Survivability—A Science Whose Time Has Come

This html article is produced from an uncorrected text file through optical character recognition. Prior to 1940 articles all text has been corrected, but from 1940 to the present most still remain uncorrected.  Artifacts of the scans are misspellings, out-of-context footnotes and sidebars, and other inconsistencies.  Adjacent to each text file is a PDF of the article, which accurately and fully conveys the content as it appeared in the issue.  The uncorrected text files have been included to enhance the searchability of our content, on our site and in search engines, for our membership, the research community and media organizations. We are working now to provide clean text files for the entire collection.

In the 1960s, U.S. aircraft fell out of the flak-and-missile-filled North Vietnamese skies in frightening numbers. Many warplanes, including the Skyhawks on the facing page, received ad hoc improvements to reduce their vulnerability. Only now, however, are we taking steps so that survivability is considered not when a plane is on the runway or carrier deck, but when it is on the drawing board.

It all began more than half a century ago, when an enterprising young aviator surreptitiously slipped a stove lid beneath his wicker seat to shield his poste­rior. After rising from those humble origins and ^strugghng through what has seemed an interminable adolescence, survivability has finally come of age as an aircraft design discipline.

As aircraft evolved from simple fabric-and-wood kites to complex structures shrouded in exotic mate­rials, numerous longevity-enhancing features periodi­cally managed to make the scene. The presence of armor plating, bullet-resistant glass, and redundant flight control systems (to mention only a few) cer­tainly helped to bring more of the boys home from “over there.” But such developments have been sporadic and usually the result of reaction to—rather than anticipation of—a new threat. That was an ac­ceptable philosophy when the lead time from concep­tion to production was reasonably short, but today’s complex weapon systems have gestation periods

60 U. S. Naval Institute Proceedings, December 1978

measured in decades. To design tomorrow’s airplanes to meet today’s threats is to design to defeat.

During the 1950s, nuclear holocaust seemed the inevitable outcome of any armed conflict involving the superpowers. Fighter planes of that era were per­fect examples of the results of nuclear think. De­signed as interceptors and armed with long-range missiles, they were intended to sprint out and de­stroy the incoming Communist hordes before they could reach Fortress America. The day of the mad, swirling, gut-busting melee at treetop level was to be no more. The stage was set for future air combat to take place in the stratosphere.

Consequently, when we found ourselves fighting in Southeast Asia, we discovered that our racing thoroughbreds were particularly unsuited for pulling a plow through the mud-and-blood world of the foot soldier. The “speed-is-life” aficionados were forced to concede that the F-4 Phantom pilot hauling iron through the bombing pattern would have gladly traded a portion of the world time-to-climb record for some self-sealing fuel tanks, a gun, and the abil­ity to turn with the MiG-21. The F-100 Super Sabre posted one of the highest loss rates of the war over North Vietnam, while the F-105 Thunderchief went thud at an alarming rate despite herculean efforts to toughen it with various fixes.

And the problems weren’t limited to the high end of the speed scale. Korean War vintage A-l Skyraid- ers, the Clydesdales of the fleet, were soon ushered south of the demilitarized zone to avoid the heavy concentrations of radar-controlled antiaircraft artil­lery and surface-to-air missiles, threats with which even their legendary toughness was simply unable to cope. Helicopters were introduced into direct assault combat for the first time on a large scale. Their star­tling loss rates at the hands of relatively unsophisti­cated personnel caused concern in Army and Marine Corps circles over the viability of their air cavalry an vertical envelopment concepts.

The services began frantic programs to develop tactical electronic countermeasures to defeat the fir^e control radar systems, and work was begun to try to harden airframes and propulsion components against gun and missile damage. The resulting humps, bumps, and bulges invariably added weight and drag which could have no other effect than to reduce range, performance, and payload. An early electronic countermeasures suite for the A-4 Skyhawk took the place of a 20-millimeter ammunition can, eliminat­ing half of the plane’s two-cannon battery. The equipment was later moved to a turtleback hump °ⁿ top of the fuselage.

cause the excessive cost and performance penalties overshadowed any increase in protection they migh^c have offered. The electronic countermeasure systems that went into service were often jury rigged, poor y tested, and maintenance nightmares. With the re suiting decrease in reliability, their already question able effectiveness was even further affected by the a sence of substantial pilot confidence. It was this state

Many potentially good concepts were scratched be-

0 affairs that provided the backdrop for the most Ambitious effort ever to analyze combat losses and ^evelop a long overdue, systematic approach to put- ^tlr>g protective callouses on our various Achilles heels.

