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Nuclear Thermal Rockets (NTRs)
Kerbal Space Program

Nuclear Thermal Rockets (NTRs)

Learn how to effectively utilize Nuclear Thermal Rockets (NTRs) in Kerbal Space Program for efficient interplanetary travel and advanced mission planning. Unlock the secrets of high-ISP propulsion.

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Learn how to effectively utilize Nuclear Thermal Rockets (NTRs) in Kerbal Space Program for efficient interplanetary travel and advanced mission planning. Unlock the secrets of high-ISP propulsion.

Nuclear Thermal Rockets (NTRs), also known as the Nerv engine, are a high-efficiency engine in Kerbal Space Program. They are characterized by their extremely high specific impulse (Isp) but low thrust, making them ideal for long-duration, high-delta-v maneuvers such as interplanetary transfers and orbital adjustments around massive bodies. Due to their high efficiency, they are a cornerstone of advanced KSP gameplay for players looking to optimize their missions.

Walkthrough
  1. 1
    Acquisition: NTRs are unlocked in the late-game tech tree, typically in the 'Nuclear Propulsion' or similar high-tier nodes. This means you'll need to conduct significant research and exploration to access them.
  2. 2
    Design Considerations: When designing a craft with NTRs, remember their low thrust. You will need a substantial amount of fuel to achieve desired acceleration, and staging will be crucial for initial ascent. Their Isp is significantly higher than liquid fuel engines, so they are best used in vacuum for sustained burns.
  3. 3
    Interplanetary Transfers: NTRs excel at Hohmann transfers and other efficient interplanetary trajectories. A typical mission profile involves using a more powerful engine for initial ascent and orbital insertion, then switching to the NTR for the long coast to the target planet.
  4. 4
    Orbital Maneuvering: For missions requiring precise orbital adjustments around large planets or moons, the high Isp of NTRs allows for significant delta-v with less fuel mass compared to conventional engines.
  5. 5
    Resource Management: NTRs consume Liquid Fuel (LF) only, simplifying fuel logistics compared to engines that require oxidizer. However, their low thrust means burns will take longer, requiring careful management of time and crew.
Tips
  • NTRs are most effective in a vacuum where their specific impulse is maximized. Avoid using them in the atmosphere if possible, as their thrust-to-weight ratio is generally poor for atmospheric flight.
  • Because of their low thrust, plan your burns carefully. Initiate burns early to account for the longer duration.
  • Consider using radiators if you plan on extended, continuous burns with multiple NTRs, as they can generate significant heat.
  • NTRs are excellent for creating fuel depots or refueling stations in orbit, as their efficiency allows for large delta-v maneuvers with minimal fuel.
  • The 'Nerv' engine is the primary NTR available in the stock game. Mods may introduce other variants with different characteristics.

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