The need for an all-weather, night tactical bombing capability was never more dramatically demonstrated than in March of 1967.
North Vietnam’s most advanced industrial plant, the Thai Nguyen steel mill, was finally approved for full-scale attack. The complex, located some thirty miles north of the capital city of Hanoi, as Vietnam’s most visible link to the industrial age. This distinction made it even more tempting as a military target. However, because of decisions made at the highest levels of the US government, it had been subjected to only restrained bombing efforts for the previous two years.
Seventh Air Force in Saigon was assigned the task of target destruction, but early efforts were thwarted by adverse weather. Low ceilings and poor visibility persisted for days, so large-scale strikes by numerous Air Force units had to be diverted to second- and third-priority targets.
Resources for this kind of assignment consisted mainly of F-105s and F-4s based in South Vietnam and Thailand. The Thuds and Phantoms had radar bombing systems, but they lacked the accuracy needed to achieve desired objectives.
In a valiant and courageous attempt to reach Thai Nguyen, Col. Robin Olds, Commander of the 8th Tactical Fighter Wing at Ubon, led a flight of F-4s through a blind letdown in mountainous terrain, using time and distance navigation into conditions of less than a 500-foot ceiling and three-fourths of a mile visibility and deteriorating. Colonel Olds filed a report that would daunt even the most daring aviator, calling the flight “the most difficult mission I ever flew!” The intended target was obscured by weather, forcing the Phantoms to hit a secondary target within the steel complex.
The lack of a means to mount an effective attack against such an important target around the clock and during inclement weather was frustrating to commanders, ops planners, and operators at all levels, and led to several high-priority “Quick Reaction Capability” (QRC) efforts to develop a near-term radar bombing enhancement in existing combat aircraft.
Twin-seat F-105F radar and fire-control systems were swiftly modified. The airplanes were quickly deployed to Korat Air Base in Thailand and assigned to a unit known as “Ryan’s Raiders.” They were flown only at night or in bad weather against important targets north of the seventeenth parallel. Although the F-105’s bomb impact error was cut in half, the improved system fell short of the needed accuracy, and the program achieved only limited success at great cost.
“Combat Bull’s-Eye” was another QRC concept that used the B-58 as a radar pathfinder, with fighter-bombers on the wing. It was tested Stateside, but never put into operation.
Seventh Air Force was, therefore, without a credible all-weather, night capability until the last months of the war when F-111As achieved commendable results against major targets in the North.
How ironic it is that on the day we downed the fifth MiG-21 – August 28, 1972, almost five and a half years after the first major effort to take out the Thai Nguyen target – I was flying cover for Col. Carl Miller, Commander of the 8th TFW, who led an F-4 laser-guided-bomb, day-VFR strike against none other than the Thai Nguyen steel mill. Result: The complex was finally destroyed!
Our experience in Vietnam clearly reestablished the need to be able to strike on a twenty-four-hour basis, although World War II and Korea were certainly no strangers to this requirement.
The F-111, wanted by Secretary of Defense Robert McNamara in the early ‘60s as a multi-mission, multi-service airplane, eventually evolved into filling the low-level, all-weather attack mission for the Air Force, and it has performed admirable. However, the fleet is small, aging, and difficult maintain. Thus, the void remains. An aircraft that may fill the gap is the F-15E dual-role fighter candidate. If flew that airplane August 23.
The Achievable Task
Flying into St. Louis, I pondered the next day’s schedule at McDonnell Douglas. It was interesting to think of the current development of the Dual Role Fighter (DRF), and to recall that this is not the Eagle’s first exposure to the air-to-ground role. The airplane has had a visual dive-bomb capability since the F-15A’s introduction into USAF’s operational fighter force in the mid-‘70s. The weapons delivery computer had air-to-ground logic, and the cockpit head-up display (HUD) presented delivery parameters symbology. Bomb racks were developed and tested. A dual air-to-air, air-to-ground role was originally intended for the F-15. However, to the delight of many of us who had pressed for specialization for several years, Air Force leadership, faced with initial low aircraft sortie rates and other considerations, wisely directed that the F-15 be dedicated to the air-superiority role.
Eagle pilots, therefore, were given an achievable task – namely, to become highly proficient in a critical mission area even though they would be provided a limited number of training sorties in which to prepare for combat.
