Document created: 21 April 03
Air University Review, March-April 1976

The B-1

On 19 September 1975 the Air Force's new B-1strategic bomber demonstrated for the first time its capability as a low--altitude, high--speed penetrator. That was the seventeenth in an orderly series of flight tests which started on 23 December 1974 and will provide data on which to base a production decision in November 1976. Behind these flight tests lie four years of the most comprehensive design and ground tests ever conducted in the development of a military aircraft. The studies on which these designs are based go even further back, to 1965 and the Advanced Manned Strategic Aircraft (AMSA)--dubbed by some "America's Most Studied Aircraft."

And yet, as the B-1 is being readied for production, some people still ask why this country needs a new bomber, or why it needs a bomber force at all. Others ask how an aircraft will penetrate advanced enemy defenses. And finally, why it costs so much to build.

These are thoughtful questions, and they deserve thoughtful answers. In this article I will briefly review the role of the manned strategic bomber and our dependence on a modern strategic aircraft to maintain the degree of parity established in the Strategic Arms Limitation Talks (SALT). I will review in some detail the B-1’s role in fulfilling this requirement for the latter part of this century and beyond; provide some insight into specific design features and test methods unique to this particular aircraft design; and discuss the cost of this system in an unstable economy.

the role of the strategic bomber

Much has been written about the Triad of strategic weapons that provide the backbone for this country's deterrent posture. The synergistic effects of our land--based ballistic missiles, sea-launched missiles, and manned strategic bombers greatly compound the problems faced by any would-be attacker who contemplates a nuclear Pearl Harbor to rob this country of its striking force. These weapons are mutually supporting.

The role of the manned bomber is unique. It alone can be launched on warning and maintained in a nearly invulnerable airborne alert, under positive control, while negotiation proceeds to resolve a crisis situation. It alone takes advantage of national decision-making capability in a changing conflict situation, and it alone can be recalled when the crisis is over.

It is generally well known that for almost two decades following World War II the manned strategic bomber was our most important deterrent weapon. Indeed, for over a decade, until the advent of the ballistic missile, it was our only strategic deterrent. What is not so widely recognized is the degree to which our deterrent posture still depends on the bomber.

SALT negotiations have resulted in a form of parity in total strategic offensive delivery vehicles, as shown in Figure 1. Most of the Soviet payload is carried in missiles, however, while approximately half of the U.S. capability depends on the strategic bomber force. This past and present dependence is indicated in Figure 2, which breaks out the intercontinental bombers separately.

If we allow our bomber force to become obsolete, so that it can no longer survive or penetrate the enemy's improved defenses, it could in time cease to be an effective deterrent. Failure to modernize the bomber force, then, would unilaterally decrease our strategic capability by some fifty percent.

The B-52 has been the mainstay of our strategic deterrent since it was first produced in the early 1950s. Since that time it has gone through a number of model changes, the last being the G and H models. Additionally, the B-52s in the operational inventory have had a number of modifications to add power and increase structural life.

These continuing modifications have increased the useful operational life of this outstanding aircraft to a full thirty years. When finally retired, it will have flown through half the history of aviation. With further modifications we might keep it flying longer, but the B-52 will still be the same size, the same aerodynamic shape, and thus will still have similar aerodynamic drag and radar cross section. Relatively little can be done to improve its reaction time. And it will lose its capability to penetrate Soviet territory as their defenses become increasingly more sophisticated. In time, the B-52 will cease to be a credible deterrent.

Compared to the B-52, the FB-111 is, of course, a more modern aircraft with higher speed and better low-level performance. However, it is simply too small to perform the operational mission of the B-1. Air Force studies of "stretched" versions of the FB-111 with new engines have shown that its capacity for carrying weapons and fuel is much too small to make it a viable alternative to the B-1. Aside from the fact that it would not cover all targets of interest, cost-effectiveness studies have indicated that as many as ten times the number of aircraft (plus additional tankers) would be required, rendering it a much more costly and less effective option.

To deter war, a follow-on bomber must possess two specific attributes: it must be able to survive a surprise attack and it must be able to penetrate an enemy's defenses. There are other requirements-- many others--but these two are primary. And the B-1 has been designed with these foremost in mind.

