// PROPULSION SYSTEMS AND ENGINE TECHNOLOGY TERM
Pintle Injector
A pintle injector is a simple, robust device used in liquid-propellant rocket engines to mix fuel and oxidizer. It works by shooting one propellant from a central post (the pintle) into a spray of another propellant coming from an outer ring, causing them to atomize and mix efficiently for combustion.
TECHNICAL DEFINITION
The pintle injector is a type of single-element, impinging-stream injector used in bipropellant liquid rocket engines to atomize and mix propellants, typically an oxidizer and a fuel, for stable combustion. Characterized by a central pintle element discharging one propellant into a concentric, radially-inward flowing stream of the second propellant, this design offers excellent throttleability, combustion stability, and manufacturing simplicity, and is notably used in the Apollo LMDE and SpaceX Merlin engines.
BACKGROUND
The pintle injector is a type of propellant injector for a bipropellant rocket engine. Like any other injector, its purpose is to ensure appropriate flow rate and intermixing of the propellants as they are forcibly injected under high pressure into the combustion chamber, so that an efficient and controlled combustion process can happen.
READ MORE ON WIKIPEDIASYNONYMS & ALIASES
- central pintle injector
- impinging stream injector
- single-element injector
- throttleable injector
- Elverum injector
USAGE NOTE
This design is particularly favored for engines requiring deep throttling capabilities, such as those used for landers or reusable launch vehicle stages.
DEVELOPERS
Organizations developing technology related to Pintle Injector.
Utilizes pintle injectors in its highly successful Merlin engine family, which powers the Falcon 9 and Falcon Heavy launch vehicles. The design contributes to the engine's reliability and throttling capability.
As the successor to TRW Inc., Northrop Grumman holds the legacy for the pioneering development of the pintle injector, which was famously used in the throttleable Descent Propulsion System of the Apollo Lunar Module.
The National Aeronautics and Space Administration has extensively researched, tested, and funded the development of pintle injector technology. Notable work includes the Morpheus project, which used a pintle-based engine for its vertical takeoff and landing vehicle.
A major US rocket engine manufacturer with a long history of developing various injector types. They have designed, tested, and manufactured pintle injectors for numerous applications, including missile defense and upper stage engines.
A US-based company that develops and manufactures liquid rocket engines for the satellite launch and hypersonic industries. Their engine designs, like the Hadley, have incorporated pintle injectors for their stability and performance characteristics.
Acquired by Vast, Launcher developed the E-2 engine, which successfully utilized a single-piece, 3D-printed copper alloy pintle injector, demonstrating a low-cost, high-performance manufacturing approach for this technology.
An Indian aerospace startup developing small satellite launch vehicles. Their flagship Agnilet engine is a single-piece, 3D-printed, semi-cryogenic engine that uses a pintle injector design.
Developing a fully reusable upper stage with a novel engine design. Their development path leverages robust and throttleable components, with pintle injectors being a key technology for achieving the required performance and reusability.