After spending $46 billion over the past decade on canceled weapon systems that were never fielded, the Pentagon may have to wait at least 10 more years to recapitalize its equipment, a new report says.

Todd Harrison, the senior fellow for defense budget studies at the Center for Strategic and Budgetary Assessments (CSBA), highlights the “lagging pace of recapitalization” for certain types of equipment in his Analysis of the FY 2012 Defense Budget. The non-partisan think tank released the 74-page report yesterday in Washington.

Harrison cites equipment concerns, including the average age of aircraft in the Air Force’s fleet now standing at 24 years and rising to a projected 27 years by 2020. Harrison points to oft-mentioned culprits–“exquisite” requirements for the systems that require too much time and money. Even though the defense budget for acquisitions has grown 44 percent in real terms since 2001, he says, lower quantities of equipment have been purchased and the Pentagon continually delays plans for the systems out beyond the Future Years Defense Program (FYDP).

Over the past decade, Harrison notes, at least a dozen major programs in the Department of Defense (DoD)–including the Army’s Future Combat Systems modernization effort and the Marine Corps’ Expeditionary Fighting Vehicle–were terminated without any operational systems being fielded. The sunk costs of the terminated programs add up to $46 billion in then-year dollars, he says. The CSBA report also notes programs such as the F-22 jet fighter and DDG-1000 destroyer for which the Pentagon curtailed plans.

“While the cancellation of individual programs may have been justified due to significant cost overruns or technical challenges, the aggregate effect is that a significant portion of DoD’s investment in modernization over the past decade did not result in force modernization,” Harrison writes.

Some of the canceled efforts are being replaced with other programs, and some of the developed technologies can be salvaged. Still, CSBA notes “much of this investment in time and resources is not recoverable, particularly given the outlook for DoD’s future topline.”

“From this perspective, DoD missed an opportunity to recapitalize its inventory of equipment–an opportunity it may not have again for another decade or longer given the fiscal constraints the nation now faces,” Harrison writes.

He maintains that the relatively high level of funding dedicated to developing new weapon systems “has been a major factor in cost overruns on acquisition programs” and “has undermined DoD’s ability to fund for the quantity of new weapon systems needed to correct the lagging pace of procurements over the past two decades.”

The ratio of procurement to research and development funding the defense budget is 1.4 to 1 in the fiscal year 2011 spending plan, but was 3.5 to 1 during a peak in the early 1980s, according to the report.

This recent trend, though, could change. The current ratio of 1.4 procurement to 1 research and development would change to 1.5 to 1 in the Pentagon’s FY ’12 budget request, Harrison notes.

Also, the FYDP the Pentagon submitted with the FY ’12 budget proposal would further increase procurement monies while decreasing those for research and development. The ratio could rise to 2 procurement to 1 research and development by FY ’16, he writes.

Still, Harrison cautions in the report: “But this projection of increasing procurement and decreasing (research and development) funding in the future is at odds with recent history–such a situation has occurred only once in the past 35 years.”