Spiral development and the F/A-18: parallels from the past emerge in spiral development of the F/A-18A through F variants - Best Practices

Program Manager, May-June, 2003 by Jeffrey A. Wieringa

Spiral development is being invoked as the preferred current method of procuring weapon systems. Although it is generally accepted that spiral development was first articulated by Barry Boehm in 1988, some of its distinguishing features, such as a cyclic approach for incrementally growing a system's degree of definition and implementation, can be found in the archives chronicling the Navy's development of the F/A- 18 strike fighter, with particular attention to this aircraft's most recently enhanced variants--the single-seat F/A-18E and the dual-seat F/A-18F Super Hornets.

Historical Background

Parallels from the past may be worthy of study by those in charge of spiral development in the future. Interesting comparisons can be made between the Navy's developmental efforts with F/A1-8E/F, a truly evolutionary development, and more revolutionary developments in weapon systems attempted over the years. Those who are to implement spiral development in the future might gain valuable insight from a study of the F/A-18E/F. Even the original F/A-18A, which first flew on Nov. 18, 1978, was in some ways a precursor of spiral development. It had started out with the objective of producing a truly multimission strike fighter, one that could replace both the aging F-4 Phantom in the fighter role, and the aging A-7 Corsair II in the light attack role. In addition to being truly multimission, the F/A-18 was also designed to be affordable, not only in developmental and acquisition cost, but even more importantly in life cycle cost where the key to success was a significant improvement in both reliability and maintainability. All of these goals were achieved.

The original F/A-18 continued to evolve successfully, partly because it was designed from the outset with future improvements in mind. Pre-Planned Product Improvement (P3I) was that era's buzzword-equivalent of spiral development. The P3I purists, however, insisted that the F/A-18 wasn't an authentic example of P3I because its designers, developers, and managers got started without really knowing for sure precisely which enhancements it was to incorporate or exactly when or how they were intended to be incorporated.

Today these very uncertainties are considered by some to be highly useful traits in spiral development. One authority on spiral development puts it this way: "When you do spiral development, you do not know ahead of time when you start at the beginning of spiral zero where you're going to come out. As you resolve the risks, you may even redesign what you are trying to accomplish."

Digital Architecture

One of the keys to the Hornet's success, and to that of the F/A- 18E/F Super Hornet as well, was its digital architecture. The ingeniously designed multiplex bus, with its ability to integrate the evolving software of the mission computer, the flight control computer, and approximately 30 additional microprocessors located throughout the airplane, gave the original F/A-18 the potential for more than 20 years of growth and enhancement in weapons, sensors, countermeasures, and other systems. It had spiraled so vigorously that by the time the larger, longer range, more survivable, more versatile Super Hornet came to be designed, 80 percent of the Hornet's avionics had been updated so successfully that they could be used for the Super Hornet. By this time, however, the original F/A-18A/B had spiraled up through C and D versions and no longer had the electrical, cooling, and volume capacity to handle all the new weapons, sensors, countermeasures, and other systems that were becoming available for the Super Hornet.

Just as the original Hornet depended on spiral development for its success, the Super Hornet has followed the same path. The first Super Hornets, deployed on board USS Abraham Lincoln last summer, signify simply the first turn of their own spiral, but a very hefty segment at that: they embody the additional range, payload, and bringback that were the aircraft's initial objectives; they incorporate considerably greater survivability than their predecessors; and they are capable of serving as airborne tankers.

Even though the F/A-18E/F and its evolving systems and subsystems may not fit everyone's definition of evolutionary acquisition and spiral development, anyone attempting a spiral development in the future would benefit from a study of them.

Other System/Subsystems

One of the more interesting subsystems of the F/A-18E/F is its Integrated Defensive Electronic Countermeasures suite. An outgrowth of the countermeasure systems that evolved on the F/A-18A/B/C/D versions, it in turn will continue its spiral through a phased approach.

Block 1

Its Block 1 includes a proven jammer, the ALQ-165--an operationally successful jammer incorporated in late-model F/A-18CA3 aircraft and now also included in the F/A-18C/D aircraft flying with the air forces of allied nations. Additional protection is provided by the ALE-50 towed decoy.

Block 2

In Block 2, the ALQ-165 will be replaced by the ALQ-214 radar frequency countermeasures system, a "techniques generator" that determines an appropriate signal to counter an attacking missile.