Steel

I'd say maybe closer to 40% or 50% if we're being realistic. Specialist rocket motor manufacturers can get about 10% minimum with motors specifically designed for deep throttle capability. I highly doubt an amateur designed and produced motor, designed mainly for ease of manufacture and potential reusability, would be able to get anywhere near that, especially in it's first few iterations. Moreover, due to the limited control hardware that will be onboard, the monitoring and fine control to get reliable deep throttling is probably not attainable. I would do the calculation assuming 50% minimum throttle to be on the safe side, then any improvements over this are a bonus. Also bear in mind that the thrust of a motor does not vary linearly with throttle setting.

You are quite right, turns out the word I actually should use is "sapient"

No, I don't think that will work, with these kind of 'journalists' if you actually try to tell them facts they just shout "FAKE NEWS" at you before rolling around on the floor dribbling and frothing at the mouth.

I believe it's a play on GTOW (Gross TakeOff Weight) for aircraft, so I think it stands for Gross Launch (Off) Weight. Could have just been reading that wrong all this time though! Also, with a launch weight that low you're beating a Lambda 4S by almost an order of magnitude.

That is outstanding. Sadly published on a different day to the ones above, nonetheless an amazing piece of journalism i'm sure!

"A swizzle stick, stowed by the overhead switch and circuit breaker panel, enables a pilot to position switches and rotate selectors on the opposite side of the cabin. With this arrangement, one pilot can control the complete spacecraft and temporarily free the second pilot of all duties." [1] [1] NASA Project Gemini Familiarization Manual, 1966 Revision, Instrument Panels Section, https://en.wikisource.org/wiki/NASA_Project_Gemini_Familiarization_Manual

Ok, but with the lightweight and low cost flight computer that is required for these things, along with the limited amount of sensors that will be available due to mass restrictions, can you actually program enough redundancy into the computer so that it can make those throttle movements in the required time? Basically what I'm saying is that surely with clustering comes a decision to either install more sensors and computers to be able to compensate for harware failures in-flight, or you just have to accept a higher chance of mission failure due to a hardware failure? EDIT: Also please understand I'm not here to discourage, just to play Devil's advocate.

I agree, it's a long argument! Back on topic: I've been reading through and it seems that you guys are looking at parallel staging and clustering. Surely for a low-cost rocket this is the opposite of what you want to do as you're introducing multiple failure points and extra monitoring requirements. It would only take one engine to underperform by 20% and your whole stack cartwheels off into the distance. I think this is why most small launchers use a three stage solid motor design. Light and let it go, no monitoring, no complicated guidance and control systems, no complex stage separations. That's not to say solid motors are the way to go (for reasons discussed before) but I think having potentially 8 cores (including strap on boosters) for a first stage is an absolute nightmare for failure mitigation

Even to someone as (sadly) aware of the Express as I am, this surprised me. I knew they published a lot of dreadful stories, but five in one day about the end of the world or alien sightings genuinely shocked (and saddened) me a little.

And this is why we don't read the express! If you want to get an idea of the kind of people who do read it I'd encourage you to go and read through comments on articles on their Facebook page; if you don't lose faith in humanity within 30 seconds you're made of sterner stuff than I. But in all seriousness, this is a newspaper who regularly publish stories about the impending end of the world, don't take their science section at all seriously. Just to put this into context, here are four articles that they published TODAY: END OF WORLD WARNING: Watch biggest explosion EVER on Moon as NASA warns we could be next [1] ROGUE planet heading towards Earth, shock theory suggests [2] REVEALED: The shocking reason USA ALLOWED Russia to win Space Race with Sputnik [3] ALIEN SENSATION: Video of tests being carried out on 'suspected ET being' emerge [4] EDIT: I found a fifth - bear in mind these were all published on the same day: Extraordinary sight of 'alien UFO disappearing into portal seen across the globe' [5]

I think in most fields these days (and in pretty much every sport) an amateur is someone who is not employed full-time to do whatever it is they're an amateur at. To qualify as an amateur rocket (at least in my eyes) everyone working on it is doing it outside of an employment setting. Thus, SpaceX, whoever did SpaceshipOne (was it Scaled Composites?), Blue Origin e.t.c are all professional rocketeers because there were paid engineers working on them. Your sailboat analogy doesn't quite work, because equally the baseball bats used by amateur players are made by professionals, but they are still amateur players. In rocketry, the rocket is "the player" in a sense, rather than the tool used by the player (like a sailboat or a baseball bat).

