Ed Heinemann, Douglas' chief designer, later to win fame for the A-4 Skyhawk, fearing that the "United States" class was vulnerable to cancellation, proposed a significantly smaller aircraft of loaded weight, capable of operating from the USN's existing carriers. Heinemann had reasoned (correctly) that as technology developed, the size and weight of nuclear weapons would substantially decrease, which increased the rationale for designing a more compact bomber. However, figures such as USAF general Hoyt Vandenberg ridiculed Heinemann's proposal as "making irresponsible claims". During this period, the USN and USAF were vigorous rivals, each seeking to maintain funding for its projects at the expense of the other in a time marked by drastically declining defense budgets; specifically, USAF officials frequently voiced their open opposition to the construction of the "United States"-class carriers.