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R.A.P.I.E.R. Engine

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R.A.P.I.E.R. Engine
Part image
Hybrid engine by
C7 Aerospace Division and Rockomax Conglomerate
Radial size Small
Cost (total) 3 600.00 Fund
Mass (total) 1.20 t
Drag 0.2
Max. Temp. 3600 K
Impact Tolerance 20 m/s
Research Hypersonic flight.png Hypersonic Flight
Unlock cost 35000 Fund
Since version 0.23
Part configuration rapierEngine
On the surface ✓ Yes
On the ocean ✓ Yes
In atmosphere ✓ Yes
In space ✓ Yes
Test by staging ✓ Yes
Manually testable ✓ Yes
Liquid fuel engine
Maximum thrust 175 kN
Isp (1 atm) 320 s
(vacuum) 360 s
Fuel con­sumption (1 atm) 11.14 Jerry-can char.svg/s
(vacuum) 9.90 Jerry-can char.svg/s
Thrust vectoring 3 °
Jet engine
Maximum thrust 190 kN
Isp (max) 2500 s
Fuel con­sumption 0.10 Jerry-can char.svg/s
Intake air consumption 1.45 Air unit/s
Thrust vectoring 3 °

The R.A.P.I.E.R. Engine (Reactive Alternate-Propellent Intelligent Engine for Rockets) is a hybrid engine. It can change between an airbreathing jet and a liquid fuel engine. It has the feature to auto adjust, changing between jet and rocket mode automatically when it runs out of intake air. This engine is an in-game counterpart of the real life SABRE engine, which is also visible in the naming as both are named after swords.

This is the first stock engine which has multiple engines incorporated into one part (four in this case).

This is the first engine which has two different manufacturers. Prior to 0.24 one of the manufacturers seems to be misspelled. Instead of Rockomax Conglomerate an o was missing attributing it to the Rockmax Conglomerate. However, the description text used the common spelling and the manufacturer entry was fixed in 0.24.


This engine has two modes of operation. An AirBreathing mode in which it runs on liquid fuel and intake air like a jet engine and a ClosedCycle mode in which it runs on liquid fuel and oxidizer like a rocket engine. The air-breathing mode is far more fuel-efficient and delivers slightly more thrust, but just like normal jet engines it only works in the atmospheres of Kerbin or Laythe.

The engine can either be set to switch automatically to closed-cycle when the intake air runs out or it can be switched manually between the two modes.

The hybrid feature makes this engine especially useful for single-stage-to-orbit designs. The engine has less efficiency than comparable jet or rocket engines, but because it can switch between modes, it may be a better choice than a Toroidal Aerospike Rocket for orbital insertion. This engine is one of the few engines that do not provide electric charge when active, another example being the LV-909 engine.

The R.A.P.I.E.R Engine has a very low maximum specific impulse in its air breathing mode compared to other jet engines. It is not an optimal choice for long range cruising type jets. It has a high specific impulse in rocket mode however.

Product description

The R.A.P.I.E.R (Reactive Alternate-Propellent Intelligent Engine for Rockets) is a joint venture between C7 Aerospace and the Rockomax Conglomerate. Designed to fill a gap in the design requirements for sustainable single stage to orbit aircraft, this engine combines the best of rocket and air-breathing thrust technology


  • Cost decreased from 5900 to 3600 (and made meaningful), manufacturer name fixed, mass decreased from 1.75 to 1.2
  • Initial release
Default parts
Jet engines Basic Jet EngineTurboJet EngineR.A.P.I.E.R. Engine
Liquid fuel tanks Oscar-B Fuel TankROUND-8 Toroidal Fuel TankFL-T100 Fuel TankFL-T200 Fuel TankFL-T400 Fuel TankFL-T800 Fuel TankRockomax X200-8 Fuel TankRockomax X200-16 Fuel TankRockomax X200-32 Fuel TankRockomax Jumbo-64 Fuel TankKerbodyne S3-3600 TankKerbodyne S3-7200 TankKerbodyne S3-14400 Tank
Liquid fuel engines LV-1 Liquid Fuel EngineLV-1R Liquid Fuel EngineRockomax 24-77Rockomax 48-7SRockomax Mark 55 Radial Mount Liquid EngineToroidal Aerospike RocketLV-N Atomic Rocket MotorLV-909 Liquid Fuel EngineLV-T45 Liquid Fuel EngineLV-T30 Liquid Fuel EngineRockomax "Poodle" Liquid EngineRockomax "Skipper" Liquid EngineRockomax "Mainsail" Liquid EngineR.A.P.I.E.R. EngineKerbodyne KR-2L Advanced EngineLFB KR-1x2S3 KS-25x4 Engine Cluster
Solid fuel rockets Sepratron IRT-10 Solid Fuel BoosterRockomax BACC Solid Fuel BoosterS1 SRB-KD25k
Monopropellant fuel tanks Stratus-V Cylindrified Monopropellant TankStratus-V Roundified Monopropellant TankFL-R1 RCS Fuel TankFL-R10 RCS Fuel TankFL-R25 RCS Fuel TankMk2 Monopropellant TankMk3 Monopropellant Tank
Monopropellant engines O-10 MonoPropellant Engine
Jet fuselages Mk1 Fuselage - Jet FuelMk2 to size 1 AdapterMk2 FuselageMk3 to Mk2 AdapterMk3 Fuselage
Fuel transfer FTX-2 External Fuel Duct