Why can’t one aircraft do it all?

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.”

4 thoughts on “Why can’t one aircraft do it all?

  1. In the 80s, Boyd would talk about something much cheaper than the F16, much more flying hrs per maintenance hrs, much more lower maintenance skill level, etc (significantly larger number in the air, combo more for the buck & higher flying hrs) … what was being pitched for F20/tigershark. The F20 forces realized that they would never be able to sell F20 domestically so they positioned for export. Then they found that the F16 lobby getting “directed appropriation” USAID out of congress for all F20 candidates (claim was that F20 candidates would say that they would much prefer F20, but they could effectively get F16 for free, but would have to spend their own money for F20). There were some justification that having all these other countries with F16s made F16s less expensive for the US (ignoring the USAID). It reminds me of the story told about “forcing” Marines to take Abrams M1s (even tho M1s exceeded weight limit for 90% of Marine mission profiles), in order for the Army to get the manufacturer’s quantity discount.

    • Thanks — we actually worked with Boyd on such a project, the CAS-X. It would have had most of the A-10’s firepower, most of its armor, significantly smaller visible and radar signatures, and much greater agility down where it counts. Much cheaper than any alternatives for high-level CAS, that is, against folks who shoot back.

      Another problem with the F-20 was that potential customers could listen to the Northrop salespeople, then be told how great the F-16 is by blue-suited USAF fighter jocks. Also, the F-20 looked suspiciously like the F-5, which many of them saw as a beginner’s fighter for countries who couldn’t handle a real one.

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