Updated on: 6 October 2007
Posted on: 6 October 2007


Glenn Chapman who kindly wrote the Neography, and Driftsites page about the U-2 program for the U-2 section of the this web site, has offered to do something in the other Blackbird program he worked on the Senior Bowl, D-21B drone.


The D-21B and Project “Senior Bowl”

As I Remember It


The Lockheed D-21B and modified Boeing B-52H combination was the nucleus of Project Senior Bowl from January, 1968 until July, 1971 when the project was terminated. It was formed from Lockheed Aircraft Advanced Development Project’s M-12/D-21 combination which failed after only four flights.

Lockheed ADP, or Skunk Works, gave the M-12/D-21 system the name of Tagboard. The D-21 Unmanned Aerial Vehicle (UAV) was the heart of this program. It was designed as an extremely high speed, very high altitude reconnaissance vehicle, in effect a much smaller, unmanned A-12 or SR-71, but with different equipment. It was considered to be a “one way aircraft,” meaning that each D-21B would fly one time only and then self-destruct. Two Lockheed A-12 aircraft were modified to carry the D-21 on the dorsal fin at the rearmost part of the aircraft between the engines and vertical stabilizers. A second cockpit was also installed for a systems operator for the D-21. These aircraft were designated by Lockheed as M-21. The only difference designation-wise between the A-12 and M-12 was the use of “M” which supposedly was to indicate “Mother” aircraft. The “D” for the D-21 supposedly was to designate the “Daughter” aircraft. The designation of “21” was intentionally reversed from the “12” for security reasons to create a little confusion. (?)

When a D-21 crashed into an M-12 as it was launched on the fourth mission, the M-12 and D-21 were both lost, as was one of the two crew members aboard the M-12 who drowned in the Pacific Ocean after ejection from the aircraft. Plans were then advanced by the head of ADP, Clarence L. “Kelly” Johnson, to modify the D-21 to be launched from B-52 bomber aircraft. This eventually became the beginning of Project “Senior Bowl,” which ultimately became designated by the Air Force at Beale AFB, California first as “A-Flight” and finally as the 4200 Support Squadron. This unit, although designated as a squadron, was really a wing-level unit and was primary responsible to Strategic Air Command. Administrative functions were through 14th Air Division at Beale; operational functions were through SAC and other still-classified hierarchy.


Senior Bowl consisted of the D-21 modified to be carried from an underwing pylon, similar to the one used for launching of the X-15, on a B-52H aircraft. This caused the D-21 to become designated as D-21B, which is the vehicle on display at most museums except for the Museum of Flight in Seattle. This unit is the only existing M-12/D-21 display anywhere. All others, to my knowledge, are D-21B vehicles. There was no mock-up, model, or working drawings of a D-21A to my knowledge, although there may have been some sketches. Therefore, the progression went straight from D-21 to D-21B.

The major modification of two B-52H aircraft for the D-21B was the elimination of the ECM operator’s and tail gunners panels at the rear of the top deck of the bomber and the installation of identical launch control panels for D-21Bs on the right and/or left pylons. Two camera mounting stations in the left and right forward wheel wells of the B-52H were installed. These mounts held 35mm very high speed cameras that looked through an optically-ground window in the side of the forward wheel well to record the launch of the D-21B from the B-52H. The cameras were aimed at the D-21B from different angles and with different lenses which captured the D-21B as it dropped from the pylon. These cameras had film magazines which held 1,000 feet of color film and ran at a speed of about 100 inches per second. There was also a down-looking high-speed camera inside the pylon to catch the D-21B is it dropped away from the aircraft. When played back on a normal 16 inches per second projector, the film provided a very, very slow motion viewing of the D-21B launch. These films were used to document the millisecond by millisecond launch of the D-21B and, if any problems resulted during the launch, the films would help to find out what went wrong and why. Addition of the special pylons, telemetry gear, communications systems, and associated wiring and instrumentation completed the modification of the aircraft.

All D-21B vehicles launched by A-Flight and the 4200th Support Squadron were from the starboard, or right side, pylon only. The port side pylon station was never used during this time. Although some publications have shown pictures of the D-21B hanging from the port side pylon, I personally never saw this configuration. These are either from sorties flown by the Skunk Works or the picture negative has been reversed. Personally, I feel the latter is what is seen in these books.

