How do You use the LV-N Atomic Engines and prevent them from overheating?

[Lulix]

Does it help to add more Engines to my craft to destribute the load on more Engines.

Or do they just overheat by running at full throttle and need to be shut down.

Did they got "nerved" then?

Edited June 14, 2015 by Lulix

[Wanderfound]

Does it help to add more Engines to my craft to destribute the load on more Engines.

Or do they just overheat by running at full throttle and need to be shut down.

Did they got "nerved" then?

Attach the LV-N to something with a lot of thermal mass (like a big fuel tank), and attach things with lots of surface area (solar panels, fins, etc) to that tank. You can run the engines to 90% overheat with no problems; if it goes past there, just throttle down a bit.

[Lulix]

Thank you

[Black Dog]

First of all: More engines result in more thrust, but decrease the maximum range you can get out of your fuel. So more engines will only help if you plan on landing somewhere and then getting back into orbit.

Second: I've built more rockets with "Nerv"s than i can count, and even though they tend to get into the dark red overheating status they never seem to actually reach it, unless you try a non-stop 100% burn with a total of deltaV of over 4.000 m/s. And even then you can just shut them off for a minute or so and they are good to go again.

So my tipp is: if you just wanna propel a probe through the solar system use a single "Nerv". If you wanna get back up from somewhere (and have a lot of time) still only use 1-4 but add an additional "Poodle" or "Rhino" as a kickstarter and to utilize the fuel out of all the adapters that have oxidizer on board anyway.

[Laie]

It helps a lot if you attach them directly to a tank, the larger the better. Skip the small adapter tanks; don't put any "insulators" between the engine and the tank (like reaction wheels, structural parts, batteries.... pretty much everything that is not a tank). Quadcouplers are totally out of the question. There's many reports of people running them in this way without severe problems. The whole vessel may begin to glow red-hot, but no explosions.

Alternate solution: edit the the configuration file and reduce the heat output. That's what I did. In it's current state, the engine isn't "nerved" but broken.

[Lulix]

Here is my upper-stage,

The small fuel tanks, need to be emptied before the engines get to hot or they will explode.

But the Engines do overheat after 2 minutes at full throttle and need to be shut down.

That must be new since 1.0 release..

[Randazzo]

If you're into mods you could check out Heat Management or Heat Control.

I know some folks tend to have the "Agh! Mods!" reaction, but honestly, it's better than having wings stuck all around your engine.

In my humble opinion.

[Lulix]

I will look into those mods!

And after all i like that heat from reentry or engines is a thing now.

Gives us more stuff to fiddle with/around

+ Rep to you all

[FancyMouse]

One good thing about the heat management mod is that it is really not using anything fancy - heat sinks and radiators are both just tweaking stock-available settings. Honestly I don't think LV-N itself is the problem but rather the lack of its accessories (which become available in those mods).

[Rickenbacker]

Did they got "nerved" then?

I see what you did there!

Anyway, attach them to a big tank, maybe put a few small wing parts (from the "aerodynamic" tab) on the bottom of it as radiators, and you're good to go for at least a several minute long burn.

[Foxdemon]

Also a tip: only use liquid only tanks, because for some reason it works a crapton better then depleting normal tanks from oxidizer. if you use that, the lv-N becomes better then the terrier at a lower mass. Ppl always say you need heavy crafts for the lv-N to be useful, but i made a pretty small probe using the short mk2 liquidfuel tank that was more efficient than with a terrier

[Teilnehmer]

Ppl always say you need heavy crafts for the lv-N to be useful…

Or high ÃŽâ€v value.

[ajburges]

Also a tip: only use liquid only tanks, because for some reason it works a crapton better then depleting normal tanks from oxidizer. if you use that, the lv-N becomes better then the terrier at a lower mass. Ppl always say you need heavy crafts for the lv-N to be useful, but i made a pretty small probe using the short mk2 liquidfuel tank that was more efficient than with a terrier

That one is quite easy. The dry fuel ratio of a rocket fuel tank with no oxidizer is horrid. Dry mass percent is roughly doubled. Chemical engines also do poorly when all tanks can be half full at most.

Don't use the Lv-N for probes though. That 3 tons is a lot of weight for something with a payload of under a ton. The only time nukes are good for probes is to beat 5 km/s single stage without ion engines.

