A mixed force of inexpensive “visual attack” and relatively costly fighters and all-weather attack planes would cost more, not less than an equal-number force of the more capable combat aircraft

The high/low-mix concept is the latest innovation proposed within the Office of the Secretary of Defense (OSD) to solve a very real problem which the services have been facing for a number of years: providing adequate numbers of fighters, and other tactical aircraft, in the face of budgets which procure less and less while the threat continues to increase. The idea of using a mix of aircraft to accomplish the total tactical mission is hardly new. In the fighter field, mixes have always existed as several years are normally required to phase out the old models when the new ones are introduced. The Navy, in particular, has used a different type of high/low mix in its carrier operations, by combining relatively costly fighters and all-weather attack airplanes with an inexpensive “visual attack” model to give an optimum complement. But OSD now proposes to buy simultaneously a fully capable fighter and one with a markedly lower capability.

The proposed high/low mix concept is being enthusiastically supported within the OSD as a policy, and by some members of Congress as an expediency, to reduce defense expenditures, despite the fact that no proof has been offered that reductions will occur. A service- or industry- initiated proposal of this nature would have been subjected to exhaustive reviews, and some form of justification required. On the other hand, an OSD idea too often gains acceptance without adequate study.

Currently, grossly unfair figures are being used in an attempt to prove that the country cannot afford to replace its F-4 inventory with the F-14 and F-15. The latter two are quoted at prices on the order of $20 million each while “lightweight” fighters are advertised at $3 million. Differences are ignored, or hidden, of one figure being perhaps a program average in current-year dollars with R&D amortization included while the lower figure is an estimated unit production fly-away goal in fixed earlier-year dollars.

The F-14/F-15 models were started only after years of study as to what was needed to counter threats which were, and are, well recognized. Before funds are diverted from their procurement for designs with much less capability, realistic studies should be done to determine the degree of monetary savings, if any, which might be achieved by changing to alternative programs.

It will be recalled that last year’s prototype proposal by OSD for an F-14A substitute was shown in Congressional testimony to cost more and to do less. Specific comparisons on these programs, can only be done within the services, but some insight as to the purported advantages can be gained from an examination of a completely hypothetical mix of high- and low-capability fighters in comparison to the single high-capability design. The background of experience on which the examination is based is that of carrier aviation, but it is probable that the general conclusion will apply almost equally to the Air Force case.

Mix High End

The definition of the high end of the mix is quite conventional, and would follow past practice in designing the airplane to be capable of meeting the entire threat spectrum as it is projected by the intelligence community. As part of a carrier strike group, it would have a radius of action commensurate with the attack airplanes with which it operates. Its primary armament would be radar-type missiles for operation in all weather conditions. A crew of two would be carried to cope with the workload anticipated for operation in a high-threat ECM environment and to increase the effectiveness of its long-range missile system. Speed, climb, and maneuverability would be as high as practicable without making the design excessively large and costly. Although in the general size and weight class of the F-4, it would be superior to it in all respects. Against the enemy’s very high altitude and high supersonic speed threats, it would rely on its weapon system and long-range missiles. Against F-4-class threats, its missiles would outrange the enemy in a head-on attack, while in close, its speed and maneuverability would permit guns and IR missiles to be used effectively.

Mix Low End

The low end of the mix proves more difficult to define, since the advocates of the concept have yet to be very precise as to which portion of which threat the low-capability fighter is supposed to defeat. Although started by the Air Force as technology demonstrators, the YF-16 and YF-17, by the very fact of their existence, have tended to become one definition of the low end of the mix, and pressures are being exerted to have their development continued into operational vehicles for the Air Force, and possibly for the Navy.