Because the D-21B was powered by a ramjet engine, it needed to be accelerated to beyond Mach 1 to “light off.” This had originally been the purpose of the M-21 aircraft. It was decided that, in order for this to happen when launched from the pylon of the sub-sonic B-52H, the D-21B would need a rocket booster capable of propelling it to around Mach 1.5 or so for light off. After a pre-programmed amount of extremely volatile solid fuel had burned out and the D-21B had ignited, successfully, the rocket would separate from the D-21B. It would be recovered and sent back to the Skunk works and rebuilt by the vendor of the booster to fly with another D-21B. We in “A-Flight” and the 4200th jokingly referred to this booster as “the cigar” because it resembled one very closely.

This special solid fuel rocket was developed through Lockheed sources. Once the D-21B had been installed on the B-52H right inboard pylon, this rocket booster was mounted to the underside of the D-21B at the original connecting points which had once held the D-21 to the back of the M-12. It had a burn time of about ninety seconds, which got the D-21B to the calculated speed for light off.

The B-52H with it’s D-21B and booster rocket combination mounted on the right pylon would take off for the required sortie. At a precise pre-planned point in time and geographic location, the Launch Control Officer (LCO) on board the B-52H would start the sequence of operations by dropping the system from the pylon. All operations for and by the D-21B and it’s actual and peripheral equipment was by way of four large “perf tape” magnetic tape spools which was the memory for the computer system in the D-21B hatch. At the time, this was considered “state of the art” while today it is just an old antique. Each perftape was programmed by the D-21B INS technicians in accordance with orders that came down for the mission to be flown. A few seconds later the booster rocket would fire, the D-21B would light off, the booster would egress the D-21B via explosive bolts after burnout, and the D-21B would begin it’s sortie.

After deployment and completion of the mission, the D-21B would decelerate, drop to about 60,000 feet, the equipment hatch would be egressed from the D-21B through use of six explosive bolts, and was recovered by C-130H “cat’s whiskers” aircraft. Shortly after hatch egress, the D-21B would self-destruct.

Initial program cost of the D-21B delivered from the Skunk Works to the 4200th and through the mission to destruction was estimated a 5.5 million dollars each, including the rocket, mission evaluation, operation of the B-52H, and all other program-incurred “per mission” expenses.
Project Senior Bowl’s operational life lasted from summer, 1967 until it’s abrupt termination in July, 1971. During that time, “A-Flight” and the 4200th Support Squadron launched about sixteen D-21B vehicles from the B-52H both as training and as operational sorties.

At the time of the operation, Senior Bowl was one of the best kept secrets in the military. Only a very few select people were cleared for the project. Everyone in the project was cleared to top secret and had, in addition, a special project clearance which enhanced the top secret level. The level of this clearance was, and still is, in itself extremely highly classified. All Senior Bowl personnel that I knew were cleared to the same level, regardless of rank or grade


In the summer and early autumn of 1967, Strategic Air Command (SAC) began putting together the nucleus of the Air Force unit which would maintain, prepare, launch, fly, and recover the D-21B from these modified B-52H aircraft. Assignments were levied throughout Strategic Air Command for approximately 180 officers and airman of varying skills. The skills required for Senior Bowl were:

1. Those personnel who would fly or work on the B-52H only;

2. Those personnel who would work on the D-21B only;

3. Those few personnel who would be involved with both the B-52H and D-21B;

4. A small specially trained component of Security Police who would be responsible only to A-Flight and, later, the 4200th Support Squadron;

5. Supply, administrative, and other support personnel who would not directly be involved with the B-52H or D-21B, but were an important part of the project.

In addition to the Air Force personnel who would make up the project, many Lockheed and vendor support and advisory personnel were part of the team.

The requirements for all personnel were extremely stringent. Air Force was in effect hand-picking these individuals so they could get the best they could find for Senior Bowl. In November, 1967, I received my assignment while I was a staff sergeant avionics specialist stationed at K.I. Sawyer AFB, Michigan.

When I asked where I would be going and what I was to do, I was told the assignment was for “A-Flight at Beale AFB, California.” I asked what the numerical designation of the outfit was and was told it only said “A-Flight, 14th Strategic Aerospace Division (SAC), Beale AFB, California” and nothing else.

