the demand would come from... Perhaps some commercial entities would want to launch sizeable (Skylab size) 'space hotels' in one shot, with it?

[Themohawkninja]

Not sure where the demand would come from... Perhaps some commercial entities would want to launch sizeable (Skylab size) 'space hotels' in one shot, with it?

Perhaps the existence of the rocket itself will generate demand. Companies might now go "well, now that we have this new, really heavy launch platform, what should we put into space with it?"

[Nibb31]

Perhaps the existence of the rocket itself will generate demand. Companies might now go "well, now that we have this new, really heavy launch platform, what should we put into space with it?"

Yes, but it doesn't work that way. A rocket needs to be designed for a specific purpose. If you don't have a purpose *yet* then you lose focus on why the rocket is being designed. I'm looking at you, SLS.

[SargeRho]

It kind of does work that way, actually.

[Tommygun]

Well Energia was built about 25 years ago. I haven't heard of any big calls for it.

In an ideal world it would be great to have these super heavy designs around, I just don't see anyone making money off of them.

[Albert VDS]

SpaceX will need a bigger engine if they want to make anything bigger than the Falcon Heavy.

OK, you can put more Merlin engines under a bigger fuel tank, but that will just give you an other N1 disaster.

[Shuttle]

OK, you can put more Merlin engines under a bigger fuel tank, but that will just give you an other N1 disaster.

As far as I know, N1 blew up 3 of 4 times because NK-15 had an unreliable turbopump that was completely redone in NK-33. I didn't read much about Merlin but I guess it is very well-tested and reliable engine so comparison with N1 is not correct

Edited December 29, 2013 by Shuttle

[Nibb31]

SpaceX will need a bigger engine if they want to make anything bigger than the Falcon Heavy.

OK, you can put more Merlin engines under a bigger fuel tank, but that will just give you an other N1 disaster.

None of the N1 failures can be attributed to the sheer number of engines. They were more due to poor manufacturing processes and lack of testing, which were inherent to the industrial site more than anything else. The causes were:

- A broken pipe caused by vibrations.

- A loose bolt ingested by a turbopump causing it to explode.

- Attitude control failure.

- Pogo oscillation caused engine starvation and cutoff.

These are things that can happen to a single engine rocket if you don't test it properly. The problem was that the rocket had to be assembled at Baikonur, which had rather rudimentary industrial facilities and insufficient tooling (this is also why the N1 used spherical tanks instead of cylindrical ones). It wasn't equipped with proper test facilities, so there was no way to properly test each individual stage other than launching it.

Anyway, SpaceX is currently working on a bigger engine called Raptor:

http://en.wikipedia.org/wiki/Raptor_%28rocket_engine%29

[Albert VDS]

Okay, the comparison to the N1 isn't t a good one if you look at the reliability of the NK-15 and the Merlin engines.

My point is if you add more engines you increase the probability of something going wrong.

[Nibb31]

Yes, but you reduce the criticity of a single thing going wrong. An engine out on a Falcon 9 core doesn't necessarily result in a loss of mission. The other engines can compensate by burning longer. An engine out on an Ariane 5 however...

[Albert VDS]

You don't need to have 1 big engine. Why not something like 3 or 5.

[TheCanadianVendingMachine]

With the asparagus staging, wouldn't it work like this -

= is pipes

| is close off

O is tank

O=|o|=O

So, when they stage, the close offs, will, well, close off. And then pressurize the tank

[Nibb31]

Of course, that's the theory. However, there is still a lot of engineering in making those close-off valves safe and reliable, avoid having residual fuel or droplets around the rocket when you fire the separation pyrotechnics, making the turbopumps transition safely from cross-feed to core mode without hiccups, managing the fuel balance and the inertia of the fuel flow and lots of other tiny technical problems that would crop up during development.

It adds complexity and lots of failure modes to deal with.