The Future of Manned Aircraft

March 1, 1963

In the debate over our strategic deterrent, manned aircraft are getting much the worse of the suppositions. The assumed invulnerability of their silo-based ICBM successors is highly questionable, purely on technological grounds. In the tactical field, survivability of low and slow Army aviation over the battlefield is even more debatable. New improvements in jet engines make possible further development of the TFX concept which could fly for longer periods on the deck at supersonic speeds, and an endurance bomber which could fly for days. In short, the new technology strengthens rather than weakens the old arguments for manned aircraft.

For military tasks of all types, the United States is rapidly shifting its major reliance to missiles and away from high-performance aircraft. Defense Secretary Robert S. McNamara’s fiscal year 1964 budget presentation offers no hope to brighten the clouded future of the strategic bomber, and it raises strong questions about the future acceptability of tactical aviation as presently conceived by the USAF.

In the strategic field the situation is clear. The Administration’s justification of the budget is slanted to prepare the US to accept a philosophy of nuclear stalemate (see AIR FORCE/SPACE DIGEST, January ’63, page 28 and Editorial, page 6 in this issue).

In Mr. McNamara’s words, “We are approaching an era when it will be increasingly improbable that either side could destroy a sufficiently large portion of the other’s strategic nuclear force, either by surprise or otherwise, to preclude a devastating retaliatory blow.

Therefore [there is] . . . a great mutual in­terest in seeing to it that they are never used.”

To attain this stalemate posture, the Secretary says, “…we must concentrate our efforts on the kind of strategic offensive forces which will be able to ride out an all-out attack by nuclear-armed ICBMs or submarine-launched missiles in sufficient strength to strike back decisively.”

The ‘Case’ Against Manned Bomber

Clearly, manned bomber forces, even if dispersed and partially on airborne alert, do not fit into this new strategy. Mr. McNamara downgrades the bomber on two main counts. First, he says, “Manned bombers on the ground are quite vulnerable to surprise ballistic missile attack.” Second, the Secretary says that, “. . . the B-52 must be committed to its targets, if at all, early in the war because it would be vulnerable on the ground to missile attack. Common sense requires that we must not let ourselves be inflexibly locked in on such a matter.”

Essentially the Congress is being asked to believe that by eliminating one of the three means of strategic attack presently available (bombers, ICBMs, and Polaris missiles) the US is increasing its flex­ibility and strengthening its deterrence. No mention is made of the position that manned strategic aircraft greatly enhance operational flexibility by allowing: recall of an attack; unmistakable displays of resolve, through stepped-up airborne alerts and large-scale maneuvers, such as were used in the Cuban crisis; wartime assessment of target damage; location and destruction of mobile targets; a close matching of the weapon to the target; and, when the occasion calls for it, the use of very-high-yield warheads.

A strange timetable for reshaping the strategic forces has been presented by Mr. McNamara to the Congress. The entire B-52 force, all fourteen wings, will be needed in service for at least five more years, through fiscal year 1968, he says. This is at least three years after 800 out of the planned 950 Minuteman ICBMs are scheduled to be operational, four years after the 108 scheduled Titans are in place, and around two years after the bulk of the Polaris submarines are commissioned.

It is hard to believe that the big bombers will survive that long. Even if a large-scale retirement is not ordered, the aircraft are wearing out ahead of their time through heavy use in airborne alerts and the hard buffeting of low-level flights for which they were not initially designed.

However, the most significant sign for the future the strategic aircraft is the fact that no B-52 rep­lacement is under development—or is even being considered for development.

Mr. McNamara has tried to head off critics of his policy by explaining his position in great detail to the Congress and to carefully selected reporters. Still the matter may develop into a major public debate.

On the technical side, Mr. McNamara’s conclusions as to missiles can be challenged on several counts. On the crucial question of just how vulnerable are ICBMs in silo emplacements the Secretary says, “Fully hard ICBM sites can be destroyed but only at great cost in terms of the numbers of weapons required to dig them out.” Apparently he believes that this will be true for some years after the phasing out of the manned strategic bomber and certainly beyond the next five years, to which the current DoD planning is addressed.

