AngelLestat

I dont like this.. I did not read the paper, but I imaging that the amount of electricity you need to waste is considerable, also... solid propellant... Those things are just relevant for rocket hobbyist today. And if you want a solid booster, why make it throttleable?

This dude is worry for other kind of "what if" No to mention the cost of hypergolic fuels vs ch4+lox. If you have something similar to dragon engines (8 engines 2 by side), even if one does not ignite, it will be ignite due the flames of the side by side engine. But you can even design a different solution that will be perfect for these kind of ignition to even decrease these problems, and dragon can even work with 3 engines if it wants. We had difficulties in the past with respect to ignition and keeping cool cryogenic fuels, that is already part of our past. I am not the one proposing.. this is sevenperforce´s idea. And I encourage that, I like when somebody put its brain to work to see if they can come up with better ideas, because is the kind of people that does not accept the world as it is, they want to improve it. And even if we fail in that try.. doing those exercises is the best way to learn about the topic. Speaking of crossfeed, in the falcon heavy case will allow reusability without reducing much its max payload (you increase efficiency and your side booster comeback faster, no need to return so many km to the launchpad)

those were real breakthroughs... going to space without gps or or fancy instruments, designing with pure ingenuity and just using a paper, pencil and math. Now they waste billions with the help of supercomputers or tons of different testing machines or chambers using all the knowledge gather from the effort in those days, without even bothering to engineering something new, and even with all that, they are too scared to accomplish the same things that was accomplished in the 60s.

Hipergolics was the best solution we fund until now, this does not mean there is not a better solution. Now we are capable to ignite methane-ox using laser ignition with a 100% of chance in milliseconds. In fact in 2012-2013 a lander using methane ox for RCS and main thrusters was tested (project morpheus) showing successful results, even taking into account that use another ignition tech than the one that describe this paper Of course this tech still needs more development, but hipergolics handle and use is not something super safe either. That is not the definition of crossfeed in the space industry, the tanks needs to have another engine to be called crossfeed.

ok.. but the context is far away from a chemical talk, in fact chemists usually said h2o instead water. I remember that my chemistry teachers always mention h2o.

http://chemistry.about.com/od/chemistryglossary/g/water-definition.htm Water Definition: Water is a chemical compound consisting of two hydrogen atoms and one oxygen. The name water typically refers to the liquid state of the compound. The solid phase is known as ice and gas phase is called steam.

No, water is the liquid form of H2O and ice is the solid one, there is no way to go around that

haha, they had time to made this research? Ok I did a quick read, but I don't find where it said that this is possible in mars. THe graphic show 22% earth gravity and 2.4 m/s vertical velocity, that is no enough for mars.

But you need to reduce in the superdraco thrust due engines tilt angle. So it will let you with 700 or 650 KN, which no sure if is enough. Also the superdraco engines are in that position (without nozzle) to protect the engines from the reentry. Take into account that the second stage should be use for any other payload and the spacex solution is try to manufacture the same pieces to reduce cost. I personally dont like hypergolic fuels, I guess they should be part of our past, more when we can remplace them with better technology. I will like to see a dragon v3 with methane using laser ignition for RCS and engines. The idea to remplace the engines in the second stage with the draco engines using a attached tank is not bad (in case some engines had a problem, you can do the eject abort with only 4 instead 8 (there is no other engine pushing behind you). No sure how safe it is to have the engines so close to the capsule for long burns, heat can be an issue? But well, we lose efficiency in 2 ways.. engine tilt angle and nozzle. If those things can be managed with a clever design, then we have a cheap dragon launch.

Newton´s third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body. I am sure that you will be able to run on water on the moon, but with mars gravity.. mmm not sure if is possible.

