sevenperforce

The game will not load vessels with a root part more than 2.5 km away from the root part of the vessel you are controlling, so it is impossible to build a vessel larger than 5 km long.

Only would have been possible if (as was the case in Eyes Turned Skyward) the F-1 could be modified to downthrottle considerably. A single F-1 would have had too much acceleration at burnout.

Successful staging and MVac ignition. Entry burn startup. Entry burn shutdown, successful. Nice clean view of the droneship! Although the landing pad has been scoured clean. No logo. Nominal parking orbit. Falcon has landed! Not that I had any doubts.... The soot levels on a new booster are so low...it feels weird.

Liftoff.

Presumably you are supposed to only stage with the spacebar. But this seems straightforward enough if you do a serially-staged rocket and simply construct it in the right order. Capsule, chute, decoupler, tank, engine, decoupler, tank, engine, decoupler, tank, engine.

That looks delightful. Very nice job. It's actually the third stage of the Saturn V, on top of a first stage that is a cluster of tanks borrowed from other rockets and lofted by eight small kerolox engines. It was referred to (with an equal mix of sarcasm and adulation) as "Cluster's Last Stand". The Saturn 1B flew multiple times before the Saturn V during the early Apollo missions to test parts of the lunar stack (technically, then, the Saturn V's third stage = the Saturn 1B's second stage, not the other way around). After the final Saturn V lofted Skylab, Pad 39A was modified with a 200-tonne steel "milkstool" that lifted the Saturn 1B up to the same height as the Saturn V, so they could use the same crew access arm and umbilicals for the upper stage and crew capsule. The Saturn 1B was an upgrade of the Saturn 1, which flew with essentially the same lower stage but with a cluster of RL-10 engines for its second stage, rather than the single J-2 that would be the workhorse of the Saturn V's third stage.

I'm thinking a reusable lawn chair ascent vehicle that takes drop tanks to the surface of Vall and then returns to meet an orbital transfer stage that refuels it (and has a Mk1 capsule to give the Kerbal a new flag). The transfer stage takes it to Bop and Pol in turn, where it lands on each in a single stage, returning to refuel and re-flag between. After those two, the orbital transfer stage takes it to Tylo, drops its empties, and drops the capsule in low Tylo orbit before acting as the descent stage and first ascent stage. The reusable ascent vehicle provides the second stage of ascent and the Kerbal circularizes and reaches the capsule on EVA props. Via a single linear monoprop thruster and a small extra tank, capsule has just enough dV onboard to leave Tylo's SOI, which with repeated gravity assists can get it on a Laythe-crossing trajectory. It brakes into low Laythe orbit to meet the Laythe lawn-chair sortie vehicle and refuel, which was placed at the start of the mission via aerobraking with the mission's only heat shield. That heat shield takes the Laythe sortie vehicle down to the surface and is dropped, and the ascent vehicle descends on chutes so the Kerbal can plant the flag. The ascent vehicle takes the Kerbal back up and he circularizes once more on EVA to reach the capsule, which has enough dV to leave Laythe's SOI and get gravity assists back to Kerbin.

That's what orbital rendezvous is for. Take only what you need to each surface. I suck at gravity assists or I would give it a go.

Pretty sure a Falcon 9 could put an entire second stage with payload into orbit on Kerbin. During the AMOS-17 launch, when SpaceX expended its used Block 5 booster, staging took place at 9520 km/hr or 2.64 km/s. Plus Kerbin's gravity drops off faster than Earth's, resulting in less gravity drag as you ascend. The only reason you need a light, short-turnaround surface-to-LEO craft is for crew, and with crew you either need a heavy LES or extraordinarily high vehicle safety margins. Entirely unfeasible. It's always going to be easier to just enter a phasing orbit and wait until your re-entry trajectory brings you down close to your home space port. Phasing orbits are essentially free, and refueling requires velocity-matching which requires you to be under power.

You definitely don't need four that size -- Tylo is the biggest challenge in the Jool system. And you can drop it lower by more parallel staging and using the jetpack for the final circularization. So perhaps doable. Given the single-engine-design constraints, I may write a script to identify the maximally efficient parallel staging design for a monoprop Tylo KLV. It's a balance between dropping empty stages as fast as possible and having too many decouplers.

UPDATE: I was able to make Tylo orbit with ease using a 1.5-stage, 4-tonne lawn chair ascent vehicle so something smaller is probably doable. Definitely if you use the jetpack.