• Ability to Survive a Surprise Attack. One of the unique features of the manned bomber force is the ability to launch on warning, thereby achieving an additional measure of invulnerability. There need be no question of confidence in the strategic warning system, for the bomber force remains under positive command control. But the bomber must be able to take off following a minimum warning, such as might be expected from an attack by sea-launched ballistic missiles (SLBM). The bomber should have a short takeoff run to enable it to get into the air quickly and be able to accelerate rapidly to high speeds and escape a base that may be under attack. It should be hardened to the effects of nuclear blast and radiation, and its design should permit dispersal to a significant number of airfields. These requirements have greatly influenced the design of the B-1

The B-1 is designed to launch in less than half the time of the B-52. With its swing-wing in the forward position, it has a relatively short takeoff roll; it can accelerate rapidly after takeoff to a higher speed than that attainable by the B-52. It is the first aircraft specifically designed to a high blast and radiation hardness requirement, and even its white paint plays a significant part in reflecting the radiant heat from a nuclear blast. The combination of these factors will enable up to sixteen B-1s to survive an attack severe enough to permit escape by only one B-52. Further, the smaller B-1 has been designed to utilize about 150 more airfields than the wider B-52, thus permitting wider dispersion in times of crisis. This feature further increases the B-1's survivability potential and enormously complicates a potential aggressor’s offensive problem.

• Ability to Penetrate. The other primary requirement of the bomber force is penetration. This requirement, more than all others, has driven the design of the B-1. Both the B-52 and the B-1 can fly to the enemy defenses. The B-1 carries a significantly greater payload, and its swing-wing and specially tailored fan-jet engines use less fuel; but both will get to enemy territory. Today and for an indeterminate time dependent largely on our adversaries' actions, the B-52 can penetrate those defenses. In the period from 1985 and beyond, however, the B-52s penetration task would be extremely difficult, and the B-1 will be available. The B-1 could penetrate under the enemy's radar near treetop level at high subsonic speeds. This high-speed, low-altitude requirement largely dictates the swing--wing design, even if a supersonic flight capability were not desired. The low radar cross section is also significant, denying acquisition until the B-1 is within one-half to one-third the acquisition range of the B-52. To complicate the enemy's defensive problems further, a sophisticated defensive countermeasures system will automatically (or manually, if desired) acquire and jam a wide range of enemy acquisition radars.

The inherent capability of the B-1 to fly at high supersonic speeds further complicates the enemy defenses by requiring a defensive capability to defend against high-altitude supersonic attack. The flexibility to fly any combination of these missions is the best guarantee of a reliable penetration capability.

Each successive aircraft design should result in a better product than its predecessor. But each successive design is a harder and usually costlier job. One has knowledge of additional problems that are to be avoided and capabilities that are highly desirable. The B-52 experienced fatigue problems requiring major wing rework. The F-111 had a major wing root problem with the use of high carbon steel, requiring costly inspection and retrofit. The C-5 experienced static load problems in the design of its wings. All aircraft designed to date face problems with windshield bird impact. Obviously we do not wish to encounter these problems with the B-1.

In addition to the normal technical problems in designing and developing a large swing-wing aircraft with significantly higher performance than that previously attained, we undertook to avoid the problems of the past. To accomplish this, we were the first to institute fracture mechanics as a requirement from the time of contract award. Special fracture-tough alloys were specified, and hundreds of aircraft specimens and sections of various size were tested to failure. If fatigue cracks did not develop by the end of the specified test cycles, they were artificially induced, and the specimens were then subjected to design limit loads. To assure a fatigue life at least equal to that of the B-52, a B-1 lifetime of 13,500 hours was specified, and aircraft components were designed to withstand four times this service.

Major sections of the aircraft were subjected to static tests. The aft fuselage, with its massive titanium spindle that holds the movable horizontal tail, was static-tested to limit load and on to ultimate load in a number of flight conditions. The aircraft's critical wing carry-through section, which connects to fuselage components and to the movable wings by pivot pins, was similarly tested. An additional series of large structural specimens will shortly commence four lifetimes of fatigue testing.

