Restructure: USD fix + updated descendants

# [TECH] Jet Engine

**The Jet Engine** (gas turbine) replaced piston engines for aircraft propulsion (1940s), enabling supersonic flight, mass air travel, and cargo transport.

## Overview

Frank Whittle (UK) and Hans von Ohain (Germany) independently developed jet engines (1939–1941). The turbojet compresses air, combusts fuel, and expands hot gases through a turbine to generate thrust. The turbofan (1960s) added a large fan for efficiency; high-bypass turbofans power all modern airliners. Gas turbines also generate ~25% of global electricity. The Rolls-Royce Merlin's success and the subsequent jet development programme created the modern aerospace industry.

## Key Actors

- **Companies**: Rolls-Royce (UK), Pratt & Whitney (US), GE Aviation (US), CFM International (US/FR joint)
- **Inventors**: Frank Whittle (1907–1996), Hans von Ohain (1911–1998)

## Key Patents

- Whittle, F. UK Patent 347,206 (1930) — jet propulsion (application)
- von Ohain, H. DE Patent 317/38 (1936) — jet propulsion

## Economic Value

Global aircraft engine market: **\$USD 95 billion/year** (2023, Roland Berger). Aviation enabled by jet engines: ~\$USD 900B/year airline revenue; global air transport enables \$USD 3.5T in trade and tourism.

## Notes

Roland Berger *Aerospace & Defense* 2023. IATA *World Air Transport Statistics* 2023.

## What This Enables

- **[TECH] Rocket & Space Launch** — Rocket propulsion evolved from jet engineTurbopump engineering; turbopump design draws directly for liquid-fuel rockets drew heavily on gas turbine technology.
- **[TECH] Satellite Communications** — Reliable heavy-lift launch vehicles are needed to deploy communication satellites; all derive from jet/rocket propulsion lineagecompressor and turbine design.

# Parents

* [SCI] Aerodynamics
* [SCI] Turbulence Theory
* [TECH] Aircraft (Piston Era)
* [TECH] Petroleum Refining