Destroying hard emplacements primarily is a matter of increasing either warhead yield or guidance accuracy, or both, in the attacking weapon. On either score the future doesn’t look too promising for an all-hard-site ICBM force. According to Administration announcements the Soviets significantly increased the yield-to-weight ratio of their nuclear weapons during their most recent series of tests. And there is no reason to believe that further progress is not possible.

On the other score, there is widespread belief that missile accuracy can be increased dramatically in the next few years. In a state of the art vs. time review of missile and space systems by H. H. Koelle, Director, Future Projects at NASA’s Marshall Space Flight Center (Astronautics, November 1962), Koelle reported that, “For many years guidance accuracy was the limiting performance factor, which led to re­quirements for high-yield warheads. But, through the extension of presently available technology of sensors and terminal control, we can now see the achievement of a true hard target capability before 1970.” (Italics supplied.)

If Mr. McNamara is wrong on this crucial point, then the case for an “invulnerable,” second-strike, stalemate posture begins to fall apart.

Apart from budgeting and politics, the case against the manned aircraft rests on the accuracy and the power of the latest defensive weapons. If nuclear-armed antiaircraft systems can destroy virtually all of any bomber force, regardless of its size and regard­less of its speed of attack, the bomber becomes a highly unattractive offensive system.

However, in testing the validity of the premise of complete defensive superiority, it is well to start with Mr. McNamara’s own starting point. He cautions that global nuclear war is “a vast unknown.” But as this nuclear enigma is debated, it seems that manned aircraft are getting much the worst of the suppositions.

For instance, the first step in any airtight air defense is to use very large warheads in the defense. Weapons in the size range of the last Soviet tests when detonated at high altitude can damage aircraft and fatally irradiate crews at distances up to several hundred miles and over tens of thousands to hundreds of thousands of square miles. The Soviets, with rela­tively few rockets equipped with these weapons, could make the Arctic a very dangerous place for SAC. Such area coverage would be a potent first phase in the defense. Closer in, interceptors would maneuver against the bombers, firing small atomic weapons. The third and final phase would be ground-launched missiles, which are being steadily improved.

Potent as this arrangement sounds, SAC comman­ders believe that tactical maneuver and ingenuity, coupled with electronic countermeasures, decoy mis­siles, and penetration aids of several types, can be combined to outwit this defense in a determined at­tack. This opinion is strengthened considerably when one remembers that the vital nerves of the defense are a radar net not unlike our civil air traffic control system. Such a system is extremely vulnerable to attack.

The point here, however, is that no modern offensive system, manned or unmanned, is immune to extremely potent counteraction. There is grave doubt about the “relative invulnerability” of the ICBM in its silo. Also technical authorities believe that an ICBM intercep­tion system will become practical.

And when the use of very large “area” weapons is discussed, the Polaris system can be examined in the proper light. The same basic, very-high-yield weapons that threaten the manned bomber over the Arctic also threaten the Polaris submarine. Multimegaton depth charges, if you will, lobbed over relatively short ranges from the Russian mainland can clear immense areas of the ocean. This enemy capability forces on the Polaris the same requirements for timely action and tactical ingenuity that SAC must satisfy. There just aren’t any cheap or easy answers.

Unfortunately public debates on hardware have a habit of degenerating into meaningless furors. The B-70 controversy and the still-warm battle over Sky-bolt are good examples. They were both exemplified by emotionalism, oversimplifications, conflicting state­ments, and exaggerations on both sides.

Now a press association story, apparently drawing on information from some overenthusiastic elements in the Air Force, has described a supertype of B-52 replacement which, as described, would rest on a shaky technical foundation.

