Difference between revisions of "LV-N "Nerv" Atomic Rocket Motor"

From Kerbal Space Program Wiki
Jump to: navigation, search
(Usage: changes for 0.22)
(better explained its lack of usefulness as a lander engine)
 
(49 intermediate revisions by 33 users not shown)
Line 1: Line 1:
 
{{:LV-N Atomic Rocket Motor/Box}}
 
{{:LV-N Atomic Rocket Motor/Box}}
  
The '''LV-N Atomic Rocket Motor''' is a low-thrust, high-efficiency [[rocket engine]]. It is modeled after the real-world [[wikipedia:nuclear thermal rocket|nuclear thermal rocket]], which uses a fission reactor to heat liquid hydrogen and propel it out of the rocket nozzle; however, as of version {{Check version|0.21.1}}, it is still a hybrid design which is powered by [[liquid fuel]] and [[oxidizer]]. This is largely due to programming constraints, as stated in it's parts.cfg file, although the real-world equivalent could use other liquids for propulsion, but then with a lower efficiency.
+
The '''LV-N "Nerv" Atomic Rocket Motor''' is a low-thrust, high-efficiency [[rocket engine]]. It is modeled after the real-world theoretical [[wikipedia:nuclear thermal rocket|nuclear thermal rocket]] (NTR), which uses a fission reactor to heat its propellant and force it out of the rocket nozzle to generate thrust (as opposed to a normal rocket, which ignites the propellant and uses the energy released by the resulting chemical reaction for that purpose).
  
 
== Usage ==
 
== Usage ==
The LV-N has a quite low thrust (the [[LV-909 Liquid Fuel Engine|LV-909]] being the only engine in its size-class with less power) and with 2.25 tons a very high mass, giving it the worst [[thrust-to-weight ratio]] of all liquid-fuel engines. Its fuel efficiency while in the atmosphere is also rather poor. But as soon as it gets out of the atmosphere, its fuel efficiency suddenly becomes superb. It has a vacuum I<sub>sp</sub> of 800 s, the best of any liquid-fueled engine. Only the [[PB-ION Electric Propulsion System]] is better but with even less thrust.  
+
Unlike other rocket engines, the Nerv consumes '''only liquid fuel'''. As such, a Nerv-powered craft should make use of liquid fuel fuselages (like the [[Mk1 Liquid Fuel Fuselage]]), which contain only liquid fuel and no oxidizer. Alternatively, rocket fuel tanks with the oxidizer removed can be used, although this results in an extremely poor mass ratio.
  
This remarkable efficiency makes it quite popular for interplanetary travel. It is not recommended that the player attempt to use this engine to escape atmosphere or even the gravity of large moons.  
+
When outside the atmosphere, the Nerv has superb efficiency, with a vacuum [[Specific impulse|I<sub>sp</sub>]] of 800&nbsp;s: higher than any other [[liquid fuel engine]] and the second highest in the game overall, beaten only by the [[Dawn]] ion engine. Compared to the Dawn, it has 150x greater thrust per second of [[Isp|I<sub>sp</sub>]]. Its combination of comparatively high thrust and high efficiency makes it a popular choice for interplanetary stages.
  
It will overheat, but it will usually stop at about 1/3 through the overheat bar.  As of version 0.22, it will no longer overheat and explode when placed under a [[Rockomax Jumbo-64 Fuel Tank]].
+
The Nerv has a [[thrust-to-weight ratio]] of approximately 2, the lowest of all liquid engines. This makes it a very poor choice for large landers, or other craft that will need to move large masses against strong gravity. Its [[Isp|I<sub>sp</sub>]] and thrust while in atmosphere is incredibly poor; at Kerbin sea level, its thrust-to-weight ratio is below 1 and thus prohibits first-stage rocket use. For these reasons, the Nerv finds its niche in orbital and interplanetary maneuvering of larger crafts that can't afford to use the extremely low-thrust Dawn engine.
  