The logical progression of structural tests is from parts, to major structural specimens, to a complete airplane. The number 2 aircraft has been designed and instrumented for structural tests and has undergone static testing to design limit loads in a specially designed fixture at Lockheed-California at Palmdale. During these ground tests the 2000-odd strain gages were calibrated for use in subsequent flight loads testing in actual flight.

The actual aerodynamic design of the aircraft is believed to be the most comprehensive yet undertaken. Over 22,000 hours of wind--tunnel testing have been conducted to confirm and improve the design, utilizing 44 models in 18 different wind tunnels.

Subsystems. Concurrent with basic aero and structures design and tests, the designs of the various subsystems received their own qualification. A flight control mockup, dubbed the "Iron Bird," accumulated over 1800 hours in operating mass-simulated control surfaces with the actual hydraulic plumbing and components. Of particular interest was the operation of specially actuators and motors utilized in a 4000-psi hydraulic system.

The landing gear was tested through hundreds of cycles, and tires, brakes, and shimmy dampers were similarly tested in specially designed simulators.

Unique Features. By and large, the B-l design does not "push" the state of the art. It does, however, use the latest techniques and developments to attain a substantial improvement in overall performance. Among the unique features are an Electronic Multiplex System (EMUX), which avoids the use of some 30,000 wire segments; a Central Integrated Test System (CITS), which records 3148 system measurement items during flight to provide trending data for extended usage of engines and other components-as well as maintenance data for rapid turnaround. The 240-volt power system is virtually unique to aircraft design, as is the 4000-psi hydraulic system.

But perhaps the most distinctive feature of all is the overall redundancy requirement-the aircraft is designed to "fail operational, fail safe." In brief, this means that the aircraft must still be able to accomplish its operational mission after failure of any one major subsystem. It must be able to sustain any additional failure of that subsystem and still be able to land safely. With few exceptions, the present design meets these requirements. For example, two completely separate flight control systems are utilized--one mechanical and one an electrical "fly-by-wire" system --each with some redundancy integral to itself. Normally the systems are integrated, but they can be operated separately in the event of failure.

Also unique are the structural mode control system, which senses aircraft motion and dampens out structural bending through the use of small canards on either side of the cockpit, and a Fuel Center-of-Gravity Management System, which automatically repositions the fuel load to maintain the aircraft center of gravity within safe limits during wing sweep operation and weapon delivery.

With all this pretest, how is the flight-test program progressing? As befits a program with a single aircraft and a high investment, we are proceeding at a conservative pace. But our progress is going quite nicely. We are well into the B-1 flight-test program and have encountered fewer problems than one would expect in a program of this magnitude and complexity. Those that we have encountered have been relatively minor in nature and have not significantly delayed development or testing.

To date, we have operated all aircraft systems, including numerous full sweeps of the wings. We have performed airborne refuelings and supersonic flight several times and have demonstrated the airborne restart capability of the engines. Five test pilots, including one from the Strategic Air Command/Air Force Test and Evaluation Center, have flown the aircraft.

We have extended the flight envelope to the high "q" (dynamic pressure), low-altitude regime. This was accomplished by progressively measuring aircraft response to flutter outputs mechanically induced by five flutter actuators installed on the aircraft wings and tail. The key flutter point, .85 Mach at an altitude of 500 feet over the Pacific, confirmed the B-1's ability to perform its design mission: low-altitude penetration at high subsonic speed.

Our goal is to demonstrate the overall capability of the aircraft, attaining some 250 flight-test hours prior to the production decision in 1976. Aircraft 3 will contribute about 50 hours to this total, with offensive system tests commencing this spring.

From a technical standpoint, the health of the B-1 program is good. Careful planning and methodical testing have paid off in that we have avoided the major technical problems that plagued so many programs in the past. We have minor problems, of course, the type one encounters and resolves in the normal course of research and development, but nothing of a nature to hinder our test and development program. If I were to look for the greatest challenge we have faced to date, it would probably be weight growth.