What you mean with a maximun speed of 5900m/s?? I guess you want to said 4900 m/s Yeah but your numbers are very sharp as I said before and they does not have into account drag (those 1700m/s and 30km altitude you get for almost free), neither structural reinforcement for a 2 stage vehicle with a deploy system (long area doors is a safety concern, the vehicle can be broke in half). I dont know how to explain it in few words, but you will only realize of the trouble you get into if you try to imagine the deploy system at scale. Make some draws and you will notice that is not a problem that can be skip it so easily. Then you need to deal as I said with the reusable second stage... how do you solve that? No.. you should recover the second stage, you kill all the launch rate and cost saves of the whole vehicle. That is the point that it sale most with skylon.. it does not matter if its payload is similar to falcon9, if the cost is even 10 times lower than falcon9 fully reusable. Companies would design their sats or payloads to fit the skylon. Again.. the benefit of just refuel and launch again without even need to make huge calculations to achieve trajectory or staging, or operation (take into account all the operations that requires to launch a falcon9, all the systems), all those details + assembly and mostly "TIME", are the ones that saves money.. The amount of payload you can rise to orbit is secondary. So your payload to orbit in reusable mode (heat shield, legs, aerobraking, etc) will reduce your payload to 25 tons with lucky taking into account the extra lost due drag from the first stage. Other thing.. in your case, if you want to launch your first stage sable from the equator, you need to have enough fuel left to go back, in the skylon case you just need to go back 1 vehicle, no 2, and the wings can save a lot of deltav. I dont see problem docking inside the hold, those maneuvers are done at almost 0m/s. If you want a tug able to return from GTO, it will need a lot of mass to make it reusable and resist the reentry at those speeds, the amount of deltav you save with aerobraking is not enough to enter in such mess. The gto tugs returns almost emptly with almost no mass, so just a little of fuel left can achieve the orbit change. If a client wants to push up the GTO payload limit, then he should make its own ion propulsion to achieve gto from LEO.

why it will go down if you are investing the money in something with more revenue??? Even from 2013 economic consultants are saying that renewable energy has more revenue and lower risks than fossil fuels, from that year wind and solar drop their prices around 20%. The oil prices will stay in an average of 30 to 40 dollars, because they are already losing a lot of ground vs renewable, in fact they drop the prices just to fight the change and to avoid new fossil reserves to be exploit it, because they know that the oil time is reaching its end, so they need to sell most of the oil before that happen. http://www.bloomberg.com/news/articles/2016-01-14/solar-and-wind-just-did-the-unthinkable (take a look to the video) http://www.washingtonsblog.com/2015/04/bloomberg-news-renewables-overtake-fossil-fuels.html If the people who only cares about win more money are telling you that renewables are the way to go, why you want to go in the opposite direction? But if you dont want to hear me or to my sources, hear your own people (2 days ago): https://ipolitics.ca/2016/03/09/fossil-fuels-probably-dead-says-canadian-pacific-railway-ceo-hunter-harrison/ You are missing the huge change and revolution that is happening with hydrogen in many countries, Japan is decided to jump to a hydrogen economy, they will produce hydrogen from wind in fukushima (nobody left there, so nobody will complain about wind turbines), they will produce hydrogen also from a new type of mineral, the hydrogen fuel cell cars cost around 45000 dollars are already subsidized by the government for a selling price of 10000 dollars. Many companies are already lessing these cars and they will produce its own hydrogen, which they will get paid to help in the storage. Germany goes in the same route, california, iceland, Denmark, taiwan, UK and many other countries, all seek a future hydrogen economy. Current hydrogen production is already in the past, now you have cheap methods to produce hydrogen from methane capturing the co2, and electrolysis or reversible fuel cells are dropping cost at super high rate. You said it, batteries are produced in huge amounts and still its cost is very high.. Elon Musk gigafactory will double the world production and this will be just enough to reduce the batteries cost by 25%. About those air batteries are still "air". I told you.. there is no news on renewable energy that I did not read before, that air battery it seems it will be like fusion, always 10 years ahead, the same with graphene layers able to split the moisture in the air to increase the range of fuel cell cars by a lot, it was tested in laboratory, but until you have a commercial application and it works in real conditions is always 10 years ahead or more. Batteries now has 80% to wheels efficiency, electrolysis 82% (normal) and fuel cells in current cars 55%, they are still way below its practical efficiency limit, for electrolysis 90% is easy achievable in the next 2 years, it can reach 120% if it takes waste heat from external process, fuel cells has its practical limit at 80%. But as I said.. it does not matter efficiency when you compare clean energy sources.. only the final cost, and h2 can have much lower cost because it helps to storage And batteries exist since 1780... But it does not matter, because batteries had their big investments and development push in the last 15 to 20 years, fuel cell and electrolysis had their incentive push just 5 years ago. About the efficiency is the same that I say.. they will no keep improving so fast as before, but you will see that in fuel cells. What you mean? electric renewables? And why energy density is so important for you that you prefer to ignore cost, weight and recharge time. In the whole world, yeah.. but many countries will achieve that just for the 2030. I show you bloomberg and you show me "thestar.com"? Is like talk about climate vs weather. Sales, stocks and many other things goes down and up, but the overall trend is what it matters. Each time you will see more and more Hybrid engines, just make a quick search on google with news and you will realize of that.