In this report, both the USAF and DoD are said to be studying a “camel-like” airplane called the “Drome­dary” which can stay aloft “three to eight days,” and thus be immune to destruction on the ground.” The description of the “Dromedary” included the fol­lowing: “It could fly low and slow, hugging the ground and eluding enemy radar defenses . . . might perform reconnaissance as well as cargo and troop transport missions . . . could carry a horde of con­ventional and nuclear weapons . . . [including] short-range missiles . . . decoy missiles to enhance its con­siderable ability to penetrate enemy defenses might also be designed for high-altitude operation and powered for short supersonic speed bursts.” This wraps just about all of the manned aircraft missions into one airframe and engine system. Such claims aren’t much closer to reality today than they would have been thirty years ago.

It is true that the Air Force again is looking closely at long-endurance aircraft. And the idea is much more attractive than it was three or even two years ago. Several new technical advances can be com­bined to promise an endurance of three and possibly four days for an aircraft with a modest military pay­load. Compared to present-day performance this would be almost miraculous. Few airplanes now in service, when loaded, can stay aloft more than twenty-four hours without refueling.

Naturally, there are penalties. Any “three-day” airplane would have to be optimized in terms of struc­ture, aerodynamics, and powerplants for this one ob­jective. It would have to use propellers or a very large diameter turbofan. Its wings would have to be designed to perform well at relatively low subsonic speeds, and its structure would have to be relatively light. All of these features are directly opposed to the requirements of supersonic attack aircraft.

The Air Force today, in its Dromedary-type studies, is looking at a cross section of designs, ranging from strictly long-endurance aircraft to those with penetra­tion capability gained through a sacrifice in endur­ance. At present, the trend slightly favors endurance over penetration ability.

The technical case is very strong, but it can only be undermined by exaggerated reports such as “three to eight days’ endurance for attack aircraft.” Raising false hopes among the manned aircraft’s numerous supporters in the Congress and the public can only weaken their arguments and eventually disillusion them.

The doom of the manned strategic airplane could be sealed in no more certain fashion than by spending the next several years in a futile attempt to develop a hydrocarbon-fueled “dream” aircraft meeting impossible specifications.

Unfortunately, the best hope of combining endurance measured in several days with high payload, high- and low-altitude capability, and supersonic speeds lay in the perfection of the nuclear aircraft engine, a project starved by the Eisenhower Administration and killed by McNamara.

What Future for Tactical Air

In the tactical aviation area no firm policy exists today. Military doctrine concerning the relationship between ground and air forces in wars with either nuclear or conventional weapons is undergoing experimentation.

The cost effectiveness and general desirability of the F-111 (TFX), the only combat aircraft that has entered development under the Kennedy Administration, will again come under close scrutiny as this experimentation progresses.

So far the most radical approach has been the recommendation of the Army’s Howze Board on Tactical Mobility. Apparently, the Board’s main a accomplishment has been to resurrect the World War II argument as to whether tactical airpower should be parceled out to ground units and controlled by the ground commanders; or whether it should be TAC fashion, with a major percentage of its effort devoted to winning the air battle and on interdictory strikes.

It probably would be more accurate to say that the Army Board does not want to eliminate the swift air strikes at targets of opportunity which are the corner stone of TAC’s interdiction philosophy. Rather, they want to take the whole Army along on such strikes. They visualize future wars being won by air-assault divisions and air-cavalry brigades moving swiftly over hundreds of square miles of territory, striking at enemy forces outflanked by the air movement.

According to this theory the air-assault units would move primarily by helicopter. Many Army officers believe that these units must be closely supported by armed, close-support/surveillance aircraft with top speeds of 500 mph or better.

In his budget message Mr. McNamara reported on the current status of these ideas. He said, “While I am convinced that these new types of units could significantly increase the Army’s capabilities, the pro­posals are so revolutionary in character and so closely related to the Air Force mission that we deem it prudent to test thoroughly the concepts before we commit ourselves to their full-scale implementation.” Funds are available in the FY 1964 budget to allow the Army to organize 15,000 men into provisional units to test the Howze theories.

