Pangea Aerospace successfully hot fire tests the first MethaLox aerospike engine
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satellite-evolution.com
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More thrust even at lower specific impulse at the start of the flight can save you a significant amount of gravity loss, engine mass etc.
It also depends on the engine configuration, you could do much better in terms of weight and density.
Engines used on a first stage typically have high thrust, but that's because they're designed with large throats, not because of the propellant they use.
A dense propellant does allow the pumps to be smaller. But I don't think that's going to help much in a NTR, since the reactor itself is heavy. The problem with an NTR is the difficulty of getting high mass flow past very thin fuel elements (the thinness necessary for high heat transfer) without destruction of the fuel elements by that flow. The thin fuel elements also ensure some fission products will escape and be carried off in the propellant.
and that gets close to my favorite - air-augmenting regular rocket engine. Very simple and bumps up your thrust and ISP up to 2-3x http://www.astronautix.com/g/gnom.html
> The engine is extremely low cost to produce, as it is completely additively manufactured (metallic 3D printing) in only two pieces.
Anyway, there's a bunch of stuff they're not including in this statement; it's like "we can print your car's engine block" but glosses over the additional whirly-sparky stuff that turns a lump of metal -- even if it is in the right shape -- into a functional engine.
The F9 and Electron both aggressively drove down costs using 3D printing
Also 3D printing has the advantage of not throwing out 75%+ of the metal stock
COST_3D-(COST_CONVENTIONAL+SALARY_MACHINIST) = SAVINGS
is more than the literally unreproducible parts 3D printing can achieve. These are not comparable quantities.
The way I see it, there are roughly infinite previously non-constructible parts that by definition we as a society couldn't test. Now that we can construct these new parts, shouldn't we test them and then use them if they are better/cheaper?
High performance heat exchangers for applications where every gram counts for example were hand made like a jewelry work at a huge expense.
I spent 10 years working in electronics, and not only manufacturing.
And you get to keep the images, which are not there for the text-only version
Go beyond 2x!
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I wonder if Pangea has done anything in an attempt to solve that problem.
If you haven't seen the SpaceX presentation on their combustion CFD software, it's a must see. They have state of the art simulation capability in this area - better than any commercial offerings.
They clearly invested massively in engine development from then on. I don't think they simply stopped.
And Raptor has turned into the best engine ever since then. Likely the used lots of simulation in development.
A personality driven channel versus engineering
With that said, he has been able to get in-situ interviews with rocket company CEOs including his amazing 2 hour almost single take video tour with Elon Musk [0] where I was able see Elon comfortable in speaking much more deeply, candidly, and enjoyably than with any interviewer/reporter prior. Tim Dodd is no professional engineer but he really knows his stuff. His personality helps bridge the gap between the highly technical and the layman.
Personally I love that Tim's personality shines through in his videos. His enthusiasm is infectious and just plain nice to see, IMO.
If you think you are to good to hear from those people then maybe you should get of your high horse.
Just because its not designed for only engineers doesn't mean it shouldn't be recommended. Find me a better video or article about areospikes.
He is an educator he doesn't have to be able to design his own engine to make good educational videos.
And Scott Manley is also not an engineer and Scott Manley actually used Tims graphics in his own videos.
Right now he is working on a 1h 30min video on Russian engines that is more detailed then anything out-there and he spend 2 years researching it.
'saint grail' ...
'the line of messianic descent was defined by the French word Sangréal.... In English translation, the definition, Sangréal, became "San Gréal", as in "San" Francisco. When written more fully it was written "Saint Grail", "Saint", of course, relating to "Holy"; and by a natural linguistic process came the more romantically familiar name, "Holy Grail".'
The 'sang real' (royal bloodline) nonsense was a much later invention (15th century).
In a meta note, that article seems to have been translated by Google.
What are the operational targets for the engine. What ISP are they getting. What chamber pressure and so on.
So far this is a neat little research project that is unlikely to go anywhere.
If it wasn't for the areospike nobody would care and would ask much harder questions. But because its areospike people love it.
Is this designed for a kick stage or a full second stage of a rocket? SSTO? Lots of questions.
