I found this doing a google search, https://accessyoutube.org.uk/play/WNkohUPIRNQ
I’ve read that these make more noise than a single prop system, which makes sense because
wait for it …there’s 2 props.
I am just wondering if this would be a more or a less efficient system than 4 single props.
2 larger contra rotating props instead of 4 smaller ones.
Just throwing this out there.