PB666

I sense I am in the presence of an acute case of loniless.

Hmm, looks like we have identified a flaw in the booster return program, you should right up a report and submit it to spaceX along with a bill. BTW, the have more than enough thrust to land with two engines. The only problem is the LZ would need to be quite large, since the rocket will drift. You would have to start the burn sooner. However if the engine failed and the burnback program was not aware, or the failure was progressive, it probably would not have time to compensate. It could just plop onto the LZ after zero fuel and a large 'popping' sound.

Things don't hang in space they drift. A space craft is orbit follows the following logic w2r = u/r2. Since all particle on the craft mean the same criteria. If you push a sheet out of the space craft in a downward direction in 1/2 an orbit it will be the maximum distance that it went down but above the spacecraft. Since there is no way to precisely confine a gaseous atmosphere, the ship will experience drag anyway, however, the best way to enter faster is to turn the ejection surface to in the prograde direction, take half the ejection mass (say a bag filled with toilet waste and old spent CO2 absorption cartridges), while tied to ship expel waste into space. [Throw the waste in the direction of the velocity vector, the prograde direction] If your vessel weighs 20 tons and you expel 5 kg of mass at 5 meters per second. This means you have given the ship .00125 meters per second of retrograde speed. If this were to occur above Earth at 30483 meters then its radius is 6401483 meters from earths center of mass. The vehicle would be traveling at 7890.93725 m/s, lowering its speed to .00125 would drop the speed to 7890.93225. Specific Orbital energy equation allows us to calculate a . . SKE-SPE = -u/2a. a = -u/(2*(SKE-SPE)). Once the mass is expelled its current radius becomes the apogee, this is because it previously was a circle, but now that it moving slower its radius will fall from that point, a then went from 6401483 to 6401480.97. However a is not the perigee, its halfway in radius between the apogee and perigee so at perigee you would be 6401478.94 (30478.94 meters in altitude, 99996.54 feet. Oh and btw without fuel the vehicle no longer has RCS thrusters so it cannot turn without reaction wheels and eventually they will max out, so more than likely the vessel will burn up upon entry.

They can do that also, and in fact if you lost an engine close to launch that is what you would have to do, but after 50 seconds, you can just balance your thrusters. There are steer problems with gimballing over time. Its sort of like turning an aircraft without using the horizontal stabilizer. Not that its a big problem because as soon as the second stage fires you can compensate, but on the re-land part of the mission you probably want to use a balance of thrusters.

I have mapped the power output of the F9 based on its accelerations, just before Max Q it drops power by about 20% but it never increases power afterwards, it continues past MaxQ with about 70% of its power and throttles down toward the end of flight. In theory with a loss of one engine (unless it was the center engine) they would have to kill one more engine, meaning they lost 22% of their maximum power; however, given that they still have a reserve of about 20% and so just operate the remaining engines at full thrust and you can still recover the first stage.

SR-71s did not take off with a full load of fuel, the landing gear could not support it and as I understand it the engines produced terrible trust at sea level and wing loading would have been too high. Many accidents close to the ground for SR-71. Another fun fact about SR-71, they use a buick v-8 engine to start its engines.

Vasmir has never been tested in any circumstance that it was required to accomplish something other than showing it can blast ions and consume lots and lots and lots of power.

They have a nine-engine first stage, slightly before Max Q that is pretty much fail-proof because they can loose any engine and they have enough thrust from the remaining engines to complete the task. it would have to be something catastrophic, like the blowing up of a turbo pump. Of course the second stage could fail to fire, in which case it will fall back to earth. There is a marginal utility of extending the life of the non-expendable version of the rocket at present, once you have recycled it 4 or 5 times you could pretty much write off the hull as its recycling value.