== Description ==
+
The engine is quite long, being almost exactly the same length as a Mainsail engine. Nerv engines on a landing stage require some interesting structure designs to get the landing gear low enough to clear the bottom of the engine.
 +
 
 +
== Product description ==
 
{{Quote
 
{{Quote
|Despite the big scary trefoil painted onto the side of this engine, its radioactive exhaust, and tendency to overheat, the LV-N Atomic Rocket Motor is harmless. Mostly.
+
|Despite the big scary trefoil painted onto the side of this engine, its radioactive exhaust, and tendency to overheat, the LV-N Atomic Rocket Motor is harmless. Mostly. Note that the LV-N is the only LV series engine to run solely on Liquid Fuel - the future is glowing bright!
|Jebediah Kerman's Junkyard and Spaceship Parts Co.}}
+
|manufacturer=RMC}}
 
 
{{Quote|Yes, I know this is wrong. NTRs don't actually burn fuel and oxidizer, but we don't want to jump into making separate tanks for the two yet.|Excerpt from the part.cfg}}
 
  
 
== Trivia ==
 
== Trivia ==
•The description of this part is a reference to the Douglas Adams nonsense sci-fi novel "Mostly Harmless"
+
* Before [[1.0]], the LV-N consumed both [[liquid fuel]] and [[oxidizer]], unlike real-world nuclear thermal rockets. This due to programming constraints, as stated in its parts.cfg file, and [[Squad]]'s unwillingness to add another tank type. Real NTRs run on liquid hydrogen, but are capable of using other propellants at lower efficiencies.  With the addition of liquid-fuel-only tanks for spaceplanes, this constraint vanished.
 +
{{Quote|Yes, I know this is wrong. NTRs don't actually burn fuel and oxidizer, but we don't want to jump into making separate tanks for the two yet.|Excerpt from the part.cfg pre-[[1.0]]}}
 +
* Before version [[1.1.3]], this engine used to [[Overheating|overheat]] when run at full throttle for the long burns typical of nuclear-powered craft (though it usually stabilized before completely filling the overheat bar)[https://steamcommunity.com/app/220200/discussions/0/350543389010139685/#c350543389011054001] but this is no longer the case and very long burns can be performed without fear of overheating.
 +
* Interestingly, the LV-N has two shrouds, one for each half of the engine. Both are toggleable in the editor.
 +
* The "Nerv" nickname is likely a reference to [[w:NERVA|NERVA]], or "Nuclear Engine for Rocket Vehicle Application", a NASA program to create a nuclear thermal rocket.
 +
* The description of this part may be a reference to Douglas Adams' ''Hitchhiker's Guide to the Galaxy'' series, in which the Earth is described as "mostly harmless".
 +
* The Nerv's use of liquid fuel, rather than hydrogen, as its propellant suggests that the true chemical identity of LiquidFuel is methane; methane is used both in combustive rocket engines in real life, and is also an attractive option as a nuclear-thermal rocket propellant.
  
 
== Changes ==
 
== Changes ==
;{{Version|0.17|}}
+
;[[1.0]]
* Initial Release
+
* LV-N “Nerv” Engine now runs solely on Liquid Fuel.
 +
* No longer has a gimbal.
 +
* Cost increased to 10000.
 +
* Mass increased from 2.25 to 3.
 +
* Isp curve extended past 1 atmosphere; Isp drops to 0.001 at 2 atm.
 +
;[[0.24]]
 +
* Cost increased from 1700 to 8700 (and made meaningful)
 +
;[[0.22]]
 +
* Alternator added; engine now generates 5.0 electric charge per second.
 +
;[[0.17]]
 +
* Initial release
  
 
{{Parts}}
 
{{Parts}}
 
[[Category:Liquid fuel engines]]
 
[[Category:Liquid fuel engines]]

Latest revision as of 05:51, 2 March 2024

LV-N "Nerv" Atomic Rocket Motor
Part image
Liquid fuel engine by
Jebediah Kerman's Junkyard and Spacecraft Parts Co

Radial size Small
Cost (total) 10 000.00 Funds
Mass (total) 3.00 t
Drag 0.2
Max. Temp. 2500 K
Volume  ?
Impact Tolerance 12 m/s
Research Tech tree nuclear propulsion.png Nuclear Propulsion
Unlock cost 45 000 Funds
Since version 0.17
Part configuration liquidEngineLV-N.cfg
Liquid fuel engine
Maximum thrust (1 atm) 13.88 kN
(vacuum) 60.00 kN
Isp (1 atm) 185 s
(vacuum) 800 s
Fuel consumption 1.53 Units of fuel/s


Thrust vectoring No
Testing Environments
On the surface Yes
In the ocean No
On the launchpad No
In the atmosphere Yes
Sub orbital Yes
In an orbit Yes
On an escape Yes
Docked No
Test by staging Yes
Manually testable Yes

The LV-N "Nerv" Atomic Rocket Motor is a low-thrust, high-efficiency rocket engine. It is modeled after the real-world theoretical nuclear thermal rocket (NTR), which uses a fission reactor to heat its propellant and force it out of the rocket nozzle to generate thrust (as opposed to a normal rocket, which ignites the propellant and uses the energy released by the resulting chemical reaction for that purpose).

