sevenperforce

I've considered it but my supply of plutonium is a bit low. EDIT: In all seriousness, one of the big things with NTRs is the design. You can get up into some really wicked exhaust velocities if you're willing to bump up to a pebble-bed reactor.

Something like this has been proposed here before, if I recall correctly. **does a quick search** Ah, no, it wasn't here; it was over on the xkcd forum. One big problem. If all you have at the base is a bell-shaped cavity, then you have no choke, where flow moves from subsonic to supersonic. If you have no choke, you have no proper rocket engine at all.

You can vary the O/F ratio in-flight to start with high thrust and then transition to lower thrust with higher specific impulse. That's how the Saturn V rocket was able to lift so much more payload (rovers, etc.) with the later Apollo missions; they adjusted the mixture ratio of the engines across the course of the flight to maximize thrust at liftoff and then increase specific impulse over time. So "what's in rocket exhaust" will vary from "reaction products plus excess oxidizer" to "reaction products plus excess fuel" over the course of a burn, at varying ratios.

Hospital supply.

If you're on Windows, use F1 to screenshot, then go to your KSP source folder where they are stored.

Yeah, my thought is to set up the eccentric tangent orbit, burn target-retrograde in the rescue vehicle until relative velocity is less than 500 m/s, then switch to Burbarry and burn target-retrograde to match.

A standard jetpack has 650 m/s of dV, per the wiki.

You can try angling the front wings down slightly and the rear wings up; this will move the COL back behind the COM. Of course, this may limit climb angle as it increases the chance of your rear wings stalling, and it will may not work very well for maneuvering. Might want canards. Some of the smaller orbital Star Wars style spacecraft would be cool.

I used a wheeled delivery system for my stock Sea Dragon:

Deduct away. But, in my defense, I wouldn't have been able to mate the stages without infinite fuel at all, not without hundreds and hundreds of quicksaves. It's just extremely tedious.

So the Deep Space Transport needs to include a Duna lander, and we're going to send a Duna Ascent Vehicle and a Duna Habitation Module to Duna separately? Or the Deep Space Transport needs to be able to mate to (and transport) a Duna lander that will be sent to the DSG separately?