The F-15 is now a mature weapon system with excellent logistics support and a high-quality maintenance force that resulted in a 70.9 percent fully mission capable (FMC) rate in 1982 – better than any other fighter in the inventory.
Many of the persistent problems of the late ‘70s, such as server parts shortages, engine troubles, long lead times for radars and engines, technicians leaving the service, and subcontractors failing to deliver or going out of business under the pressure of high interest rates and other demands, have eased.
Having flown the F-15B three years ago with Lt. Col. Murray Sloan in an air-to-air environment at Holloman AFB, N. M., and now having flown the F-5E candidate with McDonnell Douglas test pilot Gary Jennings in St. Louis, I find it almost impossible to believe the incredible advances that have occurred in fighter aircraft in less than ten years. Today’s operational F-15, when judged throughout the spectrum of performance and range of tactical requirements, is probably the world’s finest fighter. It’s a tested combat veteran with no combat losses. And while proving itself a winner time and again during the intense demands of William Tell, Red Flag, and other highly realistic competitive arenas, it has established the best safety record of any fighter in history (4.7 accidents per 100,000 hours flying time).
What one who has been away from the day-to-day operational business for awhile realized immediately is that advancing technology enables the operator to do much more – and do it more quickly, and with greater efficiency, thus easing the pilot’s mental work load and allowing better combat judgments and quicker decisions. So much information is now available through the head-up display and so much can be done with the array of switches and buttons on the stick and throttle that the heretofore-unhappy necessity of looking down in the cockpit has virtually been eliminated. Advances in aircraft handling, engine performance, radar, avionics, cockpit design, and all-important rear quadrant visibility represent a quantum leap forward.
So, the basic F-15 has, for some time now, been doing many things better than they’ve ever been done. Moreover, it has always had the capability to be an excellent air-to ground machine. The addition of a high-resolution radar (HRR), a major new development demonstrated convincingly on my flight in the F-15E candidate, includes air-to-ground radar and computational improvements that enable previously unknown capabilities in range, acquisition, resolution, grazing angles, initial navigation system (INS) update, and terminal guidance. The sheer size of the radar dish and the power that drives it (simple physics), plus the latest in digital science, provide range and resolution in the upgraded APG-63 that is not elsewhere available in a tactical system – another quantum leap!
Jim Caldwell at McDonnell Aircraft Co. (MCAIR) describes the process as “number crunching” radar returns at a high rate over a given distance and combining them to make a picture. He says, “In order to produce the kind of imagery we’re seeing with this radar we needed to significantly increase processing capacity. Hughes Aircraft and MCAIR have expended some $50 million of company funds in the effort. And we’ve had it flying for several years. The bottom line is improving survivability in that end game by getting accurate pictures with the radar at long ranges, driving into the target area, then being able to see the picture more precisely for system update and final delivery. Plus we make our airplane fully compatible with the newest standards of digital electronics and armament.”
High-resolution radar mapping is actually not new, but packaging it in a lightweight, low-volume system for use in a high-performance fighter is.
Leaving the Air Patch
My August 23 mission in the Dual Role Fighter Demonstrator (DRFD), to be flown without ordnance, was planned for about one hour, fifteen minutes, launching from St. Louis’s Lambert Field via the Viking I departure. The primary objective was to look at various features of the greater St. Louis landscape, as if they were targets, and evaluate the improved APG-63 radar performance while executing simulated attacks under a variety of conditions.
It’s obviously impossible to appreciate fully all the capability of a new system in just one flight (and even less possible to describe it all in one article). But listening to a short segment of the airborne explanation by Gary Jennings will give the reader a glimpse of the latest in fighter air-to-ground radar ability as designed for this role.
Jennings: Neat way to leave an air patch [12,500 feet above ground level by the end of the runway].
Ritchie: Foxtrot Bravo!
Jennings: We are within limits of the radar, so I’m going to command electronic map. Turn the records on, please.
Ritchie: Records on.
Jennings: There’s Scott AFB in the middle of the cursors – twenty-six miles away. There is the next map up. We have auto gain circuits in the radar that look at all the returns of the previous maps and determine what the gain should be for the next map. We are now looking thirty-one degrees left. There is the runway and all the ramps. That was forty-two-foot resolution. [Individual targets can be distinguished when at least forty-two feet apart.] Here comes the seventeen-footer, and I’m going to concentrate on the ramp area. You can see the terrain, the plow lines, and some trees. From nineteen miles away we can now see airplanes on the ramp. I’m going to freeze it thee for a second and if you would, Steve, on that left-hand control, cycle the zoom switch.
