SRFirefox

@ATEC Rocket only, non-reusable.

Here's my entry - a sub-100T rocket-only disposable launch vehicle. Running Vectors on the first stage is, of course, not the most economical choice for a disposable launch vehicle, and a Boar booster with two Thuds for thrust vector control can be substituted to save the better part of 30k funds while sacrificing less than 1% mass fraction. It then becomes a very economical disposable mid-game career booster for on-orbit refueling, though less RCS/batteries and more fuel would make it better for the job. The there are several tricks I used to push the mass fraction as far as it would go on this vehicle. Firstly both the Boar+2xThuds and twin Vectors give approximately 2-2.2:1 TWR at takeoff, allowing me to start the gravity turn almost immediately; In fact, the rocket sits on the pad with ~3* tilt in the clamps.. This reduces gravity losses by about 350-450m/s over a more sedate 1.2:1 TWR. Secondly, since the payload makes up such a large fraction of the rocket's mass, the poodle is the best choice for the second stage engine, whereas a lighter payload rocket might use a Terrier or even a Spark engine to get better delta-vee. By starting ascent with such a high TWR first stage and releasing it low in the atmosphere at high velocity, the long-burn second stage has plenty of time to expend its fuel and bring the payload into orbit. Third, the payload is as aerodynamic as possible - even with a very aggressive gravity turn drag only rises slightly over 2m/s^2 before beginning to fall again. Finally, by using the fuel tank adapter on the second stage, I am able to use 1.25m tanks to fine tune the delta-vee of the stage and use the 1.25m decoupler, which eeks out a little bit more delta-vee than the much heavier 2.5m decoupler even though the conical tank is 30kg heavier than its cylindrical counterpart (50kg + 30kg vs 400kg); those extra 320kg can go straight to payload instead. Launch Mass is 93,615kg and payload to orbit is 23,420kg making for a mass fraction of 25.017%. I leave MechJeb's Smart ASS up the whole time to show that I am not using it but only the data readouts. If I need to I will install KER and fly the mission again with that instead.

HoneyFox, is it possible to define more than one ignitor type for an engine in RSS/RO? I'm trying to code an LR-87 analogue, which was configured for A50/NTO, LH2/LOX, and Kerolox duty during it's long life. Each of which will have different EI requirements, of course. Change your upper stages to NTO/Hydrazine (MMH, UDMH, Aerozine50) type engines with Service Module type tanks until you get the hang of it. When using unpressurized (anything non-hypergolic) fuels, you need to ignite your upper stages shortly after burnout of the first stage or use ullage motors or RCS to ullage the fuel to the bottom of the stage. Using the SM type tanks with NTO/Hydrazine engines will allow you to follow whatever ascent path you wish, including large drifts between MECO and SEI (Main Engine Cutoff and Second Engine Ignition). Ultimately, your best shot at playing RO with Engine Ignitor is to learn to design rockets that will fly along a proper gravity turn which will allow you to ignite your second stage shortly after MECO (within 5 seconds). Upper stages with starting TWRs of 0.7-1 are easiest, but it is possible in RO to use upper stages with starting TWRs of less than .2 (Atlas-Centaur comes to mind). Burning above or below prograde to control time to apogee is the trick here - below for high TWR upper stages and above for low TWR stages. For examples of rockets which use ullage systems, observe the Saturn V, Falcon 9, and Centaur. The SV used small solid rocket engines strapped to the side of the third stage for ullage as they would only be used for one reignition before the stage was spent. Procedural SRBs or sepatrons with the trust limited for longer burns will work for this in RO. Remember to experiment - a longer, lower thrust SRB burn is usually better. For rockets like the Centaur, a hydrolox upper stage employed on several rockets, a pressurized reaction control system is used to provide a small forward acceleration to ullage the fuels. In RO, RCS quads around the fore and aft of your upper stage will work on lighter stages and can usually be augmented by verniers or linear RCS ports spread on the base of the stage around the main engine if you need more acceleration (hold that H key!). In either case pull up the info window on the engine to be started and watch the ignition stability, waiting for it to indicate that the fuel is stable. Until this happens, leave your throttle at 0 or you will just waste ignitions. Once it does, immediately throttle up and the engines should ignite. Make sure you're ready and know exactly how you're going to burn, because once you shut them down you're done unless you have more ignitions and/or ullage fuel or are quick enough to get in on the auto-ignition before the engine cools down. Hope this helps!

