B-57 Tactics
The American Martin B-57 was adapted from the English Canberra. It was an elegant design with state of the art aerodynamics. However the first model was not a success and it segued into the B model which was more successful. It was designed to be a tactical bomber capable of delivering a large weapons load at high speed to the area far behind the line of battle. The guns in the wings were depressed to fire 3.5 degrees down so that convoys of trucks could be strafed without having to dive to aim the guns. It could carry a wide selection of armaments consisting of bombs, rockets, napalm and flares. There were 8 wing weapons stations and 21 bomb door stations. The bomb door was a rotating platform upon which bombs could be loaded while the door was separated from the aircraft. The loaded bomb door could be rolled under the aircraft and hoisted fully loaded up into the bomb bay. Of the 8 wing stations, 4 could carry bombs or napalm up to 1000 pounds. The other four stations could carry rocket pods of seven 2.75 rockets or two 5 inch HIVAR (high velocity antitank rockets) or flare tubes of two each.. The bomb door could carry four 1000/750 GPs (general purpose) bombs or nine 500 pound GPs or four 250 pound GPs or twenty one 260 fragment bombs or twenty one 100 GPs or twenty one 100 pound white phosphorous. In the latter stages of the Vietnam war, the new Snake eye high drag munitions were introduced and were assigned to be carried by B-57s by people who had never seen of heard of a B-57. They did not fit. Instead of four 750s on our bomb door, we could only carry two high drag. Instead of nine 500 # on the bomb door, we could only carry three. I made a trip to Saigon and had a conference with the scheduling people and at the same time searched the depots all over the world for weapons that were out of date for modern aircraft but were perfect for the B-57. This search turned up thousands of the fire bombs that General LeMay used to incinerate the cities of Japan during the Second World War. These were the MK-35 and MK-36 munitions that were so successful in destroying the trucks that were funneling supplies down the Ho Chi Mein trail through Laos to South Vietnam.
When a suitable nuclear weapon was developed, it was adapted to the B-57. At that time I was a sergeant and an electronics technician working on the B-57. I had to go through a nuclear familiarization course in Colorado in order to be able to be around the weapon. The aircrews had to qualify in delivering the weapon and we were deployed from Blytheville, Arkansas to Wendover AB, Utah for training on a desert range. The target was about ten miles from our base and we could see the aircraft making their runs on the target. The method of delivery was a low altitude approach at high speed to cross the target at 50 feet or lower and then pull up into a vertical climb. The LABS computer would release the bomb just past the vertical and the bomb would go thousands of feet higher before returning to earth. In the meantime the aircraft would come over the top and head for the ground, roll 180 degrees upright, and get as far away as possible before the bomb exploded, preferably behind a hill. This was called “over the shoulder” delivery. I remember standing on the ramp at Wendover and watching the aircraft make their runs when one of them did not make it over the top and went into a spin and drifted down to the desert like a falling leaf and exploded into fire and smoke. We lost two young crewmen.
This delivery system was called LABS, or Low Altitude Bombing System, and was one of two systems designed to deliver nuclear weapons to an enemy. The other variant of this system was the “toss” mode. In this mode, an IP (Initial Point) was selected that was readily recognized and a measured distance and azimuth from the target. This information would be entered into the LABS computer and as you crossed the IP the pickle button would be depressed and the computer would tell you when to pull 4 Gs and the bomb would release at the right angle and travel many miles to hit the target.
The other system to deliver nuclear weapons was SHORAN. This was short range navigation, a system using two transmitting stations with coordinated pulses that could be superimposed by equipment on the aircraft to determine its exact position and guide it to the release point. The navigators had a hard time learning this system and wrote it up so often I was put on flying status so I could check it out in the air as it could not be checked on the ground. As far as I know it was never used to deliver weapons but the long range version, LORAN, was a mainstay of oceanic navigation for years.
As far as I know, the only time that LABS was actually used to deliver a weapon was in Vietnam. Although I was not there to witness it, I heard the story from many sources. There was a target that was dreaded above all by everyone in the squadron. That was Mugia Pass. We had lost several aircraft there because when you went down to bomb targets in the pass, the guns on the mountains on both sides would be shooting down at you. Also, several aircraft had attacked there at night and ran into mountains on the pull off. So one day when the order came down for an attack on the pass to cut the road, some of the more imaginative navigators suggested a LABS attack.