The prophetic part of Mr. McNamara’s statements concerning the future of TAC and the outcome of the Howze experiments was: “In the longer run, as the Soviet Union increases both the quantity and quality of its surface-to-air missile forces, the vulnerability of manned tactical aircraft will increase, and we prob­ably will have to turn increasingly to surface-to-sur­face missiles for the tactical offensive capability.”

This key question of survivability against modern weapons, of course, is critical to all future offensive systems. Survivability on the tactical battlefield basi­cally is much more debatable than in strategic war. Strategic weapons, such as Minuteman, can be main­tained and operated in a closely controlled environ­ment by relatively small numbers of people.

Field operations by large Army and Air Force units in a land battle are a completely different mat­ter. This is the breeding ground of the snafu. Constant movement of units and countless decisions by hun­dreds and even thousands of individuals are needed to keep all elements of the Army at peak effectiveness. This certainly is true of the Army’s mobile antiair­craft defense, both at the front and in the rear areas. These are not automatic systems. Men must make key decisions in a rough environment. This con­sideration alone would seem to preclude the assign­ment of an almost perfect rating to the battlefield AA system.

There are three major points to be considered in the survivability question. These are:

• Voluminous studies have been made of the sur­vivability of aircraft over a modem battlefield. The conclusions vary widely, depending upon the input assumptions. Almost any view can be supported by selecting the proper study.

• Speed for survival and for accurate weapon delivery are two of the major arguments. Many Army commanders believe that aircraft must fly slower than 800 mph to provide proper close air support. The Air Force believes that weapons can be delivered accu­rately at 500 mph and more. In a study for the Army one of the major airframe contractors shows that the highest survival probability is attained by flying at 150 mph, at very low altitude. This bucket-shaped survivability curve shows that the number of hits ex­pected per aircraft goes up rapidly as the speed goes to zero or is increased to 200 mph and higher speeds. Air Force studies show a curve of completely differ­ent shape. On it the most hits could be expected at zero speed and then the number falls off rapidly as speed increases, with a very low probability of hits at supersonic speeds at low altitude.

It is pertinent to note that most Army aviators agree with the Air Force studies and have a great respect for high speed over the battlefield.

It also is pertinent that the German Army com­pletely rejects the idea of using helicopters and other slow aircraft over the tactical area at any altitude. The general opinion there seems to be that the Howze ideas are completely impractical against a modem force.

• Virtually everyone sees a great need for a major series of realistic, completely impartial tests to deter­mine what the survival probability is within rather close limits. Obviously someone is wrong, and the matter should be settled before the shape of our forces is altered on the basis of some untried hypotheses.

US ground-to-air missile tests, to date, have all been highly canned. Little has been done beyond shooting down drones at optimum altitudes and speeds and bagging a few World War II aircraft on automatic pilot. It is public knowledge that a number of these tests didn’t turn out so well.

The excellent US record of exhaustive testing for nuclear weapons of all sizes and for strategic delivery systems has not carried over to tactical air defense.

Many officers in all the services see a critical need for an independent, highly objective test group with the resources, land area, and the authority to conduct long-term field tests of major elements of both the air offensive and defensive tactical forces. For in­stance, first-line aircraft and helicopters (droned) would be used with as much ingenuity as possibly by TAC and Army air units against live rounds from var­ious troop defenses for several days under transient tactical, rather than range, conditions. Unfortunately, the Howze experiments are of the old canned pattern.

New Dimensions in Aerotechnology

Great progress has been made in aircraft technology during the past five years. More progress, just as significant, can be made in the next five years.

The major new advances are:

• Variable-sweep wings (see AIR FORCE, November ’61, page 46). Good aircraft performance demands: straight wings at takeoff, landing, and loiter; wings swept thirty-five degrees or more at high altitude, subsonic cruise for maximum range or for supersonic speeds; no wings at low altitude and very high speed. The variable-sweep wings make it possible for the pilot to adjust his configuration to the near optimum for each type of flight.