Just to make sure everything is as-intended, here's a copy of my DRE configuration file. REENTRY_EFFECTS { name = Default shockwaveMultiplier = 1.0 // multiplier to the temperature of the air due to high velocity. shockwaveExponent = 1.0 // exponent to (above temperature), applied before above multiplier. heatMultiplier = 25 // rate at which heat from the shockwave is tranferred to the part temperatureExponent = 1.03 // exponent to the transfer densityExponent = 0.85 // exponent applied to air density (heat transfer is also dependent on air density) startThermal = 750 // the velocity at which the red/orange thermal FX starts appearing fullThermal = 1150 // the velocity at which it becomes full strength afxDensityExponent = 0.85 // the exponent to air density for the FX gToleranceMult = 6.0 // multiplier to the G tolerance of parts, which starts at sqrt(part.crashTolerance * 6) parachuteTempMult = 0.25 // multiplier to part.maxTemp for burning up deployed chutes crewGClamp = 30 // Any G level > this is treated as this crewGPower = 4 // exponent to the G level. G damage is added at a rate of G^power per second crewGMin = 5 // Any G level < this is ignored for crew damage, and G damage is reset crewGWarn = 450000 // when G damage reaches this level, warn the player crewGLimit = 900000 // when G damage reaches this level, start killing crew crewGKillChance = 0.01 // chance per tick a crewmember will die (if damage is > GLimit) // any part with a maxTemp over this value will have its maxTemp multiplied // by maxTempScale. ridiculousMaxTemp = 2500 maxTempScale = 0.5 }

Everything is as it came from the factory, and yes, I'm using RSS standard Earth config with RO and all required and suggested mods. Falcon 9 liftoff TWR is 1.21 and Energia liftoff TWR is 1.53. F9 and F9H are launched from KSC and Energia is launched from Baikonur.

I was using DRE as part of Realism Overhaul today and noticed that my replicas of the Falcon 9, F9H, and Energia launch vehicles, all of which have relatively high TWRs on take off (1.3-1.5). My F9 is about as close as I can get it to realistic, weighing just over 500 tonnes at liftoff. Lacking better information than external measurements on the Energia, I'm using known payload mass and external measurements to make a best guess. Problem is, both vehicles reach ~30km at between 800 and 1000 m/s, which is heating components to the point of failure. I'm finding this very odd since the vehicles are well past max Q and as far as I can tell, I'm following something approximating a realistic flight path for the F9 and F9R and doing a best guess burn for 400km on the Energia. I could go higher more quickly, but then I end up burning out well before apogee and launching into a high suborbital path. I could use a little help figuring out what I'm doing wrong.

I'll have a go at it in the morning, but do note the RD-0120CH and RD-0146U configurations for burning LCH4/LOX. While not of particular practical value at this point in the mod, its still one more thing to add, especially if realistic ISRU on Duna/Mars becomes a thing.