When I arrived at Beale on January 3, 1968 and began my in-processing, I was amazed to find out that the words “A-Flight” were a magic phrase. Personnel, Finance, and other permanent party support personnel at Beale who had heard this term had absolutely no idea as to what it was, but the general consensus among all of them was that it was a new addition to the very prestigious 9th Strategic Wing who flew the SR-71 aircraft. In reality, although we later ended up working in the immediate vicinity of the SR-71s, we never were even an indirect part of the 9th or the SR-71 program. I was indeed being assigned to a squadron simply known as “A-Flight.” I was given priority over everyone else processing with me, including at one time, a Lt Colonel who was quite upset that I took precedence over him. Actually, it was not me who had the precedence, it was the needs of “A-Flight” that had the precedence. Evidently, all base services had been informed that anyone processing into “A-Flight” would be given immediate precedence.

A few days later, I found that “A-Flight” was nothing more than a wooden single story building directly across the street from the 9th Strategic Reconnaissance Wing Headquarters Building on the main base. Incidentally, this building is still standing as this is written. When I entered this building for the first time, I could hear many voices inside and found it was literally armpit to armpit with about a hundred other men like me wondering what exactly was going on. No one seemed to know anything. One staff sergeant, who we found out was the acting First Sergeant and Chief Clerk, was the only one who knew anything and he wasn’t talking. It ended up that we would report to this building at 0800 each morning, drink some coffee and tell some lies to each other, and be told about a half hour later to go home and call in once in a while. For about six weeks this is exactly what I did. Never in my Air Force career had I had more legal time off without official leave that I had during these times. In one respect it was wonderful; in another it was extremely agonizing, which gave all of us with the project a feeling of being abandoned, useless, or worse. However, and without our knowledge, this was the time which was being used for the project to achieve the final project clearances we all needed before we could be told anything or used as we felt we should be utilized.

Around the middle of February, 1968, I was called in and brought into a room for my first meeting with our squadro9n commander, Colonel Arden B. Curfman who, behind his back later on, became known to us as “ABC.” Also with him at that time was a Full Colonel Baldwin who I would find out later was our “chief spook.” Actually, he was the Air Force liaison person at the Skunk Works for Senior Bowl. This day was the one and only time I would see him in uniform; I was told that I would refer to him as “Mr. Baldwin” from this point onward. During my time with the unit, this was the only time I have ever seen him in his USAF uniform.

I was informed I had been cleared for the project clearance for Senior Bowl and both of these gentlemen proceeded to give me the most intense security briefing I have ever received. This encounter lasted about three hours with no one except Curfman, Baldwin, me, and occasionally the Chief Clerk. When something highly classified was to be mentioned, it was not done orally; Baldwin or Curfman wrote it on a piece of paper and handed it to me to read and, after reading it, I was asked if I understood it. When I answered that I did, they immediately destroyed it by putting the scrap of paper in an ash tray and setting fire to it. Immediately prior to my briefing conclusion, the Chief Clerk came in and gathered these ashes from the ash tray and put them in a little bag for further disposition. I think I read more that day than I heard, because virtually everything they told me was very highly top secret. Most of all was information they told me concerning where we would be going to test the D-21B, how I was to conduct myself whenever I had to go to the Skunk Works or “vendor,” and where it was planned that we would use it operationally.

Later that week, along with three other men in my career field who had been cleared the same week I had been, I attended “school” at night in the same room where I had been briefed. The training was conducted by a technical representative from our vendor and lasted about a week. It consisted of very intense training on our specific system, called “the payload,” and the D-21B. The first night, before we had gotten too far into the session, I jokingly asked this man if we were going to be working on something like the X-15. He looked at me very stoically and told me that “---I was not too far off track on that.” I would find later that this individual never joked around and was very hard to get along with, but he was very good, smart, and knowledgeable on what he was telling us. After that week of school, I never saw him again.

I was in the first fifty of the new group to receive the full clearance. A few individuals failed to receive the clearance. They were immediately given an assignment to another base or unit. They had received no information other than the project name of “Senior Bowl” and that they were assigned to “A-Flight.”

