# [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** — Turbopump engineering for liquid-fuel rockets drew heavily on gas turbine compressor and turbine design.

## Discovery Character
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**Surprise level**: High — Jet propulsion doubled (and eventually quadrupled) achievable aircraft speeds, made intercontinental mass travel possible, and created the modern global economy. None of this was foreseen when Whittle filed his patent in 1930.
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**Mode**: Systematic, against institutional resistance. Whittle had a clear theoretical concept from his 1929 RAF College thesis — he understood the thermodynamic cycle. The challenge was entirely engineering: materials that could survive 700°C turbine inlet temperatures did not exist. He was repeatedly denied funding by the Air Ministry (who told him "the government is not interested") and worked for years on a shoestring. The obstacles were institutional and materials-based, not conceptual.
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# Parents

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