Northstar1989

It's only supposed to come in at a bit more than $300 million for the carrier plane development. That's a *bargain* as far as aircraft development goes... The Airbus A380 cost 14.4 Billion USD, and even the 747 off which many parts of the Stratolaunch are based came in at around 3.7 Billion USD according to Hofstra University... https://people.hofstra.edu/geotrans/eng/ch3en/conc3en/table_aircraftdevcosts.html

Sweeping the wings back doesn't affect aspect-ratio, as long as you keep the wing-area and wingspan constant. I pointed as much out in the OP already, and shouldn't need to reiterate it... The U-2 had a top speed of Mach 0.67 Nibb. Swept wings aren't useful on a plane that flies that slow, except for improving aerodynamic stability by moving the CoL back... They also make it harder to take off without bashing your wingtips on the runway, and require more ground clearance. The Stratolaunch Model 351 doesn't have to worry about this, however, as there is already massive desigmed-in runway clearance for the wings, due to the need to suspend the rocket and fuselages below the main wing... But the Stratolaunch uses 747 engines, so it's likely they designed it to fly at Mach 0.86 (where swept wings are beneficial by pushing transonic stability and drag problems to only occur at higher speeds) to get the most altitude out of its airframe... Therefore, swept wingtips ought to be useful...

A fairly simple question here- I was looking at info on the Scaled Composites Stratolaunch (which work has continued steadily on through the present despite the lack of many news releases) and wondering -why are its wings straight? https://goo.gl/images/rwK0St https://en.m.wikipedia.org/wiki/Scaled_Composites_Stratolaunch Simply sweeping the wings a bit beyond the twin fuselages and engine pods should reduce their drag in high-subsonic/transonic flight (the engines are cannabilized from 747's, so it's a good bet the Stratolaunch Model 351 is also designed to fly at around Mach 0.86) provided they are held to the same wing-area and wingspan to maintain the same aspect-ratio... (increasing wing-sweep doesn't *necessarily* increase wing area, only if you fail to reduce front-to-back wing width to maintain the same total wing-area. If wingspan and wing area are held constant, aspect ratio necessarily remains the same.) What I am wondering here is- why they don't do something similar to a raked-wingtip concept, where sweep-angle increases towards the ends of the wing- in this case only once you get beyond the engine-pods? Regards, Northstar

Mars isn't an oxidizing atmosphere/soil, in fact it's a slightly *reducing* one (which bodes well for the chances life might have once evolved there, by the way- a slightly reducing atmosphere is a prerequisite of the abiotic synthesis of biomolecules and it is believed Earth's early atmosphere was reducing as well...) The atmosphere there is already highly-oxidized, and most free oxidizing agents have been consumed by reactions (the more oxidizing agents are consumed by chemical reactions, the less oxidizing and eventually more reducing an atmosphere becomes). There is very little free Oxygen on Mars, for instance. So Mars is *not* a rust-inducing planet, precisely because it's already been rusted... Anyways, can you please try to stay on-topic? The discussion was about one very specific- keeping warm on Mars. The heat balance there is such that you'll still lose some heat and need to actively heat your habitat, but the amount of heating needed would be comparable to what you need on a cold winter night in a temperate zone on Earth. So not really the super-freezer science fiction likes to portray it as. I was thinking particularly of Nat Geo's MARS and its many sins against science when I wrote this... Regards, Northstar

I've been telling people for YEARS, including here on these forums, that Mars really wouldn't be that difficult to keep warm on because the atmosphere is so thin. On a cold day on Earth, your main source of heat-loss is convection, but on Mars the atmosphere is FAR too thin to suck much heat out of you. And besides that, you have to wear spacesuits on Mars anyways (due to the very thin atmosphere), which provide a considerable amount of passive insulation... Anyways, now the American Meteorological Society has finally released some hard facts on this I'd like to present everybody with. The following article (the link is to the summary, you can download the PDF of the article for free on the page) contains a mathematical analysis and scientific discussion of windchill on Mars, as well as a helpful table of Earth Equivalwnt Temperatures (EET's) for a variety of temperatures and windspeeds on Mars. http://journals.ametsoc.org/doi/full/10.1175/BAMS-D-12-00158.1 To give an idea of what the data looks like, a temperature of -40 C on Mars with a 20 kilometer/hour wind is the equivalent of a -10 Celsius (14 degrees Farenheit) day on Earth with still air and no direct sunshine (so slightly warmer-feeling than a -10 C night, as the upper atmosphere is warmer during the day and you get slightly more infrared radiation from the sky than at night...) Of course, -10 C would be easy to keep warm in walking around in a spacesuit on Earth, perhaps doing physical labor. Maybe even *too* warm (spacesuits are heavy and bulky, and you exert yourself a lot just moving in them...) Regards, Northstar

