Miniature variable pitch propellers and engines - video

[Altair]

Miniature variable pitch propellers and engines. 3:47 video.

Previously:

Contra-rotating variable pitch propellers - GIF
Propeller feathering - GIF
Ship propeller shaft work using chain blocks - photo

[NortonDommi]

The balance of those engines is incredible! Variable pith propellers are really interesting but few and far between now in smaller sizes and very expensive if you can find one. Another system I like for its simplicity is the Kitchen Rudder.
Here is a drop dead gorgeous boat demonstrating manoeuvres: