TiktaalikDreaming

No worries. I was also under the false impression you were doing those speeds while using wheels that were touching the ground. I was a bit shocked you could find a place flat enough. The rover mod needs to get some updating love. It doesn't even have Kerbal Wheels patches. And it predates a stack of learning things. It doesn't look absolutely horrible though, so it wasn't on top of my list to fix. Thanks for mentioning it.

200m/s is 720kph. Let's all pause for six seconds to take that in. That's more than Mach 0.5, on the ground. There's a truck tonne of physics involved and it sounds like there's a bunch of other mods keeping the CPU core busy. While there may be optimisation to be done in some mods, the root cause seems likely just exhaustion of CPU resources inherent in KSP's physics system being focused on one core.

Nice deck you have three.

The active cooled version is intended to use liquid helium cooling for the reactor walls and not rely on the propellant to avoid the reactor melting. The high ISP is due to allowing the propellant to get that hot, which limits the propellant flow rate. You're right, the flow rate of LH2 is insufficient to cool the engine. I think I've got it to the point where running it in active mode results in engine explosions in game. The regeneratively cooled mode involves higher propellant flow rate to keep things from melting, so the propellant never gets as hot, but also the reactor never quite melts, and due to higher flow rate, the exhaust velocity is lower, but thrust is higher. That *seemed* to be the set-up assumed in the sketches done up by Convair for the Nexus second stage vehicles. I haven't actually run proper numbers for the regen cooled edition yet, and they're subject to change. Or at least, the numbers I do have are from calculations I can't remember due to it being too long ago. So, Active cooled = assume external cooling system that handles buckets of heat Regeneratively cooled = reactor cooled with propellant

Nice. My estimates on the liquid fuel version are very much a case of wild guessing so far. But a molar mass of 4.66 would certainly make it more useful for what the engine's intended for. I was just spitballing a partial decomposition. But yes, the temperatures are likely high enough to plasma-ify most anything. If actually trying this, I don't know how you'd avoid weird high temperature and pressure carbon combinations and build-ups in inconvenient areas, but we have to assume some magic for KSP's liquid fuel. A quick note that the ISP for the LH2 version in high ISP assumes cooling that LH2 flow rate can't achieve, and instead a bunch of radiators that don't exist in game yet. The never finished pre-revamp version was going to look a bit like (I cleverly forgot a decoupler when launching this test);

I've recently realized I forgot to scale this engine. This may be slightly game breaking for any craft in flight, but shortly I will be rescaling and probably adding back some more nozzle length. Or nozzle length on the LH2 version anyway. The reactor core size is based off slightly optimistic (I'm assuming active neutron bombardment to decrease minimum critical volume) readings of existing studies on gaseous core reactors, and always meant to make the kerbal edition scaled down an extra kerbal factor (typically around 62-65%). So I think this will necessitate adjusting the stack node details and so on. It definitely means my fairing is wrong.

Got another few minutes and added a bump/normal map. Very early days. And it only ended up in game this early because blender was doing daft things with it and I needed to make sure that didn't carry over to the game before continuing. I updated the releases to include this, as I realized I hadn't done one since adding the bottom stack node, fairing or not. https://github.com/TiktaalikDreaming/TDAPS/releases/tag/0.4.190926

I case anyone was wondering, I'm working on a fairing so I can add a lower stack node. Initial dev was focused on getting a workable engine for my Nexus mod, which doesn't need a lower stack node for the second stage engine. But for general use, these are better as vacuum engines, so I'll be adding stackability. Teeny progress;

Yes. There's probably a few, but this was designed to be a companion to my revamped Nexus mod, as the second stage engine Use the development version on github for the best results

OK, the Liquid Fuel version now has it's own plume and some of the texture switched around, smaller pumps, etc, as mentioned above. https://github.com/TiktaalikDreaming/TDAPS/releases/tag/0.4.190921 (Edit: Note about test craft: The craft shown is mostly stock. I used a Tundra Exploration capsule (not shown) to get something 5m wide and larger RCS, and Making History tankage with the oxidizer removed.)

There's now a second version (updated model in development) using stock LiquidFuel. As mentioned above, I messed around with the exhaust product molecular mass to make it a sane choice, with vacuum ISP at around the 1000, and around 12MN thrust. I took out the actively cooled mode from the dual mode for it, as that's the "we want to maximize ISP" option, which you're clearly not doing when running kerosene through it. And dropped the mass due to less complexity, and lessened the tungsten use, as hydrocarbons should be partly opaque to gamma. Versions 0.4 onwards will have the second engine. I'm tweaking a few things on the model. I'm shrinking parts of the turbo-pump assemblies, adding some colours to some spots to differentiate things, and removing the helium lines for active cooling. Liquid Hydrogen; Liquid Fuel;

LOL. As senior moments go, it was pretty mild though. A light sprinkle will do.

Damn. When I started replying I had every intention of giving you some salt over mixing up RD and PJ, and then writing via mobile is so distracting I completely forgot. I do still at least half intend to eventually update the mod. But I barely have time to make a part from time to time at the moment, and this will be a bit more involved. So don't hold your breath.

I'm a complete noob at c#, doubly so the ksp api. I took over the mod, but the original authors were basically a team from my understanding. And the mod extends modules that are no longer extremal, since 1.5 came out. So it needs a rewrite, and so far I haven't had a decent block of time to both learn c# coding, and figure how to achieve what the mod does in the new version of the api. If you have experience in c# and some time, I'm not above getting assistance. If you were hoping for a recompile, you're out of luck.

