Will 1.0 change LV-N?

[Daze]

As the title said i was thinking about latest statement of Squad that they are changing .cfg of some engine + how fuel flow logic works. Since this it is possible that (finally) in 1.0 the LV-N will use like IRL only one resource instead of LiquidFuel + Oxidizer? What do you think guys?

[Wanderfound]

Hopefully yes, but I'm not counting on it.

LV-N's need rebalancing besides the fuel issue. The thrust is unrealistically low, as is the cost. There are reasons (largely political rather than technical) why we don't use NERVAs in the real world. The game should reflect that.

[r4pt0r]

Hopefully yes, but I'm not counting on it.

LV-N's need rebalancing besides the fuel issue. The thrust is unrealistically low, as is the cost. There are reasons (largely political rather than technical) why we don't use NERVAs in the real world. The game should reflect that.

Whoa the thrust is low for those? wouldnt increasing it make them even more overpowered? Realisim aside, from a game-play perspective I think the current rates are all right.

[Bill Phil]

The thrust is unrealistically low, as is the cost.

That would be the case, except for the fact that it has a higher TWR than some of the actual NERVA engines...

[maccollo]

I don't think it actually matter weather it uses both oxidizer and liquid fuel, or just liquid fuel, because both have similar density. If it is given a new, less dense fuel that would be interesting.

Edited March 20, 2015 by maccollo

[Vaporo]

I don't think they'll change it (even thought they really should) because of how much effort it would take this close to 1.0. Even if they just set them up to only burn liquid fuel, it completely and utterly change whatever balance that the devs have created thus far. Also, they would have to go about modeling a whole new line of fuel tanks to cope with increased requirements for liquid fuel, or implement a new system where you can swap tank types between LF+O and LF.

I think that the whole issue can be avoided, though, by calling LV-Ns a "nuclear-chemical hybrid." I don't know if the idea has any real-life merit, but it would solve the problem at hand with one line of text.

[Wanderfound]

That would be the case, except for the fact that it has a higher TWR than some of the actual NERVA engines...

Eh? My understanding was that NERVAs were supposed to have quite a bit of kick. Is the LV-N also underweight?

[Bill Phil]

Eh? My understanding was that NERVAs were supposed to have quite a bit of kick. Is the LV-N also underweight?

The LV-N is scaled down. This makes it behave differently in general.

NERVAS have single digit TWRs, usually. LV-Ns have double digit TWRs.

The LV-N is pretty much overpowered, considering it's size...

- - - Updated - - -

I don't think they'll change it (even thought they really should) because of how much effort it would take this close to 1.0. Even if they just set them up to only burn liquid fuel, it completely and utterly change whatever balance that the devs have created thus far. Also, they would have to go about modeling a whole new line of fuel tanks to cope with increased requirements for liquid fuel, or implement a new system where you can swap tank types between LF+O and LF.

I think that the whole issue can be avoided, though, by calling LV-Ns a "nuclear-chemical hybrid." I don't know if the idea has any real-life merit, but it would solve the problem at hand with one line of text.

I thought they were already working on rebalancing everything?

[Goddess Bhavani]

I don't think radically changing something with far reaching consequence as LV-N performance is something Squad would want to do considering how vast the 1.0 workload is.

That said the present LV-N while unrealistic in certain ways, actually serves as a good primer for a new KSP player that there are such things as nuclear rockets.

For realistic stats or more correct nuclear thermal rocket modelling, we can always turn to mods for that. It would be nice to have it run liquidfuel only and this could be easily simulated by modifying one parameter in the part cfg file whereupon you could hook it up to a reconfigurable fuel tank with LF only.

[pincushionman]

…whereupon you could hook it up to a reconfigurable fuel tank with LF only.

You mean like one of the jet fuel tanks we already have?

[Goddess Bhavani]

I'm not using the jet fuel tanks for LV-N fuel.