In 1968, the Air Force began a study of the air ^ar in Southeast Asia. That study culminated in the ormation in 1971 of a tri-service organization nown as the Joint Technical Coordinating Group on Aircraft Survivability (JTCG/AS). As a result of its ^w°tk, there exists today an impressive program of ^research and development that is devoted solely to of aircraft combat survivability. Funded by ^rmy, Navy, and Air Force appropriations, JTCG/AS c°ordinates the efforts of all of the services in the area ° ^Survivability, thereby eliminating a great deal of uplication of effort. It ensures that the results of ^{tests a}nd the latest state of the art developments in ⁿdustry and the academic community are made ^available to the appropriate agencies. Some of the Projects sponsored by JTCG/AS include:

The study of tolerance limits of fuel ingestion by ^urbofan-engines, specifically the TF-30 and TF-41 The development of flight control systems toler- ^anr of ballistic damage from projectiles, including '-millimeter high explosive incendiaries Extending time-before-failure of helicopter trans­missions after lubricating fluid loss P Computer modeling of hydraulic ram damage to Uel tanks, to be used as a design tool for aircraft uesigners and builders

£ The study of airflow effects on aircraft fuel fires > Investigation of nitrogen or halon fuel tank inert­ing versus 23-millimeter high explosive incendiaries

►          Development of a design handbook for configura­tion selection for the control of aircraft radar cross section

►          Determination of the vulnerability of joints in composite aircraft structures

The fruits of these and other projects are stored, along with voluminous operational data from South­east Asia and the Middle East, in a central library known as the Combat Data Information Center. Lo­cated at Wright-Patterson Air Force Base in Dayton, Ohio, the files are available to any government agency or to any suitably sponsored civilian contrac­tor. They include analyses covering such topics as crew survivability, weapon effectiveness, and tactics. Originally limited to aircraft, the data files have been expanded to include information on land vehicles such as tanks and trucks, and naval surface craft.

The surge to the forefront of survivability has been, more than anything else, a result of under­standing one basic fact: survivability means more than armor plating. Armor, by its very nature, is heavy and bulky, and for years designers and operators have been united in their conviction that the more surviv- able an aircraft, the more severe the performance penalty. The Vietnam experience did its part to per­petuate that belief, for our only approach to the problem usually consisted of adding boiler plate to existing airframes. There are few other choices avail­able once an aircraft has been built.

According to Air Force Lieutenant Colonel Rich­ard T. Remers, the chairman of the Joint Tech-

62 U. S. Naval Institute Proceedings, December 1978

Typical of the mobility and power the Soviets have designed into their air defense systems are these SA-6 surface-to-air missile batteries. Such missiles proved formidable to Israeli pilots flying U.S.-built planes during the October 1973 Middle East War. As in Vietnam, emergency countermeasures had to he installed.

nical Coordinating Group on Aircraft Survivability, a plane’s ability to survive . is a function of not only whether an aircraft can be killed if hit but whether it can be detected and whether it can be hit if detected.” ¹

The fundamental goal of survivability analysis and design is the early identification and successful in­corporation of those survivability enhancement con­cepts that increase the combat cost-effectiveness of the aircraft as a weapon system. Reduction of in­frared, aural, radar, and visual signatures has taken on increasing importance as part of the problem of reducing the probability of detection. Vulnerability of various components is being studied in depth, and exciting new techniques are being developed to help make propulsion, fuel, and flight control systems less likely to fail if hit.

As an example, new design techniques are now being used which reduce the number and severity of angular flat surfaces and keep sharp corners to a minimum. This gives not only a cleaner vehicle aerodynamically but also considerably reduces the amount of reflected radar energy. The overall effect is the dramatic reduction of the aircraft radar cross sec­tion. This improvement tends to reduce the strength of the signal returned to the enemy’s radar scope, thereby reducing the power requirement for jammers and deception devices. The power output of these electronic machines determines, to a great extent, the cost, weight, and volume penalties to be paid for the privilege of carrying them along. Thus this sig­nal reduction technique tends to reduce system cost, weight and size while, at the same time, reducing the enemy’s ability to detect the aircraft and lock on for a final fire control solution.

Although admittedly oversimplified, the foregoing is but one small example of how the systematic, in­tegrated approach to survivability works, and it does work. But, perhaps the most important thing to realize at this point is that it must be addressed from the first day the need for a new aircraft is envisioned. That need must be tied to a clear-cut mission re­quirement and must, at the same time, be matched

‘For footnotes, please turn to page 67.

with the threat it can expect to face. The art of air­craft design lies in being able to fit ten pounds o marbles into a two-pound box. Once a design is fro­zen, once the lines are drawn in ink, the chance to optimize is lost, and we are back to those humps, bumps, and bulges and to paying the attendant penalties.