The Bobcat Soviet engines' included configs are out of date and/or incorrectly written, so I wrote up a fix for my install, since I love the Energyia and Soyuz launch vehicles. I've included guesstimates tech levels (ie. 4 for the Energia engines, 7 for the RD-0146), adjusted oxidizer-fuel ratios where necessary and where I could get the info, and even added the only Methane/LOX configs I know to exist to the RD-0120 and RD-0146, as they both had the configuration proposed but not implemented. I also tweaked the mass on the RD-171, though Bobcat's could just as easily be correct as I. These configurations are designed to work without modifying the engines' original files. Finally, I've put the full real gimbal ranges of the engines that I've been able to find, but be aware the RD-171 and it's derivatives have large ranges, up to 8 degrees. @PART[NK33]:Final //Bobcat Soviet NK-33 { @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 28.5 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 71.5 } } @MODULE[ModuleEngineConfigs] { techLevel = 4 origTechLevel = 4 engineType = L+ origMass = 1.222 @configuration = Kerosene+LiquidOxygen @CONFIG[DefaultConfig] { @name = Kerosene+LiquidOxygen !minThrust{} @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 0.285 @DrawGauge = True } @PROPELLANT[LiquidOxygen] { ratio = 0.715 } @IspSL = 1.35 @IspV = 0.98 throttle = 3 } } } @PART[NK43]:Final //Bobcat Soviet NK-43 { @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 28.5 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 71.5 } } @MODULE[ModuleEngineConfigs] { techLevel = 4 origTechLevel = 4 engineType = U origMass = 1.396 @configuration = Kerosene+LiquidOxygen @CONFIG[DefaultConfig] { @name = Kerosene+LiquidOxygen !minthrust{} @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 0.285 } @PROPELLANT[LiquidOxygen] { @ratio = 0.715 } @IspSL = 1.206 @IspV = 1.018 throttle = 3 } } } @PART[RD0120]:Final //Bobcat Soviet RD-0120 { @mass = 3.45 @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = LiquidH2 @ratio = 72.8 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 27.2 } } @MODULE[ModuleEngineConfigs] { techLevel = 5 origTechLevel = 5 engineType = U origMass = 1.396 @configuration = LiquidH2+LiquidOxygen @CONFIG[DefaultConfig] { @name = LiquidH2+LiquidOxygen !minthrust{} !atmosphereCurve{} @IspSL = 1.734 @IspV = 1.319 throttle = 1.5 } CONFIG { name = LqdMethane+LiquidOxygen maxThrust = 1576 heatProduction = 150 PROPELLANT { name = LqdMethane ratio = 0.443 DrawGauge = True } PROPELLANT { name = LiquidOxygen ratio = 0.557 } IspSL = 1.382 IspV = 1.052 throttle = 1 } } @MODULE[ModuleGimbal] { @gimbalRange = 8 } } @PART[RD0124]:Final //Bobcat Soviet RD-0124 { @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 30.1 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 69.9 } } @MODULE[ModuleEngineConfigs] { techLevel = 7 origTechLevel = 7 engineType = U origMass = 0.48 @configuration = Kerosene+LiquidOxygen @CONFIG[DefaultConfig] { @name = Kerosene+LiquidOxygen !minthrust{} @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 0.301 } @PROPELLANT[LiquidOxygen] { @ratio = 0.699 } @IspSL = 1.554 @IspV = 1.011 throttle = 3 } } } @PART[RD0146]:Final //Bobcat Soviet RD-0146 { @mass = 3.45 @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = LiquidH2 @ratio = 72.8 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 27.2 } } @MODULE[ModuleEngineConfigs] { techLevel = 7 origTechLevel = 7 engineType = U+ origMass = 0.26 @configuration = LiquidH2+LiquidOxygen @CONFIG[DefaultConfig] { @name = LiquidH2+LiquidOxygen !minthrust{} !atmosphereCurve{} @IspSL = 1.654 @IspV = 1.255 throttle = 1.5 } CONFIG { name = LqdMethane+LiquidOxygen maxThrust = 76.2 heatProduction = 150 PROPELLANT { name = LqdMethane ratio = 0.443 DrawGauge = True } PROPELLANT { name = LiquidOxygen ratio = 0.557 } IspSL = 1.622 IspV = 1.03 throttle = 1 } } } @PART[RD171]:Final //Bobcat Soviet RD171 { @mass = 9.5 @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 29.8 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 70.2 } } @MODULE[ModuleEngineConfigs] { techLevel = 4 origTechLevel = 4 engineType = L origMass = 10.3 @configuration = Kerosene+LiquidOxygen @CONFIG[DefaultConfig] { @name = Kerosene+LiquidOxygen !minThrust{} @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 0.298 @DrawGauge = True } @PROPELLANT[LiquidOxygen] { ratio = 0.702 } !atmosphereCurve{} @IspSL = 1.073 @IspV = 1.053 throttle = 3 } } @MODULE[ModuleGimbal] { @gimbalRange = 6 } } @PART[RD180]:Final //Bobcat Soviet RD180 { @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 29.1 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 70.9 } @atmosphereCurve { key = 0 339 key = 1 313 } } @MODULE[ModuleEngineConfigs] { techLevel = 5 origTechLevel = 5 engineType = L origMass = 5.48 @configuration = Kerosene+LiquidOxygen @CONFIG[DefaultConfig] { @name = Kerosene+LiquidOxygen !minThrust{} @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 0.291 @DrawGauge = True } @PROPELLANT[LiquidOxygen] { ratio = 0.709 } !atmosphereCurve{} @IspSL = 1.061 @IspV = 1.037 throttle = 3 } } @MODULE[ModuleGimbal] { @gimbalRange = 8 } } @PART[RD191]:Final //Bobcat Soviet RD191 { @MODULE[ModuleEngines] { @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 29.8 } @PROPELLANT[Oxidizer] { @name = LiquidOxygen @ratio = 70.2 } } @MODULE[ModuleEngineConfigs] { techLevel = 4 origTechLevel = 4 engineType = L origMass = 3.23 @configuration = Kerosene+LiquidOxygen @CONFIG[DefaultConfig] { @name = Kerosene+LiquidOxygen !minThrust{} @PROPELLANT[LiquidFuel] { @name = Kerosene @ratio = 0.298 @DrawGauge = True } @PROPELLANT[LiquidOxygen] { ratio = 0.702 } !atmosphereCurve{} @IspSL = 1.08 @IspV = 1.053 throttle = 3 } } @MODULE[ModuleGimbal] { @gimbalRange = 8 } } Also, Having a 4m capsule and 2.5m crew cans seemed silly, so here's a rescale of the lab and crew can modules to size and mass them for 4m diameter parts. I also increased the amount of electricity used for resetting the SCIENCE from the lab, since it is measured differently now. @PART[crewCabin]:Final { @rescaleFactor = 1.6 @node_stack_top = 0.0, 0.986899, 0.0, 0.0, 1.0, 0.0, 4 @node_stack_bottom = 0.0, -0.986899, 0.0, 0.0, 1.0, 0.0, 4 @mass = 6.5 } @PART[Large_Crewed_Lab]:Final { @rescaleFactor = 1.6 @node_stack_top = 0.0, 1.830905, 0.0, 0.0, 1.0, 0.0, 4 @node_stack_bottom = 0.0, -1.830905, 0.0, 0.0, 1.0, 0.0, 4 @mass = 10 @MODULE[ModuleScienceLab} { @RESOURCE_PROCESS[ElectricCharge] { @amount = 800 } } }

