Discussion Should SpaceX create a larger engine to reduce the number of engines of the Falcon 9?

[T.Neo]

The fact is that turbopumps and such components include a lot of moving parts and are the most prone to failure. Combustion chambers problems are often related to combustion unstability, and this is something more "predictible". In fact the original R-series engines had one big combustion chamber, but the result was unstable and deceptive in terms of thrust. The quad-chambers design solved that and actually increased thrust. .

The fact is, combustion chamber failures can occur (through design flaws, procedural/manufacturing errors, structural defects, etc). Turbopumps do contribute a lot to failure risk in an engine, but not all engine failures involve the turbopumps. The recent Falcon 9 engine failure is an example of this.

In general, the more moving parts, the more potential problems, and then increased costs to make sure those problems don't happen. So a lot of "cheap" engines might actually have been a false-good-idea. Which doesn't mean it is a fatal flaw ; but that operational costs are going to be higher than expected.

That isn't how things work. To ensure high reliability, you want a decent development and manufacturing process, with strong safety procedures.

Obviously a turbopump is a complex and costly component (both to develop and manufacture). And obviously developing and building reliable components costs money. But technique affects these things far more than simply throwing money at things.

Developing a smaller, less demanding (i.e. lower chamber pressure, kerolox) engine is an easier and cheaper task. Purely from that perspective, Merlin has been a good path for SpaceX. To get the required thrust for their vehicle, they simply need to cluster those engines- which is a good deal less complex and less costly than building an all-new, larger engine.

Larger production runs improve cost through mass-production techniques and capitalisation on existing infrastructure.

I cannot find any instance anywhere in this thread where someone has claimed such a thing.

The entire premise of this thread is the suggestion that SpaceX should perform a considerable redesign of their launch vehicle and undertake an all-new engine development program due to safety issues.

Those would be some pretty serious actions to take, and if one were taking them, they'd have to have messed up pretty badly.

 

[Urwumpe]

We'll see if the future sticks to your all-capitalistic logic. Personally, I'm highly sceptical. I doubt there will ever be enough rocket launches / year to allow real mass production. Or, to begin with, new spaceports have to be built. Quickly. Rocket are not cars.

The same was said about aircraft.

 

[T.Neo]

We'll see if the future sticks to your all-capitalistic logic. Personally, I'm highly sceptical. I doubt there will ever be enough rocket launches / year to allow real mass production. Or, to begin with, new spaceports have to be built. Quickly. Rocket are not cars.

It isn't capitalism, it is engineering. And at 4-5 launches a year (which is a fairly conservative launch rate), that is already 36-45 Merlin 1s, which compares favourably to the number of engines used by the EELVs in their entire flight history up to now. If Falcon 9 captures a larger amount of the launch market, say, 10 launches a year, SpaceX could be manufacturing almost a hundred engines a year, not counting second-stage engines.

Such a flight rate isn't radical compared to some other launchers out there. The existing pad (and the pad undergoing construction on the west coast) could likely support it.

Of course rockets aren't cars, they're rockets. But borrowing some of the mentality from automotive production is not that bad an idea when it comes to launch vehicles.

 

[T.Neo]

Why is basic engineering wisdom so alien? Concepts like economies of scale and mass production are key concepts in engineering. Many people on these forums have flown on- and therefore trusted their lives to- aircraft that are economical in their niche due in part to the very sort of mass production that is almost taken as a form of conspiracy theory by some, when in regard to launch vehicles. You complain about me making statements without it being 'written somewhere' (it is written, seen and felt everywhere... sometimes things are so large that it is easy to lose sight of them), yet you talk about shortcuts and soforth. Yes, you can take shortcuts, and you will have to deal with the results. But good engineering doesn't involve shortcuts, it involves the exact opposite.

It is actually possible to improve things without making them worse. It just requires work.

 

[FADEC]

"Heavier-than-air flying machines are impossible."

Lord Kelvin, president, Royal Society, 1895.

 

[garyw]

O-F Staff Note: Thread Re Opened. Please keep it ON TOPIC.

 

[RGClark]

A suggestion to upgrade the Merlin to another thrust level to reduce the number of engines on the Falcon 9 for reliability:

Re: On the lasting importance of the SpaceX accomplishment.
http://exoscientist.blogspot.com/2012/10/re-on-lasting-importance-of-spacex.html

Elon Musk recently mentioned the possibility of creating a large new rocket engine several times the thrust of the Merlin 1:

SpaceX aims big with massive new rocket.
By: ZACH ROSENBERG WASHINGTON DC
http://www.flightglobal.com/news/articles/spacex-aims-big-with-massive-new-rocket-377687/

He says this in regards to producing a super heavy lift 100+ mT vehicle, not for the Falcon 9. It's also not clear from this article if he said this after the failure of one of the engines in the last launch.

My suggestion is if they are going to produce this large engine that they go first to an intermediate sized engine that could be used also on the Falcon 9.
...

Since I wrote that blog post in October, 2012 that SpaceX should produce a 500,000 lb thrust engine, SpaceX has announced they are proceeding to the development of a 600,000 lb thrust engine. There has been some debate though on whether SpaceX will use it on the Falcon 9. I think they almost certainly will since it will be methane fueled and one of the reasons given is that methane engines have advantages for reusability. But Elon has stated a primary focus will be to make the Falcon 9 reusable. Therefore it is likely they will use the engines better suited to reusability.

SpaceX Could Begin Testing Methane-fueled Engine at Stennis Next Year.
By Dan Leone | Oct. 25, 2013
http://www.spacenews.com/article/la...ng-methane-fueled-engine-at-stennis-next-year

Bob Clark

 

[Zachstar]

It is also possible that the engine's fate is more tied to that of the rumored "BFR" or "Big *censored* rocket" That they are working on.

 

[RGClark]

It is also possible that the engine's fate is more tied to that of the rumored "BFR" or "Big *censored* rocket" That they are working on.

SpaceX so far has only spoken of using this engine for their proposed heavy lift rocket to be used for Mars missions. A lot of discussion on it on the NasaSpaceFlight forum:

Possible SpaceX Vehicle Configurations based on recent (10/23) Raptor information.
http://forum.nasaspaceflight.com/index.php?topic=33142.0

Bob Clark