Ritchie:There’s zoom.
Jennings: It’s a little grainy, but that definitely tells me that there is one big airplane, and probably another here, and another down there. I’ll call back the original map. I’m going to command one map from freeze and we’ll look down at this end of the ramp. The next map will be recentered on the cursor position. And there are more airplanes down at this end. I’ll now go back to the original end of the runway and we’ll get ready for an eight-and-a-half-foot resolution. Nice crisp map there. Here comes an eight-and-a-half-foot resolution map from thirteen miles always. What you are seeing now are returns from the tail and the nose of the airplane and a little bit of wing. So that’s what the best radar in the world can do. Turn records off, please.
Ritchie:Records off.
During the preflight, I could help but think that the amount of internal cube (physically available growth space for new black boxes, etc.) is a primary asset when considering an existing airframe for additional mission tasking. The F-15 has a bunch! The cockpit is plenty spacious. There’s room not only for fie- and six-inch CRT screens, but also area for additional dials, indicators, gauges, and controls, as well as space to move various components until the optimum arrangement is found, a luxury never previously available in a fighter cockpit. Chief Systems Operator Wayne Wight gave a complete rear cockpit checkout and made sure everything was ready.
It was comforting to learn that the UHF radio, the single most important piece of equipment in the air battle arena, is a vast improvement over the F-4 transceiver. In November 1972, Gen William Momyer, TAC Commander, asked me to describe the most serious problem in air combat over North Vietnam during Linebacker I. “General Momyer,” I said, “We shouldn’t build another airplane, another missile, another gun, another radar, another engine, another EW pod, or anything else until we build a UHF radio that works!” There were many phone calls that afternoon from people in the communications business. The F-15 is equipped with two jam-resistant UHF radios that allow flexibility for inter- and intera-flight communications.
Jennings: Now we’re going to execute a blind bomb delivery on the railroad intersection near the town of Prairie du Rocher, and we’ll do this one from low altitude. It is currently nineteen miles away so the only thing I have to do is select air-to-ground master, and get another precision velocity update. In the production airplane, this mode would be interleaved automatically between the normal mapping modes. There is the drainage ditch, and the long black streaks that you see on the ground are shadows from the trees. Right over in this area you start seeing quite a few trees and little dots. That’s the town. The thin line coming into the town from the north is the railroad track. The intersection I want is right there. It’s fourteen miles away; fifty degrees right and we are only about 1,500 feet above ground. You can see that the radar takes that video from a low grazing angle and presents it to us from a vertical position or “God’s-eye view.” So a circle doesn’t look flattened on the horizon; it looks like a circle. We are ten miles away. There is eight-and-half-foot resolution. I’ll let it give me one more map. That’s good enough. I’m going to freeze and we’ll turn for the attack, and I’ll select cursor designate. Bingo. There we are – we’re designated. You take it from here, Steve. Would you
Ritchie: I’ve got it.
Jennings: We are 6.2 miles out. About ten seconds prior to weapons release we have to turn the radar transmitter back on for air-to-ground ranging to give us the delta height for the bomb module that determines when the bomb comes off the airplane. We are thirty seconds out from weapons release. There is air-to-ground ranging. And there are the numbers. There is weapons release!
One of the most impressive capabilities of the radar is its ability to operate at low grazing angles, meaning target acquisition at long distances and low altitudes.
The final radar target of the day was the Wood River oil refinery tank farm, acquired from seventy-five miles out at approximately 7,000 feet above ground level using a ten-nautical-mile patch map. At seventy miles, Gary switched to the 4.7-nm map (fifty-nine-foot resolution) and we were able to distinguish individual oil tanks! We then drove in to thirty-eight miles, descending to about 1,000 feet about ground level or approximately one-tenth of a degree-grazing angle. Even though the horizon was now coming between the radar and the target, vertical structures were still visible on the scope.
Again, the name of the game is to acquire and map targets at long distances, drive in using minimum radar transmission (it takes four to six seconds to generate a new picture), and update as necessary for a more precise position. More accurate target information is then available for use with electro-optical (EO) or infrared (IR) devices for final delivery.