The best maps were brought out and the navigators found IPs and measured azimuth and distance in minute detail. The electronic technicians were detailed to check out the LABS equipment. At that time we were still sitting SIOP alert on Taiwan with targets in China so the LABS equipment was pretty well maintained. (My target when I was on SIOP alert required a toss delivery and I had almost enough fuel to reach the sea after.) The navs were in charge of the mission and the mission launched with a good plan. It was a four ship mission and all were loaded with eight 1000 pound bombs. One bomb in eight was a delay fuse of 24 or 36 hours. We did this often to disrupt the repairs on the roads. The four ship approached the IP at 450 knots and the pickle buttons were pressed as they crossed the IP. When the time was up, the LABS computer signaled a pull up at 4 Gs. At the proper angle, thirty two 1000 pound bombs flew in formation for several miles before descending out of the sky to surprise the gunners protecting the road.
The only other time I know of that the LABS maneuver was used in Vietnam was the occasion when I encountered a target in North Vietnam that was so well protected that I could not attack it directly. This was in early 1966 when I, with my navigator Capt. Norbert (Nobby) Belanger, was assigned to an area about 100 NM north of the DMZ to look for trucks using the ferries to cross rivers on the route that brought supplies south. My navigator and I stayed at altitude, about 30,000 ft., until we were in the area of the most critical ferry crossings. As we approached the Trai Binh area, my nav, using some excellent binoculars from Japan, spotted a line of trucks with battle lights on, lined up for the ferry. I could hardly believe it. We were carrying eight MK-35 fire bombs and I started down to get into position for an attack. As we got to about 15,000 ft. big white explosions started going off all around us. I immediately recognized it as radar directed fire and started jinking and changing altitude and heading constantly. I thought I could outfox the gun but realized very soon that more than one gun was tracking me. There was no way I could get in position to attack without risking almost sure hits. I could tell by the size of the explosions that these were large caliber guns. I had encountered them before and knew they were 85mm. We beat a hasty retreat seaward and got out of their range. As I was dodging around I looked at the source of the red hot beer cans (more like Skippy peanut butter jars) coming up and saw two active guns shooting, one from each end of the line of trucks. I could tell from the rate of fire that each gun had its own radar. One was located at the ferry and the other was located about 3-4 miles NW at the end of the line of trucks. I figured they were track mounted 85s that intel had briefed us on.
I knew there was no way I could get above the target and do a normal dive bomb attack without getting shot down. I was not about to leave all those trucks just sitting there without doing something. Then I remembered the toss bomb option. I placed myself in line with the line of trucks about 6-8 miles away and over the water at about 15,000 and armed my eight M-35 fire bombs. I dove for the water and descended as close to the water as I dared in the dark, using the line of truck lights as a reference, and attained maximum speed. As I approached the line of trucks, I told Nobby to open the bomb door and pulled up with about 4 Gs and started pickling at about 20 degrees and finished at about 45 degrees. I continued pulling over the top and down to about 60 degrees dive. As I came down inverted I looked back over my head and saw both guns firing at us. Fortunately, I was changing altitude so fast they could not track me and the rounds went past and exploded out in front. But the most spectacular sight was the 8 M-35s opening at altitude and raining fire on the convoy. I then rolled upright and continued to as low as I dared to the water. None of the rounds got close enough for us to hear them. That really gets scary.
After I recovered from the dive to the water, I climbed up to about 20,000 and hung around over the coast to see results. The results were spectacular. The fire bombs were set to go off at about 3000 feet when dropped in a normal dive bomb attack. By tossing them at a high angle the fuses opened the canisters at a much higher altitude than normal and created a fire fall much like a water fall. There were fire streams coming from the sky from 4000 feet to 8000 feet over a 4 to 5 mile line. As the bomblets hit the ground they spewed white and red phosphorus and thermite like roman candles in all directions. It was the most awesome sight I have seen except for the time we dropped 32 of the MK-35s on a MISQUE mission one night (another tactic). We descended over the target very gingerly in case the guns were still in action but there was not a peep out of them. I briefly considered going down to strafe the trucks but decided that would be too much risk for little gain. We had enough fuel to stick around for a while and called the control ship (Hillsborough) to ask for a photo mission for pictures. After about 30 minutes things began to get active and the explosions got more intense and we counted 27 trucks burning and blowing up. We could not tell if the 85mm guns were burning but there were lots of munitions cooking off. In spite of all our efforts to get pictures of this action, none were ever made. We did not ever get credit for this attack which likely would have resulted in at least a silver star by the standards prevailing at the time.
