wumpus

I wouldn't count on high TWR off a pad unless you had some particular reason to ignore the atmosphere (like mountain or balloon launch). It might not be a bad idea to have plenty of SRBs (sugar+KNO3?) to get close to mach1 or something (even if they don't directly add much delta-v). In small rockets aero losses are higher relatively than big rockets, and the big boys don't do the obvious steps to minimize gravity losses, so I'd think in terms of mountain/balloon launch before going all out with high TWR. Don't underestimate the issues of finding a place to launch. LOHAN has quite a bit of sponsorship, but is still waiting for the FAA to give them permission to fly. I'd have to wonder if someplace like Jamaica or even "sea launch in international water" would make more sense (especially for balloon launches where you don't need a completely flat platform). Does anybody play KSP in Ecuador? Some of those mountains are ideal for rocket launches (high, equatorial, and a few with roads near the top).

If it's all that hard, somethings wrong. Elon Musk claims the first stage of the Falcon 9 would be able to get to orbit on its own (if it weren't carrying a second stage + cargo) and I'd suspect that it isn't uncommon for two-stage rockets (at least those getting a bit more than half the delta-v in the first stage. It shouldn't be that uncommon). Having a SSTO that can carry worthwhile cargo - that's a much harder thing to do.

Living through multiple launches is even more important. Having a pressurized highly corrosive material inside a container it is hypegolic with gave me the willies. Can't imagine how you would fabricate/transport the thing remotely safely. It looks great as a rocket, but how do you get there?

http://www.aerotech-rocketry.com/resources.aspx sells high-power ammonium perclorate. One rather large engine (12.6kg!) appears to have an Isp of 188s (I'm uneasy about my calculation). http://www.aerotech-rocketry.com/customersite/resource_library/Catalogs_Flyers_Data_Sheets/ldrs-27_prod_data_sheets.pdf (bottom rocket). Note that adding a vacuum bell might help. I think the LOHAN project (the one using the weather balloon) had issues even with solid rockets at extreme altitude. Of course, the solid motors had time to freeze and hit local temps. Just because it is far easier doesn't mean it is trivial. One description of a rocket is a pipebomb with an opening at one end. Once you add the HTP* you've basically added the detonator to said explosive. I'd be much happier having it as a smaller ignition device and using NO2 (not to mention NTP is likely far more corrosive than LOX, I remember a chemistry teacher claiming it was the worst (most corrosive) chemical he'd ever worked with [of course that was in high school so he might not have dealt with all that much]). That idea looks great on the launch pad, but getting it there is a nightmare. If you have NTP, the pressurized NTP+jellied hydrocarbons would make an ideal RCS unit (of course, it could still explode and start the NO2+jellied hydrocarbons making a bigger boom). * assuming you can obtain it, John Carmack of Armadillo Airspace had serious issues obtaining the stuff. I think he gave up on HTP all together. And he is at the extreme end of amature rocket builders.

Miss-reading the subway map. ~20k is for low Kerbol orbit, 6k is for kerbol intercept (which likely includes reducing your Ap within Kerbol's SOI). The Jool transfer is presumably ideal from LKO to Jool intercept (no idea how long that will take). Still, cutting the delta-v in half means reducing the order of magnitude of fuel needed by a half. That's huge. Don't forget that your 4km/s has to be done nearly in one burn (you can burn somewhat less than 1km/s first if you want, but the rest only gets Oberth advantage on a single burn). It will involve a big, big, craft for a direct flight. Or you can send a relatively tiny ship to Jool first.

Just pay no attention to the fission-based power supply needed (not a complaint, unless you are convinced that fission rockets can generate >1000Isp with reaction mass that can be stored long-term). Also please ignore the shear size of the radiators.

