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![ron_eisele Avatar](https://lunarcrush.com/gi/w:24/cr:twitter::3195245890.png) Ron Eisele [@ron_eisele](/creator/twitter/ron_eisele) on x 61.2K followers
Created: 2025-07-25 20:42:09 UTC

XX July 1973. First flight of the Sikorsky S-69 (73-21941), military designation XH-59. American experimental compound co-axial helicopter developed as the demonstrator of the Advancing Blade Concept (ABC).

![](https://pbs.twimg.com/media/GwuxVZ6W8AAqhXZ.jpg)

XXX engagements

![Engagements Line Chart](https://lunarcrush.com/gi/w:600/p:tweet::1948846252931608980/c:line.svg)

**Related Topics**
[abc](/topic/abc)
[compound](/topic/compound)
[ron](/topic/ron)

[Post Link](https://x.com/ron_eisele/status/1948846252931608980)