Any chance somebody could fork this and release a recompile for 1.2.2 with its own forum thread, as well as continue development of it there? I'm sure OtherBarry could take it back over from the forked version when he has the time and in the meantime I'd REALLY, REALLY like to see a version that is not only recompiled, but includes some long-overdue fixes like adjustments to the cost of the procedural SRB's to be more in line with stock costs, and implementation of a new cost formula where costs appropriately decrease with increasing tank/SRB size, just like with the stock parts... Regards, Northstar

Simple enough idea- I would like to suggest adding the ability to take out loans for your space program. You would borrow a sum of money upfront, and then have to pay it back later, with interest- helping to relieve frustrating Career progression bottlenecks for many players without the need for grinding contracts they find annoying... The easiest way to implement something like this would be through the Contracts system. In fact the easiest way would be to *literally* offer up "loan contracts" where you get a large advance for nothing, but an even larger "failure" cost (and no way to "complete" the contract) which is really just the loan repayment after some fixed time (this would beat having a system implementing regular loan payments for sheer simplicity and ease of implementation...) Alternatively, the "completion" condition could be to have enough Funds on-hand to repay the loan on a certain date- possibly leading to a very small Reputation boost for your space program for repaying its loan on-time. By contrast the "Failure" condition could be a large Reputation hit (but no or less Funds penalty) for defaulting on the loan... The ability to convert contract Funds to Science and Reputation through the existing administrative strategies system wouldn't be a bad interaction either. After all, maybe you're investing the loan money in R&D or a public appreciation campaign! Regards, Northstar

Basically a miniaturized glider- but a lot closer to the right idea... If they could fly something like that, maybe the next step would be a slightly larger version with a pair of miniature electric propellers they could power from solar panels and batteries (it would still run out of juice, but probably last a bit longer...) I'm curious aboutscaled-up aircraft that actually *fly* on Mars, not just glide, though... Regards, Northstar

Not relevant Codraroll or Cubinator, either post. The one about flying a Cessna on Mars is particularly ridiculous... We're talking about *highly* specialized aircraft here, and not necessarily for any real economic purpose. Not to mention, something like the Helios H-1 doesn't have *that* much inertia Cordraroll (did you bother looking it up before posting?) It has about a dozen tiny landing gear and only weighs 1600 lbs. Brakes would be perfectly sufficient to slow it down on the runway... In short... No

