While I will always be a "bomber guy" I actually spent more than half of my career flying tankers in the Air National Guard. At the time I just wanted a job, but the tanker has its own charms, which I came to appreciate.
Back in my day the tanker was everybody's last choice out of pilot training. Nobody wanted one. They were mostly based in cold, remote places and spent a third of their time sitting alert.
The lowly tanker has always been the odd man out. SAC was a bombing command. Everybody knew that bombers were the "first team" and tankers were second stringers.
When SAC went away the tankers went to Air Mobility Command. AMC was run by what we called the "t-tail mafia", C-17/C-5/C-141 strategic airlift types who really didn't know what to do with us.
Despite all that the tanker is arguably the indispensable aircraft in the fleet. It's really the plane that makes us the Air Force we are today.
The concept of air refueling was first tested back in 1923. In the late 1920s several endurance records were set with flights lasting hundreds of hours. Then in 1935, brothers Al and Fred Key set an all time endurance record of 27 days continuously airborne! The automatic shutoff nozzle they designed to make the refueling process safe is still in use today with minor modifications.
The first air refueling in 1923. If any gas spilled on the hot engine it could cause a fire. The Key brothers solved that with their revolutionary nozzle.
The British also had a working air refueling setup in the late 1930s. They used it experimentally to extend the range of their flying boats on oceanic runs. World War II put further development of air refueling on the back burner.
The Cold War and the arrival of jets renewed interest in air refueling. Jets are inherently thirstier than piston engines and the early jets were really thirsty.
The first USAF tankers were B-29s that were converted in the late 1940s. These used a probe-and-drogue refueling system that is still standard for everyone in the world except the US Air Force.
RAF Tornado refueling via probe and drogue.
The reason for that is the US Air Force, and specifically Strategic Air Command, had a lot of long range bombers that needed to be air refueled. While a bomber can certainly be refueled via probe-and-drogue, it takes a long time. A "flying boom" refueling system can pass a lot of gas in a hurry. Kind of like some people I've known.
KC-97 refueling A-7s with a flying boom. Look at the fuselage angles. The KC-97 is going full speed and the A-7s are having a tough time flying that slow.
In the early 1950s the first dedicated tanker, the KC-97 was introduced. These served all the way until the late 1970s but had some drawbacks. Being propeller driven they were slow. Even when they added a couple of jet engines they were still slow. This made refueling jets difficult. It also had to carry gasoline for its own engines and jet fuel in separate tanks. What was really needed was a jet powered tanker.
KC-97. I remember seeing these at O'Hare in the mid 1970s.
This is where things get interesting. In the mid 1950s Boeing believed they could develop a jet airliner superior to the British de Havilland Comet. There was only one minor problem. They didn't have any customers. Douglas dominated the airliner market in those days and the airlines weren't all that interested in jets.
Boeing literally bet the farm on the 367-80 prototype. They developed the "Dash 80" with no initial customers. This is the plane that test pilot Tex Johnson famously barrel rolled over Lake Washington. It's been said that Tex Johnson was the inspiration for the character "Major Kong" in the movie Dr. Strangelove. Heh. Sadly I'm no Tex Johnson and the only time I ever barrel rolled a 707 was in the simulator.
The Boeing Dash-80 prototype. This is the plane that was going to make or break Boeing.
Fortunately the Dash-80 was a success. From its DNA came the 707 airliner and the KC-135 Stratotanker. Mind you nobody to my knowledge has ever called it a "Stratotanker". It's always just "the tanker" or "the 135".
Note that a KC-135 is really not a 707. It looks an awful lot like a 707 but they're not the same. A 707 is longer, wider and has a more advanced wing with full leading-edge flaps. A 707 also has a flight engineer while a KC-135 does not.
Here's a bit of trivia. The KC-135's civilian designation was the 717. Ever wonder why Boeing went from 707 to 727 and skipped the in-between? Now you know. Then in 1997 Boeing merged with McDonnell Douglas and renamed the MD-95 the 717.
KC-135s came in three main flavors: A-model, E-model and R-model.
The KC-135A was the original. It had the same water-injected J-57 turbojets we used on the B-52G. It was, to put it mildly, underpowered. It's said that it only became airborne due to the curvature of the earth. These were dangerous aircraft and I have no love for them. My first student was killed in one when they lost water injection on takeoff from Dyess AFB. I rode in one of these exactly once and I really wasn't sure it would get off the runway.
