WASHINGTON — The U.S. Air Force is planning a combined 46 launches of its workhorse Atlas 5 and Delta 4 rockets from 2013 through 2017, a rate the service says will prevent the buildup of excess inventory even if it commits to buying the vehicles at a rate of eight per year, according to a recent Air Force report to Congress.

Seeking to curb soaring satellite launch costs, the Air Force is planning a bulk buy of its Atlas 5 and Delta 4 Evolved Expendable Launch Vehicle (EELV) rockets from United Launch Alliance (ULA) of Denver. But the strategy has drawn criticism from Congress and prospective ULA competitors, who argue that it will lock the Air Force into higher-than-necessary prices and, given recent launch rates, result in excess rocket inventory.

In its March 2012 report, ordered up by Congress in the National Defense Authorization Act for Fiscal Year 2012, the Air Force acknowledged that actual yearly Delta 4 and Atlas 5 launch rates from 2005 through 2009 were only 30 to 44 percent of what was planned. But the service noted that for 2010 and 2011, the vehicles logged a combined seven and nine launches, respectively, or 100 percent of what was planned.

Congress requested the report to gauge Air Force compliance with the recommendations of a U.S. Government Accountability Office review that urged the service to hold off on the planned EELV block buy pending better pricing data from ULA, the prime contractor on the program. In its September 2011 report, “Evolved Expendable Launch Vehicle: DoD Needs to Ensure New Acquisition Strategy is Based on Sufficient Information,” the congressional watchdog agency cited EELV launch rates from 2005-2009 to make its case that the block buy strategy would result in excess rocket inventory.

The Air Force nonetheless is moving ahead with the block buy strategy, planning to procure six to 10 EELV booster cores per year during a three- to five-year period. Contract award is expected this summer, and the service said the exact number of rockets it buys over that period will be based on the prices ULA offers for the matrix of options.

EELV launch rates were far lower than expected in the years just prior to 2010 because of rocket reliability concerns and delays on several military satellite development programs. In 2007, for example, ULA conducted only three EELV launches — two of the Atlas 5 and one of the Delta 4 — out of a planned 10.

In its report to Congress, the Air Force expressed confidence that it will achieve its planned launch schedule during the next five years because most of the satellites on the manifest will be virtual clones of spacecraft that have flown before. Several Air Force satellite programs have moved from development into production in recent years.

“This will greatly reduce the chance of development or production delays and increases the likelihood these satellites will launch on schedule,” the report said.

The Air Force also cited a pair of initiatives dubbed “Atlas ‘white tail’” and “Delta Fleet Standardization” and said these efforts will reduce the likelihood of launch delays by increasing its flexibility to mix and match among launchers and payloads. The report briefly characterized the Atlas white tail as a “common booster core for Atlas rockets” and Delta Fleet Standardization as an effort to introduce a common RS-68 main engine to be used on all variants of the Delta 4 rocket.

Rising propulsion costs, attributed in large part to the retirement of NASA’s space shuttle — which has forced engine makers, Pratt & Whitney Rocketdyne in particular, to spread their fixed overhead costs across fewer programs — have been cited as a major factor in the cost growth on the EELV program. The Government Accountability Office urged the Air Force to wait until NASA sorted out its post-shuttle heavy-lift launcher program, which is expected to have a bearing on EELV engine costs, before moving ahead with the block buy.

The Air Force noted that since September, NASA has announced its heavy-lifter approach, including plans to utilize Pratt & Whitney-built space shuttle main engines and possibly the RS-68, while also having the company develop an upper-stage engine based on an Apollo-heritage design. “Both of these actions will have a positive impact on [Pratt & Whitney Rocketdyne’s] business base, which should result in lower overhead rates and costs” for all EELV customers including the Air Force, National Reconnaissance Office and NASA, the service’s report said.

The Air Force also pledged to closely scrutinize costs incurred by ULA and its suppliers to ensure it is paying a fair price for Atlas 5 and Delta 4 launches. However, the report conceded that the Air Force “will be unable to obtain certified cost and pricing data” for RD-180, the Russian-built main engine for the Atlas 5.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...