The amount that land area increases when sea levels fall is hugely dependent on the topology of the ocean floor around Madagascar. If it's on a gently sloping region then a large change coulld be achieved with a change of only a few of metres, if it's on a steep shelf then potentially tens or hundreds of metres would be required. One question I have is wouldn't this mysterious object already fit? At it's widest (I'm assuming the part that bulges) it is 560 km coast-to-coast. [1] [1] http://www.fao.org/ag/agp/agpc/doc/counprof/madagascar/madagascareng.htm

A really interesting proposition! I reckon you'd need to do a lot of simulation work to ensure that the materials act as you've said here. High temperatures and pressures often result in behavior that goes completely against what you would expect.

While your standard DIY 3-axis dremel CNC machine is fine for a small-scale hobbyist, if we're talking high-performance rocketry turbopumps you're going to struggle. Firstly I can't imagine a dremel tool has the power to cut billet titanium or forged alumiuium, and secondly due to the complexity of turbopump parts, you'd probably need a 4- or 5- axis CNC manchine. I'd say designing in-house and paying for external manufacture is the only way to go without shelling out potentially hundreds of thousands of dollars for CNC machines. That way you can design it and then pick the manufacture method that suits the design best (be that 3D printing, CNC or something else). Everything you're saying about batteries is true, but since there's next to zero knowledge about electric turbopump rocketry in the public domain (or indeed outside Rockcetlab) then it's a bit of a stretch to suppose an amateur team should tackle it while the technology is still in it's infancy. After all, moving from pressure-fed to a turbopump set-up is an enormous amount of work and only gives you a small amount of extra performance, you can still get to orbit with pressure fed engines.

Several enormous problems to overcome with this approach as an amateur: 1. unless you access to industrial standard metal 3D printers theres no way you could make turbopumps of the necessary strength and tolerances. 2. Moving to an electric turbopump set-up on a rocket that's not designed for it is probably a bad idea. Firstly you add in a whole lot of complexity in the form of both high-power (power) and low-power (control) electronics, which in itself bring with it a whole new range of potential failure points. Secondly you also add in tens, possibly hundreds, of kilograms of batteries or supercapacitors (which are both extremely expensive) which also have to be prepared in order to discharge huge amount of energy very quickly. You're suddenly moving well outside th realms of amateur electronics.

It's a bit of a moot question. When AIs become sentient the laws will have to be updated to reflect that humans are no longer the only sentient being we know of. Right now the law has no concept of other sentient beings and so you can't really apply it EDIT: Also partially Ninja'd by @tater

Also they computers to do that most of the time, most of the people involved are basically there just to maintain the computers and feed them input data.

You could get away with an unpressurised suit, but other than that you'd definitely need one.

Oh it would absolutely rip itself apart. Of course an engine doesn't actually need the bell to function, but it would severely impact the performance of the engine, probably to the point where it wouldn't have the dV needed to reach orbit

Probably not, you just wouldn't really get any useful velocity out of it. All you'd get is a rocket at a couple of thousand feet moving at an absolute maximum of about 200 ms-1. Also, the TWR of jet engines is simply not very good for rocketry applications

I'm not sure at an amateur level you could build two stages large enough to get you to orbit. The smallest orbital rocket that's has ever been attempted [1] has three stages.

Since this sort of cloning is physically impossible it's a philosophical question at best - and to even call it philosophy is a bit of a push!

I agree with the sentiment of your post entirely My one question is thus: Have SpaceX actually made any notable advances that need to be shared in order for other companies to be able to reuse rockets? So they've done a lot of research on hypersonic engine restarts, station keeping barges and computer code to guide a rocket into a controlled landing; but it's not like any of the stuff that's actually enabled them to do what they do is top-secret patented technology. ULA and the like (the big boys) haven't got reusability because, until SpaceX actually demonstrated its possibility, there was no demand and so they didn't design for it. It's just a matter of time before other companies (my money would be on Blue Origin) start coming out with reusable launchers, and then slowly the big boys will grab onto the idea too.

[PICTURE] Now those are some sexy grid fins... So the new shape is definitely for aerodynamic reasons while ascending.

Or, if we assume this was done by professional engineers rather than monkeys, maybe it could suggest that they've extensively simulated and tested these new grid fins and have updated the software with new parameters?