Well, kind off.. it's a spike, but they're using water steam as propellent, I'm guessing to "solve" the cooling problem. So not sure if it counts (and how successful their rocket will be).
But still.. https://www.youtube.com/watch?v=QsKE_SBY-kE
What's the ISP on a water rocket? 90?
That is not a company, its a fraud. They defraud investors. They are not a real company.
I recommend ignoring them and warning people against them.
The most recent company who was seriously developing a areospike was Firefly. That was for a pressure fed rocket. They have since dropped that, and in the most recent interview between Everyday Astronaut and the CEO of Firefly he addresses why they did that.
I.e. in their illustration on the page, the two nozzles next to the spike itself?
At least that's my understanding - I just like to learn about rockets.
The TLDR as I remember it, is physical nozzles on the aerospike don't work the same way as they do on a traditional rocket. It's more like like just an exit from the combustion chamber.
The appeal of an aerospike is by having lots of exhaust port aligned around a spike, is it creates a sort of virtual nozzle that is the right size for the atmospheric pressure. And as such acts sort of like a nozzle that changes shape and size as the rocket goes through the thinner and thinner atmosphere.
This in theory gains efficiency over a rocket that has a set shape for it's nozzle, and isn't always operating at optimal efficiency due to the size of the nozzle.
* Not an expert on these things, just going off of memory
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Basically everything a layman would want to know imo.
Space elevators aren't scrapped, just on the shelf until we even have a material that let's us think they might be feasible. That said, Lunar space elevators could be done with lower-strength materials, like Kevlar, and there are some people working on them.
For Earth orbit, I think the centrifuge concept (e.g. SpinLaunch) has some promise. Still some huge implementation hurdles, but could be a huge step forward to put all of the energy for the first stage on the ground.
With a 100m arm, the will launch only like a few 100kg, a single Starship can launch 150tons.
Why in the world would anybody use spin launch?
IMO the closest thing to a space elevator realistically achievable with today's technology would be a Skyhoook: https://en.wikipedia.org/wiki/Skyhook_(structure)
As for size, honestly, that doesn't seem to be much of a problem. You still have exclusion zones, and I'd argue that the exclusion zone around a spinning device like Spinlaunch proposes would have to be fairly large in all directions. Quicklaunch doesn't have a failure mode where the payload goes sideways at its full speed. Even if Quicklaunch were on land (which it wasn't planned to be), it would still probably require a smaller exclusion area.
This is not a trivial engineering problem. And in the case of a light gas gun, not only do you need to dump all this energy into a driver to compress the light gas extremely quickly, you also then must bring that driver to a halt extremely quickly without destroying everything.
BTW did Quicklaunch even have a driver/piston? I'm not quite sure that it had.
I am in total agreement though that spinlaunch is a much worse system though.
Is your skepticism based on cargo suitability or other factors.
A Starship launches 150 tons reusable. That far cheaper and less work then building 500 Upper-Stages and shoot 500 of those rockets with a SpinLaunch system.
There is really no comparison in cost.
Maybe they could make the upper stage reusable but that would reduce the payload to and even more pathetic amount.
This system simply can not compete against reusable rockets.
PS: I don't have numbers, but I'm guessing that F9 hitchhike Transporter missions cost less per kilogram, compared to the imaginary numbers for non-existing full scale Spinlauch.
First of all, putting aside the several red-flags for why this looks like a scam, and assuming it's actually do-able, it's still not going to happen. The global space industry is built on rockets. At best, stuff like this--even if it does work--gets a "cute project, kid" pat on the back and then ignored. When was the last time any fundamental redesign of an existing technology take over an industry? It just doesn't happen.
And I think everyone involved probably knows that. You're not going to compete against Google as a scrappy startup trying to make a search engine. You're not going to compete against SpaceX as a scrappy startup trying to make alternative launch systems. Somebody, somewhere, has to understand that. So they have to be in on the scam.
Now, as for the actual idea, there are several problems. First and foremost is: energy is energy. If this thing fails, it blows up just as bad as a chemical rocket on the platform.
At least chemical rockets are based on decades-old materials science. This spinning arm malarky expects us to believe that they can support 10,000x their payload on the arm and be able to release it on a hair trigger? I suppose next they're going to tell us the arm is made of carbon nanotubes or some other unobtanium.
