Inside the Tech of SpaceX's Homegrown Rocket Engine

An anonymous reader writes with this excerpt from a look at the engine behind SpaceX's Falcon rocket, the Merlin: "The rockstar of SpaceX may be Elon Musk, but the lead man behind the fire power is Tom Mueller. He is the Vice President of Propulsion Development and founding employee at SpaceX. Musk sought Mueller out in 2001 when Musk decided to build his own rockets instead of buying some from the Russians. Musk caught wind of a rocket engine Mueller built in his garage and 'apparently had a religious experience' once he saw it. If you didn't know, Elon Musk used $100 million of his Paypal money to start SpaceX. That money was used to build the Merlin engine Mueller had designed. The Merlin engine is the first new American booster engine in ten years and only the second in the last 25 years."

Re:Simplify and add lightness

[DerekLyons]

Don't wanna run a completely isolated hydraulic system and include a zillion new single points of failure? Hmm how bout using the fuel as the hyd fluid. How bout pressurize the hydraulic "fluid" using the main turbopump.

Not so much. You've eliminated the turbopump (trading that for a modest increase in fuel system complexity), but pretty much all the rest of the hydraulic system failure modes are still there.
 

The vacuum model uses radiative cooling. I'm sure a fat cat modern contractor would try for regenerative just to boost the contract cost / profit

A 'modern' contractor would probably use regenerative because it's a very efficient means of cooling, and modestly boosts engine performance by preheating the fluid (fuel or oxidizer) used for combustion.
 
One educated in the history of rocketry will know that regenerative cooling far predates the 'modern' contractor - and was chosen even when expensive and difficult. Someone intelligent would ponder on why that might be. Confronted with reality, the dogmatic simply ignores this and repeats his magic catchphrase like a cargo cultist.
 

I hope they can stay on task with the whole "simplify and add lightness" thing. The X and XX sound a little more like something you'd see from the incumbents rather than startups

No, they sound more like something you'd see from someone who wants/needs a certain level of performance and has the budget to go after it rather than fitting together a solution on the cheap. The dogmatic may prefer they stick with his mantra, but SpaceX seems to be made of pragmatists rather than dogmatics.
 

Maybe the standard /. car example is the Merlin is as minimal as can possibly be made that'll work, like a 60s muscle car engine or a race car engine

Spot on. Which means it's horribly inefficient compared to more modern designs, along with being heavier, with less efficient lubrication and cooling, and lower performing. It's the engine of the classic car enthusiast and the biased who believe that everything was better in some imaginary golden age. To everyone else, it's a quaint anachronism.

No Garage here

[phypsilon]

I suggest you to look up TRW and the Low Cost Pintle Engine (LCPE) on the internet. Guess who was head of liquid rocket propulsion development there back at the start of the century.....

Re:Simplify and add lightness

[camperdave]

The Space Shuttle Main Engine designs (Block 0) for the test benches had a certain rated thrust. That benchmark became 100%. When the production designed engines (Block 1) came online, the improvements meant that they were capable of greater thrust than that initial benchmark. Rather than call the new value 100%, they based it on the Block 0 design benchmark. The later engines (Block 2) were capable of 111%.

The engineers working on the shuttle engines were not necessarily trying to improve thrust; not trying to eke out an extra percent or two like a dragster or racecar mechanic would. They were just doing stuff like replacing a turbo pump with a different turbo pump that had half the moving parts, or changing the casting process so there were fewer welds; things that would make the engines lighter, more robust, and easier to manufacture.