FleshJeb

The square-cube law is going to play merry hell with the mass fraction.

Symlink some directories?

Beautiful thread, guys. Thank you.

Just rewatched the Pixie Mk2 video on the prior page--I can't even describe how sublime that was. What have we lost in the name of "realism"?

And all this time, I thought the spirit of the game was to have fun... Mein Gott! I've been playing wrong! @AeroGav This looks like a fantastically fun project. You should page Azimech, I'm sure he could give some pointers on the props.

@Captain_Miffles Completely offtopic, but that's a gorgeous rig. Do you happen to have any tighter screenshots that show its layout and construction?

I see, we misunderstood each other. I'm not suggesting sticking a $10 guidance system on a $100k rocket (it would be paired with an inertial guidance system, as well), but rather something simple, robust, and "good enough". Of course it requires high tolerances, but I don't think a single arc-minute is necessary. As long as the periapsis gets comfortably above the Karman line, I should think that's good enough. Which brings us to another point: We could simply slap a commercially available INS on this thing and call it good. What's our balance between innovating and just doing systems integration of commercial (COTS) parts? Systems integration IS a tough and worthwhile subject...

Agreed on the payload. I disagree that it's sophisticated. Certainly less than inertial guidance. A dual-axis solar tracker with 4 photodiodes can be built as a completely "dumb" system for <$10. Even if the tracking system is a bit more sophisticated than photodiodes with strategically-placed shades, the algorithms and math are already well-developed. Hmm, I'm sure I could figure out a way to do one out of a side window on the rocket that could compensate for launch latitude, time of year, and time of day of launch.

That's an excellent idea. I think we could get more mileage out of making the third stage non-solid. However, that would require developing another core, and small solids are robust and commercially available. The guidance system I envisioned uses the payload camera as a sun or moon tracker. With some mirrors and some software, you could specify an offset angle to the light source that changes throughout the trajectory. Fairly similar to how heat-seeking missiles work today.

@wumpus That was a great link to the DARPA paper on Nitrous Oxide/Propane rockets. (Re-linked, since it's a ways back.) Benefits: Common, safe fuels Decent Isp Pressure-fed (Good link @Exoscientist) Throttleable Self-igniting Ability to cross-feed Already bench-tested I'm envisioning a 3-stage non-recoverable serial stack: NOP*4 - Differential throttle control. Need cross-feed to ensure that the fuel is balanced. Identical, single NOP with altitude-optimized bell and RCS control. Payload and guidance + Solid motor with carbon-fiber shell. The 5 NOP cores are identical except for the engine bell. The RCS blocks can go on top of stage 2. Maybe altitude-compensating on the first stage. Launch stages: Full throttle to g-limit and/or Max Q Full throttle to g-limit. Orient and spin-stabilize with the RCS on the coast to Apo. Fire solid at Apo.

I WAS an aerospace student. I quit after my second year and went back to being a Land Surveyor. Thanks for the info. From the article I linked in my first post: "However, the typical range of temperatures was found to be from -170˚C [103K] to 123˚C for LEO satellites while -250˚C [23K] to 300˚C could be experienced in other orbits." It may be interesting to plug these numbers into your modeling. My advocacy for radiators is also based on reducing the number of moving parts. Operations and Maintenance costs are going to be a major factor in viability. I understand that's not what the thread is about, but reducing points of failure is well-worth considering in the space environment. You could also spin your craft about the long axis to introduce a "thermal pulse rate", and reduce the need for moving parts. This might be a way to keep the scoop unfurled, and reduce the mass of its structural components. Difficult to do solar power, though. After a few minutes on Wikipedia, it appears that radiative efficiency scales with (deltaT)^4, while heat engine efficiency has a linear relationship with deltaT. I bet you could design a radiative precooler that does better than the 400W/kg you quoted in your first post. You could save mass on the refrigerator, even with the efficiency loss. In addition, you'd save mass in power generation. Another question just popped into my head: What's the refresh rate on our gaseous resource? Could we eventually impact the density of the Thermosphere? Wikipedia says that the Thermosphere above 85km is 0.002% of the 5*10^18 kg of Earth's atmosphere. So, probably not, but it's always good to check the environmental concerns. Thanks for the thread. Yours are always good for intellectual play.