Cold War classics. A KC-135A refueling an early model B-52.
The B-52 had twice the thrust but didn't weigh as much so it performed (somewhat) better with the same engines.
The KC-135E was the oddball of the fleet and some say the best of the bunch. It had TF-33
turbofans along with thrust reversers. These were somewhere between the A the R in terms of thrust and efficiency. They were only operated by the Air National Guard. I never flew one but they were generally well liked. They look almost like an A-model unless you look closely at the engines.
The leftmost is an E-model and the others are R-models. I took this one in Fairbanks AK.
The R-model, which I flew, was a different animal altogether. What they did was take an A-model and stick monster CFM-56 turbofans on it, effectively doubling the thrust. As Tim Allen used to say: More power! They also improved the systems while they were at it but the engines were what really did the trick. With all that thrust we could carry a lot more gas and the new engines were so efficient we could give more of that gas away.
I'd say that Boeing got an awful lot right the first time with the 135 and 707. To this day it still looks "right". You can definitely see 707 DNA in most modern airliners.
I would describe it as easy to fly but hard to fly well. The primary flight controls were all cables and pulleys so it was pretty heavy on the controls. Boeing took manual flight controls about as far as they could go with this airplane. Everything that came after had hydraulic controls. The rudder had hydraulic boost but would still work without it. Without the boost it was like working out on the Stairmaster.
A much younger me flying the tanker. This was 1996 so it still has steam gauges.
It was a pretty stripped-down airplane for the most part. It had a fairly basic
autopilot and no auto-throttles, auto-brakes or auto-spoilers. Only the pilot had anti-skid brakes. The copilot could only use his brakes in an emergency. It was such a Fred Flintstone airplane that even if you lost all the electrics and all the hydraulics it would still fly. You could manually trim, manually extend the gear and manually crank the flaps down.
Navigation was via.....a Navigator! We had one old-fashioned carousel INS (Inertial). If that crapped out halfway across the ocean you were down to shooting celestial.
In the late 1990s the KC-135s were upgraded to a partial glass-cockpit. We lost the Navigator but gained an extra INS plus GPS and a whole alphabet soup of airliner stuff like TCAS and GPWS. Those probably deserve their own diary, but for now: TCAS lets you see and avoid other airplanes and GPWS lets you see and avoid terrain. We found the TCAS to be especially helpful for flying formation.
There weren't too many things that would bite you in the R-model. We were never thrust limited. Takeoffs were normally made at very reduced power settings. A max power climb at light weight was like a rocket ship. The R-model set 16 time-to-climb records that still stand as far as I know.
The lovely Mrs. Kong very much enjoying her spouse orientation flight.
We had so much thrust that we were actually "control limited". There was only so much rudder back there to handle an engine-out situation. An Engine Failure Assist System (EFAS) would actually put the rudder in for you if an outboard engine failed on takeoff. Your only indication of the engine failure would be the "Engine Fail" light coming on. Once airborne we would pull the other outboard engine to idle and fly on two engines. My kind of airplane.
Upgraded cockpit with partial glass displays.
All this existed for the purpose of driving the boom operator to work. The "boomer" was the only enlisted person on the crew and was a highly skilled individual. They literally flew the refueling boom into position and had to plug the boom into the receiver aircraft's receptacle. No easy task in turbulence of if the receiver pilot is rough on the controls. I
Boom operator at work.
n the KC-135 the boom operator laid on their stomach back in the boom pod. The KC-10 gave them a chair to sit in. The new KC-767-whatever has them seated in the cockpit and running the show via remote control.
Refueling fighters only took a couple minutes. All we wanted to hear from them was "noses cold" which meant their weapons were disarmed. While one was on the boom the others would fly formation off our wing. This made for some great photo ops.
NATO F-16 over Bosnia. Royal Netherlands Air Force by the markings.
Refueling a "heavy" was a little trickier. As the receiver closed the last 40 feet their aerodynamic "bow wave" would start to push up on our tail. If flying autopilot off, I would have to run the trim every time the boom operator called a 10-foot interval.
