sgt_flyer

At first, 5 segment SRBs were already thought to be used for the space shuttle - would have allowed 9 tons of additional payload with minimal changes (adding 2 additional SRBs to the ET would require a lot of rework on the ET structure - and severe modifications on the VAB. It would also require severe reinforcement of the crawler transporters (& maybe the crawlerways too) (which were already modified to carry the shuttle's weight - SRBs are mounted with all their solid fuel already casted after all (1 4 segment shuttle SRB alone is 590 tons - more than two times heavier than an unfueled saturn V - per shuttle booster ! so imagine an unfueled 4 booster SLS - that would be a bit more than 2400 tons to transport (not counting an umbilical tower if they add one) the 'empty' shuttle + the loaded SRBs weighted around 1300 tons, on the 3700 tons mobile platform. (All that carried by a 3000 tons crawler) SLS is already costly enough like that all the new ground works and support equipment it would require would cost a lot of money. for a rocket with lots of planned launches, it's not a big deal to spend this kind of money on infrastructures do it for a rocket that'll only fly a few times, and that adds significantly to the rocket's price tag

Well, according to the wikipedia article, Hyperloop is stated to operate at 1 millibar of pressure - which is still lower than mars atmospheric pressure (or you need to slow down to compensate from the higher air pressure) Plus, the tube would protect the capsules within it from martian dust. (As air is supposed to be 'sucked' through the capsule (to prevent the pressure buildup in front of the moving capsule) the tube would also act as the 'railway' supporting the capsules (one part of the air sucked in by the capsule would be used to help the air sustentation of the capsule. Now, hyperloop is supposed to be solar powered - so a martian version would require much more solar panels for the same work.

One of the few things i hope they fix regarding fairings : clamshell possibility (with smoothing if possible), limit the amount of slowdown fairing 'transparency' in the vab generate (on larger fairings it's quite horrible ) and the possibility to fire engines from within fairings / cargobays. If they are not open ended, the engine exhaust should of course hit the fairing and do no thrust, but if it's open ended, no reason why thrust should not work - would allow us to make nice custom size SRBs

Actually, optic fibers can also be aerial like classic phone lines. But yes, it won't be cheap best bet, would be to have a fiber coming to the neighborhood, then have a VDSL broadband on the existing copper wires for the last section. (Those last section being the most costly ones, as you have to install an optic fiber for each home) Though, regarding the latency, it might even be greater than just going to LEO and back - ground stations aren't that cheap to build, so they might need to relay the signal through several LEO sats in order to have a link between the nearest ground station and the end user. And some countries (*cough* china *cough*) might see from a bad eye this kind of global network they won't be able to fully control. (Especially if the 'nearest' ground station is in a neighbor country) - so chinese market might be not avaible for selling the end user's equipment set. (And yeeeah, additional 'directional' antennas powerful enough to reach out to space - guess aircraft regulation authorities will be overjoyed ) (for a reminder, current cellphone towers reach out to max 30km - horizontally. (Birds don't have cellphones ) (at least in europe - the GSM protocol there is set up that way))

From the pictures philae took and transmitted during the 60hours after landing, ESA thinks philae landed on it's side, with one feet towards space. As for the drill unit, you can see it being deployed at around 2:10 in this video. http://www.esa.int/spaceinvideos/Videos/2014/08/Philae_s_mission_at_comet_67P Though, if the lander landed on the side, i guess they are going to have some problems. (don't know how much degrees of freedom the drill deployement system has to help in positioning the drill vertically towards the surface) Without harpoons / feet anchors securing the lander and on the side, philae's drill might not be able to devellop enough force to drill through (if trying to drill at an angle, they might be ripping the drill's head across the surface instead of drilling)