This problem is not unique to the B-1, and I know of no aeronautical or space program that has not had to face up to it. As a matter of fact, the B-1 has fared comparatively well in this regard. Its projected operational weight is only about 20 percent greater than originally predicted--a much better record than that achieved on many other programs. Weight could be further reduced at increased cost, but operational performance does not require it, and the additional expense may not be justified.

Our greatest concern, and one that is the least understood, is program cost. It has been difficult to portray adequately the meaningful changes in the B-1 program cost during this period of high inflation. Measured in terms of constant dollars--with all inflation removed--there has been relatively little cost growth forecast for the B-1 program--less than 12 percent from its beginning five years ago until its planned completion some ten years hence. There has been no growth in real terms since December 1973. Perhaps the best way to portray real cost is in man-hours per pound required to build the first aircraft, and here again the B-1 compares very favorably as the following figures indicate:

Man-hours per Pound* to
Complete First Aircraft

 *DCPR weight (Defense Contractor Planning Report)

Unfortunately, the dollar has not been stable, and inflation has steadily reduced our purchasing power since inception of the program in 1970. We also project continued inflation until the buy-out of the program over the next decade. The compounding effect is that the buying power of a dollar when we complete the program in 1985 is estimated to be only about 42 cents as compared to the buying power of a dollar when we initiated the program in 1970. As a result, our estimates of B-1 production costs increase. Figure 3 shows B-1 forecast program costs as we have reported them in our Selected Acquisition Reports (SAR) to the Congress from 1970 to the present. The bars on the left show constant dollar forecasts, and those to the right include the effects of inflation. As can be readily seen, the effects of inflation just about double the forecast future cost.

What this means, in more familiar terms, is that an automobile costing $3500 in 1970, when this program began, costs approximately $5000 today. If the same inflation factors are applied to it as to our B-1 cost estimates, it will cost over $7000 in 1985.

Throughout the list four years and particularly during the past year, we have placed considerable emphasis on reducing B-1 costs to the practical minimum. Outside expertise has been applied in the form of a high-level independent study directed by the Air Force Chief of Staff. As a result we believe the system costs no more than necessary to accomplish its required mission. A new aircraft designed today would look much the same as the B-1. Started later, with continuing inflation, it would cost much more.

What can be done to minimize further the total program cost? The effect of inflation is significant--a one percent change from our estimated rates can increase or decrease our forecast total program costs by approximately $1 billion. The trend of our economy, however, is beyond the control of a program manager.

Time, to some extent, is within our control, and this is the largest single factor affecting total program costs. If production is delayed, inflation has a longer time to act, and total program costs increase. For this reason, as well as the forecasted operational need, we believe it is prudent to avoid any delay if at all possible. We estimate that a one-year delay would again increase B-1 costs by approximately $1 billion.

A related problem that drives program costs is the creation of extended gaps between the numbers of aircraft manufactured. If the FY76 program is approved as submitted, we will face a gap of 35 months between the manufacture of the third and fourth aircraft, which itself causes some loss of learning. Extension of this gap or the creation of a gap between the fourth and subsequent aircraft would pose additional production problems.

Technically, the B-1 program is performing well. Our biggest problems involve programming: maintaining continuity and program integrity to minimize gaps and reduce the effects of inflation on our overall program cost. We are confident that, with adequate support from the Congress, the B-1 will cost no more than it must cost to provide our country with a viable deterrent into the next century.

Major General Abner B. Martin (USMA; M.S., Massachusetts Institute of Technology; M.S., George Washington University) is the B-1 System Program Director, Aeronautical Systems Division, Air Force Systems Command. After flying training and two years as instructor and flight commander, he began his systems career: four years at the Air Force Armament Center, Elgin AFB, Florida; eight years with Air Force Ballistic Systems Division, AFSC; as AFSC liaison officer, Republic of Vietnam; in Aeronautical Systems Division, AFSC; as Commander, AF Armament Laboratory, Eglin AFB; and as Deputy for Reentry Systems, later Deputy for Minuteman, Space and Missile Systems Organization. General Martin is a graduate of the Advanced Management Program of Harvard Business School and Army War College.

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