The following picture shows various spacecraft design proposals for the 1958 U.S. Air Force Man In Space Soonest program:
The bottom row depicts various spaceplanes, which should not be a surprise considering that many of the companies involved were established aviation manufacturers. The top row shows three conical designs (similar to what was finally chosen for Mercury), then a bullet-shaped capsule (like Soyuz), then dear lord what is that?!, and finally two spherical capsules (like Vostok).
Are there any details on the Avco design?
I realize that Avco later made the Apollo heat shields. Were they trying to make a capsule that was 70% heat shield?
Is it swamp gas?