Apotheosist

Hello all. So last night I watched the first The Matrix film. I've been asking a lot of my friends what they would have chosen. You don't have to have seen the film to take part, just answer the following question about what you would prefer. Red pill to find out the truth, no matter how terrible it may be, or blue pill to continue to live in blissful ignorance? At the end we can all see a statistical representation of percentage of people who would choose each Invite all your friends to take part! So what do you choose?

Should make it stock parts only

Really guys? Elon Musk. He is like the Jesus of the sane world.

Technically heat is the oscillation or vibration of atoms/molecules. So you could store energy as heat. In fact this is actually done. For example molten salt energy storage.

I don't think overpopulation is a problem. The problem is we don't have a way of moving vast amounts of people into space

I've read through all of the replies so far, they make for very interesting reading indeed. I've made a list of all the problems people have suggested. I have 25 points. Obviously I don't count the repeated ones. Overpopulation, stupidity, and ourselves seem to be the most popular ones I was thinking, maybe I should add a poll onto this thread with all the main problems so far mentioned, so people can vote which they think is the biggest one and we will all be able to see the results. What do you guys think?

What do you guys think is the single biggest problem facing humanity at the moment?

How/where can I watch it?

No. 89% with the Proton M, which has only been flying since 2001 http://en.wikipedia.org/wiki/Proton-M 62 successes/70 flights=89%. It seems to me that even after many decades, this rocket still has fundamental flaws. I hope rockets like Falcon 9 will set the standard for reliability. They are actually designed to withstand component failures, like the Saturn V did too. Thanks for the detailed explanation of why the proton is shaped as it is though, I learnt a lot! I think those universal rocket designs are awesome, I'd love to see something like that be made.

89% reliability. That's lower than average for rockets. Also I don't like the fact that when it does fail, if it's near or on the ground it spreads toxic stuff over the place. Also, what's with the six tanks sticking out the sides? It's just a visual thing I have a problem with, but if someone could explain to me the engineering rationale for it i might change my views. Oh, and just because a rocket is man-rated, doesn't make it reliable. If you have a launch escape system that doesn't matter so much. Space Shuttle had no escape system, that was still fairly unreliable.

Maybe we should discuss our least favourite rocket. Or maybe that should be in another thread. Anyway mine would be the Proton. That thing's just damn ugly. Not to mention unreliable. However, I suppose It did give us possibly the most spectacular explosion ever recently

Falcon 9 for me. The design just makes so much sense. And of course it can be used to make Falcon heavy, which will be epic. And when they can reuse the first stage, that will be momentous. But I also have a soft spot for Black Arrow The nearly invisible exhaust is cool, and it was a neat, small launcher. I also like the propellants it uses, HTP and kerosene. HTP is not cryogenic like LOX, so it can be stored for longer, more flexibility etc, also look how little suporting infrastructure it needs. And I heard somewhere that this was one of the cheapest launchers developed. Pity they cancelled it.

This is certainly the way forward. Most exciting!

Yup. It's a fine line between a solid rocket and a leaky bomb, and in fact, as the performance of solid rockets increases, (higher chamber pressures, lighter casings) the solid rocket tends towards being a bomb.

SpaceX also use Kerosene in the later stages because they can use the same engine throughout the vehicle. With slight modifications on the vacuum version of course. But having common engines vastly increases the reliability of the vacuum engine and thus the whole rocket over time. If you think about it, the engine on the falcon 9 second stage has been flown about 9x5=45 (I think it's been 5 flight of falcon 9?) times as well as the times it was in the second stage alone (5 times). That makes for an engine that has been flown 50 times. This must surely give lots of confidence in the reliability of the second stage. But the ultimate fuel for SpaceX would be methane, which as Musk said, is the cheapest fuel in terms of cost per joule, and it can even be made on mars. SpaceX is working towards methane propulsion, so all is looking well

I was a little suspicious of this, Wikipedia did say the falcon heavy could lift 53 tons to leo, and about 13 tons to GTO if i remember correctly. I thought perhaps Wikipedia had not updated it's GTO payload after the specs for the falcon heavy changed. I went on the Spacex website recently, saw that it had changed. It has info on falcon heavy: http://www.spacex.com/falcon-heavy and Wikipedia has now been updated, saying falcon heavy can lift 53 tons to leo, 21.2 tons to GTO. So it's not as extreme, just our information source was incorrect at the time.

I'm going to study Aerospace Engineering at Swansea University, Wales, UK in September. Well, if I get the grades that is which I will be finding out in 6 days. The AE department at Swansea University do a lot of computational fluid dynamics work for the Bloodhound supersonic car, which if you haven't already heard of, you will hear of it soon . Aiming for 1000mph on land! I have learnt a heck of a lot from KSP. A deep understanding of orbital mechanics, launch vehicle design, etc. Incredibly educational game for me.

Basically what you want is Reaction Engines SABRE. It does what you want, giving all the advantages you say, but they've been working on it for decades so their engine has been optimised, and all the silly ideas that seemed good at the beginning, they have ruled out. They're going to store liquid oxygen on board for the exoatmoshperic portion of the flight. They've solved the icing problem. ESA did a study on their engine, and found no technical reasons why it could not work.

The Germans had like radio beam guidance they used to bomb certain places in Britain. They would beam two different signals from different points on Europe, from France I think, using big radio transmitters. The transmitters could transmit radio beams in a straight line, like a lazer. The Germans had receivers on board bombers, they would follow these beams using headphones to listen to the beam signal, and where the beams intersected, the bombers would hear the different signal, and drop their bombs. The British spent a lot of time trying to figure out/find the frequencies the Germans used, and tried to transmit their own signals to interfere with the German signal so that the German bombers could not find their target. Wernher would have liked to have used this radio beam system to guide his rockets, but the Luftwaffe had priority on it. The Germans certainly had advanced guidance technologies. They could have used radio beam guidance to guide a rocket to obit.