This type of single-place design, optimized for close-in, visual engagements, carries only IR missiles and a gun as offensive armament. In a dogfight it should be a match for the high-end fighter, with an advantage in smaller size, but sometimes with a disadvantage in awareness. Performance in the engagement should be a standoff, if the range requirements are equalized and the same state of the art utilized in design. Equal range is obviously required in the Navy case since the fighters must escort the attack airplanes and provide air superiority over the target. (It is also this fact which allows a purely defensive fighter to be designed with a smaller fuel fraction, thereby giving better performance at the same size and weight.) Against the F-4, the pilot in the low-end fighter should win the dogfight — if he survives the long-range engagement which may precede it and if the F-4 elects to engage. Likewise, the design should be more than a match for the older defensive fighters, but should not be expected to match a new breed. Against either fighter or bomber threats in the speed and altitude range of an SST, the design is patently not suitable.

There has been virtually unanimous agreement within the services that, on an airplane-for-airplane basis, only the high-capability fighters should be considered. The only problem arises when the question of cost is introduced, and choices are offered of larger numbers of the low-capability design. Even then, most experts agree that some of the high-capability designs are required.

The relative costs of procuring either (1) all high-capability designs or (2) half high- and half low-capability designs can be estimated to give some insight on the degree of the problem. This will be done using the following first-order assumptions:

  • 800 fighters will be procured: either 800 high-capability design or a mix of 400 of high- and 400 of low-capability design. For convenience, these will be designated the HCF and LCF.
  • Development costs and unit production costs vary directly as gross weight. (Although airframe weight and weight empty are the more common factors used in cost estimating relationships, both are closely proportional to gross weight in similar types of aircraft with equal range.)
  • Both HCF and LCF have the same fuel fraction. This gives equal range and is necessary for a fair comparison.
  • The learning curve, or more precisely, the price-quantity relationship, has an 80% “slope” on a unit production basis for a “normal” production rate. (This is about average for some past procurements, and less favorable than claimed in most new proposals.)
  • The 80% slope changes to 85% when the production rate is halved. (The 5% change correlates well with F-4 experience and is less than indicated by some variable lot option quotations to the Navy.)
  • The LCF is 0.7 the weight of an HCF. (This correlates with a number of parametric studies in which performance was held constant while “military load” was reduced by changing the crew from 2 to 1, and replacing all-weather avionics and missiles with their IR equivalents.)
  • All costs are in constant dollars.

In addition to these terms, it will be assumed for convenience that development of the HCF, including nine aircraft, costs $1 billion; and unit cost of the first production, or tenth total, aircraft runs $10 million. The figures for the LCF run 0.7 of these.

F-1 shows unit production price versus quantity in the conventional manner on a log-log plot for the base case of the HCF at its normal production rate and also at half that rate. Although these relationships are normally called learning curves, it must be recognized that they include the effect of many other factors, not the least of which is the business base against which fixed charges must be written off. The larger the number of aircraft against which to amortize such costs, the lower the unit price.

F-2 converts the unit prices of F-1 to cumulative average production prices, and shows them for the HCF base case, together with the unit price associated with the amortization of the R&D bill.

F-3 shows the final cost picture. The prices are totaled for buying 800 fully capable fighters at a normal production rate and for buying half that number at half the production rate. To the latter is added the costs involved in developing and producing 400 of the smaller, less-capable fighters also at half the normal rate of production. The total cost for the 400/400 mix runs about 40% higher than for buying all 800 of the heavier and more capable fighters. If the complementary fighter had been assumed to be but half the weight of the fully capable machine, there would still be a 25% higher cost involved for the 400/400 mix.

Admittedly, these results reflect approximations, but I believe these are all of the right order of magnitude. In the real world an even stronger case exists for procurement of only the more capable fighter, because development funds for the F-14/F-15 are now largely expended and could logically be ignored in the pricing of future airplanes. It will also be observed that the prices shown have not been identified as “airframe,” “flyaway,” “program,” or “life cycle,” since this was hardly necessary for the purpose of this article. The informed reader can readily ratio the results to fit any particular definition, and also to match other assumptions as to initial production and development costs.

It seems clear that those who advocate high/low mixes in the fighter field should provide a rationale to support the concept. At the moment, the net result will be a lower capability at a higher cost — hardly the goal being sought.

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