To indicate how difficult it was to get this clearance, the following is indicated. I had in my skill a technical sergeant who was one of the original Air Force people in the 4080th Strategic Reconnaissance Wing with the U-2 aircraft. He had been to the special area where the D-21B was now at when he was introduced to the U-2 in 1957. Although that security was akin to what we were going through for Senior Bowl, he had received that clearance relatively easily compared to what it took for him to become cleared for our new project. As a teenager in the early 1950s, he and some other kids had gotten drunk one night and had to “sleep it off” in jail in his home town in Eldorado, Arkansas. Although this did not hold him back from the top secret and project clearance for the U-2, it held him back for nearly six months for Senior Bowl until it was finally all cleared up.

Nearly the entire year of 1968 most of us who were project cleared went to a classified location each week where we learned the ins and outs of the D-21B, the modified B-52H, our specialized equipment, and how we all fit in. We would meet at Beale AFB Base Operations each Monday morning at about 0600 and climb on board a civilian Fairchild F-27 turboprop aircraft for the flight to “the area.” While at the area, we were assigned rooms in mobile homes. We could not leave the area but were free to travel anywhere in it’s environs that we desired. About 1730 each Friday evening, we would again board the F-27 for the flight back to Beale. Our weekends were free to do whatever we wanted to do. Then, it would start all over again on the following Monday. Because of our relative isolation from anyone back at Beale while we were at the area, we spent our time rather easily learning all we had to know about what we would be doing and how to do it.

In December, 1968, we lost the designation of “A-Flight’ and became the 4200th Support Squadron. Many publications have called us the “4200 Test Squadron.” We were never in our tenure known as a test squadron. When we became the 4200th, we lost some of our priority we had been enjoying but still retained enough “precedence,” far more than the SR-71 boys, to know we were in a pretty elite outfit. In December of that year, we moved permanently to Beale and were housed in a nose dock near the current locations of Fuel Cell and Phase Hangars. While we were spending our time at the area, civilian contractors had been remodeling our nose dock for our operation. Also, our two B-52H aircraft, called “BUFF,” were provided parking at the farthest point at the northern end of the ramp near the alert facility.

The 4200th had it’s own security forces of Security Police who, like us, had been fully cleared for Senior Bowl. Although we were squadron level, we were in effect a wing-level operation. We were exempt from the usual inspections, Maintenance Standardization and Evaluation Program (MSEP) inspections, base details, and other irritants that everybody else on Beale had to be concerned with. We became a very close knit group, the 180 or so people who comprised the 4200th.


We never had any idea when a sortie would be levied for us. It seemed to be quite spontaneous to say the least. We would go weeks, and sometimes even months, with nothing to prepare for except lots and lots of training among ourselves. Besides us Air Force people, about 10% to 20% of the complement of the 4200th was comprised of Skunk Works personnel and vendor’s technicians, otherwise known as “technical representatives.” They assisted us in our training and helped us prepare for each levied sortie. They also provided all parts and hardware for the D-21B and vendor’s equipment.

The D-21B was constructed primarily of titanium, stainless steel fasteners, and composite structures that were in their infancy at the time. All wiring in the vehicle, especially in the equipment hatch, was teflon-coated, gold-alloyed wiring. It required whole new skills learning to work with this wiring and, because of it’s makeup, was pretty brittle and broke easily at the wrong time if we were not careful while working with it. Special solder was used with this wiring as were very unique soldering techniques. All of us who had to work with it were required to be trained by a very knowledgeable Skunk Works technician. Quite often we used a Lockheed-developed item called a “solder sleeve” that was basically an in-line “stakon-type” wire splice with a shrinkable sheathed plastic sleeve which had the special solder encircled around the inside of the sleeve. We would strip the wire insulation using high-temperature heat strippers and then put the stripped wire ends inside the solder sleeve. We would subject the sleeve to a high-temperature heat gun, something like a hair dryer except much hotter, until the solder would melt and the plastic sheathing would shrink making a perfectly spliced connection.

The stainless steel screws which were used with the titanium parts were very unique. They were mostly flat head and resembled a Phillips head. However, the slots in the head were offset and very vaguely resembled the old Nazi symbol Therefore, they became known as “swastika heads.” The idea behind this configuration was to provide higher torque when tightening or loosening them. Special swastika-type “apex” drivers were developed and we made our own screwdrivers using these apexes in an apex holder welded to a piece of 3/8” square stock about 24” long. We made our own wooden handles which we attached to the square stock and, voila, we had swastika screwdrivers.