with 4000 'low cost' satellites, some of the sats are going to fail much faster than expected.(guess the constellation would have a lot of redundant satellites to be able to wait until a new launch is made) Why not go to the extreme in simplicity then ? Digital solid state propulsion electric solid fuel thrusters would have less ISP, but no need for any kind of pressurized fuel tank. (Btw, how is spinsat doing since it has been released from ISS ? ) Nevertheless, operating such a constellation will still not be cheap once it has been launched. In LEO even if they will be placed in higher orbits than ISS, you're going to have more reboosts needed to maintain your orbits. (And with virgin galactic planning to do the same, those orbits are going to be veery crowded) So they'll need a huge workforce (+ all the administration around it) to constantly calculate & apply to the satellite the needed corrections. When some of those satellites fail, as they'll have redundancy in numbers rather than reliability, you're going to need to replacd those lost satellites sooner or later (component problem, fuel exhaustion, debris impact), needing again launch costs, however cheap they might be, it's still going to be a hefty sum. (And you still need to pay for all ground launch operators !) Afterwards, other companies with other costlier satellites, will also have an increased orbit surveillance to maintain (and even risk more failure rates, due to the increased amount of potential debris) There's, as of 2014, around 1100 active satellites in various orbits (LEO and GEO) and 2600 inactive ones. To that, you add the staggering amount of estimated debris in orbit. So adding such constellations of microsats is going to be maybe cheap to launch, but a true nightmare to operate (and not only for spaceX or virgin) Space debris disposal is not yet operational, while musk wants to launch his first sats by 2016 (i doubt F9R will be fully operationnal by then)

Except airliners are built to be reusable, and of easy servicing ! (Adding to structural integrity (to prevent stress fractures from happening too fast) and have various hinged access panels to allow maintenance without having to take apart the plane. These kind of hinged panels on a 'reusable' rocket / ssto are not good. they both decrease the structural integrity of the zone they are put on (there's a hole after all) needing to reinforce (thus add weight) to the surrounding structures. If the vehicle has to also withstand a fiery reentry, you need to make sure that the superheated air wont get inside those panels. So the choices are : either increase the dry weight to allow easy servicing (and that's bad for the kind of performances wanted with current chemical rockets) or need more time / workforce to dissassemble the thing for integrity checks and refurbishment (which adds a lot to the cost of reusability) Besides, with the kind of costly payloads that are sent on rockets, the customers will want thorough checks on refurbished parts - insurance costs will also go up, chipping away reusability savings. That's one of the problems with spacex figures - they only give material cost figures and never speak about refurbishment costs.

Seems some people did some math around SpaceX boostback + landing It looks like they need 20 tons of fuel for a barge landing (payload max weight at 80% of expandable launch) And for a return to the launch site, nearly 38 tons (they give a payload max weight of 62% of the expandable launch version) https://m.reddit.com/r/spacex/comments/2vuy1v/how_much_fuel_do_the_boost_back_reentry_and/ So we'll have to see what's more interesting by balancing limited weight penalty on the payload with Vulcan / adeline concepts vs the less complex refurbishing needed for a Falcon 9 (although, SpaceX might still need to clean up their engines after firing kerosene, while ULA vulcan LCH4 and Ariane LH2 engines won't deposite that much soot into the engines)

That makes sense, given the stage is much lighter & less aerodynamic for landing (so much more affected by wind - if they need to have more drastic weather conditions than those for normal launches, they are going to have even more scrubs. - For the weight penalty of the propellers, they did not say what kind of propulsion they would use (Airbus is experimenting on electric engines for airplanes after all, turboprops could make equal sense too) for those worried about the weight of the whole return vehicle, remember that Ariane V Vulcain 2 engine has a dry weight of 909kg (for a thrust around 1359kN, instead of 2400kN for Vulcan BE4 engines (vulcan needs two of those, so a much higher weight in their return vehicle) - besides, the falcon 9 also has a weight penalty coming from the amount of fuel it needs to keep to perform the boostback + landing. Now, the heat shields on this thing is going to be a headache - current ariane V MECO occurs at speeds near 7km/s, (though, Adeline MECO will likely be at lower speeds, but it'll still be high) and they'll need to make their wings able to withstand this reentry too !

Looks like more or less the same base concept as ULA's vulkan, but with wings and deployable propellers to return the engine section (+the stage's avionics) to a runway (no inflatable heatshield) instead of having an helicopter catching the engines floating with parachutes - afterwards, like with vulkan, they would reattach a fuel tank to reform the core stage. (The boosters were still ariane 6 SRB's) The concept comes from Airbus defence and space. We'll have to see how it ends up (though, it might be less risky than vulkan engine recovery)

erm, the lower part of the core stage is 2,05m in diameter on the real thing while the boosters largest diameter (at the bottom) have a 2.680m diameter on the other end, the core stage top diameter is 2.57m, and it's widest point (just above the pointy end of the boosters) is 2.95m in diameter