A subject that has long fascinated me, the idea that someday, decades or centuries after colonizing the planet, humans might someday be able to fly drones or even manned vehicles around Mars. To be clear, this is completely impractical as an exploration concept. NASA would have better luck with rovers or craft modeled after ultra high-altitude balloons here on Earth- which can reach altitudes exceeding 170,000 feet here on Earth (certainly high enough to fly in Mars' lower gravity and denser gaa composition). But I like to wonder and dream about whether we'll someday see winged aircraft on Mars... The non-rocket aircraft with the current altitude record for level flight is the NASA Helios H-1, which reached level flight at 96,863 feet on August 13, 2001. It was a subsonic monoplane flying-wing solar-electric propeller aircraft with an aspect-ratio of almost 31:1, a wing-area of 1976 sq ft, a wing-loading of 0.81 lb/sq ft, no wing-sweep, and a total gross weight of just 1600 lbs. Mars' mean molar mass is about 43.34 g/mol, as opposed to about 29 g/mol on Earth, and the highest atmospheric pressure is found in Hellas Planitia is about 1,155 Pascals (by contrast Earth's sea-level pressure is defined as 101,325 Pascals). So, the highest density air on Mars should have a density about (1155/101325) * (43.34/29) = 1.703% Earth's sea-level density, equivalent to the density of air at about 95,000 ft (28.956 km) on Earth... This is already just barely within the flight-envelope of an aircraft with specifications similar to the Helios H-1 (which could fly at altitudes over 96,000 ft), but Mars' lower gravity should allow aircraft to fly substantially higher due to the reduced lift requirements, and allow different optimization of aircraft to obtain higher total lift and altitude-ceiling at the expense of mass. What I am curious about, specifically, is what the best design characteristics would be of a winged aircraft on Mars... Would a solar electric-propeller monoplane like the Helios H-1 be the best option available? (even with radically improved materials, something like this couldn't be expected to fly more than a few thousand meters above the lowest-altitude parts of Mars with surface elevations below the nominal "sea level" of Mars...) Or would it be worthwhile to go with something like a biplane or even triplane design to obtain lower wing-loading and better aspect-ratio? (the Helios H-1 wings were 11.5 inches from front to back. With a biplane design, a better aspect-ratio could be achieved by making the wings thinner, to obtain similar wing-area while extending just as far from the Center of Mass...) This was actually a design-strategy in some early aircraft that allowed higher altitude-ceiling, climb-rate, and better maneuverability on some early fighter designs at the expense of top speed- and on Mars, where attitude-ceiling would be the driving design-constraint, this would probably be a worthwhile tradeoff as well... Alternatively, if provided with electric supersonic jet engines (similar to what Elon Musk likes to fancifully talk about today) or even nuclear-thermal supersonic turbojets, a better strategy might be to opt for speed instead of low wing-loading to keep winged aircraft airborne. This would require slightly futuristic propulsion methods, but there is nothing about the laws of physics that forbids obtaining your propulsion energy from batteries, solar panels, fuel-cells, and/or a tiny nuclear reactor instead of combustion. .. Supersonic design concepts might also be aided by breakthroughs in airframe design, if the Japan/MIT concept of a supersonic biplane ever comes to fruition- in which two wings are placed such that the shockwaves from each destructively interfere with each other, producing less than half the wave drag of a comparable wing-area monoplane and reduced sonic-boom. However these designs have significant difficulty with low-speed flight, and while they might be able to fly perfectly well at low altitudes on Mars, would probably have extremely high takeoff and landing speeds that would require impractically long and smooth runways for even the lightest of craft... These ideas might all seem fanciful or even impossible, but they are not so pie-in-the sky as one might think, and I would appreciate if all individuals responding to this post keep the discussion optimistic and non-critical. Let me repeat myself- these concepts are on the very edge of what is possible, and many of you may feel they are *impossible*. I do not mean this as a form of backseat or pre-emptive moderation, but I would appreciate if those of you who are critics and cynics respect those of us who would like to have a positive discussion of this concept, by refraining from quickly jumping to make such statements- as they will drown out all other discussion if you do not control yourselves from making highly-critical statements to this effect. Out of respect for myself and other forum users, please avoid statements here to the effect that flight on Mars is impossible- the assumption that most people probably hold, and this discussion is meant to reconsider. Regards, Northstar

Also, as well as a recompile for 1.2, is there any chance we could get some adjustments to the cost-scaling to match the stock parts? In particular, procedural versions of the fuel tanks tend to be much more expensive than stock tanks that hold the same units of fuel (annoying if I wish to uninstall the stock tanks and just use procedural ones to save on RAM, but tend to only play Career). Also, the stock tanks get cheaper relative to their capacity the larger their size- and it would be nice to see economies of scale like this with the Procedural Parts tanks as well... Regards, Northstar

I was reading the whole debate about the fuel tank scaling before, and was amazed that nobody mentioned that fuel tanks are pressure vessels- and therefore the ratio between wall mass and volume remains constant as they scale. So, for instance, a cylindrical tank with 2x the radius and height would have only 4x the surface area (and 8x the volume)- but its walls would also need to be twice as thick, because the stresses on a pressure vessel scale linearly with total volume (that is, the total stresses with 8x the volume are 8x as high, and thus require 8x the total tank mass to withstand- regardless of tank shape or size...) Things like insulation don't scale linearly with volume, however- so if you have an insulated tank with 2x the radius and height, it would not require 8x the total insulation mass, as the insulation thickness would not need to be any greater... However, this is just the tank thickness needed to contain the stresses for the pressure differential (zero on the launchpad, but 1 atmosphere by the time you climb high enough that background pressure becomes negligible...) and could be reduced by pressurizing tank contents less (as rocket fuels can be kept liquid at lower pressures if temperature is also reduced). Structural mass (mass needed to hold up the weight of the rocket under thrust) requirements increase as well with larger rockets- a factor completely seperate from mass requirements to maintain the pressure differential... However the same mass can be used to resist vertical loads (from the mass of rocket above a tank well section) and horizontal loads (from the pressure differential)- and in fact placing a wall under both types of load simultaneously increases its ability to resist horizontal loads- so only very tall/slender, large rockets placed under a lot of g's would require additional wall thickness beyond what is already needed to resist pressure stresses... The main increases in structural mass requirements come at joints beween different elements (interstages, internal struts, etc)- but these increases are at least somewhat offset by decreases in insulation requirements, and enter a more complex picture also including things like plumbing requirements, anti-slosh systems, fuel pumps and stirrers, and control systems.. In short, the system currently in use is a very reasonable first approximation of mass-scaling for most reasonable rocket shapes and sizes, as the real equations are usually dominated by pressure vessel mass-requirements which maintain a linear relation between tank mass and volume. Only with truly enormous, extremely tall rockets or very small ones with a lot of insulation do these scaling equations really start to break down... Regards, Northstar