When tightening these screws down, the apex would tend to dig into the screw rather than slip out of the head as Phillips head type would do. It was the same when taking them out. With the extremely high stresses during flight, the screws in the hatch covers would become even tighter. The swastika drivers made it a little easier to get them out because they would again tend to dig into the head rather than slip out. It took a lot of strength in the arms and shoulders, however, to do this and, at the time, I was in very good shape and quite strong and was one of two or three others in the shop who could break these screws loose easily. Incidentally, a screw was only used once and, if it had to be removed, was thrown away and a new one used in it’s place. This happened to literally thousands of screws over time.

If a screw was lost or damaged, we went over to the Lockheed parts person to get more screws. The first time I did this, I was asked how many I needed. I asked for a handful and was told to go count exactly how many I needed. I came up with about thirty or so and the parts man counted out exactly that many and made me sign for them. I found out later that each one of these swastika-head screws, which were about 1⁄2” long by 10-32, cost more than $5.00 apiece. A good profit for Lockheed for sure.

Once a mission was levied, the first thing that happened was to figure out who would be going TDY to the ADVON (Advance Party) locations. This usually meant that at least 30% of the D-21B and some of the B-52H people would be away from Beale while preparation for the mission was taking place at Beale. We usually had three locations:

1. The first location was to receive and deploy the B-52H/D-21B aircraft as scheduled and from there the B-52H/D-21B would depart for the mission. A few times, however, the mission was commenced directly from Beale and this location was used for return of the B-52 after launch of the D-21B;

2. The second location was the site where, once the D-21B had completed it’s mission, the hatch would be brought so that recovery operations of the equipment could occur, and;

3. The third location was a “floating TDY,” usually a Liberty Ship or Navy destroyer, which could perform secondary recovery operations of the hatch in case the “cat’s-whiskers” C-130H was not able to snag the hatch in flight.

No site-permanent personnel or personnel aboard the ships were project cleared for Senior Bowl. The captain of the vessel would be briefed by our ranking individual, usually an officer or high-ranking NCO, to only what was needed to be known by him to get us where we needed to be. Likewise, the ranking individual at the ground-based sites were briefed in the same way.


The hatch was removed from the D-21B and we took it into the Payload Shop. Other technicians started BIT (built-in testing) and IFCO (in-flight checkout) procedures on the D-21B with special test equipment in the hangar. What they would actually be doing was to simulate an actual mission using the test set to determine whether the D-21B was operating as it should. It may be hard to believe, but the same thing had happened at the Skunk Works before the D-21B had left and the vehicle was perfect, ready to go. However, while in transit between the Skunk Works and Beale, the gremlins always seemed to set in and cause the D-21B to go out of whack. Sometimes it was not too bad; other times it was horrible. Regardless, not once did we get a D-21B that worked as it should have. Nothing against the Skunk Works, because they had made it perfect. It also wasn’t our fault because, like the Skunk works people, we would again make it perfect. At least until it started it’s takeoff roll with the B-52H for it’s upcoming sortie. Again, gremlins seemed to live within the D-21B because sometimes, after launch, the whole thing would go haywire again. It just seemed that the D-21B was a very fragile and temperamental aircraft.

While these technicians were working their magic, we would begin our own checks and would prepare the payload for installation into the hatch. Once installed, we began our own BIT and IFCO checks with our test equipment. The final thing we would do was to put RTV sealant (the old red, flaky-when-dry stuff) around and on all areas of the hatch that wasn’t secured prior to putting the waterproof cover on top of the hatch. This also meant RTV under the cover and on each screw that was holding this cover down. There were about two hundred screws that had to be installed and, for one reason or another, some of the holes which had been drilled and tapped at Lockheed seemed to have moved which made it even more difficult for us to tighten down the cover properly. Somehow we always seemed to persevere. However, we with the swastika screwdrivers usually ended up “red-handed.” This RTV was miserable stuff and was hard to get off our hands and fingers. A spray can of WD-40 helped to get it off.