In 1976, Dale Atkinson, a Naval Air Systems Command civilian engineer with vast experience in the field of survivability, completed an analysis of the various policies and procedures used by each of the services as part of the acquisition process. An un derstanding of his comments is crucial to the propet recognition of the potential available in survivability'

“To field a survivable, combat effective aircraft re­quires a systematic survivability program beginning in the conceptual phase and continuing throughout the life cycle of the aircraft. The requirement for sur­vivability should be stated in the Operational Re­quirement (OR) along with the expected threat. . • ■ Significant survivability benefits can be achieved fo^r little or no penalties if survivability is considere early in the program.” ²

In response to the need for a “systematic surviva­bility program,” the Navy formally began its efforts to get into the business in 1973 with the publication of the original Naval Aircraft Survivability Program Plan. Unfortunately, it never got going because of ® lack of funding. In May 1974, the Chief of Naval Material, Admiral Isaac C. Kidd, Jr., issued a policy statement putting forth the survivability require­ments for all naval weapon systems. In January 197 came the publication of Naval Material Comman Instruction 3920.4, laying out a “. . . vigorous naval combat survivability program for each weapoo system and platform.” This was followed in May 1976 by Naval Air Systems Command Instruction 3920.1 which, after a three-year delay, finally estab­lished the Naval Aircraft Survivability Program.

The Navy’s program starts from a technologic® baseline established by the JTCG/AS-sponsored proj­ects. It pursues solutions to problems exclusive ^t0

Navy weapon systems since the work done by JTCG/aS is limited to that which has potential for ^tr*'Service payoffs.

In 1974, preliminary work was begun on the de­^Velopment of Aeronautical Requirement (AR)-107, which established uniform guidelines for organizing ^ar,d conducting aircraft nonnuclear survivability pro­grams. These technical requirements were included *ⁿ the request for proposal (RFP) for the F-18, the Navy s first major survivability project. In fact, sur- ^'vability was one factor which helped determine inal selection of the Hornet over its competition, figure 1 summarizes the program set up for the F-18 and shows how the cycle is repeated and the system ^refined after each step. To some degree, this repeti- ^tlVe process continues throughout the life of the air­^craft, allowing program managers to consider new treats and technological advances and how they apply to the system at the earliest possible time.

The metamorphosis of the YF-17 to the A/F-18 has tought many survivability-enhancing improvements

the aircraft. A series of trade-off studies was con­nected to address such topics as radar cross section and infrared signature reduction, optimum fuel ^Sequencing, liquid oxygen system vulnerability, and

F’

engine bleed air line protection. Consequently, a list of proposed system improvements was compiled, and it resulted in the incorporation of an improved bleed air system, internally buried fuel transfer lines, re­dundant flight control systems, a shielded cross-feed fuel valve, and an isolated auxiliary power unit.

But, despite what appears to be an encouraging start, the Navy’s survivability program is having some problems of its own. Funds earmarked for fiscal year 1978 were markedly reduced below what was budgeted, and almost all of the Navy’s independent survivability effort for fixed-wing aircraft was de­leted. Such projects as development and testing of ballistically tolerant jam-proof actuators, vulnerabil­ity testing of internal armament, and the develop­ment of lightweight fire protection concepts were cancelled, or at least delayed until fiscal year 1979. Only the helicopter projects remained, and they owe their continued existence in large part to the efforts and interest of the Marine Corps.

So, what’s new?” you ask. It seems that everyone has gotten the fiscal axe to one degree or another, and the future doesn’t look to hold much promise for improvement. And, if this survivability is such a nifty deal, then why shouldn’t it be able to make it

on its own merit?

The name of the game is “trade-off,” for no one aspect of the design procedure can have absolute con­trol over a plane’s final configuration. If that weren t the case, we would wind up with flying wings, fly­ing engines, or even flying bomb racks, depending on the particular fetish of the dominant engineer. At any rate, it is axiomatic that the squeaky wheel gets the grease, and, in that respect, the business of weapon system acquisition is like any other. There are shelf-feet of specifications lining the offices of the Naval Air Systems Command, each sponsor claiming head-of-the-line privileges for funds. Reality brings home the point that there are only so many dollars to go around, and in the constant battle for priorities the new kid on the block often takes a severe beat ing. It is from just such a phenomenon that the Navy’s survivability program is suffering today.