But we're not talking about any of that other stuff- just the comparative network costs. You can't say compate network costs to total costs, that's apples-and-oranges. The SpaceX network would cost less than $15 billion TOTAL, and would cover the entire globe. I'm pretty sure they can find a way to make a profit off that... The nearest satellite will NOT be 1000 km away. This is a Low Earth Orbit constellation, which means the satellites only orbit 400 or 500 km up. And the shear number of satellites is so great lateral distance should NEVER double total distance. That would require the satellite was at less than a 26.56 degree angle to the horizon. Low population-density does not mean low TOTAL population. Rural areas may have fewer people per square kilometer, but COLLECTIVELY they contain a very large population as more than 90% of the planet is rural. Musk has been VERY aggressive at *GROWING* his corporations. Necessarily, this means lots of investment in new infrastructure and low net cashflow. But EXISTING, ESTABLISHED infrastructure in Musk's corporations has proven itself HIGHLY profitable- the problem is just that Musk keeps going and re-investing all the net revenue in new projects and infrastructure instead of passing it along to shareholders. Eventually, Musk will run out of profitable new projects to invest in, and either stop re-investing or start investing in projects that DON'T turn a profit... Maybe not the best companies to invest in if you're looking to make a quick buck (like so many Americans are obsessed with- we as a country don't know how to deal with delayed gratification), but aggressive growth is a sound strategy in the medium term. There's a reason that banks and shareholders continue to consider Musk corporations a sound investment, and it's not because these financial experts who have spent decades investing are somehow dupes who have all drunk the Kool-Aid like you seem to think, Nibb.

Did you pay any attention to the numbers I put forward earlier? I used a baseline of 20 Euros/month for service and showed that it indicated a much higher infrastructure cost relative to service area than the SpaceX satellite constellation plan. If imfrastructure costs were just 1 Euro a month per person, and the rest were all profit, Musk's satellite constellation would still be a much cheaper option than ground-based infrastructure for just the USA, Japan, Canada, Australia, and Europe- and that's completely ignoring the developing nations of the world... Regards, Northstar

You're talking reduced price for reduced service. By that logic you could have NO phone service and pay NOTHING for it. The standard we were discussing was specifically unlimited data mobile networks- I'm disturbed by your constant straw-man arguments. There was a HUGE margin for profit built into the calculations I made before, when I assumed only 12% of revenue goes to actually paying fir the network. I was already discussing the floor of pricing beyond which mobile operators cannot drop and still be able to pay to pay back the costs of building their networks. Enough with your diversionary tactics and straw-man arguments. You can't beat me on the numbers, so you change the topic to something irrelrvant you csn attack or ignore the numbers entirely. Clearly- but the same holds true of literally any inmovation that turns over an established market. It didn't stop the automobile from replacing the horse, and it won't stop satellite communications from replacing ground-based networks. The economics are STRONGLY on SpaceX's side here- a satellute network of this scale is MUCH, MUCH cheaper to build than a comparable ground-based network- ESPECIALLY with reusable launch stages... I don't expect it will be a cash cow that pays for Musk's Mars ambitions, but it will revolutionize telecoms in the developing world here on Earth, which is still important- and all while turning a tidy profit which will ultimately make Mars just a little bit more attainable in the long run... Regards, Northstar

Do you KNOW how much the mobile networks in France costed to build Nibb? (Clearly not, or you wouldn't make that argument) There were an estimated 50.1 million mobile phone users in France on 2016. Each of them pays over 250 Euros a year for mobile phone coverage (10/month is not realistic for the majority of mobile users, you know that- those are only special deals- most users pay over 20 Euros/month for unlimited data in France- in fact Free Mobile is releasing an unlimited 3G LTE plan for 20/month in France and that's considered astonishing, and probably not scaleable for the entire country...) That means that mobile companies would need to charge, at a minimum, 12.525 BILLION Euros a year for unlimited mobile data. Now, let's make a conservative assumption that only 12% of revenue is going towards paying for the actual network, and that they amortize those costs over 10 years. That still means that the network of France alone would cost over 15.03 Billion Euros. That's already more than the $10 billion in American Dollars for a global satellite network, and that's just for *ONE* relatively technologically-advanced European country with a relatively favorable climate and population-density for construction of ground-based networks (countries like Norway or Canada are much more difficult). Even if France's network only costed one TWENTIETH what I estimated above, a global high-bandwith sat network costing $10 billion USD could *EASILY* pay for itself due to its much larger coverage area and ability to efficiently cover remote or inhospitable areas... Regards, Northstar