When we were finished with our BITs and IFCOs in the shop, we took the hatch back to the D-21B where the BITs and IFCOs were still in progress. The hatch would be installed in the equipment bar at the forward underside of the vehicle after all proper connections were made. One of these connectors was a square Cannon plug with 100 pins which had to mate perfectly with it’s connector inside the equipment bay. This was extremely difficult because we had little room to work around and the pins on the connector could be easily damaged. There were times when we all would take turns trying to get it right until all of a sudden it went together seemingly by itself. One time the connector was found to be damaged when the BIT was performed and more than a week went by until we got a new harness from Lockheed, took the hatch apart again, replaced the harness, performed more BITs and IFCOs, re-sealed the hatch, and re-installed it back on the D-21B. The BITs and IFCOs on the D-21B had to be started again from where it had left off, therefore becoming quite time consuming.

When the D-21B and the hatch had passed all BITs and IFCOs, it was taken out to the B-52H, again very early in the morning, under a canvas shroud, and uploaded onto the right inboard pylon. Once it was hung on the pylon, the booster rocket, or as we called it, the cigar, was brought out to be installed to the underside of the D-21B. It was at this point when things really got hairy.

Because the cigar was a solid fuel unit, it was very volatile and sensitive to static electricity which could very easily ignite it. Although this never occurred, it would have wreaked havoc with the flight line, buildings, people, or anything else. To prevent any static electricity from forming, anyone in the vicinity of 25 feet of the cigar had to wear “leg stats.” These looked like garters which had a hard rubber loop that our feet went into and a wire that was connected to a strap that was connected around the upper part of our lower leg. This strap was highly conductive and was connected via the high-conductance wire to a highly conductive pad on the loop below our shoes. Therefore, our entire body would be kept fully grounded at all times so that no difference in potential could occur that could cause static electricity to form. We had to remember to keep one of our feet fully flat on the ground any time that we had to kneel around the cigar so that conductivity to ground could be maintained. Had any static occurred any time we came in close contact with the D-21B and/or the cigar, it could have caused a low-amperage, high-voltage arc of direct current, something like lightning, which could ignite the cigar and send it on it’s way. Obviously, this would have resulted in the loss of the D-21B, probably the B-52H, maybe some lives, and a few aircraft, buildings, people, or whatever in the line of fire of the cigar. If we didn’t do anything else right, each and every member of the 4200th/A-Flight made sure leg stats were used religiously. Most of us even wore them when the D-21B was installed and the cigar wasn’t even at the site yet.

When it came time for launching the B-52H/D-21B/Booster Rocket Combo, nearly all personnel were at the squadron or at specific duty stations to take care of last minute hang-ups or problems so that the scheduled takeoff time could be achieved. Because timing was everything, if only an hour, or many times less time, went by and the bomber was not in the air, the mission would be aborted and rescheduled. Although this happened a couple of times, we were generally able to make our takeoff times as scheduled.

After launch, the B-52H/D-21B/Booster assembly would usually head out for Location Number One where it was recovered. Final launching for mission was usually done from that location. Once or twice, however, the mission requirements required mission launch directly from Beale.

Once the bomber was up for mission, it was totally out of our hands. The only people who had any control of any kind now were the bomber crew, whose job it was to get the D-21B to it’s drop point exactly on time accurately and the Launch Control Officers who were able to perform IFCO checks and had some manual control of the D-21B as needed. Once the D-21B was dropped from the pylon, very little control, other than some telemetry signals from the LCO and his panelboard on the B-52H, was possible.

Final IFCO checks were performed by the LCO and, if everything was in order, and the operation had not been recalled, (which happened occasionally) the LCO would initiate the launch sequence and drop the D-21B/Booster. Immediately prior to the drop, high speed 35 mm cameras mounted in the forward starboard wheel well and the wing pylon of the B-52H were started so that the drop could be recorded on film. One camera in the wheel well and the camera in the pylon had a wide-angle lens, and the other camera in the wheel well had a “fisheye” lens. They all looked directly toward the D-21B through a small window installed on the side of the wheel well and vertically downward from the pylon. These cameras would only run for about ten seconds, but would record the drop and firing of the D-21B and cigar in case something went haywire. After each flight, we were allowed to view these films of the drops. The action was so slow that, after awhile, it became quite boring to watch, although I, for one, watched them all. It was fascinating to see that thing drop away and light off, although it appeared to be so agonizingly slow. In reality, however, it was virtually instantaneous with only a few seconds going by until it was out of sight of the camera’s eye.