Other than the nuclear delivery tactics, the normal tactics were pretty standard fighter tactics. The B-57-34 manual recommended a 30 degree dive angle from 6000 feet with release at 3000 feet and recovery by 1500 feet. Release airspeed was 350 knots. This is well and good for the bomb range but not recommended in a high threat area. The bomb sight is adjustable but has no radar or other assistance. In other words, it is a judgment delivery system. If you think that you can hit the target with 6.8 degrees depression with release at 3000 feet and 30 degrees dive at 350 knots, you keep practicing that until you can do it. However, when you get in combat and you are being shot at by large caliber weapons, you would be crazy to use those parameters as you would be an easy target for the guns on the ground. When the B-57 first went to Vietnam, most targets were not defended by large caliber weapons and those bomb range tactics were OK. The pilots of the 8th and 13th TBS were experts at that type of delivery. But when they started going up north and encountered more and larger caliber defenses their tactics evolved to survive in that environment. Thus, the roll in altitude became higher, the dive angle steeper, and the air speed and the release altitude higher. Every pilot had his own favorite parameters and these were usually changed depending upon the threat level. Of course, the experience of the pilot was a large factor in how successful he was in his attacks since accuracy depended on judgment only.
I developed my own tactics for night attacks as we ended up very quickly as singles ship missions as two aircraft were too hard to keep separated with no lights. I assumed there would be ground fire at every target so I used very steep dive angles, 45 to 60 degrees, with release altitudes of 4000 to 5000 feet. If I encountered very heavy ground fire I would pull up in a turning climb to position myself directly over the target, often inverted so I could start another pass just by pulling my nose down to the target. It required a very good spatial orientation and you had to be an excellent instrument pilot. Many times in the wet monsoon season the visibility was so poor that it was hard to see the ground under the flares. It was much like flying in a bowl of milk. You could not use the flares as a reference to determine if you were upright or upside down because some times you were above them and sometimes below. During the pull up after each drop you had to be careful not to get so slow as to stall. A stall or spin at that altitude and in those conditions would be fatal. I am sure that some of our unexplained losses were because of this. One of the exciting things that happened was when you passed a flare close off you tail. The flare projected your shadow out in front of you and you had a momentary impression that you were about to collide with another aircraft. It made your heart jump right out of your flight suit.
The early models of the B-57 were equipped with eight 50 Cal. guns with four in each wing outboard of the engines. They were replaced on later models by four 20 mm M-39 cannon. The 50s fired at 750 rounds per minute and the 20s fired at 1500 rounds per minute giving both models a total of 6000 rounds per minute. The 50s each had a belt holding 300 rounds for a 2400 round total, and the 20s each had a belt holding 290 rounds for a total of 1160. The 50s had a retract switch that would retract the breech and recharge the guns when it was allowed to go forward. During heavy firing it could be left retracted after pulling off the target and released as you rolled in for another pass. This served two purposes: it cooled the barrels and ensured that all guns were recharged in case some had misfired. When we sat on five minute alert I made sure we only used 50 Cal birds because we did not have to pause at the end of the runway to get our guns armed. The 20s were electrically fired and had to be charged at the end of the runway before takeoff.
The recommended gun sight setting for strafing was 3.5 degrees depression. This was predicated on a firing speed of 350 knots and one G. At higher speeds the depression had to be less as the angle of attack of the wing was less, however longer ranges required more depression. The guns were bore sighted to hit one point at a range of 3200 feet and at ranges beyond that the streams of projectiles would cross and start to diverge. When I went after a gun with guns I approached from directly over it and hung in my straps at 0 G. The large caliber guns cannot shoot much above 45 degrees so directly above them is safe. In that case, I had to depress the sight more to make up for the lack of Gs and the lower angle of attack. In the daytime I would only go after a gun with guns if there was only one. At night it did not make any difference unless they had radar. There was never any assurance that you had knocked out a gun because if it stopped firing you could only assume you had killed the gunners. 20mm and 50 Cal would not destroy a gun without a very lucky hit on a sensitive part. However I have attacked guns at night with M-35s which have no high explosive content to destroy a gun and have gotten positive results. The results were not immediately evident but after a time with the bomblets spewing fire in all directions, a blue-white light would emerge and shine brightly as if from a searchlight. It mystified me at first but I finally figured out what it was. Every gun position had a bunker under ground to store its ammo. If one of my bomblets got lucky and went down the entrance to that bunker, it would set the ammo on fire and the first explosions would create so much heat that the rest of the ammo would burn, creating the blue-white light that shone out of the entrance of the bunker.
I saw this twice in one night when I was looking for targets one dark night in PAC 1. It was very dark but I could not find any truck lights so I flew up Highway One with my lights on until I got fired on. I then tried to pinpoint the guns so I could attack them but by the time I pulled up into attack altitude, they had quit firing. About that time, two Marine RA-5s contacted me and asked what I was doing as they had been assigned to take pictures of the highway. When I explained, they offered to troll for me to get the guns to fire so I could hit them. After I got into position one of them flew down the highway popping flash cartridges and drawing fire. I rolled in on the nearest gun and dropped a M-35 on it. Then the other one made a pass dropping carts and I hit another gun. They made several more passes popping carts but there was no more firing. After about 15-20 minutes the blue-white spotlight emerged from the fires of my M-35s. So I could not claim to have destroyed the guns but I sure did deplete their ammo supply. (By the way, I think the RA-5 was one of the most beautiful air machines ever built).
