Brotoro

If you want the nukes (with the new tendency to overheat in space) to survive, you need to attach them to something that can draw off the heat from the nukes. This is going to limit how you can put a nuclear engine into your design, yes. So, you can: a) Connect the nuke directly to a large tank, or Connect the nuke to other structure that can draw off the heat Then, especially if you want to make a loooong interplanetary burn, you need to make sure that the parts the nuke are connected to are not going to overheat before your long burn gets done. This can be done by: a) Making sure the parts have enough thermal mass to absorb the heat generated during the burn. This is why you must use a BIG tank. Also, keep in mind that as you use fuel the thermal mass of your tank will go down...so just because your nuke can run for 5 minutes when the tank is full, it will NOT be able to run that long when the tank is nearly empty. (So beware: test your design with the tanks nearly empty as well as full to be sure you can get home.) So you may end up having to bring along more fuel than you actually need for the mission just so the ship still has enough thermal mass to safely make your return burns. Yes, it's inefficient. Also, if you have constructed a large ship in orbit, the heat is NOT going to transfer through the docking ports well (whereas it WOULD if you made the ship pre-docked in the VAB; this inconsistent behavior must be is a bug). So beware. or, you can add enough parts to your ship that are able to radiate the heat away faster than the nukes create the heat. This may require that you either spam lots of parts on as radiators, or it may require that you run the nukes at less than full throttle (making your looong interplanetary burns even longer). This is where proper radiator parts would be useful...but we don't have those in stock.

The thought of opening parachutes in the flames of reentry just makes me cringe.

iMac 27-inch, Mid 2011 3.4 GHz Intel Core i7 AMD Radeon HD 6970M 2048 MB KSP resolution is 1280 x 1040 (my Mac's display resolution is 2560x1440) 8 GB 1333 MHz DDR3 OS X 10.9.5 I continue to get the program freeze-ups, mainly during scene changes, which have been getting more and more frequent with each recent version of KSP. This is continuing, even worse, in KSP 1.0. Activity Monitor shows that KSP's memory usage passes 3GB at those times. I'm also getting glitches like the picture below showing up more frequently in KSP 1.0. These used to happen in previous versions, usually right before a freeze...but they have showed up in 1.0 without an immediate freeze (but I usually restart the program anyway when I see them). This particular one showed up when the only mod I had installed was Kerbal Engineer (the update that's supposed to work with KSP 1.0). This was in a new sandbox game (my old save games with hundreds of flights will open in 1.0, but the freeze up in a a few minutes).

While heat pumps and radiators sound like lots of fun to play with...I think I'd prefer it if the heat generation of the nuclear engine was simply toned down (since Squad hasn't fixed the problems with running KSP under OSX...and as they have been adding more and more parts in recent versions, the problem has been getting worse and worse -- so I like the no-additional-parts solution).

Oh, hey! I like that! Thanks, regex! (And thank you Temeter for the heads up.)

A updated version of my 2.5-meter Standard Nuclear Tug can run 6.8 minutes at full throttle before exploding (the weak point again is the tank the nuke is attached to, of course). That's with the tanks tweaked for maximum fuel load and no oxidizer (it would be nice if Squad gave us the option to tweak a tank to LF-only now that we have fuel-only-nukes). Subsequent burns would be limited to shorter times, of course, as the thermal mass of the Tug decreases. This Tug (with no payload) has delta-V capacity of 4.7 km/s.

Addendum: With the central tank empty, and just the X200-8 tanks (partially) full (fuel only), the X200-8 tanks explode after 2.75 minutes of full power. The tanks were down to about 1/3 fuel remaining. So returning this Tug from Jool would require care (requiring short burns). Note that the delta-V of the full Tug is about 6.7 km/s. - - - Updated - - - No, they are still overheating and causing explosions in less time than I need for my typical burns. But the run time can be extended by putting the engines into good thermal contact with a large heat reservoir. And as you use fuel, the heat reservoir decreases in capacity. Also, I avoided putting any heat sensitive components (such as batteries) on this test ship.

I see that Temeter was reading my mind while I was gone. Below is a test of a new Tug. It uses all liquid fuel (the Rockomax X200-8 tanks have been tweaked to remove their oxidizer). The X200-8 tanks are hard-mounted to the sides of the big tank, so no more option of dropping the nukes (the environmentalists will just have to bit my shiny Plutonium ass). Will a full fuel load (and therefore the maximum thermal mass to soak up the heat), the nukes can run at 100% power for 7 minutes before explosions. And, as expected, it's the X200-8 tanks that explode. Sure, the old ships will work. They just need to be kept at low throttle (but I'm not going to throw away useful nukes already in space).

I've started testing with my old nuclear Tugs (since I have a lot of them out in space on missions). The engines are thermally isolated from the rest of the Tug because they are mounted on radial decouplers along with an extra shadow shield part and a parachute so that the nukes can be dropped and recovered in case of launch failure...which seemed like a prudent design at the time). At 100% power, the nukes explode after 75 seconds. They hardly have time to heat up other parts (just the plate they are mounted on). At 50% power, the nukes explode just shy of 3 minutes. At 33% power, the nukes explode at 6.5 minutes. One of my typical burns for Jool could take almost an hour at that power level, and would need to be done in over ten burns. At 25% power, the nukes reached an equilibrium temperature of 2418° and were still going after 20 minutes. Of course, a Jool burn for my typical payloads would require something like 72 minutes at that thrust level...and would need to be done in several burns anyway at consecutive periapses.

Well, you wouldn't want goofy massless wings.

You do realize that nuclear engines overheat in space much faster than they do in the atmosphere, don't you?