So you are taking into account the second stage of falcon9 which is not reusable and it use kerosene, your stage use hydrogen (which increase a lot your drag and it makes harder to take advantage of the air breathing mode). Take into account that all rockets pass through the atmosphere drag layer very fast, almost vertically, but an air breathing engine should spent a considerable amount of time in the atmosphere. The development cost would be much higher than falcon9, and I dont see many advantages. The best advantage that skylon has over falcon9, is that it lands, refuel and launch again. No much need for planning, operation, asembly, etc. And you can launch a lot of sats just with 1 skylon (depending its lifetime). There is when you save most of the money, that is why Elon Musk wants 2 reusable stages instead just one, even if still have assembly cost and some of operation cost that will be higher, but it can save a lot of money and increase a lot its launch rate, something that it can not do with its normal second stage, because it needs to build a new one and spent a lot of time and money in testing. A SSTO will have less probabilities of fail (1 single part), so the testing is highly reduce.

Following that theory then energy must be free as many Tesla fans conspirators suggest. But energy never is free, you can make a windmill and obtain "free" energy over its lifetime, but you spend resources and work to obtain that energy, and when it breaks someone needs to repair it or remplace it, you need to distribute that energy and storage it. So if it takes you "work" to obtain energy, then you should not waste it.

what matters most is the amount of co2 you need, which as you said, is not enough (this was knew in recent years when they discover that mars had several times lower frozen co2 of what they originally thought). So you need to drop comets to rise the dust similar to Kim Stanley Mars trilogy with many other strategies. The time that this atmosphere can stand (I read about 10000 years instead millions), but it does not matter, because in just 500 years the level of energy that a civilization can achieve is a lot (without even counting by exponential technology growth). But from our point of view (if technology stays forever with our current level), terraform any planet is beyond our reach, it would be much cheaper to fill the mars surface of domes than terraform the planet.

Ok. some said waste heat.. but it does not answer the question, because heat is the most elusive form of energy, so in global average yeah, but we need to specify a practical process in which we lost most of the energy. For me, the process in where we are most inefficient is in personal transport. There are trains or bus that are efficient, but a big % of the population just travels in a car (alone or with somebody). In resume, we are moving 1200 kg (with an efficiency of 28%) from point A to B just to transport 70 or 150 kg. That is very inefficient.

I have another quote technique for you, press quote, inside the quote find the paragraph you want to quote, take the cursor to the final of that sentence and press many times "ENTER", the quote will cut just leaving your sentence quoted, you can do the same with the rest of the quote, erasing or cutting the quote in many parts as you like. What is the difference? Other countries that no produce oil pay less for the barrel than Canada which is actually a huge producer. And dont get confuse with the current export price of a oil barrel from canada, because they are selling at that price to just maintain their infrastructure in case the oil cost rise in the future and to maintain independence. But if you take a look to the real cost of extraction + infrastructure development to achieve that, you will notice that the real cost of canadian oil barrel should be much higher. As I said.. countries was fooled by old strategies of find and exploit a resource, in my country happens the same thing, they know that they have a really big oil reserve at X meters of deep, but exploit that will require an oil barrel cost of 60 dollars, now we are consuming our oil at 60 dollars to just maintain the infrastructure we already have, which increase the transport and energy cost that in consequence increase the cost of all our products. Fuel cell (tank+fuel cell+ electric motor) has lower density than all components of a normal diesel or otto engine. Batteries has lower volume/energy density at ranges lower than 800km or power times of 10 hours vs fuel cells, but its weight is also much higher. Also it does not matter that little difference in density if the price at that point (800km range) is 3 times higher than Fuel cells, no even mentioning the time it will take to recharge that. Let me explain of other way: a car with 250km range in just 1 or 2 years will cost the same if it use batteries or fuel cells, that is the line.. If you want to increase your range to 500km, with the fuel cell vehicle you just need to increase your tank size by a 30% (which double the volume), with batteries you need to buy double the amount and your weight increase a lot. Fuel cells is a new concept which many bloggers does not understand yet, so they just cling to Elon Musk words which is the most partial in this. Right now hydrogen lacks of infrastructure, but that is already changing in many countries because that infrastructure can be paid almost by free taking into account the amount of money each country save in storage for renewable energy. Batteries had 10 years of development advantage vs Fuel cells that are just starting now, each time is harder to improve a little more in battery technology, fuel cell by other hand, they are growing much faster now and they are receiving more investing, I follow both technologies of close with google alerts, I receive 4 times more news on fuel cells tech than in batteries. In 3 years fuel cells reduce its size 3 times and lower its cost to half, a lot of new improvements are coming. Platinum cost a 30% less than gold, when few years back cost was 30% higher than gold, and fuel cells each time use less platinum with the same efficiency. Range and recharge time is not a problem of fuel cell vs normal fuels. Now you will start to see the age of hybrids, this will happen because oil infrastructure will not disappear from one day to the next, -Full electric with batteries -Fuel cell vehicles (which include oil, methane or h2) all using electric engines. -Diesel engine + generator + some batteries (or hydraulics) and electric engines But in the future the oil engine will disappear, and we will have a 70% of the transport sector with fuel cell + h2 and the rest 30% with batteries. There are strategies to make the change without hard economic impacts on local cities; after all, you are expending overall (country) much more money to not let go the oil infrastructure than make a sustainable clean change in the whole energy budget. Of course that requires very intelligent people to plan and start that change with state policies to guide it.