So they want to spin the object in a vacuum. How are they going to seal the spin chamber in such a way that they can generate a significant vacuum while also allowing the payload to escape? They show a paper or some other thin membrane door over the escape hatch that the payload punches through. OK, that means that door needs to be able to support 13.75 pounds per square inch of atmosphere. A 2m x 2m door needs to be able to hold up over 40 tons of atmosphere. The payload needs to punch through a door that is holding up over 40 tons of atmosphere. That payload needs to punch into a 40 ton column of atmosphere. At ~5,000 mph?!
So what I expect to happen is that the payload hits the column of air, creates a mach shockwave that destroys all of the windows in a 5 mile radius, while the rush of air into the chamber and clapping back around the tunnel of vaccum the payload creates blinding spike of plasma (not unlike lightning), that ends up destroying the launch chamber.
Oh, yes, there are "challenges" to "figure out". From their launch command center that was clearly designed for aesthetics more than functionality. Lots of problem solving gonna happen there.
For example: arguing about "paper" strength to resist air pressure vs vacuum and throwing around numbers like "40 tons" isn't based on any actual materials science. The burst pressure strength for pretty standard office paper is 250 - 300 kPa. Atmospheric pressure at sea level is 101 kPa. So right off the bat, you've multiplied a bunch of numbers together and come up with the wrong answer: the paper I buy from the stationary store is 2-3 times strong enough to resist atmospheric pressure against a vacuum.
Now of course, at a suitably large dimensionality, we have to worry about fiber strength loading etc. but this has so many solutions it's absurd - i.e. 2 sheets of paper with fibers perpendicular for strength, a plastic backer for air permeability, and then weaving strengthening fibers into a grid - remembering that the burst strength is quite different to the resistance to piercing forces (i.e. kevlar will stop a bullet but not a knife).
First, you're making a giant spinning thing that contains a ridiculous amount of energy. If the release of the projectile is off by a millisecond, instead of flying through the outlet it's instead flying into the wall of the launcher where it will deliver all of its kinetic energy in the form of an explosion with the energy of about a half ton of TNT, which sounds bad but really isn't compared to the arm its exploding next to that would release the energy of a small nuke if it gets damaged. This isn't a failure mode that can be monitored and avoided; eventually you're going to have a component fail or a software glitch and before the system can even register that something is wrong the launcher will be a crater.
You're launching bulk material into orbit where no one cares if the occasional launch fails so long as it's cheap, and you're wasting that on a launch system where the most minor failure results in not just the loss of the launch vehicle but the entire infrastructure for launching.
But even if everything works exactly as intended there are still issues. Your giant centrifuge spins up in a vacuum because at those speeds air resistance would be extremely damaging. Unfortunately, after you release the payload, it breaches the seal on the outlet and now you have a giant inrush of air into your vacuum chamber. Unfortunately, the giant arm is still spinning at 8000 kph. The surface of the arm is going to ablate as it moves through sea level air at hypersonic speeds, and its going to generate massive shock waves which are going to reverberate in the chamber. All those precision components for releasing your payload with extreme precision are going to be exposed to these hellish conditions. You're going to need extensive repairs or replacements after every launch.
You're doing all this and you still need a launch vehicle with its own rocket engine and propellant, flight control surfaces and surface protection for its own hypersonic journey through the lower atmosphere. Everything needs to survive ridiculous g forces. All this to deliver a few kilograms of low value cargo?
These problems don't go away as you refine the technology, they are fundamental. You will always need precision release mechanisms to avoid catastrophic failure, you will always be exposed to hypersonic conditions, you will always experience ridiculous g forces, you will always need rockets for orbital insertion, you will always be restricted to low value cargo.
It's an interesting engineering problem; they might learn some cool lessons along the way, maybe some valuable patents will come out of it, but there is no hope for developing a practical space launch method competitive with existing methods.
All we need to do now is containerise it for easy transportation across borders! Err..
My first thought on seeing the prototype was whether they've taken a map and drawn an arc in line with the rotation to see the areas that might be impacted when this thing RUDs. Perhaps they'll put it on a turntable?