In Real Fuels? Not nearly as much as in Real Life . If you can launch an infinite amount of mass into orbit, then tank volume of hypergolic fuels becomes alot less than take volume of H2 nuclear fuel. That said, no rocket scientist looks at it by volume, but by launch mass. Look at the mass of the H2 tanks. It's tiny compared to any other fuel. The balloon tanks from StretchySRB make this even more apparent. This, combined with the efficiency of even a medium-efficiency NTR makes the cumbersome task of launching huge H2 tanks into orbit worth it - the resulting mass fraction (useful vehicle mass + dead weight vs fuel) is much better for a NTR than for a traditional chemical rocket. You're too used to stock KSP to notice the advantages. Let's ask Tsiolkovsky and his rocket equation to demonstrate. We'll assume we're going to stock Jool with no aerobraking in either direction, hauling the whole ship, which comes out to 9km/s or so dV. 340s ISP hypergolic rocket 9000 = 340 * 9.81 * ln(mass fraction) 2.70 = ln(mi/20) 2.718^2.7 = mass fraction mass fraction = 14.9 800s ISP nuclear thermal rocket 9000 = 800 * 9.81 * ln(mass fraction) 1.15 = ln(mass fraction) 2.718^1.15 = mass fraction mass fraction = 3.16 Thus we see that you will need less than a quarter the mass in fuel to make the trip with an NTR, assuming tankage mass is equal (which is not always the case). However, I think you can see the advantage of only needing 2.16 tonnes of fuel for every tonne of spacecraft instead of 13.9 tonnes of fuel for every tonne of spacecraft. So yes, it is still worth it to make the launches of LH2. You'll just need to strap on some cryocoolers (thermal fins in MFS) and make some tanks big enough to haul the fuel you need. I suggest multiple launches to make life easier on yourself. If you're not using stretchySRB, then I suggest either KWRocketry or NovaPunch for some of their larger tanks (especially the 5M NP tanks).