I think everyone could see what you meant, I was just giving you grief over the word "stock". Stock size is a meaningful distinction a lot of the time though. With interstellar travel, the planet size makes less of a difference of course, as the distances get so much larger. That said, a lot of those multi-star-system mods involve less than realistic distances between stars, or at least less than we're used to out here in the outer bits of our unfashionable arm of our spiral galaxy. But you will end up needing something to traverse distances of the order of a light year through to many. And the best we've got as far as plausible ideas is probably things like Zubrin's nuclear salt water drive in full weapons grade load. And that concept is a pretty scary beast, even though "salt water drive" sounds fairly innocuous. But at best you'd be accelerating to 1-2%C then flipping and slowing down. Still talking centuries to alpha-centauri. As I said, much much better time warp. You can get similar ISP values out of the plausible fusion concepts like inertial confinement, but the TWR goes way down. The problem with fusion (as far as humans have so far figured out how to fusion, anyway) is that you need big things to make a tiny bit work. So, huge banks of lasers, or huge arrays of magnets, or ... Lots of mass, one way or the other. So, you end up with a huge craft, because your engine needs to be 1000 tonnes or so, but you don't want 5% fuel, you want 90% fuel, so now your craft is enormous. And the TWR is starting to look a bit ION ish. OK, lots better than ION, but it's not going to be doing much in the way of artificial gravity with the engines.

There's no other star systems in stock ksp. Or mods to help you get there. At least for what most people mean by stock. But....There's a few mods with silly engines. My addition to the collection But there's very little physically plausible, very fast, very efficient engine concepts that pass even cursory scrutiny. For plausible interstellar travel, you'll need a seriously improved time warp. Realistically, our best current bet using fully known technology would be Hall effect upon drives because efficiency is much more important than thrust. And the trip would take a very very long time.

What Standecco said. I've changed it again based on the assumption the average exhaust product molecular mass is around 25, instead of non decomposed kerosene at around 320. The temperatures are basically a known factor, so that plus the average exhaust molecular mass generates the ISP and thrust. And with hydrogen as a fuel, with essentially highest ISP and lowest thrust, the twr is still fairly reasonable, and the ISP is better than anything this side of ion drives, so beefing up the exhaust mass does result in a bit of a beast. But not an interstellar beast. A different order of magnitude is needed for that.

TWR above two for this thing; I may need to assume there's some hydrocarbon disassociation happening at the several thousands of kelvin going on in there. Hell, in solid cores there's a non-insignificant breaking of H2 into H and H. I should try and get the ISP above the stock NTR anyway. Then just excuse it all with waffle. AKA KSP

I just did my calculations for changing the thrust and isp for a kerosene analogue (aka liquid fuel) and the ISP got a bit crappy, but not unworkable. The thrust is through the roof. I should also drop the engine mass slightly, as the tubopumps don't need to be as massive (the density is quite different so L/s of pumping is radically down). Still, I'm not sure an NTR running on something with an average molecular mass in the low 300's is worth doing considering the ISP is now below 300. I could fudge it for KSP stockness, like the stock NTRs. Thoughts??? (see https://github.com/TiktaalikDreaming/TDAPS/blob/master/GameData/TDAPS/Parts/OCGC-NTR-LF.cfg)

It's original intent was as the second stage engine for my Nexus mod, but the idea of splitting it off is to make it independent, aka standalone

At the moment, it runs on liquid hydrogen and two included resources (really just there so you need to think about setting required amounts). It's dual mode, an actively cooled high ISP mode, and a regenerative cooled high thrust mode. I'll need to add a variant to use stock liquid fuel. The ISP will suffer, and thrust will go up. Figures currently are subject to change.

I've tentatively started a new thread for the Gas Core rocket engine here,

:LIKE: yeah, this kinda sucks More on the rad shield. I added the plume as a volume emission shader cone that tails off, and there's a bit of light from it seen here on the top rim. The exhaust will be "less" radioactive, both neutron, and gamma, than the core. Knowing the source is important, which is why each emission source gets it's own colour. The shadow shield is modelled in as a metallic opaque, which is a bit simplified. The inside/lower surface should be a gamma reflective heavy metal like tantalum, but the bulk should be layers of substances designed to slow and stop neutrons, typically hydrogen rich substances. Most of everything else is using a translucent shader with a high roughness, so it refracts and bounces a lot of scatter. The tungsten tubes I did as opaque though, seeing as that's their purpose. Not that their opaque to neutrons though. Anyway, what I'm getting at, is this is a quick and dirty job, and a realistic one would have separate models for neutrons, gamma rays, fission fragments, alpha particles (for what it's worth) and so on.

(this is me failing to resist the urge to let this go seeing as it no longer has anything much to do with the topic) Causality is one of most interesting victims of FTL. And always reminds me of the Douglas Adams HHGTTG quote "There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened." EG: Just how much of the universe is disturbed by something breaking causality?

Yep, it's quite fascinating. See also Higg's Boson, positrons, etc. The issue with negative gravity mass is that it's not predicted, just not excluded. And no one has even hypothesised how some could be made. That said, someone could stumble on that tomorrow. I'm betting it would be expensive. Like serious investment per atom expensive. But once that's done, then it's just engineering and bubble shape cleverness.