In-flight refueling

By lex, on July 20th, 2004

In flight refueling is pretty much a survival skill for a fighter pilot, especially if he’s in the US Navy.

(lots of pics, dial-up readers are forewarned)

All fighter designs are compromises – make a fighter big enough to carry a lot of gas, and you generally pay a performance tax. Building more fuel capacity makes the jet larger, requiring larger, more powerful engines to drive it at high subsonic and supersonic speeds. These engines in turn will generally use fuel at a faster rate, meaning diminished returns on the investment. A larger fighter is also a disadvantage on the carrier, where the real estate cost per square foot is probably the highest in the world.

But having a smaller fuel capacity greatly impacts flight operations, since “short-legged” fighters don’t have the endurance required to support maneuvering the ship during cyclic operations – one of the great advantages that aircraft carriers have over airfields is that you can move them around, hide them and such.

The FA-18, which some of you may know is where I passed most of my time spending your tax dollars, is considered at the lower end of the fuel bearing margin for a naval fighter.

So we have to learn to get good at in flight refueling. Success means you get to keep fighting and flying. Failure means you get to either 1) Force the ship into the wind early so you can land, and then receive an invitation to take that extended climb of shame leading from the flight deck to the bridge, in order to be graced with a short but exciting, one-way conversation with a thoroughly grumpy carrier CO (and you know how Navy captains can be…) or 2) You get to do the Martin-Baker arrival (i.e., eject) when your plane runs out of gas. Because every aircraft that takes off is going to land one way or the other. This second scenario will bring you to a long green table, with many grim faces around it and no water glass in front of your chair.

The first time I’d ever “tanked” was in the training squadron in Lemoore, California (don’t bother looking it up – you wouldn’t want to go there. If you stop your car there, don’t turn the engine off: It might not start again, and you’d be stuck.) Tanking is at first a highly unnatural act – for all your flying career up to that point, you will have been taught to scrupulously avoid hitting any part of your aircraft that isn’t landing gear against anything that isn’t concrete.

But now you are expected to maneuver in very close proximity to another aircraft, await patiently while he un-spools a relatively short refueling hose, extend your refueling probe and then place it inside the refueling basket. Which isn’t at easy as it sounds, at first.

inflightrefueling1

Oh, and when that’s over you’ll be expected to do it again at night. Because it’s darker, which of course makes it harder.

And we’re all about making things harder.

When your probe is out, you approach the basket using 3-5 knots of closure, looking to seat your probe exactly in the center of the refueling basket.

inflightrefueling2
If you miss the basket, the odds are 50-50 that your overshoot will cause the basket and hose to thump against your fuselage, which in the best of cases gives you a nasty start, and in the worst cases either knocks off an angle of attack probe that will almost certainly be swallowed by your jet intake, causing all kinds of horrible damage to one of the things that makes airspeed, or else get wrapped around your probe, leaving you in a rather uncomfortable position. And by the way, you didn’t get that gas you were there for.

If you “lip” the basket, meaning the probe hits the outer rim, the basket will slap your fuselage again, etc, etc.

And here’s the interesting thing – as you approach the basket, the turbulence around your jet’s nose will cause the hose and basket to move up and away from your jet. At this point you have to have confidence, because the physics of the matter are that it will swing back down again and let your probe ram home.

Most of the time.

Except when it doesn’t.

But if you “chase” the basket, it surely will fall back again towards your aircraft you’ll lip the outer rim, the basket hits your fuselage and etc, etc.

Sometimes we get gas from Air Force tankers, which is really cool because they carry so very much of it. Navy tankers have to land aboard the ship, so the amount of fuel that they can give is measured sparingly (oh, so sparingly) by the same kinds of performance trade-offs mentioned earlier in this post.

There are two kinds of tankers in the USAF inventory, the KC-10 and the KC-135.

The KC-10, when missionized for Navy tanking (they do these things differently in the junior service) has a drogue and basket assembly very similar to what we are used to in the Navy – only bigger. Most pilots prefer this system, but I have my reservations: Sometimes the take-up reel (which absorbs the shock of the IFR probe’s impact) doesn’t work as it was designed to do – this causes a sine wave to develop in the hose itself, which travels up to the tanker, then back to your jet (with emphasis) often snapping off the refueling probe.

Which can lead to all sorts of unpleasant consequences, not least of which (in the short term) is that you didn’t get the gas you were there for.