Most sensors, such as the Forward Looking Infrared (FLIR), have a narrow field of view. Consequently, the high-resolution radar provides an excellent complement because of its extremely accurate cueing. Essentially, it enhances quick target acquisition by “pointing” the narrow focus sensors at the target. At three miles out, for example, the FLIR takes in the target and a 360-foot distance on either side.
It is important to remember, however, that IR does not work in bad weather or under certain moisture conditions. Radar or visual options can be used if weather conditions do not permit EO or IR.
We also checked stall characteristics, sustained seven-G-level turn ability, and tested the ride at 500 feet and 600 knots. There was even time for loops, rolls, Zimmermann’s, and minimum-altitude-loss split Ss in order to get the feel of the F-15 again! It’s too bad that young aviators, having not flown the F-4 or any of the lesser-performing Century Series fighters, will probably never really appreciate how great this air-plane flies.
The much-discussed rough ride at “high-Q” (low altitude, high speed) was no problem. It would be a little different out west on a hot afternoon in mountainous terrain because the big wing of the Eagle jet has lots of lift! But a full combat load would smooth things out significantly.
Air Force Maj. Dick Banholzer, TAC’s test pilot for the F-15E candidate, says, “The high-Q ride is good to very good, similar to that of an F-4. The CFTs [conformal fuel tanks] provide some airflow smoothing across the tail and the added gross weight inherent with air-to-surface stores and additional fuel increases the wing loading at portions of the mission where high-Q flight would be required.”
Thus, I consider the “rough ride” criticism a non-factor. Also, the nine-G envelope would be expanded in the F-15E by machining a little less metal from key structural members at a cost of only about thirty-four pounds of added weight.
The two-seat fighter concept has often been a subject of debate, especially among F-100 and F-105 jocks. Being fortunate enough to have helped develop the high-speed forward air control of “Fast FAC” program in the F-4 based out of Da Nang in 1968, I came to understand early on the advantages of dual cockpit capability that proved to be invaluable in this highly successful operation.
Gary and I brought the F-15 DRFD home to Lambert Field via our own radar approach, which is a real plus, considering how important that ability would be under certain combat and weather conditions.
Two Key Points
After two days at MCAIR including personal equipment and escape system update by Jack Sheehan, the flight with Gary Jennings, plus almost two hours in the Manned Air Combat Simulator (MACS V) with Jerry Cummings, Chuck Huebner and others, and many discussions with such people as Jack Krings, Director of Flight Operations, Don Gardner, Lead Electronics Engineer, Clarence Conley, Electronics Section Chief, Gill Ballard and Jake Bryant of Pratt & Whitney, as well as Air Force experts who have flown the “E” model, several observations emerged.
It seems that two key points about this airplane have been over-shadowed by all the attention given the air-to-ground, high-resolution radar, night, in-the-weather, and under-the-weather ability of this air-craft.
The first point is that the F15E candidate has maintained air-to-air capability, retaining all of its original features. In fact, the improved radar actually enhances its beyond-visual-range (BVR) air-to-air ability, and in the relatively short-range arena of guns and AIM-9s, the increased persistence or staying power is a desirable trait. We can now engage the enemy at greater distances from home base and/or stay on CAP (combat air patrol) approximately twice as long.
On missions in Southeast Asia, I would have traded some maneuverability in the F-4 for a significant increase in real combat time. This would have given the MiG-21 and even greater turning advantage, but under the circumstances of hit-and-run tactics used during Linebacker by an adversary without all-aspect weapons, fuel was such an important and worrisome consideration that the offset would have been an overall plus. However, today and in the future, the sophistication of the threat requires more maneuverability. In the F-15E, we would have the best of both worlds.
If one can double combat time, or even increase it by fifty percent, this can ultimately be a very important tool to gain the advantage; i.e., during low altitude, maximum power, high-G combat, the lighter, less persistent airplane’s fuel asset is consumed rapidly. So by neutralizing an adversary’s initial advantage (if it exists), you become the stronger.
At first glance, most of us would choose a clean F-15 over one with CFTs for an ACM (air combat maneuvering) duel. However, after considering all the variables, and having no guarantees of exactly where and how the fight will take place or end up, the airplane with more fuel will likely be chosen. If you feel good about being able to defend yourself during the first couple of turns or series of maneuvers, fuel quickly becomes an extremely significant asset; for example, I had little worry about being downed by a MiG-21 as long as visual contact could be maintained, and felt confident regarding the chances of victory. Fighting fuel, therefore, became more and more precious with each passing second, as we had only about two minutes’ worth in the Hanoi area. Then, when it does come time to disengage, fuel is the most important factor to a successful escape.