I'll usually just fill the extra space with a monoprop or other tank, then tell MFS to do a fill-by-engine-type. Then I either empty or delete the other tank. Done!

Quite enjoying the mod, and I'm working on a full-scale Energia launcher right now to see if, hey, parallel stacks are actually possible with this. All signs are pointing toward 'maybe.' A thought popped into my head though, and I was wondering if it was possible to make gimbal range modifiable within the engine MFS screens. I could certainly use more than a degree and a half of gimballing range, especially for an asymmetric design like the Energia.

More importantly, regular aerodynamic sensibilities apply when flying in FAR. It isn't that the drag of parts is lower (often, it isn't), but that the craft is treated as a whole and not the sum of it's parts. Therefore a strangely shaped payload will usually flip out in FAR due to drag, whereas adding a fairing around said payload will both significantly reduce drag and increase control. Nosecones on boosters are a must for the same reason. The parts inside/behind these parts then don't have drag from compressing the airflow before them, but simply whatever drag their surface adds as the air goes by. When the rocket is properly sleek, then the terminal velocity goes way up. Ninja'd by Ferram himself! Awesome

I've been messing around with the KSPX and stock NTRs and I think I've come up with a useful configuration for them if you want to add it to your mod. The KSPX NTR now has about 149 hours of useful burn time (for those who like to refuel their ships) and the stock engine has about 68 hours of useful burn time. This is based on fuel erosion as the hydrogen fuel passes through the fuel element, and the data was taken from Wikipedia's site on NTRs, specifically NRX and Nuclear Furnace test firings. I think I've gotten the math right, though you should check it anyway. The generator's fuel usage is based on the half-life of U235 and effectively infinite for the sake of most KSP players. @PART[nuclearEngine] { @maxTemp = 2200 @MODULE[ModuleEngines] { @maxThrust = 60 @heatProduction = 300 @PROPELLANT[LiquidFuel] { @name = LiquidH2 @ratio = 1.0 } @PROPELLANT[Oxidizer] { @name = nuclearFuel @ratio = 0.000001 } @atmosphereCurve { @key,0 = 0 850 @key,1 = 1 420 } } MODULE { name = ModuleAlternator OUTPUT_RESOURCE { name = nuclearFuel rate = -0.000000000000000005 } OUTPUT_RESOURCE { name = nuclearWaste rate = 0.000000000000000005 } OUTPUT_RESOURCE { name = ElectricCharge rate = 0.25 } } MODULE { name = ModuleGenerator isAlwaysActive = true OUTPUT_RESOURCE { name = ElectricCharge rate = 0.25 } OUTPUT_RESOURCE { name = nuclearWaste rate = 0.000000000000000005 } INPUT_RESOURCE { name = nuclearFuel rate = 0.000000000000000005 } } RESOURCE { name = nuclearFuel amount = 5 maxAmount = 5 } RESOURCE { name = nuclearWaste amount = 0 maxAmount = 5 } } @PART[cl_large_nuclearEngine] { @maxTemp = 2200 @description = After the success of the LV-N, a new, larger version was developed for the Rockomax line of parts. This version contains a togglable post-core Liquid Oxygen injector, to boost power when you need it most. You might want to pack a dosimeter. @MODULE[ModuleEngines] { @maxThrust = 150 @heatProduction = 350 @PROPELLANT[LiquidFuel] { @name = LiquidH2 @ratio = 1.0 @DrawGauge = True } @PROPELLANT[Oxidizer] { @name = nuclearFuel @ratio = 0.0000009 } @atmosphereCurve { @key,0 = 0 915 @key,1 = 1 550 } } MODULE { name = ModuleAlternator OUTPUT_RESOURCE { name = nuclearFuel rate = -0.0000000000000001 } OUTPUT_RESOURCE { name = nuclearWaste rate = 0.0000000000000001 } OUTPUT_RESOURCE { name = ElectricCharge rate = 1.0 } } MODULE { name = ModuleGenerator isAlwaysActive = true OUTPUT_RESOURCE { name = ElectricCharge rate = 0.5 } OUTPUT_RESOURCE { name = nuclearWaste rate = 0.0000000000000001 } INPUT_RESOURCE { name = nuclearFuel rate = 0.0000000000000001 } } MODULE { name = ModuleHybridEngine configuration = LiquidH2 CONFIG { name = LiquidH2 thrustVectorTransformName = thrustTransform exhaustDamage = True ignitionThreshold = 0.1 minThrust = 0 maxThrust = 150 heatProduction = 350 fxOffset = 0, 0, 1.0 PROPELLANT { name = LiquidH2 ratio = 1.0 DrawGauge = True } PROPELLANT { name = nuclearFuel ratio = 0.0000009 } atmosphereCurve { key = 0 915 key = 1 550 } } CONFIG { name = LiquidH2+LiquidOxygen thrustVectorTransformName = thrustTransform exhaustDamage = True ignitionThreshold = 0.1 minThrust = 0 maxThrust = 400 heatProduction = 375 fxOffset = 0, 0, 1.0 PROPELLANT { name = LiquidH2 ratio = 0.7 DrawGauge = True } PROPELLANT { name = LiquidOxygen ratio = 0.3 DrawGauge = True } PROPELLANT { name = nuclearFuel ratio = 0.0000009 } atmosphereCurve { key = 0 485 key = 1 390 } } } RESOURCE { name = nuclearFuel amount = 25 maxAmount = 25 } RESOURCE { name = nuclearWaste amount = 0 maxAmount = 25 } RESOURCE { name = ElectricCharge amount = 0 maxAmount = 0 } }