This delayed response is in reply to something @MatterBeam stated a few weeks back and I have been working on the problem. Let me preface this thread with the following, since I previously posted here I have been studying the issue of energy transfer with regard to space. If fusion was a thing today and we had a rocket to get it into space a reactor, and the reactor could operate for at least a few seconds stably. IOW it meets all the criteria for functional fusion energy in space . . .the vast majority of space missions would not choose this. If you are following the Isaac Arthur videos . . .I am sorry . . . . but fusion is the smaller of the problems. Fusion electric is premised on the idea that you have to get more out as you put into it. The problem with fusion in space is compounded by the fact that the ability to get power out is worse in space than it is on land. To begine with we may not get enough power out to reinitiate. The second problem is you have to store charge to get it started, requiring mass. The process itself is hampered by the fact that steam generation is the most efficient way to get power out, which on land is benefited by the fact we can tap into lakes (such as in fission power plants, cooling towers) you can bring water from miles away to cool if you had a very powerful plant, like a fusion power plant. In space there is only two ways to get rid of energy, either as kinetic energy of exhaust or as waste radiation. As the raw nuclear power output power increases, the mass (radiator) cost of waste increases faster. So at some-point one is almost always better off using solar since its power is cooled at the source. That limit point on power is probably in the fission reactor range, not fusion. The issue of heat is very important, not because it just increases weight, but it points at the exact problem is that finding a solution to waste (i.e increasing efficiency) is a more serious problem than solving fusion power. If we had a way to efficiently utilize nuclear thermal heat, we don't need Fusion, fission would do for now. Fusion only appears to be a solution to space energy problems because we don't have it. If we had fusion we would suddenly realize how far we are from interstellar power. Of course, if you are on Europa or some other Jovian moon, fusion might be very attractive, given all the ice you have to melt, but its not in a mode in near or mid future to be plucking gasses off the sun. Its just not. Thus the Fusion powered tug I designed could never exist, it does not have enough radiator mass, probably off by a factor of 100 in constituitive vessel mass. (meaning that thus is more like 0.0001 instead of 0.01. OK so here is the analysis Spiralling out of orbit using Nuclear power is very wasteful. In this case we have 82114 Exhaust velocity engine ~330000 kg of payload and 38000 kg of fuel (dv/dt = 0.0105 factoring fuel loss as this ship spiralled out. If one where to magically burn from 160,00 km to escape it would require a 117% more fuel to spiral out instead. So matter beam you are wrong, such setups would required many days, maybe a month to leave earths sphere of influence by kicking at the periapsis to the best of the ships ability. The crux of the problem with spiraling is the the specific mechanical energy gained per unit time of burn decreases from 82.4 j/sec down to 22 j/sec with an average of about 61% efficiency, this inefficiency is compounded by the fact that the highest thrust is when the fuel is the lowest corresponds to the period when SME gain is also the lowest. This does not include the burn to Mars which from low earth orbit would only add a few hundred dV from high earth orbit would require the addition of almost 2000. The tug was designed to go to Mars drop off a load and return to earth, spiralling into orbit and burning to mars it burnt all its fuel leaving none to stop at mars, thus one would have to carve out payload to add fuel, just to reach mars. The secret to electric power spacecraft is getting weight down while simultaneously increasing power

http://www.bbc.com/news/world-us-canada-42379749

Yeah really off topic.

It depends on the engine radius and the gimbal. In some rockets with multiple engines, the engines can only gimbal outwards. If your engine is 2.5 meters from the swivle and the nozzel is 1.0 meters in radius, and the gimbal is 15 degrees it means a nozzle actually occupies a space of π*(1.0 (1+sin(15))^2, (4.98 meters) but as you say in an optimal hexagon arrangement its about 5.5 meters square. That means a 6 rocket would be approximately cover 33 square meters (effectivly 40 circled) and required a radius of 3.5 meters (about twice the form factor of Kerbals largest fuel tank). If you are playing the Earth game, youll be using alot of stage 1 tanks that size, particularly if you are upping with cryogenics.

Fun videos, although I would be totally sea-sick if I was on that craft.

120 kts at FL250 would be roughly equivalent of flying 75 (86.35 mph) IOW flying against an 86.35 head wind. Just about any plane or craft that can travel at FL250 is also capable of traveling against an 86.35 head wind, except solar powered AC which use huge wing area. Its not an exceptional speed and could easily be done by an earth made drone. Since the pilots did not give a target relative speed at horizontal AoA = 0 its hard to estimate UAS's speed. The IR does not paint unpowered wings, just heat, so that if the wings are ambient they would be invisible on IR. One problem in the IR the heat of the craft is blinding out the heat around the craft, so not easy to see detail. You can see a heat plume emanating from rear that changes angle just before and as the UAS turns. This says the UAS is a mass reaction propulsion, not some magic fairy dust vehicle. So the question is what is keeping it aloft. 1. Momentum, it could be rocket based viewed close to the top of its trajectory. 2. Center based jet engine . . . .a craft that moves air from top to bottom but expels heat out the back end. 3. Wings that are invisible to IR. The second issue is turning, Russian jet aircraft are capable of turning as high as 60' AoA so this is not an out-of-this-world manuever. Just you would not expect it around Raytheon proving grounds. In fact if you were painting a Russian jet with IR and zeroing on his position, its likely it would turn up as to increase your relative velocity to his and to bring his craft behind yours. I bet this is a drone used for testing IR, proprietary equipment. There's an assumption that aircraft have to be aerodynamic and have high glide ratios. While its desired if you want to fly from New York to Singapore non-stop, its not necessary to get to 25,000 feet or travel and any moderate speed. The problem with commercial aircraft is they are loaded with fuel, and with military aircraft loaded with equipment, ammo, and bombs. Military aircraft also have to fight drag caused by non optimal wing shape (required to get them past mach speed and manuever) believe it or not, this is what creates the speed requirment for lift off and landing. For example a fully loaded 747 has a rotation speed around 170 kts (almost half its weight is fuel), but on the other hand when its nearly empty it glides better than just about any commercial aircraft ever flown. The weight argument becomes a real bugger when talking about commercial aircraft like the Concorde, which even under the best circumstances cannot land at Vr, and must dump most of its fuel to land in an emergency (the Concorde should never have been allowed to transport civilians). But the reason for that is the plane was designed to travel far at Mach 2.0. If you remove flying above M 0.7 and over 100 miles then you create a wide range of scenarios for AC design. If you remove the payload from a craft, put in a reasonable small jet engine, hold IAS below 140kts (IAS) or M=0.8, Fatten up the wings to get more lift, you could have some pretty crazy looking stuff as long as you don't encroach on Mach speed. The problem with crazy looking stuff is that close to Mach speed, the crazier the stuff, the lower the speed Mach effects will be encountered. So it would be kind of dumb to have a large parabolic mirror or radio telescope on the leading edge of the aircraft.