"Impress me", you said? I think this should do the trick. All stock, except that I used Tweakscale here and there to make it a bit easier on myself. I also used infinite fuel for the skycranes, since I wasn't really up to spending countless hours doing a challenging skycrane stage-mating with jet engines. Fully-reusable two-stage-to-orbit relaysat launcher. Primary launch vehicle, initial payload, refueling rigs, and secondary payload were all loaded in a single "launch". No "recovery" button use. First payload, upper stage, lower stage, and recovery/refueling rigs along with skycranes and second payload, all loaded onto the runway (for space considerations) at once. First recovery/refueling rig decoupled and backed away. I didn't end up needing to use this one at all. Second rig, with upper-stage recovery skycrane attached, decoupled and moved away. Third rig with second payload and attached skycrane, decoupled and backed away. Closing the second-stage engine cowlings. Liftoff! Climbing rapidly. Tweakscaling a Vector up to 2.5 meters might have been overkill. Throttled down. Nearly a vertical ascent. Still barely doing any gravity turn. Just need to get up out of the atmosphere. That should do it! Reserving approximately 25% of first-stage propellant seems to work. Decoupling, ramps open, fairing jettisoned, Dart engines ignited! Second stage rapidly outpaces the first stage. Circularization node set. Circularized! Now, back to the first stage. Still in a ballistic trajectory. Airbrakes out. Transferring fuel down to keep the COM as low as possible. Preparing to adjust trajectory. Edging over just slightly to cancel horizontal velocity. The map view is misleading; it takes the surface speed into account for the rocket trajectory but not for the surface itself. Continuing to adjust trajectory while burning through re-entry. Engine off; re-entry is not too bad, really. Starting my (slow) landing burn. No hoverslams for me! Throttling up now that I'm dangerously close to the surface. Will I make it? I believe so! Managed, with the barest of fuel reserves remaining! Now my first refueling rig heads off for its job. Note the secondary payload mounted on top. Each of these rigs has a probe core, a docking port, a single RTG, and a fuel cell array. Approaching the target. Mated! Initial refueling. Now here goes my second rig with attached S2 retrieval skycrane. Approaching... Also mated! Fuel transfer complete; first stage is fully-fueled. Back to orbit to check on my little friend. First relaysat away and fully-functioning! Note that periapsis is above 100 km. Honestly, this had enough margin to do KTO but I didn't want to bother with it. Burning to deorbit. This took a few tries to get right. I had a very small periapsis window. Jettisoned the payload adapter. Heat shield exposed; airbrakes out! Heating up. Coming in really hot. I had to toggle the airbrakes manually to keep them from overheating. Opening the engine ramps as the KSC comes into sight. Entry burn to kill speed before I hit the water. Reached terminal velocity. Descending. Fuel is going to be tight. Landing burn started. Still descending. Made it with bingo fuel! Quite a distance from where I need to be. Skycrane time! This is where I turned on infinite fuel. Without KER is something else to help me construct it, it was either infinite-fuel skycrane or jet engines, and jet engines don't change their throttle settings fast enough to be used for this kind of finely-controlled work. Heading out to pick up the upper stage. Landed next to it; ready to maneuver into position. Hovering... Coming in slowly... Mated! Skycrane lifting off, taking the upper stage back toward KSC. Wasting no time. Leveling out. Lining it up... Steady as she goes... Easing in. Mated! Decoupled the skycrane. Landing the skycrane well away. Landed! Decoupled the skycrane with the second payload. Hovering over... Lining it up. Payload mated! Skycrane released. Skycrane down. Refueling the upper stage. Refueling rig decoupled and pulled away. Second refueling rig decoupled and pulled away. Ready for relaunch! Launched, raising landing legs. Not going to worry about recovery on this one so I'm doing a slightly more aggressive turn. Past the recovery point. First stage burnout. Second stage separation and ignition! Headed toward orbit. Fairing jettison. Circularizing. Made it! Decoupled the fairing and payload adapter (background). All systems go! Two relays put up in two launches with a single launch vehicle, no recovery. **takes a bow**

"Getting to Duna and back" doesn't quite do it for me. Getting to Duna orbit and back? Getting to Duna's surface and back? Is it just the propulsion module or does it need living space, logistics ports, etc.? If it is only intended to go to Duna orbit and back, does it need to carry a place for a separate lander? If I may offer a suggestion... The planned Deep Space Gateway will feature chemical propulsion, solar-electric propulsion, a very large solar array, and a large living space for the astronauts. It will have a forward docking port capable of docking to the DSG and it will have small side docking ports for refueling. It will be capable of getting to Mars, capturing into orbit without aerobraking, and returning to the Moon in like fashion; it will not have enough dV to carry any other payload. Here's an older description, with photos, of how it might go. Here's a more recent one: https://www.pressreader.com/south-africa/popular-mechanics-south-africa/20170701/281612420400456

The rocket will lift off with full ore tanks if you let it burn off a couple hundred kgs of propellant.