In my explorations of the Real Solar System mod, I've found that the stock NERVA engines appear to burn through their nuclear fuel in a little over a year and the KSPX NERVA seems like it takes only a few weeks while not in use. Needless to say, this makes them useless for even a jaunt out to Duna-Mars or Eve-Venus let alone trying to haul large payloads to Moho-Mercury or out past the asteroid belt. When I'm more awake, I'll look at playing with the config files to see if I can fix it.

I came across a rather entertaining bug this evening trying to see if I could get something out to Dres-Saturn. Turns out that solar panels that far out not only do not produce power as it should be, but they actually drain power. A gigantor panel in orbit around Laythe-Titan will drain approx 2 charge/second when properly oriented. Thought you might like to know.

This mod (coupled with all the other RSS support mods) is great! I made a work-alike Falcon 9 the other night, and made it into orbit with a few hundred dV to spare with my 13T payload, which I must say was awesome! A suggestion for the future would be inter-planetary tanks strictly for holding LH2. I was reading a report on using NTRs to haul payload to Mars last night and the poor mass fraction of even the big KW cryo tank struck me as annoying, if passable. This report being theoretical, it proposed using the SLS to launch 121 metric tonnes of Hydrogen slush(!) into orbit for the proposed mission, density ~81.8 kg/m^3 if I did my math correctly. Using a tank (+support equipment) that weighed 4 tonnes and was 10m in diameter, leaving us with a mass fraction of 31.25! While I don't expect a mass fraction quite that good from LH2 in MFS, it would be nice to get a mass fraction above 8-9. That said, this mod has demonstrated in several ways why we have not yet been to Mars. To get my ~80 tonnes of everything else to Duna and then a small CSV back to Kerbin, I needed something like 25 3.75x15m KW cryo tanks full of LH2. Joy. Another useful feature from the paper would be an active (power hungry) cryo-cooling plant to keep boil off to a minimum - I don't see any other way of making a long NTR trip to anywhere when boil-off will kill dV waiting for the transfer window home.

Can a standard RCS thruster be made to use MMH and Nitrogen Tetraoxide? I'm mucking about with cBBp's Dragon Rider mod, and I'm seeing if I can get it to work on that combo rather than monoprop, but if I can't get the Dracos to run on the same fuel as the Super Dracos, I'd rather have one propellant supply instead of two.