The KC-135 on the other hand, has a rather short, hard rubber hose and a massively heavy refueling basket.

inflightrefueling3

I actually prefer the -135, once you’re used to it. The basket doesn’t move as much on the approach, and if you’re at least half way towards the socket, your probe will slide home.

On the other hand, the -135 isn’t known as the “Iron Maiden” for nothing in the service, and getting hit by one of these things can shatter your canopy, turning your warm, comfortable, familiar environment into a 300 mph maelstrom.

I’ve always like the word maelstrom, by the way.

Anyway.

The stories of nuggets “stalling at the basket” are legion – guys get right to the tipping point, and somehow can’t move the throttles up that last little bit to close the deal. Once over the sea of Japan, I hectored a young guy with one word as he stalled at the basket – “Courage.”

He got in, we got our gas, and we got the mission complete.

This is probably as good a time as any to share with you an anecdote that I received from an officer I used to work with (interspersed with my translations):

Since it’s probably been a few months for you, I’ll have to tell you about the quite unpleasant experience I had with the good ol’ Iron Maiden 2 nights ago… I volunteered to be the sacrificial “back-side tanking” section of hornets so we wouldn’t have 4 sections simultaneously vying for use of the same target. It was an 1830 launch, 2000 recovery and as we headed west towards the target watching the sun set the scattered clouds became more broken and finally overcast. The bombs (actual GBU-12′s!) never got dropped, and we headed back to the ship to find the KC-135 in order to get back on ladder (ed: fuel state required for recovery). It was right overhead mom (the carrier) with only one chick (fighter) in tow, but it was clearly in and out of the clouds, judging by the way it lit them up through the goggles (night vision devices, NVG’s). “No worries, I’m sure he’ll get clear” I thought. The rendezvous progressed ok, but the tanker spent more time in the clouds than out. NVG training rules aside, the goggles and the radar were fine to keep track of him and his chick. Fortunately my wingman took off his goggles early and got complete vertigo during the join up – his exact words were “I think I’m upside down”. I  convinced him he wasn’t and we got his mental gyro re-caged by the time we were in port observation. I made my call and was cleared into pre-contact. As I settled out the jet behind the beast, it didn’t feel terribly bumpy, but the basket was ALL OVER the place. I remember thinking to myself how the 135 is supposed to be a little more stable than that as I made the approach. Not even close. I think my radome made it closer to the center of the basket than my probe. Another try, another, another…I asked if the boom was locked down – of course it was, and after another few minutes of stabs and I got in – along with a 2 inch spark of static. That was comforting. Staying in the basket turned out to be even harder and I damn near tore that hose off due to all the bouncing around. We never did get back to VFR (visual flight rules – clear weather). I got my 2K (2000 pounds of gas, roughly 300 gallons) and gleefully eased out, thankful I still had all my probes intact and bummed that it took me so long. My wingman never got in and I told him to give up so I could find him a Hoover (S-3 Viking – so known because the sound of its engines is remarkable similar to a vacuum cleaner). Clearly the most difficult tanking experience of my young life.

The next cycle not ONE JET got into the basket which made me feel a little better about my flailing so much. There are times it’s good to be sitting on Mom.

Too true – it is wisely said that “It’s better to be on the deck, wishing you were in the air, than in the air, wishing you were on deck.”

My most exciting personal tanking mission (the competition is fierce) is when I was in the Arabian Gulf prior to an Operation Southern Watch mission, and refueling off an S-3 in a “sucker hole” among some thunderstorms. We were ringed pretty tightly on all sides (you do not want to fly into a thunderstorm at the best of times, far less when tanking), so the Viking pilot had the turn wrapped up pretty tight, and just getting into the rendezvous position was an act of will, as much as airmanship. Just as I settled into the basket, a static electricity discharge (read: lightning bolt) arced from the clouds to his jet, down the hose to my jet.

It felt really, really weird. I felt the shock enter through my right hand on the stick and exit through the sole of my right boot, having bounced around for a moment in the fillings of one of my molars. The gas stopped flowing (the refueling store itself had gone sneakers-up), and I was pretty sure that there was a hole somewhere in the aircraft’s skin (there usually is, when the electricity exits the jet). And I still had a four-hour mission in Iraq, which I couldn’t possibly execute without additional gas.

So I did what any of us would do: I called back to the ship, and asked for the position of the nearest functional tanker.

 

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1 Comment

Filed under Best of Neptunus Lex, Carriers, Flying, Uncategorized

One response to “In-flight refueling

  1. Pingback: Index – The Best of Neptunus Lex | The Lexicans

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