Mmh - i'll look into it (though you'll need some free space with no parts in the way of the bearing if you want a stable version that don't go too high over the locomotive)

Yes, but for a 400kw reactor, having to manage 300kw of thermal waste for a 25% efficiency thermal cycle will still require a bigger cooling system than if you only need to manage 40kw of thermal waste for a 90% efficienct direct conversion (that's at least the efficiency figures they hope to reach for direct conversion) That's the inherent problem with solid fuel based nuclear reactors as a whole - they can't let the reactor fuel rods go too hot - so they can't benefit from high efficiency cycles. It's no wonder there's researches on Gas core / Molten salt reactors which can run at higher temperatures

To have good power to weight ratios in a reactor, we need something extremely efficient - not a 25% efficiency reactor. (Because the less efficient, the more radiators you'll need to keep it cooled) So we'll have to look into direct conversion reactors - like the Fission Fragment dusty plasma reactor concept. But if we go towards this kind of direct conversion technology, it will already have more ISP in thruster configuration on it's own than using it as a reactor to power ion engines We already have lots of researches done that would allow us to create all kind of what would be 'sci-fi' technologies - if we had the adapted dense power sources / batteries - until we have those - most of those 'sci-fi' technologies will remain on paper (or only test versions in a lab )

Mmh - checked the video - that upper stage was a gold foil wrapped Fregat, not a volga

Outside of some info mods like KER or rcs build aid, i like to play stock. Tried some mods, but i always come back to stock building - 1st, because people will be able to play & build upon my .craft files without having to download any specific part mod i could have used. 2nd - because i like having to find ways to use the provided stock parts to create new looks / mechanisms

hehe yeh, bearings made of those small wheels require a lot of tweakings to work properly (i would know, i used them in my jet engine pack ^^ ) hint : the new fairings allows for quite nice, compact and low part count bearing bodies @Mad rocket scientist - do you need a fairing based bearing for the linkage ? - it'll be roughly as high as the fairing part, + the height of the wheels

I'll see what i can do for a Leap engine - though these 'waves' might induce a high part count As for helicopter engines, unfortunately, torque engines of this size are not enough (even with 11x 1.25m reaction wheels my tests for propellers barely reached 11m/s in this new atmo - horizontally on the runway !), and i'm not sure those bearing could easily support the weight of an helicopter.

turbofans don't emit visible light everything's masked by the turbine's blades (and there's even less light visible from the main fan ^^ unless you have a fire in your turbofan which is baaad

Feel free to disassemble them to create your own be just prepared to have to do a lot of tiny adjustements if you want to recreate a small bearing all building techniques i've used are derived from what i posted on the open source thread (notably the open ended fairings and the rotation / translation tool trick )

Don't forget to tell how to start-up those engines fans

Maybe not some new parts, but at least having stock tweakable control surfaces range would be interesting (would allow to make a lot of cool things from this ) - maybe the possibility to have some extendable flaps too.

Personally, i find that drag is currently completely insane for non streamlined objects (well, that might be because contrary to FAR, stock aero model doesn't occlude anything that is not behind nosecones or stuffed inside fairings / cargo bays). (I have a roughly 23 tons replica that has really high drag because of the wings making off the shape) - it can't get faster than 42m/s of horizontal speed at sea level - with a TWR Slightly above 1 (can't even climb to vertical because of drag) Looks like the various terminal velocities are currently wayy too low. (Heck, you can almost land safely with only A.I.R.B.R.A.K.E.S....)

Well, i have a range of various diameters animated turbofans at 1.4m (for the low bypass), to 1.9m and 2.4m for the high bypass versions (and the 1.9m versions comes also with a long airduct variant for tailjets ) http://forum.kerbalspaceprogram.com/threads/121800-Kerbal-Electric-animated-Turbofan-engines-New-Low-bypass-KT-8D-jet-engine-%21

the tanks will not need to sustain these kind of pressures - that's why they are researches on metastability (Think of red oxygen of something like diamonds are to carbon) Now, i've not found how broad this is metastable (ex, if it requires only 1 gpa to maintain metastability, it's still too much ) Now, the main problem would still be the pricing of such fuels - producing those metastable fuels would require very expensive facilities and energy expenditures (create such pressure would require gigantic amounts of energy) - so you'll have an extremely expensive fuel. So, you'll soon run into the problem of needing to balance this extra pricy fuel vs the costs of a larger, but cheaply fueled, rocket