There is no “welcome wagon” in Washington; no friendly neighbors come to help you get established- Thus, inertia is often difficult to overcome. The problem is amplified by a certain lack of education- The only Navy-sponsored course in aircraft surviva­bility is taught once a year at the Naval Postgraduate School in Monterey. It was offered for the first tim^e in the fall quarter of 1977. The Air Force has for some time had a similar course through its Air Force Institute of Technology and offers other training and orientation programs for its procurement personne already in the field. The course at Monterey is part of the aeronautical engineering curriculum, and it has *^l hard time reaching the system acquisition manage­ment students. Of the 26 officers in the origin*¹ class, only three were from outside the aeronautic^ engineering curriculum, and those three were fron¹ naval intelligence.

Certainly, part of the problem with making the program move lies within the growing community ⁰ survivability experts. Those who have become entrenched in the business come into town lugging huge briefcases and piles of computer printouts cov ered with mystical printing. They often offer simp ^e answers to complex problems and often fail to engag^e in plain talk with their fleet counterparts. When tv>'° or more get together, it can be like Babel revisited ^t0 the uninitiated. Such an approach can tend to alfor* ate a potential fleet customer quickly. SurvivabihA will have to sell itself to the fleet and will be able t° do that only by talking in terms those in the flee¹

understand.                                                                               __

Another problem lies in the very process of sur­vivability assessment. Played with computers, mat

Modeling, scenarios, and unbelievable but unavoid­^able oversimplifications, the results can often be grossly misleading, especially when taken out of con­^text. Recent congressional testimony concerning sur­vivability studies of the cruise missile serves as a per- ^ect example. Two survivability experts analyzing the ^same system appear very much like two magicians forking out of the same hat. When one pulls out a abbit and the other a skunk, they both have man­aged to produce small, furry animals but with some fundamental differences. The most perplexing aspect °f this type of analysis is that it deals in relative rather than absolute terms.

For example, an F-14 Tomcat analyzed in a given

-                                                                                                                                                                                            ---- J •                                   l Uf utt j

testing before the threat must be faced. Above left, a gunfire, into an F-18 wing tank simulator to test the capability of the composite wing skin to withstand damage. Above, an A-4 mounted on a high-velocity airflow facility is hit by a high-explosive round during vulnerability testing. Left,

A-4s are subjected to fire in order to determine the amount t time pilots have to escape during carrier deck fires.

theoretical situation might have a probability of mis­sion success of 75%. After modification with some newfangled fix, it might then be reported to have a probability of success of 85%. The only meaningful conclusion that can be drawn is that the new fix, under the conditions assumed in setting up the problem, will improve the aircraft mission success chances by 10%. Real life is quite complex, and although com­puter simulation is becoming better each day, there is still a lot of linear approximation invblved in mathematical modeling. For this reason, the actual probabilities are in themselves meaningless unless a potential enemy agreed to the terms of the hypothet­ical combat and, in addition, God agreed to make the world linear for a day.

Development of our first antiaircraft missile sys­tem, the Nike-Ajax, began in 1945, and it was de­ployed for the first time in 1953. The early 1960s brought an explosion in missile technology which

was capitalized on by most major military powers. Even so, a decade after the concepts became realities, we found ourselves flailing around in North Vietnam trying to develop reasonably effective tactical coun­termeasures against surface-to-air missiles.

The U. S. Army first deployed its hand-held in­frared antiaircraft missile, Redeye, in 1962. Yet, when its Soviet counterpart, the SA-7, showed up in force in Southeast Asia during the 1972-73 cam­paign, there were few effective countermeasures to protect the slow-flying helicopters and propeller- driven aircraft. In the I Corps area of South Vietnam the OV-IO Broncos were directing air strikes from 9,000 feet, and every C-130 Hercules was a potential target for a Vietcong with a Strella missile.

These cases are but two examples of dealing with a threat after the fact, although the technology had long been common knowledge and had been de­ployed in the form of an operational weapon system. In the case of the infrared missile, a look at the great progress made in the use of low-infrared paint schemes and component-shielding techniques gives one an idea of what can be accomplished when the pressure is on. Will we wait and do the same thing with laser and electromagnetic pulse (EMP) coun­termeasures? A look at the European order of battle makes one wonder if we will have time.

And one must also wonder about the case of the F-14. A lot of money is being spent on the program to make the system work. What if today’s methodol­ogy had been available to the designers of the Tom-

cat? Would a comprehensive survivability survey which took into account such things as vulnerable areas and multiple systems failures not have detected the fact that a gross, catastrophic failure of one engine might also take out the other engine in short order? Think of the potential savings in terms of ret­rofit and replacement costs, and the cost of the sur­vivability effort begins to pale in comparison.

