LFB KR-1x2 "Twin-Boar" Liquid Fuel Engine

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LFB KR-1x2 "Twin-Boar" Liquid Fuel Engine
Part image
Liquid fuel engine by
Kerbodyne

Radial size Large, Radial mounted
Cost (total) 17 000.00 Funds
(dry) 14 062.40 Funds
Mass (total) 42.500 t
(dry) 10.500 t
Drag 0.2
Max. Temp. 2000 K
Impact Tolerance 20 m/s
Research Heavier rocketry.png Heavier Rocketry
Unlock cost 65 000 Funds
Since version 0.23.5
Part configuration part.cfg
Liquid fuel engine
Maximum thrust (1 atm) 1 866.67 kN
(vacuum) 2 000.00 kN
Isp (1 atm) 280 s
(vacuum) 300 s
Fuel consumption 135.96 Units of fuel/s
Thrust vectoring 1.5 °
Liquid fuel tank
Liquid fuel 2 880 Units of fuel
Oxidizer 3 520 Units of fuel
Testing Environments
On the surface Yes
In the ocean Yes
On the launchpad Yes
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 LFB KR-1x2 "Twin-Boar" Liquid Fuel Engine is a liquid fuel engine with a built-in liquid fuel tank.

Like all liquid fuel engines, the Twin-Boar is throttleable, both by the main throttle and a thrust limiter tweakable. The minimum thrust level required for this booster to lift its own laden weight is 17.5%. In addition, the liquid fuel booster can be run longer by adding additional rocket fuel tanks, which the Twin-Boar will draw from.

This booster contains two engines at the bottom which are added radially, so the base of the booster is wider than a usual large tank. It also does not allow any parts to be attached below it. It contains the same amount of fuel as the Rockomax Jumbo-64 Fuel Tank (2880). The thrust is higher than the Rockomax "Mainsail" Liquid Engine and is thus the most powerful large-sized engine. However, its Isp is slightly (5-10 s) lower than that of the Mainsail at all altitudes.

The Twin-Boar is the only part that is simultaneously a liquid fuel tank and engine.

Product description

This liquid fuel booster system is a very purposeful piece of engineering. Instead of relying on single engines or solid rocket boosters, the KR-1x2 employs two modified KR-1 engines, fed by a built-in fuel system, as the source of its immense lifting power. All that self-contained goodness comes at the cost of not having a mounting point for its underside, and not being quite as efficient as dedicated engines. It also comes at quite a literal cost as well.

Kerbodyne

Usage

The LFB KR-1x2 is an unusually good engine. Once the weight and cost of the fuel + tankage is subtracted out, it weighs almost the same as a Mainsail, but has 33% more thrust while actually being 13% cheaper. It's similar to a pair of lower-efficiency Vectors. The Twin-Boar also has highest thrust to weight ratio of any liquid fuel engine in the game and the second highest thrust to cost ratio, second only to the LV-T30 "Reliant" Liquid Fuel Engine. This makes it an excellent and cost-effective mid-game launcher for larger payloads.

It is also the best engine in the game for first stage recovery. It has a high impact tolerance of 20m/s, and being very tall makes it extremely buoyant in case of a splashdown. Even in the case of a bad landing which results in partial disintegration of the rest of the stage, the integrated fuel tank is always recovered, so the recovery percentage in case of a crash landing is higher than for other engines.

Trivia

  • The name LFB KR-1x2 might be a reference to the Advanced Boosters, a future Space Launch System Block 2 component.
  • The names "KR-1x2", "Twin-Boar", and the part description all imply the existence of an LFB KR-1 "Boar" Liquid Fuel Engine. However, no such part exists.

Changes

0.24
  • Changed cost (5900 -> 16400), reduced Isp from 320-360 s to 290-340 s, changed description.
0.23.5
  • Initial release