There's nothing in the definition of hybrid that requires pressurization, just that at amature levels you can expect exclusively pressure-fed engines. Turbopump-fed hybrids (even using NO2) might well be useful engines that require being able to dwell in space and possibly allow multiple burns (just don't expect to see them without NASA-sized budgets). 1. You want a CNC instead of a 3d printer. This allows you to use the material of your choice (likely forged aluminum for weight or possibly a strength/high melting point metal. Possibly even titanium depending on your CNC machine). While building a CNC machine out of a dremel tool is a major undertaking itself, you can probably get access to one a lot easier than even a mid-ranged industrial 3d printer. 2. The batteries needed for an electric turbopump should scale the same as the Rutherford engine rocket labs uses. The key is likely LiFePO4 batteries (they can pump out their power faster than most batteries) and having them all wired in parallel (or as close as possible to all discharge along with the stage*). Also while such design might not be "amature electronics", many EEs are familiar enough with power supply design and can presumably figure out much of the differences involved (turbines are *slow* compared to modern power supplies. Expect to get away with "obsolete" things like iron core inductors to reduce weight). I suspect a team capable of reaching orbit would have no difficulty recruiting someone capable of designing such a system. * if the batteries are a significant part of the weight of the booster, you've just discovered a great way to do asparagus staging: switching between battery sources should be trivial [for switching in values of time measured in microseconds].

If you are already willing to wait a few years for the resonances to match, I'd strongly re-consider the Joolian slingshot. Delta-v to Low Kerbol Orbit from Kerbin = ~20km/s. Delta-v to Jool from LKO ~1km/s. Don't forget that slingshoting close to Jool gives you tremendous Obereth (just in case you need more of that 20k that Jool doesn't directly give you), and you will have even more Obereth doing a burn at Low Kerbol Orbit (to fix your return trajectory). Even if you find the resonance, you still have to build a ship capable of getting on that trajectory. https://www.youtube.com/watch?v=uNS6VKNXY6s [Scott Manley delivers an incredibly bad game into the Sun using RSS/RO. Direct burn of a SLS-based/sized rocket got roughly to Mercury, Jovian slingshot (plus correction) got into a collision course with the Sun].

Doesn't matter. Humans simply are lousy at that type of analysis. This is why the airlines have to be so obsessed with safety: one downed plane sticks in the mind so much more than tens of thousands of car deaths annually. They *see* the crash on TV, they don't hear about the crashes (when a car crashes that isn't news. That's expected. So of course humans aren't afraid of it). I'd be fairly surprised if adventure tourism didn't include things like skydiving. They aren't selling safety, they are selling [perceived] risk (and bragging rights from the risk).

Cyclers have a fairly limited advantage for cargo, unless you have enough of them so that the your tugs from you gravity well (orbit, surface, whatever) to the cycler are always in motion. For high-Isp/low thrust, the trip to Mars (or wherever) may be shorter than the trip in and out of the gravity wells. The main advantage is for people who want more room than an Orion or Dragon to stay for several months. I suppose you could try some sort of "fishing reel" approach (occasionally suggested as a cheap orbital elevator), but I have yet to see a workable approach. Fusion has some serious problems, and many of the benefits could be had with fission. If you go the fusion->electricity->VASIMR route, you wind up with roughly as much radiators as the solar panels you replace (although this may be ideal for going through the Van Allan belts). Your other means is to use the same [magnetic] apparatus that contains the plasma as the nozzle of a rocket. This gets rid of all the "Ve melts your rocket" issues, and provides direct cooling by removing heat out the rocket. You still need all kinds of heat to get rid of the heat from the energy you needed to start fusion, and the heat radiating out of the main fusing section.

I'd strongly suspect that many of the people drawn to space and have the means for such a trip already own a plane or use private jets (fractionally owned or similar). Safety there isn't at all similar to commercial airlines (I suspect it is close to driving a car). In fact, I'd rather compare safety against a driving trip from Washington DC to New York City (or perhaps LA to San Francisco, I understand that elsewhere rail is more popular, but in the US people dither between trains for DC-NYC and ignore the rest). But yes, safety will be critical.

Since orbital velocity is roughly half of escape velocity, you are trying to get a delta-v sufficient to wipe out your solar (kerbol) orbital velocity. This is roughly equal to escaping Kerbol, so you really should be thinking about a Jovian slingshot. Scott Manley had a video on "dumping things into the Sun" and showed how important Jovian slingshots are. Adjusting a jovian slingshot to be roughly in a good return for Kerbol sounds difficult, but it should be easier to bring along more delta-v to correct things (plus all the Oberth of Kerbol). Judging from the wiki, you might even be able to do science in the atmosphere. I'm not sure making probes survive at those levels.

