There are “wings” on the boom/stem of an aircraft refueling tanker. Is the purpose for stabilizing the boom? If not, what is the purpose?
The “flying” boom is so named because flight control surfaces, small movable airfoils that are often in a V-tail configuration, are used to move the boom by creating aerodynamic forces. They are actuated hydraulically and controlled by the boom operator using a control stick. The boom operator also telescopes the boom to make the connection with the receiver’s receptacle.
per wiki.
The wings actually move. There is an operator in the tanker aircraft that maneuvers the boom into a socket of the receiving aircraft; the wings tilt under the operator’s control to exert aerodynamic pressure on the boom end to get it aligned properly. The pilot flying the receiving aircraft is just supposed to keep his aircraft as motionless as possible relative to the tanker.
This is different from the probe and drogue system where the hose from the tanker is not guided but just hangs in the slipstream, and the receiving pilot maneuvers his whole aircraft to insert his probe into the drogue basket. Probe and drogue is mechanically simpler and lighter allowing the tanker to carry more fuel or multiple hose stations, but boom and socket requires less pilot skill and can pump fuel much faster.
ETA: shoulda refreshed. Poster **danhanegen **covered it pretty well.
That wiki is pretty good.
Our own JHBoom used to operate those things. Perhaps he’ll stop by for some more hands-on perspective.
The USAF refueling system was designed to refuel bombers. Which aren’t maneuverable enough to use the other common standard, probe and drogue, where the tanker trails a hose and shuttlecock thingy and the receiver flies a rigid probe into the shuttlecock like a hummingbird poking a flower.
Instead, the bomber slides up almost under the tanker and tries his best to just hold still. Then the boom operator does the fine tuning to fly the end of the boom near the reception chute in the top of the bomber then extends the boom the last couple feet to plug into the bomber’s receptacle.
As USAF extended aerial refueling to fighters & transports and such in the early 1960s, they kept using the same system so all their airplanes would be compatible with all their tankers.
“Try a little tenderness…”
Huh. I never thought to look up the name of that song, despite the fact that I can’t help but play that scene in my head whenever I read about midflight refueling. It’s such a perfect juxtaposition of adolescent sexual innuendo (“shuttlecock”, “probe insertion”, not to mention the visuals) with the threat of thermonuclear war.
This is precisely the aspect I was curious about, thank you!
Dr. Strangelove Your post/username combo is the best I have seen in a while.
Those boom operators lay face down on a chair/table type thing and face rearward and watch the boom and aircraft they’re refueling out of a small window. We had a family friend who was a boom operator and we got to tour the plane at a local air show when I was really young. When my dad pointed to the boom operator’s area and explained that the guy operated on his belly, I took that to mean he did in-flight stomach self surgery.
So, just in case that question comes up in this thread, turns out my dad was way wrong and that’s not what they do at all!
That was certainly true in the KC-135. The operator lays on a sorta massage table looking out a fairly small window. For the more spacious KC-10 the boomer has a nicer facility with an upright seat and a much bigger window. But he still sits facing aft in the rear of the aircraft.
For more modern tankers, including the KC-46 that’s about to start deliveries, the boomer sits up in the cockpit with the pilots and does the whole job looking at TV screens.
KC-135: https://upload.wikimedia.org/wikipedia/en/c/cf/KC-135_boom_operators_station_boom_pod.jpg
KC-10: http://www.aviationspectator.com/files/images/KC-10-Extender-187.jpg
KC-46: http://files.abovetopsecret.com/files/img/mt53d6c1c8.png
Looks like the basics have been covered, so I’ll throw in some more detail.
The KC-135 has two boom flight control surfaces mounted in a V-tail configuration, called ruddervators. The boom operator controls them with a flight control stick in his/her right hand, which has a direct link (via control cables) to the hydraulic servos that drive the ruddervators. There is no mechanical or electronic assist, besides whatever mechanical advantage is built into the pulleys, levers, and bellcranks of the boom flight control sysyem.
The KC-10 has three boom flight control surfaces - an elevator, and two rudders mounted to the ends of the elevator. The boom operator controls them with a flight control stick in his/her right hand, which sends signals to a computer called the Boom Control Unit (of course, with the world being a small place and all, a fellow Doper was a project engineer on the BCU back in the day), which then electronically commands the hydraulic servos that drive the elevator & rudders. Since the boom flight control system is fly-by-wire, there are a few features in the system that reduce the workload on the boom operator, and reduce the stresses on both the tanker and receiver airframes, and the boom itself.
The telescoping (in and out) of the boom is controlled with a separate control stick in the boom operator’s left hand.
Any other questions, fire away…
Speaking of fires, ever seen any fires during a refuel?
St Elmo’s fire and static discharges, yes. Flames due to combustion of flammable materials, thankfully no.
On the flip side of that question, I have seen a not-insignificant ice buildup on both the receiver aircraft and the boom. That made for a tense few minutes (which felt like several hours) while we climbed out of the cloud/icing layer.