Nonetheless I'd suggest it's probably safest to build this thing in a concrete pit such that failure results in a big hole, and not hot and spicy hypersonic plasma flung across the continental USA.
You need to build a non reusable rocket upper stage for every couple 100kg or material you want to launch.
Starship fully reusable will end up with 150t per LAUNCH. How many spin launches do you need to get the same cargo as a SINGLE Starship launch.
In no way would it ever be cheaper.
You could potentially build a skyhook on the moon, which a space elevator is merely a special case of, but you lose a lot of the advantages of a space elevator - namely you still need something to blast off the surface to reach the skyhook, and you have to carefully time it because everything's moving at extremely high speed. Saves a lot of fuel though.
If you use a rocket that's fine you just point in a different direction and burn, but if you're trying to launch, say, a few trillion tons of stuff, you need something a tad more efficient
Its far easier then on earth.
One the moon you might just use a mass driver instead, at least for bulk materials. And if not that a reusable rocket works just fine.
You need to build a non reusable rocket upper stage for every couple 100kg or material you want to launch.
Starship fully reusable will end up with 150t per launch. How many spin launches do you need to get the same cargo as a single Starship launch.
300 Upper-stages you need to build and launch or launch literally one Starship. Good luck with your competition.
Almost all of those alternative launch things make almost no sense once you make fully reusable rockets work.
One limiting factor of a rocket engine is the exhaust cone. This big dome-shaped piece of internally cooled structure tries to make the burning of fuel most efficient by controlling the shape of the exhaust reaction. In atmosphere you need a different size than in orbit to burn optimal, that's one reason why staging is done and the second stage is much different in cone size.
Since in aerospike the direction and shape of the exhaust gasses is different, air pressure is used as a "dynamic cone" making single-stage to orbit" rockets much more feasable. I'm not sure if we want that at all, though.
To reach maximum theoretical performance, a rocket engine nozzle needs to expand the exhaust to be of equal pressure as the ambient air. Being too underexpanded can actually destroy the engine, and even well before that being over- or underexpanded saps efficiency, so you can improve performance by specializing for the pressure you target. But of course, as a rocket ascends, pressure falls. This means that the expansion ratios of traditional engines are compromises over the pressure range they are expected to operate in.
Aerospike engines use a neat hack to make a "virtual nozzle", where the pressure of outside air is used to push on the exhaust stream. This makes it slightly less efficient than a traditional de Laval nozzle that is specialized for the exact pressure, but it can maintain that not-perfect but high level of efficiency for the whole ascent, from atmospheric to vacuum.
When everyone was trying to build single stage to orbit vehicles, aerospikes sounded very promising as they would allow a single engine to be used from the launch pad to vacuum with reasonable efficiency. However, now that first stages are routinely returning to the launch site and landing on their own, SSTOs are not nearly as attractive, and with a two-stage architecture, you want to give the second stage a proper vacuum engine, and then the first stage won't lose that much if it's optimized for near-sealevel conditions. I'm not sure aerospikes make that much sense anymore.
Take a traditional bell nozzle engine. The shape of the bell is designed to redirect the exhaust in the correct direction, but one of the design parameters for the shape is the ambient air pressure. If you design it to work at a specific altitude, it will be less efficient at other altitudes.
The aerospike is more efficient over a broader range of altitudes. (That is, if you take the average efficiency over a wider range of altitudes, the aerospike wins. If you pick one altitude or a narrow range of altitudes, the traditional nozzle wins.)
Instead of having a lift stage and an orbital stage, aerospikes can theoretically do both, meaning one cohesive vehicle from launch through orbit.
The weight savings and reusability factors are huge if SSTO setups become feasible.
The issue with an aero spike is that the benefits just aren’t there for a multi stage rocket. We do multi stage rockets to balance the needs of high thrust at the launch pad with the need to minimize our final non-payload weight in orbit. Varying the bell design to match flight profile naturally plays well with this approach. If you’re going to ditch parts of your rocket for weight saving during ascent, you might as well tune each stage for the altitude it will actually work at. Motors that need to work at all altitudes are pretty rare, the only ones I can think of are SSTOs in theory, and the space shuttle main engines.