I mentioned the MISQUE mission. If I ever knew, I have forgotten what that acronym stands for. It was a precision radar located somewhere in Vietnam or Thailand that could direct aircraft to a point in the sky to release their bombs so as to hit a designated target. It came into use in the wet monsoon when many of the targets we wanted to hit were obscured by clouds. It was a very boring mission because you dropped you bombs from about 20,000 ft. and then went home. The MISQUE sites had the ballistics for all our bombs so they knew when we should pickle. When I called and asked them if they had ballistics for the M-35, they said no. I asked them to try to get them and a few days later they called me and said they had them. I contacted the targeting office in Saigon and asked them to find us a suitable target and explained what I wanted. A couple of nights later we got the frag order for a MISQUE drop on a storage area along a river in Laos. I led a flight of four loaded with 8 MK-35s each. The MISQUE site had given us the fuse settings to have our canisters open at about 5000 feet. The target was about six miles long so I briefed my flight on how to release the weapons. The aircraft has an intervelometer that can be set to release bombs at a specific interval but most of us did not trust it. Besides, it was located in a dark and hardly accessible corner of the cockpit. When we got to the target, by a miracle it was clear. When the radar told us to start pickling, I counted over the radio to eight about one second apart and then #2 did the same, and so on. After #4 finished releasing we broke formation and each went to a pre briefed altitude so we could roll over and watch the show. And it was spectacular. By the time we rolled over my first canisters were opening. You could see the flash of the primer cord exploding that separated the canisters into two halves and then the hundreds of bomblets started separating and as they fell they leaked white and yellow phosphorous. This created a waterfall of fire that just kept getting longer and more spectacular. And then the bomblets started hitting the ground and spewing fire in all directions like roman candles. We held overhead for about 30 minutes and the fires just got more and more fierce. I have never seen anything more awesome.
The other bad weather delivery method involved an EB-66. This was a B-66 equipped as an electronics warfare aircraft. They had ground radar mapping and all the warning equipment for operations in hostile radar environments. On the only mission I was on, I led a flight of eight, each loaded with 4 750# GPs and 9 500# GPs. The 500# GPs were all delay fuses set from 12 to 48 hours. I have no idea what the target was. We found the B-66 in Thailand and finally got joined up after I convinced him that we could not catch him unless he slowed down to our speed of about 420 knots. We had four aircraft on each wing of the B-66. We had a very long approach to our target and I have no idea where it was but it was in North Vietnam. He gave us a 30 second warning and I ordered bomb doors open and bombs armed. We had set our intervelometers before takeoff so all we had to do was pickle one time. As he started his countdown from 10 he got to 7 and then yelled “Sam Launch, Sam Launch” and broke up and away. That left us setting there quivering, fat and heavy. I took up the count at 3 and said “3,2,1,pickle and break from the ends”. As the bombs were released 4 and 8 broke followed by 3 and 7, etc. We never did see a missile. I had some bad things to say about the B-66 crew in the debriefing.
As I have said, the B-57 as a weapons delivery platform was only as good as the pilots flying it. After all the old heads from Japan rotated out we got mostly fighter pilots or experienced instructors from Training Command and they easily mastered the skills necessary to deliver weapons accurately. However, after about two years the Air Force was scraping the bottom of the barrel for pilots and we started getting some who had been flying a desk for years, and if they flew at all, it was transports or bombers. Since the 57 had a B in front of it, the weenies at Personnel figured they would be able to fill the slot. Some of them could not even fly a pitch out landing pattern. To them anything over 30 degrees of bank was an unusual attitude. We were supposed to teach them to roll upside down and pull the nose down to 45 degrees dive and hurl their bodies at the earth. It was a near disaster and the effectiveness went down and the casualties went up. One Lt. Col. was to be the new Squadron Commander but he just could not learn to dive bomb on the range at Clark. When his training was supposed to be over he was not ready and I recommended to my boss, Col. Chuck Yeager, that he be given a Flying Evaluation Board and grounded. He told me to give him a few more rides and then to pass him. He then told me I would have to go over to Vietnam with him and fly him on my wing until he improved. He did not improve much and came back from missions with fragment damage from his own bombs because he would press too low trying to hit the target. I would not let him drop near friendly troops. He did survive but I do not think he ever flew night missions.