And how about the A-7 Corsair II? The high- bypass-ratio fan engine was long thought to be insen­sitive to foreign object damage and fuel ingestion relative to its straight turbojet cousin. Subsequent investigation has shown, however, that the TF-30/TF- 41 series of engines is very sensitive to fuel ingestion in particular. Would that little piece of knowledge have affected the decision to drape fuel cells precari­ously over the intake duct like saddle bags on a pack mule’s back? Perhaps it would have been a good idea to protect those tanks a little more than they were protected in Vietnam, and how nice it would have been to pay for the extra protection in 1968 dollars rather than today’s!

We have been discussing survivability of tactical aircraft but should by no means leave out the rest of the Navy’s flying inventory. The P-3 Orion operators who will be laying mines, moving in close to iden­tify potentially hostile ships, and lugging Harpoon missile's into the war at sea have a vested interest in this new discipline, as do search and rescue and LAMPS (light airborne multipurpose system) helicop­ter people. Every aircraft that flies should be built around some degree of survivability analysis, for small arms fire and hand-held infrared missiles can even bring the threat of combat damage to tradi­tionally noncombat utility and transport aircraft.

The survivability course already in existence at Monterey should be expanded and made a require­ment for all system acquisition management stu­dents. An understanding of survivability is a funda­mental tool of increasing importance without which a program manager is ill-equipped and, as pointed out earlier, it applies to trucks, tanks, and ships every bit as much as it does to aircraft.

One notices in the grocery store that everything from rock salt to disposable diapers is “organic, re­cyclable and biodegradeable” because it must be in ^0rder to sell. That is what the public wants. Aircraft companies are not dummies and they, too, have their ^ears to the marketplace floor to hear the direction from which the approaching herd of customers is coming. Survivability has become a key selling Point, so slick pamphlets and color movies are al­ready extolling the virtues of product after product in ^tetms of survivability. The Navy doesn’t need prop­^aganda, nor does it need lip service, and the only Way _{we w}pj _ever k_{e a}kj_{e t0 see} through the smoke is ^t0 have people properly trained in the field of sur­vivability. Although made in 1976, Mr. Atkinson’s comments are still valid today:

• • . progress is being made in the survivability area. However, there are a considerable number of ^voids which require continuing high priority effort. The individual services’ policy statements for weapon ^systems appear to be adequate; however, the im­plementation of these policies during the specific air­craft system acquisition programs has not been con- ^Slstent in many cases . . . the resources and man­power available to survivability programs within the services are not adequate to meet the requirements in ^a number of cases. . . . It is too late to consider survivability ^after the systems are in combat. ”³

Certainly, the very existence of the Navy’s pro­gram is encouraging, and the benefits offered are °ften obscure, ill-defined, and overridden by more ^traditional cost-effectiveness considerations. Surviva­bility in itself is not the answer to all of our prob­lems, but it certainly deserves its day in court. Evi­dence indicates that, properly utilized, it can mean the difference between victory and defeat in a world where we seem bound and determined to start the game from a position of disadvantage. The instruc­tions, directives, and organizational diagrams are all in place. The magic diet needed to put muscle onto that skeletal framework is dedication. It no longer is a question of whether we can afford to spend the money; it is now a question of whether we can afford not to.

tA 1965 graduate of the U. S. Naval Academy, Com­mander Sapp completed flight training in March 1967 and then served as a flight instructor at Whiting Field until July 1968. He was an original member of Light Attack Squadron Four (VAL-4) flying the OV-lOA Bronco. He served in Vietnam in 1969, then made the transition to flying jet aircraft in 1970. He served with Attack Squadron 82 (VA-82) in the \JSS America (CVA-66) from 1970 to 1973, flying the A-7E Corsair II. In 1972-1973, he took part in offen­sive operations against North Vietnam. His combined service in OV-lOs and A-7s amounted to a total of 343 combat missions. In February 1976, Commander Sapp's designator was changed to 1510 (aeronautical engineering duty officer), and he began two years of study at the Naval Postgraduate School. Earlier this year, after receiving his master’s degree in aeronautical engineering, he began serving as Weapon Systems Man­ager at the Naval Air Rework Facility, Pensacola, Florida.

'Richard T. Remers, "Design for Reduction of Aircraft Vulnerability," Joint Technical Coordinating Group on Aircraft Survivability (JTCG/AS) document, June 1976.

Dale Atkinson, An Analysis of Current Survivability Policies and Pro­cedures Which Impact the Systems Acquisition Process," study project report PMC 76-1, Defense Systems Management School, May 1976 "Ibid.