Years ago, there was a concept floating around the Pentagon called the “hi / lo mix.” The idea was that you couldn’t afford the thousands of expensive but highly capable fighters the Air Force and Navy wanted, so you bought a reasonable block of them and filled the fleet out with a large number of less capable but cheaper “lo” fighters.
This concept reached concrete form with the F-15 as “hi” and the F-16 as “lo.” Logical, but as Scott Bledsoe & Mike Benitez show in their paper on War in the Rocks, “Rethinking the Hi-Lo Mix, Part I: Origin Story,” this is not exactly how it happened.
I was a bit player in this drama, working for Tom Christie in the TACAIR shop of OSD’s Office of Program Analysis and Evaluation. We’re talking 1972 – 74. One of my jobs was to look into the analytical justifications for the hi/lo mix, and in particular, the justification for a “lightweight fighter (LWF).” At the time, there was a prototype program involving the YF-16 and YF-17, but no plans to put either into the budget (Wikipedia has details). The Air Force’s solution was F-15s everywhere, and they had models that predicted enormous kill ratios, on the order of several hundreds to 1, for an all-F-15 force.*
It turns out to be very difficult to justify a force mix if all you have is a single mission (air-air), a measure of effectiveness (kill ratio), and costs. The math drives you to buying which ever is the more cost effective — all of it and none of the other. Plus there was the Air Force argument against sending US pilots up in inferior fighters.
One way modeling and analysis can lead to a mix is for one aircraft to be better in certain subsets of the mission and the other to have advantages in others. This was the argument we made in PA&E: Grant the F-15 its “beyond-visual-range” capability, of which the LWFs had none, but point out that both the YF-16 and YF-17 would better in close-in maneuvering combat. If the costs work out, then you can get a mix. Bledsoe and Benitez illustrate this with the A-10, better at a variety of close-in tasks, and the F-35, which should have advantages in missions where higher speed and stealth are important.**
There are lots of other complications that Bledsoe and Benitez point out. One is the multi-mission versus single mission debate. The theory was that aircraft that could do a variety of missions, from CAS to counter-air, would have to be very complex and so very expensive, whereas single mission aircraft could be a lot cheaper but of course less flexible from a total force standpoint. But then there’s the “jack of all trades, master of none” argument, and in particular, do you want to lose an F-15 (or F-22) to MANPADs, AAA, or even gun fire down in the weeds? That debate still goes on.***
I’m anxiously awaiting the second installment of Bledsoe and Benitez’s essay.
*Somebody in PA&E pointed out that if so, you’d have a max requirement for maybe 100 F-15s to eliminate the entire USSR / Warsaw Pact fighter force. After that, the USAF edited their briefings a little more carefully.
**It’s worth pointing out that in some areas, in particular advanced aerodynamics and electronic flight controls, the YF-16 had more advanced technologies than the F-15. So it wasn’t just hi-tech/expensive vs. lo-tech/cheap.
***Ironically, perhaps, the F-16 and now the F-35 are considered “multi-role fighters.”