if you want a special geometric shape for the foam, then yeah, 3d print can solve almost all structures. But a much cheaper way to achieve a foam is using other techniques which creates random bubbles inside meanwhile the metal or material is cooling. These materials provide high stiffness at very low density, higher melting point, they can even work as sound insulation, absorption of high impact energies regardless of the impact direction, electromagnetic shielding and vibration damping.

incredible view.. perfect place, good shot.. But damm, that guy was super annoying with the phrase "oh my god", I guess his whole lexicon was 10 words.

I guess the answer more close to the true is from StrandedonEarth. The heat does not have much to do, more than just provide the energy needed for the chemical reaction. In case the heat is the only effect you will saw the Leidenfrost effect, which prevents the fast heat transfer, you can see objects drop in water that are much more hot (2500c) and nothing happen.

If they use that money to improve the renewable infrastructure, the cost of oil will rise due transportation cost, which is also good because you need to incentive people to change to renewables! What you mean by bad performance? The only thing bad on hydrogen vehicles right now is the lack of fuel stations or places to recharge. The efficiency of hydrogen conversion does no matter if in the future would be equal or even lower cost than battery electricity. When you compare co2 free technologies, efficiency does not matter, the only that matters is final cost. No, because at the same time it will cost more to maintain the oil infrastructure, nobody will keep investing in oil companies which between other things it will increase the cost for those companies. About your SUVs example, I guess you are confuse.. It does no matter your power requirements, from a cellphone to a Bagger 288, the only thing that matters is the time you need to provide that power and how fast you need to recharge it. Batteries are cost efficient only for things that no require more than 3 hours of use AND with slow recharging needs. Fuel cell are cost efficient for things that require more than 3 hours of use OR fast recharging needs. The oil subsidies data that was shown few pages back, it only has into account the oil cost of electric generation just in USA, it does not have into account all the oil infrastructure and their subsidies for all the oil applications in the world. So oil is still hard subsidized, but you dont need to force people to change.. people will always choose what is better for them, but if you keep subsidizing oil infrastructure instead to invest in renewables, you will go nowhere. Each person can not see the overall cost that keep burning fossil fuels has, but governments can, they see their revenues go down due climate change all years and the money they lost being delay in a new power alternative.

mmm, I did not think about that possibility, but we are talking of a second stage with wings? is reusable? How it will land again? No sure about how a mechanism of big doors and deployment + heavy heat shields and extra operational cost can have more sense than 1 stage to orbit. Because I dont really find more hard steps in the skylon design than in this 2 stages launcher. You can find a design that might work, but it really worth it?