Edited June 15, 2015 by ajburges

[John FX]

I must admit to just not using the NERVA since 1.0. I recently wanted to make a miner for minmus and thoguth "Ah, I`ll use a NERVA" but then I placed it and found a poodle got more Dv from a mixed tank and I didn`t want to rebuild the miner so it now has a poodle instead of a NERVA. I may use one for interplanetary but I have enough cash in my career game which means I don`t need to and let`s face it, the TWR is awful.

The low TWR, the chance of explosion, the odd fuel choice (compared to every other engine) means they just don`t get used anymore in my games.

I used to use them for everything but now they sit atthe back of the cupboard with the old sandwich maker, the ARM grabber and a load of spaceplane parts...

[Warzouz]

Futher more, if cost become part of the equation, the Nerva is worse again.

For example I'm working on sending a small space station around Eeloo (to refuel a science stripping mission). I jumped on a LVN interplanetary stage. I tested a 450dV burning for 16minutes (iwht 8 LVN). Heavy red, but no explosions.

Then I tried one Rhino and pack of fuel. : Higher mass, sure, but higher TWR (easier to navigate) and much lower price (20%). Since I usually use rocket SSTO**, The Rhino configuration cost less than the LVN configuration.

My heaviest launcher can put 240T to LKO for 450funds/Ton

My Eeloo preparations aren't finished. I'm still not sure I I pack the landers with the station in LKO or if I fly 2 missions and meet there (as I usually do). But my Duna mission don't use LVN.

[Mister Dilsby]

When attached to tanks, I think they don't give as much trouble as people think. Here's a good case study, an all-liquid fuel SSTO that lifts off on three turboramjets then circularizes on two LV-Ns.

It gets pretty hot on the way up due to atmospheric heating... and then because of low TWR I have to burn the LV-Ns for a few minutes to get circular.

Here it is coasting to apoapsis, pretty well cooked.

I actually really like the LV-N the way it is. In my designs it comes close enough to overheating to make things exciting, and requires me to plan subsequent burns with enough time for cooldown. That adds a realistic dimension to the game, for me.

[Nich]

I am not sure how the games raditive heating model works but in real life 2 or 3 fins are your best bet. Once you hit 4 the fins heat starts radiating into each other which reduces their effectiveness.

[jarmund]

My mothership has four Structural Fuselage (MK1), with one LV-N each. Each of these also has a gigantor solar array for radiating heat. What I do is that I stick these on radially to the main ship body, feeding fuel to it via hoses from a large stack of MK3 liquid tanks. They can burn continually for at least 5 minutes (which is plenty for me) without any overheating.

[justidutch]

Just the other day I built an all-purpose system explorer engine vehicle, with plenty of docking ports for expansion. The idea is that this will be a reusable engine stage for going to and returning from all bodies in the system. It has eight LV-Ns, which might be overkill, but it also has capacity for about 50,000 units of fuel. I haven't travelled anywhere with it yet, other than get it into orbit. It circularized on the nukes, only about a two minute burn so probably not a good test, but I don't think the heat will be too much of a problem. Each engine is attached to a small adapter tank which is attached to a wing part, which is attached to the largest MK3 tank. I'll have better pics in the future (it's the ship on the right)…

[tutike2000]

I am not sure how the games raditive heating model works but in real life 2 or 3 fins are your best bet. Once you hit 4 the fins heat starts radiating into each other which reduces their effectiveness.

Pretty sure the game doesn't take other parts into account when calculating radiative heat loss/gain. So 100 fins will work 100 times better than 1 fin.

[Laie]

I am not sure how the games raditive heating model works but in real life 2 or 3 fins are your best bet. Once you hit 4 the fins heat starts radiating into each other which reduces their effectiveness.

When I see photographs of real-life RTGs (or rather, their casing/heatsink) they look very much like the one we have in-game. That is, six fins. Apperently having more is better than spacing them further apart. And when you think about it, six fins still have a 60° arc each, which isn't all that bad.

Just the other day I built an all-purpose system explorer engine vehicle, with plenty of docking ports for expansion. The idea is that this will be a reusable engine stage for going to and returning from all bodies in the system.

Neat Ship! Personally, I've given up on the Universal Tug as it turned out to be way too large for almost all missions. A generic Modular Design created a lot of overhead (returning, sorting, refuelling...) and also caused part count issues. I'd recommend to build one basic tug that's good enough for almost anywhere (will be about 1/3rd as large as this one) and have a rear docking port where you can attach the heavy-duty booster to eject your Jool-5 mission.