If we could get a falcon 9 with aero spikes it would theoretically be an improvement, but not a huge one. All the gains would be in the edges of various stages where say, the stage 1 motors are flying above their designed altitude. The efficiency gains are there, but they might be completely offset by increased weight, cost, cooling concerns, etc.
Aerospike nozzles are spike nozzles where the spike is cut short and "replaced by air". They are shorter and usually lighter than equivalent bell-shaped nozzles, but they have bigger surface area in the critical section - most heat-loaded part of the engine - so cooling them is harder. For small engines the problem is cooling, and for big engines there is a problem of area where to put those engines (for large rockets length and weight of nozzle isn't a problem, but cross-section of the rocket, where the engines have to be installed, is), so aerospikes have different trade-off than bell-shaped nozzles.
The next question is which version is more energy efficient. Again, my very naive understanding is that they seem to be kind of similar. The space elevator is less efficient than you might think, because you can't just run electrical wires up and down it. The weight would be a problem, and resistance losses over such a long cable would be high. Instead, you might send power through the air with a big laser, but that also comes with efficiency losses, in the same ballpark as rocket engines.
And of course, Starship has the obvious advantage that it seems like it actually might work with current technology. I think this comparison is an interesting way to highlight what a big deal it will be, if Starship does work.
But arguing that Starship achieves basically the same thing seems wrong to me.
Starship is subject to the rocket equation. That means all but a few percent of its launch mass is rocket fuel.
Space hooks of all sorts require some transfer of energy, but the idea is it's on the order of magnitude of the actual potential energy gained.
Edit: It strikes me as implausible that we'll get unobtainium with sufficient material strength to build a space elevator without accompanying superconductors run through the elevator structure, but when I ran the numbers, current lithium ion batteries are about 1/60th of the energy density of mass moved from the highest equatorial point on earth to geosync orbit.
Not so very different from the rocket equation, you're right, if we decide there's no way to convey energy through the space elevator.
It's all sci-fi anyway!
Has Musk ever said that's what the Boring company is going to do some day?
Even if you assume a sufficient good mass driver, you still need a rocket upper stage. And those mass drivers would always target the same orbit.
You really have to construct a very specific scenario to beat reusable rockets anytime soon.
On the moon if you want to mass deliver ice blocks to a specific fuel station it makes some sense.
If you're looking at sci-fi fixed infrastructure for access to space, the orbital ring looks more plausible.
It's out there, but unlike a space elevator it doesn't require gigatons of unobtanium cable.
I'm still dubious of the benefits of the aerospike but I'm happy to see the pursuit.
The trouble is that SSTO is on the margin of the possible and mastering reuse of a 2 stage system is a certain win whereas the SSTO is risky. You have to perfect quite a few technologies such as the aerospike engine, very lightweight tanks and thermal management system and get them to all work together and really be able to reuse them without tearing it down each time like the old STS.
The napkin math seems workable, but rockets require a lot more than napkin math.
Having said that, Shuttles were almost SSTOs in the sense that the fuel tank could be placed in orbit (and reused as pressurized habitation space, with some extra work). Maybe some SLS-derived work can add some very large volumes able to dock into a future space station.
That is super cool! I gotta dig into that.. pity they never did that. It would be neat to have an ISS module that was a re-purposed shuttle external fuel tank.
Still it performed better than Tsiolkovsky and everyone else thought a chemical rocket could perform because running rich with extra H2 lets you get a better ISP since it lowers the molecular weight of the exhaust even if it does lower the temperature a little.
Yeah... I kind of cheated. "Almost", but a lot of the kick came from the SRBs.
In vacuum, an aerospike will not be as efficient as a maximally expanded traditional nozzle. If you could conjure an aerospike raptor from thin air, you'd still probably want the vacuum engines there, but you'd of course want to replace the sea-level ones with the spikes for higher efficiency immediately after stage sep (when all 6 are firing).
And don’t forget the landing. Aerospikes are easier to justify if you are doing a propulsive landing.
I'm not even sure if Starship will light all 6 engines on separation. Its a question of gravity loses vs lower ISP of sea-level engine. Maybe they turn them on for a initial boost and then turn the center 3 engines off.
Does that answer your question?