That's a nice view of the robotic arm grappled to the Dragon.

Just giving folks an idea what you are talking about. There is no reason that Node STA could not be used. My opinion, for what its worth, Raffaello is cooked, well done in fact, it served as part of the assembly of the ISS in the days of space shuttles and it will not be used again (barring some freak return of the space shuttle). STA is undressed, which basically means it can be anything.

https://en.wikipedia.org/wiki/Raffaello_MPLM#/media/File:STS-100_MPLM_Raffaello_is_moved_to_the_payload_canister.jpg currently being being house at KSS. https://en.wikipedia.org/wiki/Exploration_Gateway_Platform#/media/File:ExplorationGatewayPlatform_components.jpg https://en.wikipedia.org/wiki/Node_4

Which gets back to the original problem, DSG is still more or less a concept.

The orbit I saw only comes very close to the moon sometimes. Such a transport goes to DGS offloads its fuel into the cryogenic storage then either burns into a solar orbit or returns back to LEO for more fuel. I need not stay near the moon for any length of time. Of course the DSG itself has to be different from ISS. If the ISS were designed today it would be different from itself., that goes without saying, that does not mean that classic spacecraft cannot interact with it.

I don't see a reason they wouldn't work, provided they do not spend alot of time in orbit before transferring.

This particular tank is a fuel tank and cryo fuel carrier, 1/3 rd fueled is just enough to get it into orbit where it can be refueled and reach inside the EM system, basically using half its fuel to get there and sending the other half to the user. A Larger system could carry fuel and return to LEO. Frankly however, the cheapest way to get fuel from launchpad to LEO is not going to be a cryosystem, but the Falcon9 heavy. So the best bet is to match the fuel tank size with the payload capacity of the F9H to LEO. The rocket as such can take itself into orbit at 7788 - 200 km from 4000 m/s orbital velocity as a second stage on this single engine, its PL is the fuel tank and the engineering that goes with docking. This is assuming that the DSG would be a cryogenics spacecraft gateway.

side drag is a major problem for short thin rockets. Edit, as Magnmoe says, this rocket will not reach orbit, in fact it probably would not reach 1/3rd of the mechanical energy required to reach orbit.

I estimate that our species as we know it is around 200,000 years in age with leaky barrier to out lying species, this would set the time to previous being less than 5million years, and more likely there was a previous barrier around 2.0 million years ago. So for a control, under less selection it was 1.5 million years, the Sun won't begin expanding is size greatly for 200,000,000 years, so that means many species forming events can occur in that time. The light speed time delay has nothing to do with sensing the presence of life. And in particular we might have a sample return mission. Even if we need to be in sensor range we could have a platform in LMO. But we don't, artificial intelligence has evolved to the point it could make all the determinations, but without contaminating life on Mars, or it contaminating us. You mean about teleport . . .beam me up scotty . . . I hoped you were just joking.

Let me refute some his reasons for going to mars. 1. Life sampling - actually better to let sterilized machines do the sampling. 2. To save our species - not actually true, if we colonized Mars, in the time frame in which the human species might suffer a species ending calamity on Earth our martian counterparts would have evolved into another species. There would be tremendous selection pressure to do so on Mars given the radically different way Martians would live. Such a calamity avoidance can also be done on a space colony with the caveot that from a space colony we could easily recolonize earth when things settle down. And what if the villians decide to nuke Mars. YOu can move colonies and see bad things coming, you cannot see a major nuclear strike from space on mars. As one scientist pointed out if we need to terraform earth or Mars, terraforming Earth back to Earth again is alot easier. At the cost of building one self sufficient colony on Mars complete with transportation back to EM system you could build 10 space colonies with equal numbers of individuals. (because at the beginning you have to transport everything from earth and land it on Mars) 3. Technology boom - Yes but the same boom can be achieved by building a working space factory or a colony in space or as planned a lunar colony. 4. Inspirational - Yes the moon landing was so inspirational that we never went back in 40 years, that we slashed the space budget by 10 fold. Inspiration is not all that its cracked up to be. Risky also, what kind of finger pointing occurred after the challenger disaster, what kind of finger pointing will occur if astronauts die in transit or landing or are basically trapped on mars. We could literally start a colony tomorrow in space, have a space station, just start adding structure, when its large enough cleave the structure into two parts, the second part then goes on and become its own station.

You still have at least 500 m/s of drag and gravity waste to deal with at an end. And by the way spaceX hasn't dealt with anything, they have only created concepts, concepts that appear to changing rather frequently.