Possibly. Getting off of Tylo would be tough.

It survives the flight profile while the engine is active and providing cooling, etc.; re-entry is much more challenging. Actually being able to perform controlled re-entry of an orbital vehicle is a huge challenge.

Skylon is unworkable because the underexpanded engine plume torches the back end of the ship in rocket mode. If they get this working and can make it good, great. It reminds me of a design I proposed a while back. The challenge is making reuse close with positive payload. Any engine that is good for SSTO is better for the first stage of a TSTO.

100 per planet; 80 per moon. I have updated the rules to add more point opportunities. Also @bayesian_acolyte now has more points.

China does it. Long March 5 uses kerolox boosters, a hydrolox core, and a hydrolox upper stage. Apart from China, the only operational rockets with liquid boosters are Falcon Heavy, Delta IV Heavy, and Soyuz-2, all of which use a single prop for the entire rocket (I am treating the Soyuz-2 kick stages as part of payload). Technically, India uses liquid (hypergolic) boosters on its first stage, but the core is a solid rocket and the boosters do not separate, so it's more like a cluster stage than proper boosters. Energia used RD-170s for its boosters and an RD-120 for its center core, so that's a mix of kerosene and hydrogen. The Pyrios booster proposal for SLS would have used kerolox boosters with a hydrogen core. With oxygen-rich staged combustion, I don't think the BE-4 can ever reach the same raw chamber pressure as the Raptor, which is the primary driver of the Raptor's ridiculous TWR and Isp. Full-flow staged combustion is a beast. The other variable is the size of the payload and where you are sending it. With a very small payload going to a high-energy orbit, a low-thrust hydrolox stage suffers less than it would with a larger payload and LEO or MEO. Of course a kerolox stage is still going to deliver more total dV but if the hydrolox one is staged high enough and fast enough it doesn't matter.

Vulcan already has to worry about loading both liquid methane and liquid hydrogen.

So I am going to have to call foul on the re-entry heat setting; that just makes it too easy (like turning gravity down or something). And points are only multiplicative for the number of relays dropped in; otherwise you only score once for each achievement. You would have been better off sending one to Minmus and one outside Kerbin's SOI.

Stan rocket kegstands? I'm really looking forward to Vulcan because as far as propellant allocation choice goes, it's pretty close to optimal. Solids to get you off the pad quickly and kill gravity drag, a high-performance methalox sustainer that has good mass fraction AND good specific impulse, and Centaur on top. No energy penalty for recovery because there's no boostback; just a little extra dry mass for the heat shield and chute (which, again, doesn't kill you because it's first-stage). The only thing better would be to swap in Raptors for the BE-4 (better thrust and better specific impulse) and something like a stretched Falcon 1 first stage with the Merlin1Ds to replace the solids.

I mean, the rocket equation is the rocket equation. dV is linearly proportional to specific impulse and proportional to the natural log of mass fraction. Since the specific impulse range of most bipropellant rocket engines is within a factor of 1.35, which is dramatically less than e, the advantage will always go to mass fraction. Obviously there are issues like staging velocity and TWR which are larger forcing functions on total dV. The longer first-stage burn time actually hurts you with respect to TWR, because the Falcon 9's TWR grows much faster than the Delta IV's. And FH is simply a much bigger rocket than DIVH. It is twice as heavy.

Nah, it's not about gross weight; it's about prop fraction. Centaur has a prop fraction of 9.3:1, not much better than the tanks in KSP. The propellant fraction for F9US is more than double that. It's not even close. It will have slightly better mass fractions but not dramatically so. Insulation is heavy and hydrogen is fluffy. These are not true balloon tanks; tank mass is closer to being linear to prop mass than it is to following the square-cube law.

You need more than just a tower -- you need the bunker and the ziplines and uprating for the TEL (it's a different mechanism) and so forth.

Small point here -- Falcon Heavy and Falcon 9 can both launch within a short period of time, but not if Falcon 9 is crewed, because pad 39A is the only one that can support FH, and it is the one with the crew access arm. You could launch crew on F9 and then let them loiter until you could set up FH on 39A but I don't know how many days it would take. It would probably be easier to just crew-rate FH in the first place than it would be to retrofit pad 40 for FH.

Got up to 224 m/s...could probably do better on the runway. Little discovery...drainvalve plumes don't collide, so you can stack them end on end with no problems. If I tilt it further over I can get to 251 m/s.

Who's to say they didn't?