In John Boyd's (declassified) 1966 Energy Maneuverability [PDF] report, studies were done on the F-4 and on the MiG-21 and those studies were applied to the F-15, F-16 and F-18. My questions:

  1. Why wasn't this theory applied to the F-14?

  2. Was this due to the fact that it was a carrier-based aircraft?

  3. Or did it have to do with the variable sweep wings that would change how the energy bleed changed with changes in the sweep angles at different speed?

The F-14 was developed well before the theory of Energy Maneuverability was published, but improvements were made in F-14s till the late 1980s. With the early development of F-15s the Energy Maneuverability theory was utilized to improve its performance but same wasn't done or at least mentioned anywhere.

  • $\begingroup$ F14 simply wan't quite optimized based on EM in the beginning and there's so only so much you can do afterwards. E.g. can you really remove the sweep wing and make more weight budget for the engines? $\endgroup$ Commented Jun 14, 2018 at 11:55
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    $\begingroup$ Actually, there is an optimum sweep position varying with Mach and lift coefficient. The F-14 had computer controlled sweep which did exactly that, optimize sweep for the current flight condition. The claim that energy maneuvrability theory was not applied is bunk - it just wasn't called that way. $\endgroup$ Commented Jul 10, 2018 at 4:52
  • $\begingroup$ The most significant consequence of EM theory is the emphasis on the engine. F14 only has a barely usable 1st gen turbofan and have already done its best. EM is only practical after the next generation of engines enter service. $\endgroup$ Commented Mar 27, 2022 at 12:07

3 Answers 3


The Energy Maneuverability theory is primarily a conceptual design framework. Its role is to be a guideline in creating the requirements for your aircraft.

This is something well above the manufacturer's level of responsibility. The requirements are created by the buyer, like the US DoD; the manufacturer's job is to design a machine to meet them, with some leeway. And not all modern fighters are based on the E-M theory.

It's not impossible to use a new design framework if you were doing a Hornet to Super Hornet kind of 'Hollywood remake'. But otherwise, an aircraft is created to do a job, and that general job persists through upgrades. Every design choice is a compromise; to get more of X, you need to lose some of Y. Only with a major technological leap could you fit more of X without that loss.

The F-14's job was to maintain long-range CAP around the CVBG. It needed to detect incoming Soviet aircraft at the longest possible range and intercept them before they could launch their missiles.

The USN had very good reasons to dedicate their top fighter to this role. While the Soviet Navy (VMF) has never been a force the USN had to reckon with, the Soviet Naval Aviation (AVMF) has. Its workhorse was the Tu-22, a supersonic bomber with AS-4 missiles; they're large enough to take out a carrier, and, impacting at Mach 3.5-4.5, outside the realistic capabilities of contemporary SAM, AAM and CIWS to intercept. With a standoff range of over 300 nmi, AVMF bombers would be out of the reach of the Californias at the time of launch. This left CAP essential to carrier survival.

For this job, a fighter needs several things. It needs the range and endurance to patrol far enough from the carrier to help. It needs a powerful long-range radar to spot it before launch. It needs good supersonic speed to have a shot at a Mach 1.8 aircraft. It needs to carry heavy long-range missiles to reach the target.

You'll notice that dogfighting a Mig is not on the list above. It's certainly within the F-14's role, which it performed successfully in Iran, just not as critical as fleet air defense.

Attack roles aren't in that list either. In the 1970s, they have been mostly filled by Skyhawks, Intruders and Corsairs. The F-14's design, including its swing wing, was a product of its high speed interception requirements, combined with low-speed needs of taking off with limited power and maintaining long patrols.

Even if the E-M theory was fully developed and accepted at the time, it's not likely that following it would have improved the F-14's performance without compromising its primary role. With the end of the Cold War the requirements changed, freeing up the F-14's carrier slots for multiroles with an offensive focus.

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    $\begingroup$ Develop a carrier based aircraft to protect a carrier to transport a carrier based aircraft to... $\endgroup$
    – jean
    Commented Jun 14, 2018 at 17:46
  • $\begingroup$ ...To do all sorts of things. Three dedicated strike fighters served contemporarily with the F-14's fleet air defense career. Plus, the F-14 soon got its own strike capabilities, if limited. But its primary role has always been protection. You design for the worst-case scenario, the best case is easier to take care of. $\endgroup$
    – Therac
    Commented Jun 14, 2018 at 17:51
  • $\begingroup$ @jean As Therac said, you're missing the idea of multi-weapons cooperation: strike aircraft needs to be protected by fighters, and all fighters need logistics. ANd fighters will protect logistics. $\endgroup$ Commented Mar 26, 2022 at 13:15
  • $\begingroup$ And it should also be noticed that F-14 performed well against other aicrafts, such as in Iraq-Iran war. By the way, did they fight against MIg 29 during this war? $\endgroup$ Commented Mar 26, 2022 at 13:16
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    $\begingroup$ @totalMongot No, the MiG-29 was way too modern. Iraq only had older MiGs. But the F-14's were the only fighters to have killed any Soviet-built aircraft. Everything older had no success. So the teen series were a necessary and major step forward for the US. $\endgroup$
    – Therac
    Commented Mar 26, 2022 at 16:20

In my understanding, EM is not a serious 'theory' that can be 'incorporated' in the aircraft design. It tells nothing new to engineers, even in the 60s. Rather, it is a convenient tool to evaluate (some aspects of) fighter aircraft performance and therefore to develop the most appropriate combat tactics. This is a typical situation with pilot-centric theories and data in general.

So in terms of such evaluation, it probably was applied to F-14 and many other aircraft at some point. If the formula gives a reasonable prediction of outcome, why not use it? That's very much the task of Air Force.


It's not becaue the F-14 has variable sweep wings or is a carrier aircraft.

EM works just as well for variable sweep as for fixed wing. EM is a measure of the excess energy available to climb or accelerate, in a dog fight. That physics principle isn't changed by having variable swing wings or being a carrier aircraft because laws of physics which describe these aspects such as F= m x a and PE (potential energy) = m x g x delta(h) still apply.

(I'd normally post this as a comment, but comments that are seen to be answers get deleted, so, sorry for a half-answer... I expect someone will provide a more complete answer.)

  • $\begingroup$ So later variants of F-14 would have incorporated EM theory. This would be de facto hence not mentioned anywhere, right ? But then why does use of EM theory in F-15 is much emphasised ? $\endgroup$
    – Huntkil
    Commented Jun 14, 2018 at 10:30

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