C-17 moving into the contact position
Once in contact, refueling a heavy might take 20 minutes or so. The four refueling pumps were hydraulic powered and each one could pump something like 1000 pounds per minute.
All of our fuel was in the wings and the belly. We could only pump gas out of the forward and aft belly tanks so we'd sometimes have to gravity drain fuel into those tanks during this whole process.
The most important thing was to leave yourself enough gas to get home with! Sometimes the receiver might need more fuel than the planned offload so it took some quick arithmetic to figure out just how much you could give away.
Refueling a NATO E-3A somewhere over Bosnia on Christmas Day 1996.
The tanker was a versatile aircraft and had several missions it could perform.
Airlift: The "C" in KC-135 stands for "Cargo" and we could play airlifter if we needed to. I think we could only carry 4 pallets worth of cargo but we could carry it a long way and we didn't break when got there. C-5s especially had a tendency to get somewhere and then break for several days. We could put roughly 50 people in the back, sitting uncomfortably in web seats. We could also put airliner seats back there and carry 20-25 people in a "VIP" configuration.
Fighter Drag: When a fighter unit is deploying somewhere, one or more tankers will play "mother hen" and lead them across the ocean, refueling along the way. Usually we'd have their mechanics and spare parts riding in the back. KC-10s were especially good at this because they could haul so much cargo. I got to drag some A-10s over Egypt (saw the pyramids!) and drop them off somewhere in Saudi airspace while we went on to Crete.
Air Bridge: Take off from somewhere, meet up with a cargo plane like a C-17 that's going a very long way and refuel them. That way the C-17 doesn't have to land somewhere and take a chance on getting stuck there. We did this out of Spain during our last little Middle East adventure. We'd meet them over the Mediterranean while they were going "downrange".
Refuel Bombers: What the tanker was originally built for. Back in 2004 we picked up some message traffic that the North Koreans might try something while we were tied up in Iraq. We were rushed out to Guam to refuel B-2s that were doing a "show of force" in the Pacific.
Force Extender: Fighters burn a lot gas, especially in combat. Normally the tankers orbit a little ways back from the front lines to "top off" fighters going in and out of bad-guy country. We did this a lot during Bosnia and Northern Watch.
A refueling drogue could be attached to the end of our boom, allowing us to refuel Navy or NATO fighters.
There have even been cases of tankers venturing into bad-guy territory to rescue a fighter that was shot up or running out of fuel. Several tanker crews were credited with "saves" during the Vietnam War. Pretty gutsy because a tanker is utterly defenseless. You had no weapons, no jammers and no warning gear. You had to hope somebody told you that something was coming after you. Your only defensive maneuver was straight out of Monty Python - Run Away!!!! You couldn't outrun a MiG, of course, but with enough head start you
might outrun his fuel supply.
KC-135 modified with wingtip refueling pods. I never flew with these.
The one drawback of the KC-135 was that it could refuel Air Force fighters or Navy/NATO fighters but not both on the same day. A short hose with a drogue on the end could be attached to our boom. I liked flying with the drogue because that meant we'd get to see something out of the ordinary like Mirages or Tornados.
I'm told that the short hose and hard metal basket made for a very difficult refueling. If the fighter got out of position that hose could actually whip around and bash his airplane (bad).
Some KC-135s have been modified with wingtip pods that allow them to do both probe-and-drogue and boom refueling but I've never actually seen one.
Despite being a late 1950s airplane the KC-135 still has a lot of life left in it. On average they only have about 14,000 flying hours on them. I flew a 757 the other day that had 88,000 hours! Corrosion and spare parts are bigger problems. An old plane can be kept flying almost indefinitely but it gets more and more expensive over time. They'll probably be around until 2040 depending on how quickly we buy 767 tankers to replace them.
The selection of the 767 tanker warrants a diary of its own at some point. There were an awful lot of political shenanigans involved in the process. For now I'll just say this, and I may get hate mail for it. The US Air Force exists to do a job, not to subsidize Boeing. If an Airbus design would have better met the requirements of that job then so be it.
For now just know that wherever US or NATO forces are involved the good old KC-135 will be there. The tanker motto was "Nobody kicks ass without our gas". It's never the star of the show but if they weren't there, the star would never get onstage.