I think with the Chinese one it's stuff falling off from the structure between the stages. If you look at the sequence of photos, when the rocket is closer to the ground, you can not see the open structure. You can only see the open structure later on, after the white debris has fallen off. This open structure between stages is typical in Russian rockets like the Proton and Soyuz. So yeah my bet is it's just thin material used to cover up the open structure, to stop any debris getting in there during assembly, transportation, on the pad etc.

I believe it's ice forming from the moisture in the air. The falcon 9 has ice on it because it uses liquid oxygen as an oxidizer, which is very cold (about minus 180 degrees Celsius), cold enough to form ice on the outside of the liquid oxygen tanks. This ice is falls off during liftoff because of the vibration and movement of the rocket. There is no ice on the kerosene tank as the kerosene is at ambient temperature. This ice only forms on rockets with cryogenic (very cold) propellants. The proton rocket doesent have ice on it because it uses dinitrogen tetroxide, not liquid oxygen. However, not all rockets using cryogenic propellants have ice on them at liftoff. Rockets with liquid hydrogen don't usually have ice forming on the outside of the tanks, because they are usually well insulated. Liquid hydrogen tanks have to be well insulated because it is cold enough to liquify, even freeze the oxygen in the air. Having frozen oxygen on the outside of your tanks is much more dangerous than just frozen water. Take a look at the space shuttle external tank, you don't see ice falling off that at liftoff. That is because it has that orange/brown foam insulation around it. Having ice falling off that tank would be VERY dangerous as it could hit the shuttle orbiter. For other rockets that don't have their payload latched on to the side, but on top, like the Falcon 9 or Saturn V, It's ok to let the ice fall off. Adding insulation would just be extra weight.

Wow, that is extreme, I never made the comparison to realise that. Indeed SLS will be more expensive than it needs to be. I wonder if NASA's better performance will make up for their higher cost for launches to higher energy destinations.

The SLS uses higher performance propellant in it's later stages (core main stage and third stage), namely LH2/LOX. This should give the SLS considerable performance/mass efficiency advantages for launching on high delta v trajectories, (moon, asteroid, mars, beyond). Higher specific impulse gets much more important in the later stages. Liquid hydrogen/liquid oxygen vacuum propulsion engines get 450-460 seconds of Isp, compared with maybe 340-350 for lox/kerosene, and 370- 380 for spacex target for their next generation lox/methane engines. As I said higher specific impulse propellants, like hydrogen, give a big boost for the higher energy trajectories. For low energy applications like LEO, things like RP1 will do, spacex is competitive. With the higher energy trajectories, NASA should have more of an edge, purely by the technology of their rockets. As an example of the performance advantages of higher specific impulse for higher energy trajectories, just compare the Ariane V and Proton M. Ariane V uses cryogenic hydrogen/lox in core and last stage, proton uses N204/UDMH in its first three stages, Kerosene/lox in the fourth stage. Both these rockets can take about 20 tons to LEO, but Ariane V can take 10 tons to GTO (Geostationary transfer orbit), compared with only 6 tons to GTO for Proton.

You really want a mass produced reusable rocket. Like airplanes are. That means you need to get the size of the rocket right. No point having one huge reusable rocket to take all cargo into space, the cost of building it would be too high. No point having millions of small reusable rockets, the payload will be too small. Must be tricky to get the right numbers. Regarding cost of fuel for the falcon 9, I remember seeing musk say it's around $200,000, which compared with the roughly $60,000,000 price of launch, that would make fuel costs be one third of one percent of the overall launch cost, which I have also seen musk say.

I think the philosophy SpaceX is taking to reusability is to make the first stage have as high a mass ratio as possible, by having very high thrust to weight engines, and lightweight, pressure stabilized, aluminium lithium tanks with flight pressure stabilization. I read on Wikipedia that for the first stage of falcon 1, only 5% of the liftoff weight is the rocket itself, and 95% is propellant. The reusability features they're adding on falcon 9 R have to be as light as possible. The landing legs are made of carbon fiber, and the pistons that actuate them use helium gas as the working fluid, all to make it super light weight. The lighter the rocket is, the higher the mass ratio, so the less fuel you need to keep on board after stage separation to propel yourself back to the launch pad. It's easier to have a higher delta v in the first stage with the small amount of leftover fuel if your stage hardly weighs anything. Adding parachutes just makes it unnecessarily heavy, means you need more fuel to fly back to pad, etc. Of course you could use only parachutes, instead of leaving some fuel in the tanks. But parachutes really suck. I mean, they give you no control of where your rocket lands, your rocket will just end up downrange, you cannot fly back to the pad. You have to land in the sea if you want a soft landing, because even if you double the size (and weight) of parachutes, they will only slow you down by a quarter (or was it one eighth?). This is due to the square/cubed nature of how parachutes work. Even landing in the sea is still quite rough, not to mention the saltwater damage. If you want to use parachutes on land, you will need airbags, which just adds more weight and complexity. Or you could use retro rockets to slow the final descent, like the Soyuz capsule....but oh wait...we don't have any fuel for retro rockets because we used up our weight budget on parachutes and airbags....remind me again why didn't we just use pure retro rocket landing in the first place? Pure rocket propulsion reusability is better performing, not to mention the time and money needed to re pack the chutes, replace airbags, maybe haul the stage out of the sea if you chose to do that, check for saltwater corrosion, etc. Winged boosters have some of the same problem, extra weight, more complicated, need a big runway, the lower mass ratio means you cant have as much delta v to propel yourself back to launch pad. Elon knows what he is doing.