I've often wondered what might have inspired Rab Hamilton's [ref. GACCH] design for his helijet in Specail Agent 21, June 4th 2066  pictured above. This TV21 design went on to become the SpaceX Golden Astronaut P3 Helicopter, the connection between them having been established way back in 2009, featured on the blog here.
Well, having been pointed to a website called Ridebuzz containing a neat Supercar advert by reader Jim Potter, I noticed this old illustration for 'helicopter cavalry' and thought, hmmm, there's something a little P3 about those little helijets.
A quick google took me to the Modern Mechanix blog where more illustrations are shown. You can see the entire article on that excellent site.
They appeared in Mechanix Illustrated magazine, April 1956 and were called 'Sky Horses'.
Not sure if there's even the slightest connection between sky horses and Rab Hamilton's helijet but it fun to research! What do you think readers!
PS. Thanks Jim P!