I've found that MechJeb's ascent autopilot is fairly useless for FAR launches (surprise surprise), so I've been flying with SAS to stabilize the roll axis while I adjust pitch and yaw. Your comment has lead me to redesign my latest launcher with more care into how the axes are controlled. I am using one large 1900kN KW engine for the core and locking its gimbal, then placing four 'vernier' 100kN coxswain engines around it to control pitch and yaw in the lower atmosphere. I'm also using four delta wings as fins for aerodynamic stability and then putting small control surfaces at the tips for roll control only. Even a slightly sloppy gravity turn was enough to get my 14T payload into orbit. The difference was night and day, thanks for the help!

I'm playing with this combined with MechJeb2, KW Rocketry, FAR (of course), and NathanKell's Modular Fuel System and Real Solar System. When flying a moderate sized rocket ~100-150 tonnes, I'm getting horrible oscillations when actuating the controls past 200m/s or so. It seems possible that the engines are staying inline and the whole rocket is moving about the gimbal, as the appearance is that the entire rocket moves side to side as the main gimbal and control fins. I'm still trying to pin down the exact cause, but I could use some help knowing where to look and what to look for. The test rockets that demonstrate the worst problems are inevitably 3.75m part behemoths with payloads in the 8-15 tonne range. Without the reinforcement mod and even with stock parts I'm able to get small payloads into orbit.

I noticed you throttled down your 1st stage to reduce the gees to something manageable. Believe it or not, the real Saturn V did something similar for the same effect - it shut down the central engine right around 5 gees. That was a very cool recreation of Apollo, many props to you! I've been playing with the mod a bit and I'm enjoying it very much. One of my mods is not playing nice though. When I stripped out all mods except FAR and RSS, I was able to get a 3 man capsule to orbit with a few hundred m/s to spare. With all other mods installed, I had a horrible time controlling rockets that I thought should otherwise be stable. Over-control and terrible oscillations were the name of the game. My mod list was as follows: KW Rocketry, MechJeb2, a few parts from AESAerospace, I^3's radial drogue, Enhanced Nav Ball, a few parts from KSPX, MechJeb2, and the Triggertech Kerbal Alarm Clock. I initially removed Farram's joint strengthening mod, but that did not fix the problem. I've started adding mods back in until I find the culprit, so I'll keep you updated.

As I was messing around with welding my service vehicle's service module into one piece, I noticed that the drag was cumulative. In KSP, I believe the way drag affects an object is based on it's weight, so a weighted average based on mass would be the the best representation (by KSP standards) of the drag of a welded object. I might also suggest you add a rounding pass to the part coordinates, though I doubt the difference between 5.38657E-12 and 0.0 is terribly important. One other thing, I had issues with getting one node of a welded part to function, would it be useful if I sent you a copy of the part for analysis?

Success! I made it to orbit with about half of the remaining oxidizer, and barely used the aerospike in the process. Using the aux thrust from the NERVAs, I was able to hold onto the last two jets until ~37k. This is where my flightplan differs significantly from yours. When above ~36k or so, atmospheric drag (especially with the intakes closed) becomes very small. With a short burn at about 25* with the aerospike, I pushed the apokee to T-2:30 and then used a few minutes worth of nuclear engine burn to push it to ~160k, the location of my future space station. It worked a charm, following the first four and a half steps of your plan worked brilliantly. Thanks!

The Argo spacebus is a pretty awesome craft. I've gotten it into orbit a couple times, but I have a few critiques for it. Most importantly, the intakes that cannot be shut are causing serious drag problems when the nukes are engaged. This wouldn't be a problem if it could get up to 2000m/s on the jets alone, but I've only managed around 1600m/s on jets before the last two flamed out. I have been unsuccessful at pulling it apart to re-allocate the action groups to close those intakes. I'm also having issues with fuel displacement and trying to see through the clipped tanks to transfer it around. I'll get back to you if I can 'fix' any of those problems. That said, can't beat putting sixteen intrepid astronauts in orbit at one time!

Name: SRFirefox World Preference: Tylo (yes, Tylo. Don't look at me like that) Character Name: Cmdr. Hans Kerman Resume: Station and Satellite support network around Kerbin, including construction/refueling stations around Kerbin and the Mun. Landed 4 Kerbonauts on Tylo with one vehicle and returned them safely to Kerbin in 3 years. Lead several missions to Moho and the Moholes. Commissioned DS1 and Charon, an orbital platform and base complex on/around Eeloo. Final population 12 Kerbonauts. Developed the Winter series of reusable launchers, 11-25T to orbit. All reusable stages propulsively landed.