No sure what you want to said.. you mean mach 5 or mach 25? Take into account that you can even attach a small and expandable h2 tank (cryoballoon maybe) to reach the equator or the best location to launch in case you want to maximize your payload to geo or other special orbits. No sure if they said you need 25 mach more of speed after you achieve 5 mach or you just need 25 mach in total.. maybe the first one. It would no need the tug for different kind of low orbits, because it will depend on the payload mass, less mass it means you have extra fuel to spent in space without the need of a tug, but the tug is a great idea because it needs much less propellent to achieve an orbit and go back instead push the whole skylon and then deorbit. It also can use a ion tug to place many different small sats in their orbits, but with this tug the skylon would not wait until it complete the task, it will go back to earth, land, then many days after launch other sats and recover the ion tug. But I want to remark that the biggest issue of a 2 stage vehicle fully reusable (using sable in the first stage) is aerodynamics, take a look to skylon: You think someone can achieve a similar drag coefficient maintaining aerodynamics and reusability of each stage the same as a whole? Also the benefit of skylon size is re entry heat, in the reentry is emptly and light, the overall density is very low, so it reach only few hundreds of degrees vs 1200c of the space shuttle, this mean a lot of weight save in thermal insulation (going up and down). I will bet all my reputation that we will never see a 2 stage fully reusable vehicle using sable in the first stage, it does not have sense by these and many other reasons.

They need 25 mach to reach orbit speed, so they achieve 20% of the speed at 28km altitude which is most of the atmosphere drag. It is a substantial help for a second stage, but... the development cost and mostly the operational cost of a 2 stage launcher is higher than 1 stage to orbit. Imagine a design in which a first reusable stage vehicle can reach 5 MACH with something else attached to it, no way... The image that was post it few pages back would not work. You can make it as a rocket in front, but when this detach it will change all the aerodynamic and mass equilibrium of each of its parts.

Well, I imagine that this pipeline could be used for hydrogen transport in the future. But yeah.. Canada is committing another huge mistake with its ongoing commitment to oil. But this is a complex topic, is not so easy to analyze, because countries had founds.. but a big part of the infrastructure is made by private companies, and we have thousands of old companies which are still tied to the only thing they know to do.. which is oil applications. So It is no surprise to see that the wheel keeps rolling. Take a look to this graphic: http://knoema.es/rqaebad/cost-of-producing-a-barrel-of-crude-oil-by-country The difference between the bar and the red point is the real cost of the oil barrel, Canada is paying a lot of extra money for its oil barrel instead buy it to foreign countries, this is because politicians get their head wash (by oil companies) on old energy strategies based in exploit and secure resources, because it can provide energy independent and in case the oil in the world run out, they will could have enough to sell. Which is completely pointless, because if all that money would be put from the beginning in "true" renewables sources and infrastructure, they get the same energy independence and the revenue would be bigger (without counting the real economic cost of climate change and pollution or the environment). The European Community did in 2014-2015 a HUGE study on the cost of change to 100% renewable energy including the transport sector, the conclusion was that they just need to spent almost the same money they spent each year in their energy budget, so there is almost no extra cost for most of the countries, this can be done for 2050. But well, hydrogen is a real alternative to all those companies that are tied to the oil industry, because they can produce hydrogen from fossil fuels with a 90% of co2 capture which they can also sell for high quality carbon fibers, they can sell h2 in the fuel stations, they can even produce locally in each station, people can produce in their houses too, at lower cost than storage that energy in batteries, the natural gas grid can be used as storage and to distribute h2 without need of trucks, because you can put a h2 filter in any exist that will only let pass h2 and not methane (in can be measured and charged separately) H2 can be burned in residential homes or industry, reducing the amount of co2. Wind and Solar can be enough, they are very competitive and cheap, this include to the whole transport sector, which the 70% will use h2. You will keep using oil to make plastics or tons of other products, but the problem with oil comes when you burn it. Wind is the energy source with less environmental impact of ALL, is the cleanest source of energy, even if you use the 100%, it does no affect the climate because the amount of power in the wind is hundreds of times more just in the surface, if you go with airborne technology that it will be the most economical form of wind, you can have much much more. But it is a better solution to combine solar and wind, because solar produce only in day hours which is the moment of major consumption. That is wrong, you can storage any excess producing h2 when the energy is cheap that will be used in the transport sector or in the natural gas grid. By excess I mean that your energy sources will produce as minimum output enough to supply the electrical grid, and all the excess is used to make h2.