That's Captain Future, who also had some Jeffrey Jones covers.
Dunnae about a Cap'n Future (and definitely dinnae know Jeff Jones painted this cool shirt--thanks for the lead!), but I will put up the other Frazetta painting of this guy
The Captain Future paperpack reprints didn't have a distinctive "Doc Savage"-style logo and the covers varied wildly from a photo-montage to a couple of Frazettas to Jeff Jones.You can see the complete paperback series at...http://homepage3.nifty.com/captainfuture/gallery_e.html
Thanks! I knew about the other Frazetta, and even own a copy of Quest, but dinnae notice the blurb on that Jeff Jones cover was about Cap'n Future (member-I'm so broke I can't even pay attention)