According to the infallible Scott Manley, Dragon[2] would make a fairly good Orion replacement, but since it doesn't have a service module (nor any plans yet for one), it would be fairly limited in lunar missions (basically taking the free return back to Earth). That said, the video includes a lot of schedules that are full of "Elon Time". I can see dragon[2]s being used to lift crews to the ISS, and I can see Falcon Heavy launching soon. I just can't see Falcon Heavy launching astrotourists around the Moon right after Falcon 9 is crew rated. Considering it is a standard government program, I'd assume that CST-100 can lift a crew to the ISS and possibly one bell and whistle per congressional staffer involved, but no real capability beyond ISS. https://www.youtube.com/watch?v=P_LLNuLhEXc

As far as I know, you can buy ammonium perchlorate solid rocket engines (sized similar to black powder engines)[in the US], at what I'm sure is a much steeper price. This should give you some decent Isp for the upper stages. Stages beneath that would likely be a hybrid rocket (popular for larger sizes). I'd recommend aerodynamic fins while possible, leaving the thing spin stabilized (the rotation needed is rather low, it shouldn't interfere with the aero controls, assuming they are raspberry-pi controlled). I don't know exactly what the goal is (although the name includes "orbiter"), but "the register[.co.uk]" (a tech news/rumor site) is attempting a fairly serious go at such a thing and is presently stalled in bureaucracy (FAA at a New Mexico spaceport). It uses a first stage powered by weather balloon. As mentioned above in the thread, air-ignited stages can be tricky and there were even more problems for the LOHAN crew attempting to ignite rockets at weather balloon altitude. Also I'd expect that using weather balloons will get you higher much easier than jets, at least for rockets sized for amature builders. http://www.theregister.co.uk/science/lohan/

Obvious, to do [anything] correctly you will be stuck with a numerical solution. But I would suspect that a solar orbit would be the most accurate of simply computing the velocity you have and the velocity you need and figuring out just how long that will take. The big gotchas are you can't use any "subway maps" or other previously generated delta-v tables as they all assume Oberth and other things you won't have. Oddly enough, an Earth-Mars burn will spend nearly all its time in Earth orbit (unfortunately in the Van Allan belts which is a huge problem, especially for the solar panels). And what would a KSP forum answer be without a Scott Manley link:https://www.youtube.com/watch?v=000zDI2nmq8&list=PLYu7z3I8tdEknQK8KQqHA5sc0wbvj2q7z&index=20&t=6s I'm not sure which one has it (there are three parts) but it does show how the delta-v calculation goes. Not sure if Oberth is included "for free", if so you have to make sure it isn't calculated in your answer.

The gold standard for sharing remains the orange tank. For a better answer, you have to look at your cargos. Is there a common satellite that you lift? Or perhaps some sort of self-contained ISRU lander that you have developed? Perhaps a deliverable MPL-LPG2 lab? Or perhaps a standard interplanetary vessel? If you have something like this, you build something to lift them. Otherwise, lifting is measured in orange tanks.

I really have to wonder if Hubble-level resolution (the shuttle cargo bay was sized to fit a specific keyhole spy satellite, Hubble was sized to fit that same bay) can really be justified for such things or is that generals knowing nobody gets to ask why. I'd much rather have a low-angular resolution wide-angle image of the ground so I could see anything new. Note that storing that type of data and doing image comparisons at that speed was probably impossible when the shuttle-sized spy-satellites when up.

Googling said Play d'oh costs $5/lb, while LEGO is a bit more (and certainly used prices). Personally, I couldn't bring myself to burn LEGO. Note that assuming a $100 Saturn V kit (it is more like $140 from LEGO [sold out] and $193 from Amazon) and the 5.6 lb shipping weight is all LEGO (right), that is $20/lb (and generally considered a good value by brick, although "classic" [simple brick collections] can be had for $16/lb).