Whoa, whoa with the time estimates- isn't SpaceX working on an entirely new launch-facility or two at alternate sites? They might be able to attain a much higher launch-rate if they double their launch-sites from 2 to 4... Regards, Northstar

Still not getting how that works. Chilling cryogenics shouldn't increase their density hardly at all. In fact I had a long debate over on the RealFuels thread a year back because, not realizing LOX and most rocket fuels are incompressible, I spent a long time arguing that chilling or pressurizing LOX *should* increase its density, based on a bit of stubborness and a knowledge-gap I'm not proud of... Unless the LOX is superchilled to the point some of it freezes into a slurry. That's a different story... Also, this reminds me- whatever happened to the idea of adding tiny bits of aluminum powder to the fuel supply of rockets to increase the fuel-density? Aluminum powder burns quite violently, and it sounded like a nice way to get a fuel-density closer to hypergolics without any of the nasty toxicity issues those involve, and the higher fuel-density should make up for lost ISP, and then some, at least on launch stages... EDIT: And I guess I was right way back when. Durther research shows LOX can increase in density more than 10% if chilled enough, and by 1-2% if pressurized enough. <REDACTED BY MODERATOR >

The writer of the first article had a laughable knowledge of ricket science. He literally called KeroLOX a non-conventional rocket fuel, even though it's the MOST conventional rocket fuel in existence (we used it back in the 60's on the Saturn rockets, for crying out loud). He also wrongly stated that KeroLOX has less mass than HydroLOX (that's laughable, as the main reason HydroLOX is preferred is that you can use less mass of IT- although its reduced density means you need a bigger rocket to hold the same fuel mass...), and seemed to think that KeroLOX is less tolerant of loiter times on the launchpad than HydroLOX due to its cryogenic nature (HydroLOX is, of course, *FAR* more cryogenic than KeroLOX). Clearly, the writer was a moron. Possibly he just assumed that whatever ULA's been doing is easier and more conventional, and that SpaceX must sonehow be doing the difficult and new thing with its fuel choice. Which is, of course, the opposite of the truth (SpaceX does plenty of hard things, but opting for KeroLOX over HydroLOX is not one of them)- and thus really showcases that the writer was writing from complete and utter ignorance... It's sad how little the media- including even many science writers- understand about rocketry... Regards, Northstar

Very impressive. I'm always amazed by how far the Russian scientists were ahead of the USA in things like designing gas-core nuclear thermal rockets... Regards, Northstar

Seriously man, drop this. You have no right to complain about people going off-topic in one breath, and then go off-topic yourself in the next. It's almost as if you don't really care what's off-topic, and just want to use that line to suppress any opinions that contradict your own... If you want to keep this discussion focused, practice what you preach, and take the discussion of the feasibility of ITS and colonization to another thread (you could even start the new thread!) Regards, Northstar

Nobody agrees with you more than I that Musk's Mars plans are an important part of understanding what SpaceX is doing- but discussing Mars colonization inevitably brings the Trolls out who think they own this thread and will dismiss literally *any* Mars colonization scheme as impossible and stupid, no matter how much factual evidence and reason you confront them with showing them that they are wrong. As such, it's best to just have these discussions in a seperate thread, like I tried to do originally... Regards, Northstar

I don't mean to sound like a backseat moderator, but please move these discussions to another thread. Even I agree at this point that these discussions about the details of syrface colonization or economics have gotten far too out of hand. And, I originally posted about such concepts in a different thread entirely before some musguided moderators merged it into this thread ages back! (hides under table) Anyways, can we get this back on-track to duscussing SpaceX's current activities please? And will the OP or a moderator please re-name this thread to identify it as jyst being about SpaceX's current missions ONLY (with a seperate thread for future plans?) Regards, Northstar

Let's try to keep this all on-topic from now on. The last thing I will say about all this us that Musk's plan might still prove yseful for early NASA missions even if it doesn't lead to colonization. SpaceX has shown that it can consistently develop launch capability for less than a third of their competitor's prices. So by all accounts, the ITS booster should be cheaper than SLS. That will necessarily give NASA a lot more payload mass to play around with when designing their missions. Ok, tangent over. Can we start a new thread for any more of these theoretical SpaceX discussions? And moderators, PLEASE don't merge it with this thread again!

At this, point I agree.