MarcAFK

I second the request for more powerful RCS, it would be a nice option to allow launching fully loaded containers which weigh a few hundred tons each. I've about to reach orbit with my starmover after about a week failed launches and redesigns. I've learned that due to the weakness of stock RCS, it's highly unlikely to launch an 800 ton payload without ensuring it's as rigid as possible. Also short squat radial boosters are excellent for stability, though I've had a lot of problems with discarded stages ramming into the rest of the rocket, I shouldn't have been dumping radial boosters during a gravity turn anyway. The successful launch: 860 tons fully fuelled, 280 of that being liquid hydrogen. Enough to haul 600 tons from duna with 1700 dv. This was the final booster configuration I used: Always plagued with problems, even this launch did not go smoothly, you can see 5 14400 tanks with rhinos at the very bottom of the stack, the first booster stage damaged half of these and they were discarded for symmetry, luckily there was barely enough fuel left to reach orbit without that final stage. Features include 3 cargo racks with docking ports for carrying colony modules, or senior docking ports for larger payloads. 3 Kontainers attached with docking ports, 8 enclosed cargo bays, and 12 radial MKS tanks. Also 12 radially attached docking ports around the drive section allowing the easy attachment of an additional 860 tons of fuel tanks. These would allow a staggering 2800 tons of freight to be delivered back to Kerbin from Duna, or a much smaller quantity from Jool, or deliver a decent colony setup to Laythe.

That's a view from the side, it's hideously unwieldly and no didn't make it to space . My next attempt will be completely unmodified FTT, I won't try moving 2,000 tons of metal, and It'll have a more realistic amount of dV, just as soon as I can work out how much is the absolute minimum needed for travel from duna to kerbin.

Well I'm trying to launch this monstrosity : : Ignore the big gold tank, that's just 2000 tons of liquid fuel. I couldn't get a good shot of the starlifter, but it's approximately 400 tons of ship, 600 tons of liquid hydrogen, and can carry 6 containers of metal ore which is 2000 tons with about 1300 dV, which should be enough to get from duna to kerbin. It needs another toroidal SAS, and more struts. Also I should have used mainsails for the launch, I don't know what I was thinking using those big Vacuum engines.

I managed to get one up with a buttload of extra boosters and structural support. I've modded tanks to be lighter and structural parts to be stronger, I might now be able to get one up with only a single booster stage, obviously I can't use the nuclear engines at ground level, but they're fairly effective once you get past about 15 kms. In fact I'll throw a starlifter together now and see how she goes. Oh I almost forgot, that first attempt barely fit in the VAB, I needed to install hanger extender to fit the booster stages in

The weight and capacity of containers needs balancing, a stock ore can weighs 2 tons and carrys 15 tons of ore. A Hexagonal Kontainer is about 4 times the volume but half the weight, and holds 250 tons of metallic ore, and a bit more of Metals. A standard international shipping container like you would see on a truck is very slightly smaller then a Kontainer and weighs only 2.2 tons with a capacity of around 26 tons. I'm thinking that stock ore cans hold about the right amount but maybe are a bit heavy. I'm thinking a 100-200 ton max capacity is probably good, for comparison most other resources the Kontainers hold weigh less than 100 tons. I've been thinking about this and aren't sure what to make of the numbers, the maximum weight isn't really excessive, but I think the different resource types could be a little better balanced. EDIT: I'm an idiot, stock capacity is exactly based on litres, weight then adjusted by the resource density, so in theory a container would have a flat 36,000 capacity of everything except for (LFO). I'm assuming that rocket parts being a fifth of their actual density would be to account for safe packaging etc? It all seems pretty good then capacity wise. EDIT: I've noticed the Kontainer 2 actually has the same volume as the container 2.5m, also I can confirm the misaligned nodes on the cargo racks, I had to turn on the non strict alignment cheat to get them to attach, after a few launches the ship just decided to explode spontainously on the launch pad. Also I can't seem to get struts or fuel lines to surface attach to the structural parts or the fuel tanks.

I threw together a test vehicle, a 7.5 ton payload, to that I added a 3 ton engine and enough fuel tanks to reach 48 tons. Which is a 15% payload. With Liquid fuel/oxidiser and a skipper was about 3500 dV, liquid fuel and an LV-N was about 8700 dV, the current Spherical liquid hydrogen tanks and an LV-N burning liquid hydrogen at 800isp gave me 3200 dV. Lowering the tank weight to about a ton brought the dv back upto 8400, half a ton was about 9200 dV. It seems that about 15% or less is about the value you need. I'll record the exact details and put it onto github. Btw the tank actually holds 5.3 tons of fuel, my earlier numbers were are a little off, but a tank weight of 1 ton is 15%. I've pasted my findings as well as suggested values onto the github, my reccomendations are: Small spherical tank: 64,000 fuel. Dry weight .85 tons. Dry fraction 15.78% Triple small tank: 192,000 fuel. Dry weight 2.1 tons. Dry fraction 13.19 % Large spherical tank: 500,000 fuel. Dry weight 4.5 tons. Dry fraction 11.27%

I can't be sure about using real world values though, liquid hydrogen is hideously difficult to contain and boils off significantly when stored, the extra mass might include refrigeration and other advanced storage technology that prevents this from occurring. In hydrogen fuelled cars this is an extreme as the tank, cooling systems and safety features can weigh 10 times the actual fuel. But the problem is no matter how efficient your engine is you can't get significant delta-v if your empty tanks are too heavy. However since it seems that people are having trouble making a working rocket using the current values, so I suppose a good rule of thumb is to find a value that works well and stick to it? I'll do some testing with various weights of tank using a standardised rocket weight, payload and fuel ratios, with different fuels and engines. It may be that the current weight is fine but if I find that a skipper is out performing a nuclear rocket then I'll know there's a problem.

I've found a few other mods with poorly aligned nodes, and noticed that on the cargo racks too, It looks like the node is slightly too close to the model so you can't attach anything to the rack after it's placed because of part clipping. You can either change the part's properties to allow part clipping, or move the offending nodes around. I did this today with the disaligned nodes of the skydock 250 in the Multipurpose colony modules pack, trial and error took a while for me to get it right. Speaking of the LH2 tanks, I noticed they seemed excessively heavy so I did some calculations, a 5 meter diameter sphere of liquid hydrogen at the same pressure as the space shuttle's main tanks used would weigh 4.484 tons, that's pretty close to what the tank actually holds, which is good, but, the tanks weighs something like 6 tons, now the space shuttle's tank weighs in at 26.5 tons, length wise 64% of the tank is for LH2, assuming the tank doesn't need to be significantly stronger for hydrogen compared to oxygen (bad assumption but lets just assume for now) that means 17 tons of the tank is for the LH(we're also ignoring the fact that the ends of the tank and intertank are a significant part of the tank's weight so a simple subtraction of 36% of the weight is also wrong, but bear with me), it holds 106 tons of LH2, so the dry percentage is about 16%. The FTT tank however weighs almost 4 times this fraction.. Lastly during the life of the shuttle approximately 10 tons was shaved off the weight of the external tank, so that represents about an extra 40% weight on top of the 16%, a low tech LH2 tank therefore might be approximately 22% dry weight. For comparison most of the liquid tanks in KSP are around 10% dry weight. So the 75k LH2 tank might weigh between .800 and 1.2 tons.