[Daze]

The perfect thing would be that they introduce a new resource "NuclearFuel" (or LH2)

Edited March 20, 2015 by Daze

[Bill Phil]

The LV-N needs nuclear fuel ( plutonium or some other nuclear reactor material) and liquidfuel. Not to mention we need a nuclear reactor... Perhaps in the tech tree it could come before the LV-N? That and nuclear fuel storage.... To extend the operating time of an LV-N, or something like that.

[Alias72]

The LV-N needs nuclear fuel ( plutonium or some other nuclear reactor material) and liquidfuel. Not to mention we need a nuclear reactor... Perhaps in the tech tree it could come before the LV-N? That and nuclear fuel storage.... To extend the operating time of an LV-N, or something like that.

This is a non-issue. The nuclear reactor in a NERVA engine is included in the engines structure. Also nuclear fuel is used primarily because it does NOT run out quickly. These engines would not need to refuel for decades. rebalance is the most important thing. maybe operating a NERVA engine could reduce your programs prestige.

[RabidMonkey]

The LV-N is overpowered compared to the first-gen NERVA designs. But if it's compared to the Timberwind designs proposed as part of the "Star Wars" program, then it's insanely weak. I built a quick-and-dirty config using the specs for the Timberwind engines, and they were ludicrous. Single-Stage-To-Eeloo using a Rockomax pancake tank ludicrous. There should be a rebalancing of the LV-N, but I don't think nerfing it further is the answer. It should generate ElectricCharge at all times - after all, there's a nuclear reactor running in there, and adding a generator to it would be trivial - and definitely a reputation hit if used inside Kerbin's atmosphere. Definitely increase the cost and require ONLY LiquidFuel as well. Bad Things happen when oxygen meets Uranium at high temperatures. Uranium is already pyrophoric, so adding LOx would turn it into something last seen in the Soviet Union in 1986.

[Bill Phil]

This is a non-issue. The nuclear reactor in a NERVA engine is included in the engines structure. Also nuclear fuel is used primarily because it does NOT run out quickly. These engines would not need to refuel for decades. rebalance is the most important thing. maybe operating a NERVA engine could reduce your programs prestige.

No, it's an issue. We need better power sources than RTGs and Solar Panels. So we need reactors. and proper scaling of the energy a solar panel receives.

Kerbal isn't realistic already. They have a smaller reactor than anything we have. Little over a meter in diameter. So, it's logical to assume that they would have less Nuclear Fuel in it than we have.

[Random Tank]

The KSP NERVA isn't underpowered at all, it's just scaled down. In fact, if you look at the stats of the proposed NERVA-2 stage of the Saturn Rockets, the KSP NERVA is actually overpowered compared to it.

The thrust of the NERVA-2 stage was 333.6kN in vacuum; but as everyone seems to be ignoring, the dry mass of the stage was 34.019 tonnes; and (as always), Earth's gravity is 9.81m/s^2

A quick calc shows that the TWR of this stage is 0.9996; very close to 1 (as this is a circularization and ejection engine, the TWR doesn't need to be as high). But this is the TWR of the STAGE, not the ENGINE; I don't know how heavy the fuel tank is, but as it's a big one, lets assume 10 tonnes.

So if you re-calc with the tank weight taken off, you get an engine TWR of 1.417. The KSP NERVA has a engine TWR of 2.718, nearly double. And balance says that a bigger engine should have higher TWR, to make up for the fact that the increased weight reduces dV, this really should be the other way round... or at least the KSP NERVA has less than 1.4 TWR.

Then it comes down to ISP.... the KSP NERVA has a Atm/Vac ISP of 220/800, whereas the NERVA-2 is actually more efficient with 380/850. To be honest, if the KSP NERVA recieved the TWR nerf that it technically should have, I wouldn't mind if it got the ISP buff; makes it so the engine can have more dV, still allows it to be a transfer engine as it should be, but means it's awful as a landing engine, also as it should be...

