[positronic1]

I can see where the cover illustration for this issue became mis-identified as being Buck Rogers. In the early Buck Rogers comic strip, Buck used a 'jumping belt' or pack made of an antigravity substance called "inertron" -- propulsive power was supplied by the wearer's own legs. A further development (mentioned in the story "Armageddon 2419 AD") led to small rocket motors encased in inertron blocks. Much later in the BUCK ROGERS comic strip the anti-grav 'inertron belt' gave way to the more familiar-looking personal rocket pack, and "inertron" was seldom mentioned any more. On this Frank R. Paul cover, it's not apparent what method (if any) of propulsion is in use -- the device worn here seems to be limited to anti-gravity levitation alone. Presumably the character depicted here using the device is Richard Seaton, the hero of E. E. Smith's Skylark series.

Link to the book: Amazing Stories - First 2 Buck Rogers Stories