sevenperforce

The difficulty, I think, is in the whole "packing aluminum into your cylinder" aspect.

I need to set an action group to control the "free pivot" tweakable/toggle on the AGU, but it's not showing up. Any idea why?

Eh, I don't like it. It's not really realistic to mine aluminum to refuel a solid rocket; you can't refuel a solid. Better to have a hybrid rocket full of solid reducer that uses oxidizer from attached tanks as a resource. You can mine for more oxidizer if you want.

This is unclear. Are you talking about a carrier aircraft, like stratolauncher, or an SSTO with drop tanks?

Yes, but I'll interpret that loosely.

The ICBM is suborbital so it needs to be intercepted outside of the atmosphere. Or you can use a persistence mod if you want to do the interception inside the atmosphere. This makes it more tricky (but also a lot closer to the real thing).

You can launch from anywhere you want; it just has to cross 70 km and re-enter. But launching from farther away, or from a higher latitude, will get you bonus points. I'll accept proximity interceptors for Level 3, but the point of Level 4 is to match the GMD system used by the Pentagon, so it needs to be a kinetic kill. If your level-3 proximity interceptors don't actually kill the ICBM you can still get points for trying (or for demonstrating that a payload the same size as yours could have rendered a nuclear device inert). Also note additional edits above.

Yes! Once we have submissions, I'll create a leaderboard, and I'll be ranking submissions within each level based on difficulty. If you make your vehicle identical to an actual launch vehicle or if you can do something crazy like a sub launch, that'll put you on top in your level!

Kerbal Space Center is home to nine structures: Astronaut Complex Flag Pole Launch Pad Runway Spaceplane Hanger Tracking Station VAB Administration Building Research & Development Center You are a rogue agent who has infiltrated the KSC with a mission to sabotage the Space Program. Your plan is to wheel out a launch vehicle under cover of darkness, then fire it...sideways. Your goal is to take out as many of Kerbal Space Center's structures as possible in a single launch. You only have one shot before you will likely be caught, so you've got to make it count. Scoring will be based on the number of structures you successfully destroy, with scoring within each bloc based on launch vehicle weight. I'm expecting people to simply put everything on the launch pad at angles and stage once to fire it all, with the angles preplanned, but if you want to launch a platform into space and use MIRVs to do your dirty work, that's fine too!

In honor of the Missile Defense Agency's successful kill of a simulated high-velocity ICBM launch, I thought I'd throw together a unique challenge. We KSP players have a special appreciation for just how difficult it is to hit a suborbital rocket with another suborbital rocket. For this challenge, try building the components to test an ICBM interceptor defense system! Level 1: Build a multistage ICBM that crosses 70 km, re-enters, and strikes a defined target. Level 2: Using HyperEdit or a mobile launcher, build and launch an ICBM to hit Kerbal Space Center. Level 3: Design and demonstrate a kill vehicle capable of intercepting the ICBM before it hits Kerbal Space Center. Level 4: Design and demonstrate a four-stage solid-fueled interceptor with RCS-based guidance on the fourth stage, capable of intercepting an ICBM above the atmosphere. Good luck! EDIT: If you want to reach Level 3 or Level 4 but don't want to spend time on Level 2 (or don't have HyperEdit), you can substitute by placing your target in orbit and then burning retrograde so you hit it when it's suborbital. EDIT 2: Stock KSP has no good high-velocity heat shields, so it's fine to turn on "Ignore Max Temperature" in the cheats menu if you need to.

Beautiful, just beautiful.

Because, rocket equation.

The whole prograde half of the sky would glow, but it would be brightest and bluest in the center while fading continuously to red and then to black at the terminator. There would be no defined edge. As Steel said, you can mod anything you want; it just depends on how true-to-life you want to make it. The stock engines in KSP aren't very true-to-life, after all. A realistic hybrid rocket would be less like a traditional liquid-fueled rocket and more like a restartable solid booster, perhaps with a limited throttle range. Ideally, it would use oxidizer as a resource but not liquid fuel, and once it was expended it would not be refuelable (unlike a liquid rocket, where you can transfer fuel from another ship). With LACE, again, it depends on how realistic you want it to be. The real-life LACE concept is very problematic; it takes ridiculous amounts of liquid hydrogen to liquify air (so much that you end up just dumping hot hydrogen overboard instead of burning it), and the mechanism to separate the LOX from the liquid nitrogen is heavy. You also run into the reverse rocket equation problem; if you're collecting remass and oxidizer on your way up, your net thrust is the difference between total thrust and the momentum you are losing as you collect air. The faster you're going, the more momentum you lose with every kilogram of air you collect. For KSP, however, one could envision a modified engine precooler that takes liquid fuel as a resource and generated oxidizer; that plus a RAPIER would basically be LACE. Since KSP only has one liquid fuel type, a triprop engine isn't very easy to pull together. You'd have to mod to create new fuel types. Short of that, you could simply have an engine with a tweakable that can gain thrust in exchange for sacrificing specific impulse (or vice versa); that's basically how a triprop engine works in practice. Another solution would be to have an liquid engine that consumes monopropellant in addition to liquid fuel and oxidizer to increase thrust while losing isp. Since the monoprop in KSP is basically hydrazine, and a triprop engine could conceivably burn hydrazine in addition to hydrocarbon and LOX, that might be a good way to do it without making things overly complicated.