Usage

Unlike other rocket engines, the Nerv consumes only liquid fuel. As such, a Nerv-powered craft should make use of liquid fuel fuselages (like the Mk1 Liquid Fuel Fuselage), which contain only liquid fuel and no oxidizer. Alternatively, rocket fuel tanks with the oxidizer removed can be used, although this results in an extremely poor mass ratio.

When outside the atmosphere, the Nerv has superb efficiency, with a vacuum Isp of 800 s: higher than any other liquid fuel engine and the second highest in the game overall, beaten only by the Dawn ion engine. Compared to the Dawn, it has 150x greater thrust per second of Isp. Its combination of comparatively high thrust and high efficiency makes it a popular choice for interplanetary stages.

The Nerv has a thrust-to-weight ratio of approximately 2, the lowest of all liquid engines. This makes it a very poor choice for large landers, or other craft that will need to move large masses against strong gravity. Its Isp and thrust while in atmosphere is incredibly poor; at Kerbin sea level, its thrust-to-weight ratio is below 1 and thus prohibits first-stage rocket use. For these reasons, the Nerv finds its niche in orbital and interplanetary maneuvering of larger crafts that can't afford to use the extremely low-thrust Dawn engine.

The engine is quite long, being almost exactly the same length as a Mainsail engine. Nerv engines on a landing stage require some interesting structure designs to get the landing gear low enough to clear the bottom of the engine.

Product description

Despite the big scary trefoil painted onto the side of this engine, its radioactive exhaust, and tendency to overheat, the LV-N Atomic Rocket Motor is harmless. Mostly. Note that the LV-N is the only LV series engine to run solely on Liquid Fuel - the future is glowing bright!

Rockomax Conglomerate

Trivia

  • Before 1.0, the LV-N consumed both liquid fuel and oxidizer, unlike real-world nuclear thermal rockets. This due to programming constraints, as stated in its parts.cfg file, and Squad's unwillingness to add another tank type. Real NTRs run on liquid hydrogen, but are capable of using other propellants at lower efficiencies. With the addition of liquid-fuel-only tanks for spaceplanes, this constraint vanished.
Yes, I know this is wrong. NTRs don't actually burn fuel and oxidizer, but we don't want to jump into making separate tanks for the two yet.

Excerpt from the part.cfg pre-1.0

  • Before version 1.1.3, this engine used to overheat when run at full throttle for the long burns typical of nuclear-powered craft (though it usually stabilized before completely filling the overheat bar)[1] but this is no longer the case and very long burns can be performed without fear of overheating.
  • Interestingly, the LV-N has two shrouds, one for each half of the engine. Both are toggleable in the editor.
  • The "Nerv" nickname is likely a reference to NERVA, or "Nuclear Engine for Rocket Vehicle Application", a NASA program to create a nuclear thermal rocket.
  • The description of this part may be a reference to Douglas Adams' Hitchhiker's Guide to the Galaxy series, in which the Earth is described as "mostly harmless".
  • The Nerv's use of liquid fuel, rather than hydrogen, as its propellant suggests that the true chemical identity of LiquidFuel is methane; methane is used both in combustive rocket engines in real life, and is also an attractive option as a nuclear-thermal rocket propellant.

Changes

1.0
  • LV-N “Nerv” Engine now runs solely on Liquid Fuel.
  • No longer has a gimbal.
  • Cost increased to 10000.
  • Mass increased from 2.25 to 3.
  • Isp curve extended past 1 atmosphere; Isp drops to 0.001 at 2 atm.
0.24
  • Cost increased from 1700 to 8700 (and made meaningful)
0.22
  • Alternator added; engine now generates 5.0 electric charge per second.
0.17
  • Initial release