Mind you, thermodynamics was my worst subject. I'm much better with electricity and magnetism. I understand about the turbine. To sum up: What I called "wasted energy" is needed to compresses the gases to a useful state. I wrote the day/night theory poorly. 1) Electricity generation: Run some radiators face-on to the sun to heat up a heat-storage medium, and then store it in an insulated tank. On nightside, you reverse the process, while running it through a heat-engine. This is probably less mass-efficient than solar panels and batteries 2) Ignoring the day/night cycle, Nightside/shaded space in certain orbits is colder than the boiling points of oxygen and nitrogen. We're starting with hot compressed gases--Is it physically feasible to run that through a radiator without expending the full energy necessary to liquefy it? Is the energy required to push it through a radiator less than what you've shown to mechanically liquefy it? I suppose this depends on the starting temperature and pressure of our gasses. (Perhaps I'm violating a law of thermodynamics here.) Perhaps this could be run as a continuous process, rather than needing to add mass for gaseous storage. I can envision being able to fractionally distillate it within the radiator structure as well.

There was some study done to look at the effects of having all commercial jets grounded for three days after 9/11/01. http://news.psu.edu/story/361041/2015/06/18/research/jet-contrails-affect-surface-temperatures http://globalnews.ca/news/2934513/empty-skies-after-911-set-the-stage-for-an-unlikely-climate-change-experiment/

I only gave this a brief skim--Please forgive me if I misunderstood anything. You have to get the captured gasses up to orbital velocity. The current plan looks like this energy expenditure turns into heat via friction. This seems like energy not being used. Why not run them through a turbine before they get to initial storage? Mass increases are the turbine and possibly more batteries. Mass decreases in other power generation. Orbiting between day and night is a free heat pump. Can this natural cycle be used to generate power or do work? Can radiators be used to liquefy and distill the gas? Some numbers here: http://www.astrome.co/blogs/how-do-satellites-survive-hot-and-cold-orbit-environments/

See this as well:

Very loosely-based on Rogue Moon by Algis Budrys

I know, it just irritates me beyond reason. I've spent a many hours in every version since, and it's less fun for -me-. I have FAR, Deadly ReEntry, Kethane, RemoteTech, and ScanSat, and I can write my own config files for most of the new engines--So, I'm not missing anything significant, and I don't have to keep track of caveats/workarounds for new bugs. 1.01-1.04 was such a mess, I just gave up.

0.25 -- In contrast to Mr. Zoo, I'm being serious. Editor Extensions has Vertical Snap as a toggle in that version. A code change in 0.90 made this toggle impossible. Since I spend 90% of my time building, to upgrade would almost double my mouse movements and keypresses. I've been a draftsman for 25 years, so minimizing the number of inputs I have to make is a big deal for me.

What am I going to do with all these cats I just ordered? My introduction to exponential growth was the grains of rice on a chessboard problem. And if you really want to have trouble sleeping, look up Von Neumann probes.

Welcome to the forums! Reaction wheels will only rotate (or stop rotating) the ship. They use electricity only. Mono is fuel for little engines (RCS) that allow you to translate AND rotate. No electricity needed. RCS is used to do fine movements such as docking ships together. You can turn RCS on and off by pressing R. The green light to the left of the navball will come on. The normal WSAD keys will rotate the ship, just like with the reaction wheels. IJKL will shift. H and N to go forwards and backwards. http://wiki.kerbalspaceprogram.com/wiki/Reaction_Control_System http://wiki.kerbalspaceprogram.com/wiki/Reaction_wheel Does that answer your questions? Feel free to ask more.

Even better when animated!

Riding Rockets was highly recommended by Mary Roach in Packing For Mars. Which is also a fun book, but less about spaceflight.

I explore with VTOL-capable craft. They all have a 0.625m docking port on the rear, between the two primary jets. When I get low on fuel, I fly an identical craft out, and park it behind the other one. Then, I engage the VTOL engine at <1.0 TWR on one of them, pitch up a little, and back it into the other craft. Dock, transfer fuel, undock, and fly the tanker home. You can also do this with a "stretch" (longer/more fuel) version of the original craft.

I'm pretty sure those were "medical supplies"... New to Thievery Corp?!? Have some trip-hop: Morcheeba: https://youtu.be/1CTBOskmXaE Portishead: https://youtu.be/BmxXHF9C3Yg Massive Attack: https://youtu.be/GPTY6l_PX5k?t=1m (Cover by Aurora - Better than the original IMO) Fly safeTM.

That's odd. You'd think they'd prefer the tracks, because the tires will burn.