# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/Dc9ZxHuSJV9
- **Gondola URL:** https://gondola.cc/posts/70280835-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/ec7ceff9e7.jpg
- **Posted:** 2026-09-06T20:34:52.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A cutaway turbofan tells you what the cowling hides: a jet engine is not one machine but four, bolted end to end and turning at different speeds on shafts nested inside each other. (Link in bio to get one)

Air enters through the fan. On a modern high-bypass engine, roughly nine tenths of that air never reaches the combustor at all. It is accelerated by the fan and dumped straight out of the bypass duct, and it generates around 80 percent of total thrust. The core exists mostly to turn the fan.

The remaining tenth goes through the compressors. Alternating rows of rotating blades and stationary vanes squeeze the flow stage by stage, each one adding pressure and temperature. Overall pressure ratios on current engines exceed 50:1, and air leaving the final compressor stage sits around 600 to 700 degrees Celsius before a single drop of fuel is injected.

Combustion then happens at roughly constant pressure. Fuel burns continuously in an annular chamber and gas leaves it beyond 1700 K.

Then the turbines take their cut. High-pressure turbine blades sit directly in that stream, and the alloy they are cast from melts below the temperature of the gas washing over them. They survive because they are hollow single-crystal castings with no grain boundaries to creep along, sprayed with ceramic thermal barrier coating, and fed cool compressor air through film holes that lay a protective blanket across the surface.

Two spools, two shafts, one inside the other:

- LP spool: fan, booster stages, low-pressure turbine
- HP spool: high-pressure compressor, high-pressure turbine

They spin independently, often in opposite directions, because the ideal speed for a two-metre fan and the ideal speed for a small core compressor are nothing alike.

Everything downstream of the flame is a negotiation between temperature and time.

#stemantics #turbofan #aerospaceengineering #jetengine #mechanicalengineering

## Stats

- **Views:** 19,971
- **Likes:** 228
- **Shares:** 0
- **Comments:** 3

## Tags

jetengine, turbofan, mechanicalengineering, aerospaceengineering, stemantics

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