Difference between revisions of "CR-7 R.A.P.I.E.R. Engine"

Revision as of 17:27, 29 February 2024

CR-7 R.A.P.I.E.R. Engine
Hybrid engine by C7 Aerospace Divisionand Rockomax Conglomerate
Radial size		Small
Cost	(total)	6 000.00
Mass	(total)	2.000 t
Drag		0.2
Max. Temp.		2000 K
Impact Tolerance		20 m/s
Research		Aerospace Tech
Unlock cost		35 000
Since version		0.23
Part configuration		rapierEngine.cfg
Maximum thrust		105.00 kN
Isp	(max)	3200 s
Fuel consumption		0.67 /s
Intake air consumption		4.02 /s
Thrust vectoring		3 °
Maximum thrust	(1 atm)	162.30 kN
	(vacuum)	180.00 kN
Isp	(1 atm)	275 s
	(vacuum)	305 s
Fuel consumption		12.04 /s
Thrust vectoring		3 °
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 CR-7 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 one of the first stock engine which has multiple nozzles 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.

Performance and usage

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 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 as it saves the weight of a separate engine.

This engine is one of the few engines that do not provide electric charge when active, another example being the LV-909 engine.

Unlike the other jet engines, the R.A.P.I.E.R. has a rear mounting point.

Air-breathing

Like other jet engines, the air-breathing mode only works in the atmospheres of Kerbin or Laythe. The air-breathing mode has lower specific impulse than the other jets, though still a order of magnitude higher than most rocket engines. On the other hand, it delivers better performance than the J-X4 "Whiplash" Turbo Ramjet Engine at high speeds (~1,000 m/s and higher) and altitudes (~17,000 m and higher), making it a good choice for high-speed atmospheric flight. Its top speed is ~2,100 m/s in Kerbin's atmosphere (Mach 6.2). Its most fuel-efficient flight profile is Mach 3.6 at 17,600 m altitude.

Closed-cycle

The closed-cycle performance is merely mediocre. Its specific impulse is in the middle of the pack compared to other rocket engines. As a pure rocket, its thrust-to-weight ratio is worse than any conventional rocket. However, the R.A.P.I.E.R. is lighter and more compact than having a separate jet engine and rocket, and has a moderate amount of ISP, comparable to most rocket engines. This makes the R.A.P.I.E.R a good choice for single-stage-to-orbit (SSTO) where use of the rocket can be kept to a minimum, but not practical for extended spaceflight.

Product description

Changes

1.0.3

• Jet engine I_sp halved, thrust reduced

1.0

• Mass increased from 1.2 to 2.0; cost increased from 3600 to 6000; maximum jet thrust reduced from 190 to 140; maximum liquid fuel thrust increased from 175 to 180.

0.24

• Cost decreased from 5900 to 3600 (and made meaningful), manufacturer name fixed, mass decreased from 1.75 to 1.2

0.23

• Initial release