• Engine development borders on the miraculous. Operational turbojet thrust-to-weight ratios today are about eight to one, and well beyond predictions of ten years ago. The forecast is that thrust-to-weight ratios on propulsion engines can reach twelve or fif­teen to one and that lightweight, rather low-life en­gines for lifting purposes on VTOL aircraft will go to twenty to one. Specific fuel consumption on gas-turbine engines has come down drastically in the past few years. It is now believed possible to build a regenerative turboprop engine (the exhaust air used to heat compressor air entering the combustion cham­ber) with a lower fuel consumption than the best reciprocating aircraft powerplants of the past.

• Penetration aids, electronic countermeasures equipment, devices to fool and attack defenses, and low-level flight and navigation systems are all being improved at an impressive rate. This is a highly sen­sitive area but success here is vital if high-performance manned aircraft are to remain operationally effective.

• Laminar-flow control is the most important question mark on the technical horizon today. This Air Force-sponsored low drag type boundary layer con­trol system, developed at Northrop, is scheduled for full-scale flight testing in the very near future. The entire aviation world is watching this project, and many engineers believe that it will be possible to im­prove the aerodynamic efficiency of subsonic cruise aircraft by fifty to 100 percent—that is, to raise the lift-drag ratio (L/D) from the present standard of eighteen or twenty to one, to between thirty and forty to one. If this improvement is achievable at a practical cost in weight and complexity, a rapid rev­olution in airplane design will follow. Range and en­durance will increase remarkably, and the cost of transporting passengers, cargos, and weapons by air will tumble by major percentages.

If all of these basic developments work in practice, and have reasonable penalties in weight and com­plexity, the aircraft of the future will be much more powerful, versatile, and economical than those of to­day. By any past standards, the percentage improve­ments in performance will be very great, in some categories 100 percent or more.

Two major new advantages are possible for future aircraft. One is relatively long-range flight at high speeds on the deck, which is considered by most ob­servers to be absolutely necessary for successful attack against defended targets. The second is very long endurance (in the neighborhood of three days), but this can’t be combined with high-speed flight.

Outside of transports of all types, which will be better in the future, two classes of aircraft can benefit substantially from these technical advances. The first is the long-endurance airplane of the Dromedary and ASW types. The second is the attack aircraft of all weights.

The only new attack aircraft under development is the F-ill, and it illustrates pretty well what can be done. With its wings folded back out of the way, it is the first aircraft which can fly for a few hundred miles at sea level and still have enough fuel to cruise for many hundreds of miles more.

At altitude the F-111’s speed is limited by its alu­minum airframe. Enough power is available for Mach 3 or better, but the Navy and Air Force decided to stick with well understood construction techniques, rather than to use steel and add another major new development to the program.

For an aircraft of its size the F-ill will have ex­cellent STOL capability by taking off and landing in 3,000 feet (this is not the ground roll), even on sod fields. This will be achieved primarily by rotating the wing forward to a zero sweep angle and the use of rather large, low-pressure tires on the bicycle land­ing gear which is stowed in the fuselage B-52 fashion.

Undoubtedly, VTOL aircraft will be an important development of the future. VTOL aircraft offer the possibility of solving the most pressing problem for aircraft in any type of war today—dispersal. One air­craft per takeoff and landing site is the ideal from the vulnerability standpoint, but it is practically impos­sible logistically. VTOL capability also exacts a heavy penalty in range and other performance from an air­craft. Many TAC officers believe that the STOL F-111 dispersed on 3,000-foot strips (there are some 1,000 prepared airfields of this length in Europe and countless sod fields) in groups of about six is about the best compromise between logistics ease, aircraft performance, and low vulnerability on the ground.

However, new aircraft will not be omnipotent in any sense. The new technology only strengthens the old arguments for manned aircraft and eases up a little on the old arguments against them. The primary question of the day, “Do we still need manned air­craft?” is not limited by technology.