As soon as the D-21B and cigar were dropped, automatic sequencing within the D-21B started from the perftape computer. About two seconds after the drop, the cigar would ignite, the automatic flight Control system (AFCS), Inertial Navigation System, (INS) and other systems inside the D-21B and the hatch began their work to get the ramjet on the D-21B started, put the vehicle into proper trajectory, egress the cigar after about a ninety second burn, and commence programmed operations from the on-board computer. Now all that could be done, other than a few actions that could be taken by the LCO, was to wait. One of the most important of the LCO commands that could be given to the D-21B was the “destroy” signal if anything went wrong that required instant destruction of the bird for safety and/or security.

At the proper time in the mission, payload equipment would begin operation until the computer determined it was time to shut it down. The D-21B was now sent into it’s final leg. At a pre-determined point, explosive bolts would fire and the hatch would be egressed from the D-21B. The hatchless vehicle would continue on it’s way until, at another pre-determined point, an explosive charge would ignite, destroying the entire D-21B into a meaningless pack of trash, ashes, and whatever other residue resulted from the destruction.

After egress, the hatch would drop until about 15,000 feet or so, a drogue and main chute attached inside the hatch would engage, trailing the hatch a few hundred feet from a cable. On this cable were calculated markings that the C-130H would (hopefully) engage the marked spots on the cable and the hatch would be retrieved into the aircraft and delivered to Location Number Two for recovery operations by the 4200th/A-Flight personnel.

If the C-130s missed their target, the ship (Location Number Three) would attempt recovery operations. If this happened, all recovery operations were to be performed by the 4200th/A-Flight people on board the ship and, after docking, would be sent forward to a facility for analysis. I was on these ships four different times and not once did we have to recover the hatch. It was either recovered by the C-130 or was lost completely.


Senior Bowl and the 4200th/A-Flight lasted only three years. It was a very difficult operation to perform, even with the state-of-the-art technology of the day that was available to us. Only one thing had to go wrong to cause the mission to be in jeopardy and usually one problem would lead to more problems which, ultimately, cascaded to cause less than desired results. The operation was extremely expensive and proved not to be feasible at the time. Our successes were overwhelmed by our less than successful or totally unsuccessful outcomes. Kelly Johnson and his Skunk Works geniuses did far more than was required to achieve success as did we in the 4200th/A-Flight. We were very highly trained, and each member of the squadron, regardless of our skills, were extremely well qualified and capable of performing our duties successfully. Although there were a few individuals who either could not cope with the high security, family separations, or other stresses put upon us, there were definitely very few of them. There was one individual who I felt should never have been accepted into the project and that was because he was not nearly as security conscious as the rest of us and he ended up very drastically being terminated from the project. Another individual, a member of my shop, was also terminated from the project for his less-than-ethical financial etiquette which ultimately led to a courts-martial. Although he was acquitted, he too, although less drastically, was terminated from the project. It undoubtedly affected the rest of his Air Force career, provided he was allowed to have a career. As for the rest of us, we were an extremely close-knit group who just failed to get it right with the short time we had to do it in.

Three months prior to the termination of the project, many of us, especially those of us with overseas-imbalance skills or critical skills, received orders for Vietnam. This would be my second full tour and, including a ninety-five day TDY there with the U-2 in 1964, would be my third trip to this “Paid Vacation In A Tropical Paradise” called Vietnam. I was at Tan Son Nhut AB near Saigon when, in August of 1971, one of the members of my shop showed up and told me that the 4200th had been abruptly shut down and operations terminated one day a few weeks earlier. Operation Senior Bowl and the D-21B had come to an unceremonious end.

As of this writing, I believe much is still highly classified about Senior Bowl and the D-21B. We all had to sign all kinds of security paperwork that we jokingly referred to as “burn before reading” that in effect said we would never mention the term D-21B nor discuss what we did while part of Senior Bowl. I have never been briefed as to downgrading of security of this project, and have to assume that much of what cannot be told will forever, or at least for a very long time, remain secret. I agree with this fully. However, I also feel the D-21B itself, like the U-2 I had worked on earlier, has become unclassified, with most of it’s equipment still covered under the national Securities Act.

Someday, like the U-2, SR-71, the F-117, and other once “black” operations, all may become known about Senior Bowl. Until that time, this is all I feel I can report on this unique operation I like to refer to as an “unsuccessful success.”

© Glenn R. Chapman


Back to the main SR-71 page