mbaryu

I've had success with a non-plane SSTO (though it could be converted to a plane easily enough): plasma nozzle + positron reactor + lots of positrons. I didn't bother with refueling, but the basic structure has enough lift to take all the hardware needed to refine fuel. To make it easier to handle in atmospheres I gave it some small LF tanks. For everything else, a giant H2 tank. I can see if I can dig up a craft file for it later. This is, however, fairly high tech, so not suitable to an early career build (I used it in mid career).

Perhaps you could block fuel usage I'm afraid not. I'm afraid the refuelling mechanic never took into account for more than one reactor. It's one aspect I want to address when I overhaul the nuclear salt reactor. In general, I would recommend using one nuclear reactor per vessel to prevent issues and it also offers mass bonuses as a single big reactor has a lower mass than multiple smaller reactors with the cumulative same capacity. The first time I encountered this was on a station I built to breed Tritium and beam power using four MSRs. The second time was on a spaceplane using 4 Lanter Engines. Since they were running on enriched Uranium, the onboard ISRU drained them while making UF4 and I was unable to refuel them. The second instance is more of a problem because using multiple nuclear engines on a vessel is pretty standard. I agree that in most circumstances using a single reactor is a better use of mass. I've noticed that the UF4 in tanks can't be used to refuel reactors. I've never figured out what's going on or if that's even intentional. At least for one of the other reactors you can only refuel it when it's fully shut down.

Hahah! Indeed. I wouldn't worry too much. If I'm reattaching IR parts in flight, I'm pretty much expecting explosions

This could happen quite easily with KAS/KIS. I'm curious how much IR would freak out if you completely detached something, then built it into some other vessel (but not enough to give it a try just at the moment :) ).

Oh cool, I thought I was doing something wrong and moved on to positrons + plasma.

Very Kerbal of you!

I haven't been able to reproduce this on a simpler craft and the one that had the failure was ridiculously complex, so I suspect something else was going on. It still points to a strange power distribution problem. I didn't see any evidence of geforce spiking (though who knows when exiting warp) and I'm pretty sure the heat sinks were much more than necessary. Certainly wasteheat wasn't near max.

@FreeThinker I was able to reproduce the problem with a similar ship in a totally different situation. The ship has 2 plasma nozzles with positron reactors and MHDs, and a QSR. The plasma nozzles worked fine until the ship crossed from Kerbin SoI to Kerbol SoI. After that I had to shut down the QSR to get the plasma nozzles to work.

Interesting. I see the rationale, though I think there are three problems with it: 1st, even a PBH wouldn't have a lot of impact on the atmosphere and PBHs are many orders of magnitude larger than what I suspect the Quantum Singularity Reactor is supposed to use (I assume based on the fact that it feeds in Hydrogen or Helium that it is an unstable size, which means fairly small). 2nd, if that were the reason, why could I then power it up inside the atmosphere? 3rd, The ship has a bunch of MHDs, one for each positron reactor, which haven't been turned off (this is how the ship was originally launched, after all). So something is wrong with the power feed to the plasma nozzles if that's the case. But it's definitely a weird problem.

Great, that makes sense, thanks! However there's still the problem of the example 3 which causes the plasma nozzle(s) to fail after entering the atmosphere. The bizarre workaround is to turn off the singularity reactor, then power it back up after entering the atmosphere (although at high altitude so there's still near 0-g acceleration).

Also the Quantum Singularity Reactor produces positrons. The rate of production of the free electron laser is so low that in career mode it took me less time to develop the more advanced tech (and faster production) than it took to recharge a single ship using the free electron laser. However the quantum singularity reactor is also massive and seems unable to connect to any nozzle to provide thrust (it says it can be hooked up to a magnetic nozzle, but the thrust produced is minuscule).

I'm currently puzzled by something I've been experiencing for a while. This seems to apply to plasma nozzles (when I replace the plasma nozzle with a krusader, the problem seems to go away). KSP 1.6.1, and the previous 2-3 releases of kspi, situation is vacuum. Game is career with the positron reactor fully upgraded. Ship design is a simple stack: mini molten salt reactor and thermal power plant, positron storage, probe core, large Lh2 tank with graphene radiators wrapped around it, positron rector, nozzle. With the plasma nozzle, the ship sometimes will operate properly, and I get a reasonable expected amount of thrust. However more often I get 0 thrust. The engine seems to pulse a tiny bit of thrust when I throttle up, but then immediately goes back to 0. Occasionally on more complex vessels I also get a small percentage of expected thrust (like 1%) which seems to very slowly ramp up (though not to 100%). As stated above, if I replace the plasma nozzle with the krusader, the craft works perfectly (albeit with lower ISP and higher anticipated and actual thrust). What is going on? What am I doing wrong? Edit: Craft file: https://gist.github.com/chris9871/c0648ff8c48e4cfc700cad2d76ab340c Edit 2: This design appears to work: https://gist.github.com/chris9871/a7445410fdc09bb042f4cea05da0fe8b Note that in the working design, I've removed the molten salt+ therm and replaced them with an mhd on top of the positron reactor. Edit 3: This design works except in a weird case: https://gist.github.com/chris9871/52934705a37fd646583ea7ab30a01e0f In this design, power up the black hole reactor, then quicksave and reload. _then_ enter the atmosphere (of kerbin). After entering the atmosphere, the nozzle stops producing thrust. Edit 4: PS On a side note, the triangle radiators on testr3 seem to have a noticeably lower weight to heat dissipation ratio than other head radiators. This doesn't seem like it was intentional, though I can't tell for sure.

I figured it was something like that. Not to worry, I've downgraded for now

Yes:

There's an interaction between KAS 1.2 and Extraplanetary Launchpads 6.5.1 that causes EL to break when selecting a craft in the UI (definitely including a craft that does not have KAS parts). I'm guessing it has to do with one or more of the deprecated parts. Reverting to KAS 1.1 solves the problem.