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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."
One of these days...
I'll meet you at the intersection of "Should be" and "Reality"
And not with a paid team working on a pay check.
No religious experience here (then again, never seen in person) but everything I've read is the Merlin series is all about Chapman's "simplify and add lightness" which a lot of the old time aerospace pioneers used to use before they became profit munching incumbent contractors.
Pintle injector for throttling, stability, and some wall cooling. Damn good idea.
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. Damn good idea.
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, but they're the "simplify and add lightness" people so simple radiative. Hardly a new idea for vacuum nozzle cooling, but a damn good one anyway.
They also show great judgment in knowing their own limitations, they buy their turbopumps from a specialist. Things that need to be custom they do, things that can be COTS are COTS.
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. Unless they have secrets up their sleeves, which is certainly possible.
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, whereas the incumbents are more like a modern engine which is mostly an elaborate emissions control system, oh and with an engine bolted onto it almost as an afterthought.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
"Merlin" is an engine brand of Rolls-Royce, a V12 piston engine from the 30's onwards used in a wide variety of aircraft. I can imagine raised eyebrows in their offices, but would they actually sue? I hope not, that would show these lawsuit-happy Yanks what British class really is.
I'm surprised you're so down on tokamak research which has actually produced large quantities of energy in tests (22MJ thermal in 1.5 seconds from the JET run in 1997, for example) while describing the con-artists like Polywell and Focus (zero joules in several years of funding and self-promotion) as "promising". At least you're not carrying a (fusion) torch for Fleischman and Pons.
SpaceX is supposed have about 10-20% ex-NASA people, mainly younger folk. Dont think of NASA as automatically bloated - it was the only game for aspiring rocket scientists before the 2000s. Recycling NASA people preserves some of their experience. One of the problems with the Orion program is that a lot of the good Apollo ideas had been lost due to retirement of those engineers and loss of record.
Goddard wanted to build spinning engines which used the rotary pressure to increase thrust-to-fuel ratio; visible in his posthumous patents.
Some basic info at (follow the links):
http://www.halfwaytoanywhere.com/
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.....
Well fusion is easier for electricity since it does not really matter if it masses a 1000 tons. So since we can't do the later we can't do the former.
Antimatter does not need gamma ray reflectors. When a proton and and a antiproton combine you get Pions. Not gamma rays. About 1/3 is each of the pi+,pi- and pi0. The pi0 does almost immediately decay into gammas and there goes about 1/3 of the energy. But the pi+ and pi- live for long enough and are moving pretty close to the speed of light. Since they are charged they can be directed by a magnetic nozzle. So we can even without much magic (other than generating and storing antimatter) have a antimatter engine with about 50% or even fairly close to 66% efficiency.
Even with 50% efficiency you can get away with pretty reasonable mass ratios for start stop upwards of 50% the speed of light.
However the only gamma ray reflector we could do a a dense block of Tungsten that is heated to close to its melting point by all rearward directed gammas. And a mirror system to send the radiated energy (from the white hot W block) backwards. It would need a rather thick block of Tungsten... so your probably going to be slower than not having it. An interesting calculation to work out for the evening perhaps.
If information wants to be free, why does my internet connection cost so much?
Your endorsement falls flat when looked at in context. You are talking about atomic drives: hot gasses or ion propulsion from a fission reactor. The parent was talking about harnessing the power of the sun. Grandparent was talking about the difficulties in creating antimatter. Y'all need to get on the same page!
What the hell reflects gamma-rays anyway? Neutronium?
A black hole's event horizon, from the inside? Kind of impractical for a nozzle, though.
Ezekiel 23:20
Bussard was a nuclear physicist. This was not outside his field, it WAS his field. He worked on Tokamaks long before he began his adventures into electrostatic (electrodynamic? polywell is weird) fusion.
I don't 'believe' that Polywell will work. I think it's worth investigating, and the US navy is doing so. I am satisfied. They will decide if it works or not, and I will accept their conclusion. I am NOT a nuclear physicist, and do not pretend to be one.
But I have read enough, from Bussard and others, to doubt Tokamaks. They have not yet reached ignition, producing more heat than it took to start the reaction - they cannot run on their own. ITER is _supposed_ to do so, but then they expect it to fail in short order because (as you just said) the materials science is not good enough to resist the effects of radiation bombardment on the structure. It's insanely expensive, and has been '20 years away' for longer than I've been alive.
You know a experimental power station that cost about 10-20B over the 20-30 year lifetime is in fact not that expensive at all. Note that a plain old nuke plant cost about 10B to build. And a cool 1B even for a 1GW coal plant. Hydro cost even more.
Did you also know that plasma containment is getting better *faster* than Moore's law? In the last 20 years there has been a increase in containment of something like well over a million (can't be bothered looking it up). Also did you know that the ITER crowed have *never* been given the budget they expected. So the joke of 20 years always is strongly based on the fact they have not had the finding they said they would need for that to be true. Also even new fission is going to take 20-30 years to validate, before wide scale deployment.
We are in this energy thing for the long haul. 20 years even 60 years of sustained investment is the kind of long term planning we need to be doing. Sure we should have a more diverse portfolio, even the ITER guys have at times strongly supported that (other times they have been told to keep their mouths shut). But the whole "my fusion idea is better and cheaper but the baaad ITER people are taking all the money" is false. A bunch of scientist killed the SCC years back because they thought the money not spent on that particle accelerator would be available to them. It wasn't. They got no increase and set back particle physics 20 years. Fact is these R&D items are tiny line items in government funding programs, its not a zero sum game. kill one and there is *more* reason to kill another. Not less. ITER is not stealing anyone's funding. Kill it and that money goes away.
Finally the Buzzard Polywell really tries to pretend a whole bunch of both theory and experimental results are wrong. The facts are that the probability of a T nuclei and a D nucli undergoing fusion is >1000x more than the chance they scatter off each other. Thus they *always* thermalize faster than they fuse. Add electrons, and again energy sapping ion electron collisions are 1000x more likely giving there energy up as x rays. For any other reaction those numbers are far far worse.
Yes i am a nuclear scientist. Or at least i was.
If information wants to be free, why does my internet connection cost so much?