With a little bit more research, I managed to find the stats for the Russsian NTR, the RD-0410, which is much easier to compare to, as it weighs 2 tonnes (250kg more than the KSP NERVA), is a very similar size (only slightly larger) but has 35.3kN of thrust... making it have an Engine TWR of just under 1.8. It does have an even higher Vac ISP of 910 (Wow), but still the KSP NERVA is overpowered compared to it...

Edited March 21, 2015 by Random Tank
RD-0410 Stats

[Jouni]

The NERVA stage was considered as a replacement for the S-IVB stage, so we can use its stats as a basis for our estimates. The S-IVB had a 1.8-tonne engine, 104 tonnes of propellant, and 14.1 tonnes of non-engine dry mass. The NERVA stage would have had 144.3 tonnes of propellant, so we can use 19.6 tonnes as our estimate for the non-engine dry mass. That leaves 14.4 tonnes for the engine. Hence the NERVA would be 6.4x heavier and 5.6x more powerful than the LV-N.

[Alias72]

http://fas.org/nuke/space/nerva-spec.pdf pg 50 launch weight of engine shall be:

35, 200 lbs.

15966 kg

thrust is from pg 18

75000 lb

333616 N

twr = T/M = 33400/16000 = 2.0875

These are design requirements. They should be used as an indicator of final performance. Units converted to metric for the sake of intelligent life everywhere.

[quasarrgames]

YOU'LL HAVE TO PRY MY NERVA FROM MY COLD, DEAD HANDS!

I love it the way it is! Do NOT take anything about it away from me!

[Daze]

YOU'LL HAVE TO PRY MY NERVA FROM MY COLD, DEAD HANDS!

I love it the way it is! Do NOT take anything about it away from me!

Nice arguing

[quasarrgames]

Nice arguing

Ok then, how about this:

The NERVA, or LVN if you prefer, is just the perfect late-game engine. It's got enough isp for good interplanetary burns, yet it also has enough TWR to not make said burns super-boring. Thus, it is also one of the most diverse engines in the game, able to be used on anything from spaceplanes in the upper atmosphere to interplanetary motherships to low to medium gravity landers. This engine could take you anywhere you wanted to go in the game, but it would still require some creative designs to get there.

Also, it's actually one of the most balanced engines in the game. it's actually slightly underpowered, if we assume that a balanced engine has about 64% of a real engine's thrust. After all, both real-life NERVAS and LV-Ns have 800 isp, and the LV-N has about 60% of the TWR of the NERVA (NERVAS had 7, the LVN has just over 4).

[Daze]

Well as i expected you didn't understand my post.

I'm not talking of nerfing or make it powerful, simply to use a coherent fuel for nuclear propulsion

[Francois424]

I would be fine with it being changed... I am also fine with it NOT being changed.

The beauty of KSP in that regards is that editing the .cfg file is so easy that if I feel something has no practical value in game, or is redundant and is never used, I can easily go in, modify the said engine, and test. I never touched the LV-N tho, mainly because every engine in KSP uses 2 resources or fuel. Unless the game is modified to handle a lone fuel-type, I cannot modify it to use only LF (or Kethane as I thought doing).

I did buff the ION-Engines to 5 thrust, long before the Devs "buffed" it to 2, mainly because it was too boring.

I also tweaked the Rapier to combine the ramjet power/isp with the Poodle power to make it a used engine. Otherwise I stuck with jets and something else.

Either way, I wouldn't mind a game modification to add/remove as many fuel type to engines, and making LV-N use whatever they will use. It makes way for me to modify a part to act as an electric propeller too if this is done.

It would be a good thing afterall... but I don't think it's something they'll do in 1.0. I'm half-expecting 1.1 or 1.2 or 1.05 to be that "Balance pass on all existing technos" patch. Time will tell.

[GigaG]

I think that once we get outer planets like OPM and the like (I'm sure that KSP will do that eventually), the LV-N won't seem quite as OP.