Plus, it is notable that an Eagle with CFTs actually has the ability to attain a higher angle of attack than one without, at the same gross weight, due to lift generated by the shape of the tanks. Also, CFTs are removable using normal maintenance procedures in a few hours.
The second key point has to do with utilization of the advanced APG-63 mapping during a daytime VFR attack when defenses are likely to be most intense.
High-resolution radar takes advantage of the current explosion in digital technology. The ability of this radar to process large quantities of information at extremely high rates is the real difference in participating at the leading edge or forefront of today’s science. In other words, the more data available and the faster it can be processed into useful information, the better the chances for success. This simply means more maps at higher resolution and greater ranges in shorter periods of time. This combination is most desirable in a ground-attack problem. The key is to have a high-resolution map that is very young and, therefore, with intelligence on it that is very good! So the requirements of this type of sensor are precisely coincident with advancing technology. This is not necessarily true with other sensors such as the eyeball, IR, and EO, which become quite distorted at low angles and long distances.
Almost everyone assumes that for purposes of discussing the various merits, requirements, deficiencies, etc., of the DRF, the attack will be made at night or in the weather. But what if it becomes necessary to attack on an afternoon with good visibility and just enough high cloud cover to diminish the sun’s effect on everybody and his brother who will be lined up to take a shot Under such conditions, the old “pop-up” maneuver for final target acquisition is dangerous! Thus, the ability to accomplish, in day-VFR conditions, what so many have been discussing and debating as a night or bad-weather function, seems to have great relevance. It’s a reverse benefit that is overlooked in most scenarios.
Size and Muscle
I haven’t mentioned size, which almost everyone says is the F-15’s biggest drawback; and frankly, it was my first reaction after the first flight and fight in 1980. However, in the BVR and night/all-weather roles, it is obviously much less a factor. True, the Eagle presents a larger radar depending on the detection angle; but if the Soviets can’t tell the difference between an RC-135 and a 747, then maybe we worry too much.
Besides, there’s a price to pay for anything in life, and for the DRF to do all we’re asking of it, size is necessary.
Terribly important to the entire concept of the DRF is what’s referred to as “muscle factor.” This simply means the load-carrying ability for both fuel and weapons and the brute power to push such heavy payloads through thick air at high speed and low altitude for many miles.
Over the years, some fighter airplanes have accepted external loads better than others. The F-105 did it well; the F-86 and the F-100, not well at all. And while performance obviously deteriorates at higher weights and drag numbers, the F-15 has a thrust-to-weight and aerodynamic margin that allows it to carry heavy loads gracefully and retain very respectable performance. For example, takeoff distance, under the same conditions, for a max gross weight F-15, 68,000 pounds, is only 1,400 feet longer than for a clean bird at 42,000 pounds (3,500 feet vs. 2,100 feet). Major Banholzer has demonstrated the airplane at 75,000 pounds under standard day conditions resulting in a takeoff roll of approximately 4,100 feet!
A typical F-15E tangential carriage load would be twelve Mk 82 500-pond bombs, four AMRAAMs (Advanced Medium-Range Air-to-Air Missiles), a LANTIRN pod, and three fuel tanks. With this load on a Hi-Lo-Lo-Hi mission, using a 100-nautical-mile dash and retaining tanks, combat radius would be an impressive 684 nautical miles.
Competition for new systems is almost always beneficial in that, like anywhere else in the marketplace, it forces time lines, deadlines, claims, and budgets to be met. It normally results in technological advances, more creativity, a more cost-effective operation, and a better end product. The people at MCAIR generally agree that competition for the DRF contract has resulted in a better Eagle.
And when searching for the best way to begin to fill the void described earlier via the quickest, easiest, and most cost-effective route, the new Eagle presents a very strong case. Plus, it is definitely time for a decision and a production schedule ASAP in order to meet this longstanding requirement.
Never again should we send our very best pilots into such miserable conditions with so little chance of success, as we did in 1967 during the attempt to destroy Thai Nguyen.
About the Author