Looking at some of those "look at how big this rocket is" charts, I'm guessing New Glen has the longest first stage booster. Assuming drag of a cylinder scales with length, it should be the most aerodynamic (least drag) booster out there. This should make slowing down more difficult, but I'd expect it stages so the thing gets to fly horizontally through the atmosphere far enough (and high enough) to replace the braking burn. I'm not sure whether these are giant steps, or simply building to a different scale is mostly a matter of money.

The only way SRBs will be "worth it for the money" is if they are lifted to LKO by spaceplane and taken from LKO to Eve via LV-Ns. And even then it will be hard to justify. The problem of bad Isp is compounded every time you supply it with delta-v. I like SRBs. I'm even aware of times they make sense to use as second stages (rare, but similar to the times it makes sense to reduce their thrust). But don't expect to be able to justify them much past the surface of Kerbin.

If I was designing the Raptor, one thing I'd strongly consider is having it boosted by Falcon Heavy side boosters (possibly more than two). Possibly without a proper lower stage at all. The upper stage might light on the pad,assuming you didn't want to risk upper atmosphere ignition, or might not (it wouldn't produce significant thrust till much later, but still possibly worth it). There has to be a wide range of tonnage between FH full re-use and standard Raptor, and you would think it would make sense to cover most of it. Then again, most of the "really massive stuff to LEO" plans are for Mars transport. Although I suppose eventually customers will exist wanting massive satellites in LEO. Or simply want even bigger things to GSO than Falcon Heavy can supply.

Back during the end of the Cold War, the US Navy dragged the Missouri and New Jersey back into service. It was widely claimed (and quite believable) that it would already be unfeasible to build (even with the money being thrown around at the time) from scratch. After a turret exploded (killing just about anyone nearby) it became clear that the guns would require complete redesign, at which point I'd expect only the outer hull armor to be left original. Both ships are now floating museums. Of course, since the only real mission of such a ship is shore bombardment (submarines and carriers are superior for hitting other surface vessels), there really isn't much difference between a WWII battleship and a heavy cruiser (unless the cruiser sinks due to a turret explosion). Presumably the Navy's current railgun project can be considered something like this. The other thing a battleship provides is a wildly different set of weaknesses. Normal missiles, such as the exocet, would simply bounce off. What you would need is something on a high ballistic arc (which defenses could easily pick up) to avoid the armor and do damage (and I imagine that the USSR developed plenty back when two American battleships were lumbering about).

That seems well after a "final" Falcon 9 design. Also if they are building 20 falcons and have nearly a dozen used boosters in storage, just what do they plan on launching? I another thread (probably a SLS-bashing one) someone pointed out that the Saturn V was built to go to the moon, not the moon chosen because we built the Saturn V [note: Kennedy originally wanted Mars, but was told that it was beyond our capabilities]. Does Musk really have that many satellites to launch?

Back during the early shuttle era it was clear that NASA couldn't launch the [2?] Saturn Vs it had as museum pieces (I think one is in Redstone, Alabama the other is at KSC). While I'd assume that virtually everything is documented (but the .01% that isn't will surely bite you), I'm sure it also includes knowledge that only existed in somebody who launched Gemini and Apollo spacecraft. There was a small army scurry around making sure the right things happened at the right time during the countdown (while the countdown was critical to hitting the window, its real purpose was making sure everything happened on schedule). I'm not sure if SLS included the revived F1 (Apollo main engines) or not. These things effectively *had* to be 3d printed because the welding techniques simply aren't used anymore and simply couldn't be done (and of course you would need both welder and inspector. You might eventually dig up the right "maker", but who is that into inspection?). I remember reading about bits that included thick steel welds (heatshields?) and thinking that in the 1960s you could find a ton of welders with battleship experience. Good luck finding such now. Technology depends strictly on infrastructure. Ideas help, but if you can't build it with available parts (or build such parts) it isn't happening. If an engineer can design something with parts from Newark/Allied/McMaster-Carr, the product can be shipped on time. If not, you have a massive R&D project.

Declare N2 RCS thrusters as "not a burn"? Electromagnetic braking (certainly possible. Wouldn't like to be the test pilot)? Where did you get this from anyway? I can't find any indication of weird NG re-entry plans.