The Aircraft and Weapons division chief with the US Air Force Cost Analysis Agency has made a series of suggestions in a research paper for keeping the price of a sixth generation fighter down after analysing a myriad of cost-overruns by the B-2, F-22 and F-35 programmes.

A reoccurring theme throughout many of the suggested measures is a need for the USAF to maintain a disciplined focus on a narrow set of unchanging priorities for their next generation fighter. The research paper was presented at an International Cost Estimating and Analysis Association workshop in June 2018.

One suggestion is that the USAF develop their next aircraft by focusing on one major item at a time and then incrementally adding other system upgrades – an approach that has worked on previous aircraft programmes.

“As in the case of the F/A-18E/F, an incremental approach was followed that began with a new airframe, but used existing avionics,” wrote David E. Stem, Aircraft and Weapons division chief with the USAF Cost Analysis Agency and author of the paper. “As time progressed and avionics technology could be developed outside the main program, it could then be incorporated into the aircraft.”

This focused, incremental approach is contrasted with a history of making major changes to several features of military aircraft at once, while moving from the prototyping stage to the engineering, manufacturing and development phase, a practice that was especially true of the Lockheed Martin F-35 programme, says Stem.

“The desire to enter production before development was completed resulted in a concurrency between the two phases of the program where design changes were being fed to aircraft already in production,” he says. “Traveled work, essentially manufacturing retrofits, plagued the test aircraft as they were being produced causing delays in the flight testing. It also caused early production aircraft to be delivered that did not meet the full capability as outlined in the [system development and demonstration] contract.”

The report recommended building off a prototype design that is production representative, citing the F-16 as an example of a light weight fighter that largely was unchanged when it went into full-scale development and production.

A few of the suggested changes fly in the face of the USAF’s philosophy of modern fighter design and would force the service to majorly rethink its operations, however.

One such recommendation is that the service relax its radar cross section requirements. The desire for stealth drives many design tradeoffs with systems such as internal avionics, internal weapons, internal fuel, making it difficult to accommodate changes to the aircraft later, says Stem.

The USAF has built much of its strategic thinking around stealth technology, including its upcoming heavy bomber, the Northrop Grumman B-21 Raider, and so reducing an emphasis on an aircraft’s radar cross section would be a major change.

Another proposal is to challenge designers to use less software in their aircraft functionality. Software development snags have frequently caused delays and cost overruns on the F-22 and F-35.

However, that suggestion is counter to the prevailing trend of evermore software-controlled functions on aircraft. For example, in 1960, software accounted for 8% of the functionality in the McDonnell Douglas F-4 Phantom, compared with 80% of the functionality in the Lockheed Martin F-22 Raptor in 2010, according to research published in the Air and Space Power Journal.