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

Revision as of 20:57, 7 April 2020

LV-N "Nerv" Atomic Rocket Motor
Liquid fuel engine by Jebediah Kerman's Junkyard and Spacecraft Parts Co
Radial size		Small
Cost	(total)	10 000.00
Mass	(total)	3.000 t
Drag		0.2
Max. Temp.		2500 K
Impact Tolerance		12 m/s
Research		Nuclear Propulsion
Unlock cost		45 000
Since version		0.17
Part configuration		liquidEngineLV-N.cfg
Maximum thrust	(1 atm)	13.88 kN
	(vacuum)	60.00 kN
Isp	(1 atm)	185 s
	(vacuum)	800 s
Fuel consumption		1.53 /s
Thrust vectoring		No
Electricity generated		5.0 ⚡/s
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, 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

The LV-N has low thrust and a very high mass, giving it the worst thrust-to-weight ratio of all liquid engines. For this reason, it is a very poor choice for propulsion in skycranes, despite its high vacuum specific impulse. Its I_sp while in atmosphere is also quite poor, making it not recommended for operation within atmospheres or for landings on larger bodies.

However, when outside the atmosphere, its efficiency becomes superb with a vacuum I_sp of 800 s, by far the highest of any liquid fuel engine. This remarkable efficiency makes it quite popular for upper stages as it is ideal for interplanetary travel. With the 1.0 update, this engine consumes only liquid fuel. As such, it is much more mass-efficient to build your craft with tanks that only contain liquid fuel and no oxidizer. This mass gain allows the LV-N to compete with the LV-909 "Terrier" engine in terms of heavy payloads.

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. It is quite long, being almost exactly the same length as a Mainsail engine. LV-N 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

Trivia

• The description of this part contains a reference to Douglas Adams' Hitchhiker's Guide to the Galaxy series, in which the Earth is described as "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.
• 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.

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