I've been working on my entry to this challenge for about a week now, and I think I have the launch vehicle family to do the job. Now I just have to choose which one I like best. Each one of these vehicles is rated very near it's maximum payload to 100km LKO, and requires precise flying to achieve orbit with it's rated payload. The test payloads are a stack of 4 ton Kethane refiners with a 0.5 ton probe core attached. I use a combination of MechJeb and hand-flying to make sure they get where they need to be. Also, while the first stage cores all get re-entry flames, they only hit the lower atmosphere at ~1400m/s and Deadly Re-entry doesn't even bring up a heat meter. Without further ado, the Winter series of launch vehicles: Flurry MRLV The Flurry launch vehicle was designed specifically to carry the Kraken Crew Service Vehicle into orbit, and as such features single engine-out capability* and extra fuel in the second stage. The Flurry is also the first of it's kind in reusable launch vehicles, recovering it's stretched Crystal boosters by parachute splash-down and the first stage by propulsive landing in the Kerban Ordinance Test Range, 360 kilometers east of KSC. Kerb-Rated Payload to LKO: 11.5 T (12.5% derated) Fuel Load: 88 T Mass Fraction: 10.22 Fuel Usage per Tonne Payload: 7.65 T Liftoff Mass: 130 T Liftoff Thrust: 1690 kN TWR @ Liftoff: 1.33 *Flavor text only Kraken Crew Service Vehicle The Kraken CSV is the workhorse of Kerbin's kerb-rated vehicles, putting up to seven kerbals comfortably into the arms of an awaiting station or ship. The Kraken is not designed to be long-term habitation for it's inhabitants, and relies on existing architecture to support it's crew for long-term missions. The KCSV can be launched unmanned as a contingency or lifeboat to larger craft and stations. A modification to the original design, the Long Range Rescue and Resupply variant, has been designed for missions requiring up to 1000m/s extra dV or supply delivery to LKO. V4 now includes reusable Flurry Reusable MLV. Crew: 2-7 On Orbit dV: 200m/s Hypergolic, 200m/s Monopropellant Service Ceiling: 150km circular equatorial Launch Vehicle: Flurry MRLV Snowstorm HRLV As Kerban scientists became more and more ambitious in their persuit of lofty goals and loftier space stations, station modules being dreamt up by engineers became too heavy for the Flurry to lift. Instead of giving up on the Flurry design, engineers simply stuck to the Kerbal tradition of MOAR BOOSTERS! The core of the Snowstorm is similar in tankage to the Flurry, though slightly larger, and the boosters are Flurry first stages used in their entirety with nosecones. Like the Flurry, much of the Snowstorm is reusable - both boosters and core are designed to land propulsively. The core makes the hop to the KOTS, while the boosters brake and return to KSC. Payload to LKO: 20 T Fuel Load: 136 T Mass Fraction: 10.05 Fuel Usage per Tonne Payload: 6.8 T Liftoff Mass: 201 T Liftoff Thrust: 3160 kN TWR @ Liftoff: 1.64 Squall HRLV Evolved from the Snowstorm launch vehicle, the Squall uses four standard length Crystal satellite booster first stages as long-burn boosters, adding 400kN of liftoff thrust to the Snowstorm design. This in turn allows the use of a heavier second stage, doubling both it's thrust and fuel capacity. The new design allows for an improved mass to orbit ratio of 9.16 over the Snowstorm's 10.05. Like the Snowstorm, the first stage and main boosters are propulsively landed for reuse. The Crystal boosters are light enough to be recovered under parachute and splashed down. Feasibility tests are underway to determine if sustainer recovery is possible. Payload to LKO: 28 T Fuel Load: 176 T Mass Fraction: 9.16 Fuel Usage per Tonne Payload: 6.29 T Liftoff Mass: 261 T Liftoff Thrust: 4020 kN TWR @ Liftoff: 1.57 I will update later with pictures of the launch and recovery of the propulsively landed stages of each vehicle. To Be Continued....