# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/Das_sXCvVeX
- **Gondola URL:** https://gondola.cc/posts/67970790-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/a31dde8513.jpg
- **Posted:** 2026-07-12T18:34:37.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A jet engine has to eat a bird and still not kill anyone. That is not a metaphor. It is a certification requirement, and it is tested with a compressed-air cannon.

Bird ingestion testing under FAA Part 33.76 and its EASA equivalent is one of the most violent rites of passage in aviation. A brand new engine, worth tens of millions, is bolted to a test stand, run up to full take-off power, and fed carcasses fired from a gas gun at roughly 180 to 200 knots to replicate the closing speed of a climbing airliner.

The requirement scales with fan inlet area, and the pass criteria differ by threat:

- Medium birds, several fired in rapid succession: the engine must not lose more than 25 per cent thrust and must keep running for a defined run-on period
- Large flocking birds: sustained thrust with no hazardous failure
- Single large bird, up to roughly 3.65 kg on the biggest fans: the engine is allowed to die. It simply must not burn, must not burst its casing, and must not shed debris that could threaten the airframe. A controlled shutdown is a pass

That last one is the part people misunderstand. Certification never promised you a running engine. It promised you a contained one.

The physics explains why. A fan blade tip on a large turbofan moves at 350 to 400 m/s. At that closing velocity the impact pressure on a bird vastly exceeds the strength of muscle and bone, so the carcass stops behaving like a solid and starts behaving like a fluid. Engineers model it as soft-body impact, often with smoothed particle hydrodynamics, because what actually arrives at the blade is a high-velocity slug of water at about 950 kg per cubic metre.

Hence the blades. Hollow titanium with an internal truss, or carbon fibre laminate with a titanium leading edge, engineered to deform, absorb and slice rather than snap at the root.

Survival is not the standard. Failing safely is.

#stemantics #aerospaceengineering #jetengine #turbofan #engineering

## Stats

- **Views:** 30,891
- **Likes:** 248
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- **Comments:** 10

## Tags

engineering, jetengine, turbofan, aerospaceengineering, stemantics

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