I would like 1) an audible overheating alarm. 2) a key (and assignable keyboard key) that I could press to toggle the heat display on/off for a quick look at WHAT's overheating.

I think procedural wings are the answer. But I don't think they will happen.

But is that good? If the nukes can't transfer their heat elsewhere, won't they just explode all the faster? And, the ablator is getting used up, so this is not a solution if you want to make reusable nuclear Tugs.

I thought Squad fixed the tendency of the boosters to nose inward on separation. I certainly know that when I tried an old ship (which had sepatrons placed to counter the nose-in effect) in 1.0 those boosters came off violently flipping nose-out (because of the action of the sepatrons). - - - Updated - - - They added new nose cones that are angled. Normally people would put those on the side booster with the point on the inward side (to look like a Proton rocket)... but if you put them on with the nose pointing outward, is the new aero clever enough to push the nose of the booster outward upon separation? (like you see on the British Thunderbird missile.)

And I'm happy for you that you could enjoy it. But the kinds of missions I like to do involve sending lots of large payloads to Laythe or Duna or such. I have literally spent hours and hours taking care of tedious interplanetary transfers with long nuke burns to get this stuff done. 18-minute burns for Jool injection were common, with armadas of half a dozen ships. And physical time warp often didn't help because the ships had lots of parts...so even at 2x or 3x time warp, the game was still running at slower than real time for these burns. Therefore, the prospect of having to run my nukes at less than full throttle does not appeal to me at all. What used to take a few hours could take days of free time now. And having to add lots and lots of extra parts to combat the problem would only exacerbate the laaaaaaaag issue. So, at the moment, I don't think I'd want to do any more missions with the new nuke limitations. So this makes me very sad...because I used to like playing KSP. And thank you for that. But I missed where Squad has officially expressed a concern about the overheating nukes problem, and saying that it may be a problem that needs to be addressed.

The things that I care about in Kerbal Space Program are, in order of importance: 1. Proper handling of rocketry (the rocket equation must work, etc. KSP does acceptably well here). 2. Proper handling of orbital mechanics (we don't have n-body, but the patched conics works quite well). 3. Everything else. The only reason I play KSP is because it meets points 1 and 2. If it didn't, I'd drop it like a hot Nerva. The fact that KSP has purple planets and ice moons too close to the sun, and such things as these, does not annoy me a whole lot. I don't even mind the overly dense planets, since the devs need only posit the existence of a super-dense form of matter (perhaps baryons made from the heavier quarks are stable in the KSP universe)...and since that dense material only needs to live in the cores of the celestial objects where is isn't going to affect points 1 and 2 above, it won't hinder me enjoying the game. It can also explain why a low mass star can produce the luminosity we see from Kerbol, since the pressures and temperatures of the normal matter just outside the tiny super-dense core will allow conditions for fusion of the normal matter. The water physics is moderately annoying...but this is a "fly rockets around" game and not a boat game...but I surely hope they fix this at some point. But it doesn't mess with points 1 or 2 much, except for spacecraft recovery. KSP's aerodynamics were terrible before, but they are greatly improved in 1.0, so I mark those as acceptable now, but still with room for improvemment. The lack of proper chemistry of the propellants annoys me...what exactly ARE fuel and oxidizer? I wished squad would pick some real propellants and use realistic numbers to determine their tank volumes and masses (and, no, the players who aren't interested in such things don't need to be concerned with the details)...since this affects point 1 for those who want to dig deep into the rocket science. I don't mind little green aliens. I don't mind the kerbal sensibility and humor. Those things can be in the game without affecting points 1 and 2...and they make the game fun.

I was referring to the heat model for the nuclear engine part. If we are complacent with glossing over realism, Squad will have no incentive to fix any. So I will not be complacent. Especially if this is just a question of balance when there are better ways to balance the part.

A Nerva's shadow shield is built into the engine, right on top of the reactor core where the smallest size shield can be the most effective. I assume the KSP nuclear engine has a particularly massive shadow shield because the engine has a rather high mass. If Squad wants to screw over the nuclear engine, they have plenty of realistic ways to do it. First, they could lower its Isp, since it should be lower given the high molecular weight of liquid fuel (since liquid fuel obviously CAN'T be hydrogen...you'd need MUCH larger tanks to hold that much liquid hydrogen). Second, they could implement radiation in KSP (it seems very silly not to have radiation in a space game anyway) to make them more difficult to use by limiting how close they could be to kerbals while in operation). Third, they could give the nuclear engine a long tail-off thrust (like the spool-down on a jet engine), because once you scram the reactor, there is still going to be a lot of very short half-life nuclides producing heat, so you need to run fuel through the engine for a while after cutoff. Then using the engine becomes an interesting challenge. They certainly didn't have to implement a faulty heat model that indicates and propagates misunderstanding of this particular rocket technology.

Amorymeltzer is correct. Except that solid objects aren't going to get blue-hot before vaporizing...but the hottest stars are bluish hot.

I wanted to see the Invisible Rocket take off!

What are they using for radiators on their nukes?? I need to know.

My kingdom for a hose!

...And I now have a full set of bars. Now to see if I can keep the nuclear engines on my Tugs from exploding from overheating.

I got my old SSTO Crew Carrier rocket to orbit on the first try. Unfortunately, it didn't have much fuel left in orbit, and some parts exploded off of it on reentry. So below is a cut-down four-kerbal version that got to orbit with 551 m/s of delta-V to spare. And the secret to getting it back down safely was the addition of three speed brakes (the speed brakes keep it nice and stable through entry, too).