.....probably not.

Uselessly pedantic note: technically it glows white; it only appears orange because the atmosphere scatters higher-energy wavelengths, filtering out blue and violet light and leaving behind a nice warm orange glow. The sun is white when viewed from space.

For a concept like this, I wonder about the net payload impact of putting an altitude-compensating nozzle on the upper stage so it can fire at launch to improve TWR. Could go either way, I think. I'm a big fan of parallel staging, obviously.

Because if everyone had that attitude there would only be one car manufacturer, one American fast food restaurant chain, one enormous coffee shop chain and one football team in the world I mean, if it cannot outperform F9FT even on paper, why invest in it? I wouldn't invest in a fast food restaurant intended to compete with McDs unless it could actually outperform McDs at something.

"weight of the payload and shroud" is the interstage assembly, as I noted. And, as mentioned by mag, the ET carried the SRBs anyway.

Make the carrier vehicle a ducted rocket -- vertical liftoff, immediate gravity turn with the drag of the wings being exchanged for partial lift -- and we might be in business. But if it can't beat a Falcon 9 FT, why bother?

No. A ship in warp is not moving at all; rather, the space around it is moving. Moreover, Cherenkov radiation is the result of interactions with the local medium; a vacuum has no medium and so there is nothing to interact with.

Ran some numbers once more (apparently this is all I do) after I realized that the dry mass of the SLS core is rather higher than it ought to be. The Space Shuttle's Super Light Weight Tank held 733.5 tonnes of propellant with a dry mass of 26.5 tonnes; the SLS core carries 22% more propellant but masses three times as much. Add it up and it's about 40 tonnes of extra mass, not counting the weight of the four RS-25s. That 40 tonnes is divided between two things: the interstage assembly, to support the upper stage, and the engine mount and thrust structure, to support the engines and distribute their thrust, and to support the thrust of the SRBs. Can't do anything about the interstage, but if we went with a super-Atlas configuration with an engine skirt, the majority of the thrust structure could be jettisoned. Conservatively, I'll say 30 tonnes is jettisonable thrust structure and 10 tonnes is interstage and non-jettisonable thrust support structure. If I run the numbers with that, dropping the skirt structure along with the engines, then a core+skirt configuration can send 50.6 tonnes to LEO with no SRBs at all (jettison at 68% propellant consumption). If the core is launched with SRBs and no skirt, payload to LEO increases to 109.7 tonnes. If the launch uses the core, the skirt, and the SRBs, payload to LEO goes up marginally, to 112.2 tonnes (jettison at 71% propellant consumption). Of course, it may be that the skirt thrust structure is required for the SRB launches, making the "Core + SRB" configuration infeasible. However, the "Core + Skirt" configuration is still quite promising. It would be able to deliver ICPS + Orion + SM to the planned staging altitude and velocity for EM-1 without needing SRBs.

Tomato tomatoe. The core has the capacity to inject the ICPS + Orion + SM into a circular LEO, but to avoid leaving the core in orbit, MECO occurs in, essentially, an 1800 km x -10 km orbit.

Nah, that makes it too complicated. The winner is whoever can reach orbit with the lowest maximum velocity relative to the surface below 70 km.

So upon review, I think the "70 tonnes to LEO" capacity of SLS Block 1 actually includes the ICPS and Orion+SM. The ICPS has a wet mass of 30.7 tonnes; added to the mass of Orion and its SM, that's a total of just 57 tonnes. So the ICPS is included in the payload; the "payload" uses its TLI engine to raise perigee. It's just a coincidence that the low TWR of the ICPS (0.2 gees) means it would be incapable of lifting more than around 70 tonnes to LEO, if it were used as an LEO lifter rather than a BLEO departure stage. Hence the confusion.

Hmm...after checking the mission schedule, it does look like EM-1 will be the only flight of the SLS Block 1 with ICPS; all other missions will have the Block 1B upgrade and fly with the EUS. So the "70 tonnes to LEO" capability of the SLS is meaningless, since it will only ever be lifting a 28.5 tonne payload (the Orion with SM), and it will be sending it to the moon. 70 tonnes to LEO is what the SLS+ICPS could do, fully expending the ICPS, but since the core and boosters can take 70 tonnes to LEO without needing the ICPS, the ICPS would never be useful for LEO launches. I still think it would be better to give the Orion's Service Module some drop tanks and skip the ICPS entirely for EM-1, but what do I know?