I'm not imagining anything, I'm using real world physics. For your fuel to flow, it has to accelerate from zero speed - and that takes time and distance. And the force is only one gee at ignition, which just adds further difficulty - the force flowing your fuel varies radically from ignition to burnout. Sorry, wasn't trying to use "imagining" pejoratively; I probably should have said "visualizing". Anyway, I'm still not quite sure what you're suggesting. Flow in any fluid is a function of the instantaneous force vector, not time or distance. The rocket comes from zero acceleration (one gee) to full acceleration (4+ gees) instantly at ignition. Of course it takes time and distance for that acceleration to be translated into airspeed, but that's inconsequential to the fuel flow; the fuel doesn't care how fast it is going, only how forcefully it is accelerating. Moreover, the use of parallel staging means that for (at least) the lower stages, the acceleration only varies slightly over the course of the burn. Obviously the lowest-acceleration state is at ignition, but ignition is the least of our worries since it is by definition not a steady-state situation. The viscosity of a non-newtonian fluid may vary in response to shear force, static pressure, and temperature. A steady-state combustion would involve a range of shear forces and temperatures across the fuel column. It is not difficult to conceive a fluid composition which would take advantage of the force and temperature gradient to achieve the desired flow, melt, and vaporization behavior. Feel free to enumerate them. High combustion stability, wide throttling range, extremely high thrust-to-weight ratio, relative ease of fuel acquisition, higher reusability, and lower tank/structure dry mass. If it turns out that the gel-hybrid approach doesn't work, we can always use a more heavily congealed cook of napalm and make it a traditional hybrid rocket. More heavily gelled gasoline -- to the point that it is basically rubberized -- would work just fine. The isp for N2O+PTB is so low that it IS problematic. I looked at this before I looked at HTP; if you imagine strapping together dozens of the HEROS-3 rockets you still never get into orbit...you run into this problem. Yeah, I looked at delta-v budget a few pages back; there's a whole spreadsheet and you can download it yourself if you like and vary the constants. That's really cool (literally and figuratively)! Would be much easier to get a working engine prototype than the HTP design. One problem I do foresee is the whole pressurizing-the-fuel-with-the-oxidizer-via-bladder issue. Dunno how I feel about that. But as far as getting your hands on the propellants is concerned, it is definitely hard to beat propane and nitrous. We do know it works, to some degree, since the first liquid engine ever flown by the Soviets used gelled petrol and a liquid oxidizer. Melting the nozzle would definitely be a potential issue; this is going to be VERY hot. I don't know whether regenerative cooling would be beyond the capacity of amateurs. Propane would be a great heat sink but you still have pressurization problems.

Please provide some additional details/requirements for the Duna Mothership and the DST Logistics. I don't use mods (other than Tweakscale) so I don't have KIS/KAS. I can certainly use a cargo bay with docking ports, though. What does the Duna Mothership need? Is it intended to work as a cycler? Will it aerobrake or capture burn? What does the logistics module need? Does it need engines or is it the hab only?

Man, that was gorgeous.

Unfortunately this doesn't get us anywhere. Largest, or lowest part count? What scores higher -- a really large station with a medium part count, or a medium station with a really low part count?

I would happily share the craft file but I didn't have a chance to upload it. However, the screenshot I have above identifies all the parts, including the probe core. Everything is right there in the screenshot, labeled.

I won't make an issue of it!

What does Kerbal Engineer give? I'd prefer not to include stuff that makes it way easier to fly. Part of the challenge is recreating it; it's a very simple design.

Well, for what it's worth, I'm sorry we were so hard on you for your first post. The thing is, there are a LOT of challenges and people learn pretty quickly what works and what doesn't. Please don't take the pushback personally; it's just a hint that there are a lot of things to keep in mind in order to make a good challenge. Welcome to the forums!

This challenge is simple. We all start with the exact same rocket, patterned after a Delta IV Heavy (I'll explain why in a moment). We all have the same payload: three large ore holding tanks and a probe core. The challenge is to fill the ore tanks as full as you can and still make orbit with a periapsis over 85 km. Here's the rocket (you can build it yourself in a few moments): Three orange tanks with Skipper engines, large nose cones on the side tanks, Rockomax and TT-70 decouplers, a Poodle upper stage engine, an X200-16 upper stage tank, and the smallest probe core. I suggest autostrutting everything. Since we all have the same rocket, this challenge will come down to piloting and nothing else. I chose the Delta IV Heavy design because it introduces a range of variables associated with throttling down the core engine or transferring fuel in order to maximize effective dV. The amount of ore you choose to attempt will greatly affect TWR, which will change your gravity turn accordingly. I chose 85x85 (or greater) to add an additional variable as far as lofted trajectories are concerned. Obviously, no MechJeb or other piloting mods. Good luck!

So now you can drop tanks and engines? Uh, that's called staging. Which means it is not in any way an SSTO...like, not even a little bit. We can use mod engines? Great. I'll just "mod" the cfg of the Dawn engine so it has a sea-level TWR of 50 and can run on a single RTG. Torchship time! I hate to rag on the OP too hard here, but this challenge just keeps changing and changing in every conceivable way.

Falcon 9v1.0 with Dragon is posted, and here is Falcon 5 for your viewing pleasure! Falcon 5: