Inflight refueling

[9GClub]

Jetboys (and girls),

Every time I've ever seen a shot of aerial refueling ops (-135s, KC-10s, etc.), the aircraft (both the tanker and the refuelees) appear to be in a shallow bank..... is this SOP or am I drunk? I vaguely remember directing this question to a military pilot awhile back, and I believe his response was "No, SOP is straight and level....." I'm not convinced......

Also, for any of you military folks out there, how difficult is this operation? I'm guessing the basket is a bit easier than the boom..... how the heck do y'all do this thing in some jets (Viper, etc.) when the doors are on the dorsal spine behind you?

Cirrus should look into making a probe standard equipment on the SR22..... along with the 'chute. And a snackbar and washing machine and makeup kit.

 

[MachPi]

Refueling can be done in any controlled attitude. Doesn't matter what the bank is, although I seem to remember 30 deg was the reg limit. Anthing more than that in level flight and the mounting gee made it harder to do for any length of time.

Like any part of flying, with experience comes ease. Hooking up over the pacific in bumpy weather for 45 minutes of AR isn't something a newbie could do, but that same guy a couple years later should be able to do it. At that proficiency point, the main problem is trying not to zone off, which is problematic with half a million pounds of KC10 just a few feet from your windscreen.

Also, as far as how it's done: the navy drives up to the drogues, which are just trailing out there. The AF gets in the boom's neighborhood (the envelope), then the boom operator 'flies' the boom into the receptacle.

How do you know where the envelope is? Same way a driver on the road knows where he is in his lane, and how far away he is from the middle stripe: he uses (even if only subconsciously) visual aids. For example, the driver might know he's within a foot and a half of the white line because, from his perspective, the white line disappears below his windscreen right at the first bend the windshield wiper makes. Exactly the same principle used in AR.

 

[Sarka]

I used to fly AR's in KC-130's years ago and if I remember right MachPI is right about the 30 deg bank limit (might have been 20 deg...can't remember for sure). It may depend on a/c type. Straight and level is preferred, but many AR's are conducted using a racetrack pattern, which could account for the photos while banking also.

I also flew on a couple AR photo missions and I think the photog's just find that a shot with the the planes in a bank is more astetically pleasing. It just looks better. That's probably why you see them in banks in most of the shots.

 

[RJP]

What you're seeing is the tanker after the fighter flight-lead has finished his refuelling. After the straight-and-level portion of the track is finished there's a mandatory radio call from the tanker. "Uh, xxx flight, we're now 'autopilot off' and the co-pilot is flying. Turning in one mile". This is at the exact moment the wingman of xxx flight is pulling into the pre-contact position.

Honest.

 

[TonyC]

While aerial refueling can theoretically be accomplished at any bank angle (we demoed 90 degrees at CFIC) the normal limit is 30 degrees, and the vast majority is conducted wings level, level flight. It can also be conducted in a climb or descent, but the vast majority is conducted straight and level.


The next time you're on the interstate, find an 18-wheeler, and pull up behind him real close. I mean like 12 inches close. When you're that close, you'll immediately identify references on the back of the trailer that you can use to stop your movement relative to the trailer. If it moves left, you'll immediately want to correct to the left, etc. IT will move, to be sure - - and you'll move - - at that distance the airflow around the trailer will make your vehicle do things you're not familiar with. OH, and you'll want to keep the brake lights in your peripheral vision and your toe near the brake pedal just in case. This will give you a slight appreciation for A/R from a two-dimensional perspective. Add in the third dimension (up and down) and quadruple the speed, and you'll be in the right neighborhood.


NO, NO, NO, NO ! Don't do that - - do NOT tailgate the 18-wheeler. It's dangerous!

Oh, which reminds me of a WARNING in the flight manual - - flying in close vertical proximity to another aircraft is HAZARDOUS!


Duh.

 

[Eagleflip]

Don't forget that there are two generic rules are always in effect for fighter pilots during ocean-crossing refueling ops:

1. When getting gas, you will be IMC. Every time.

2. ...And you will think that you are darn near 90 degrees of bank no matter what.

That crazy vestibular system...there isn't any way around it, anyone doing refueling in the weather will at some point think...nope, they'll know the tanker is being flown by Bob Hoover, doing gentle aerobatics all the while. Or maybe Tex Johnston. Heck, maybe CitationKid's flying the dang thing for all I know. One thing is for certain.

They're trying to kill you.

Just about the time you are ABSOLTELY POSITIVE that guy has gone ape and is enjoying his little session of "let's toy with the stumpy fighter pilot, do wingovers and drink hot brewed coffee," you happen a glance down to the ADI and discover...

...3 degrees of bank to the left.

D'oh!

Then it's off the boom, up to the wing, fly into the clear. Double d'oh!

 

[Sarka]

The next time you're on the interstate, find an 18-wheeler, and pull up behind him real close. I mean like 12 inches close. When you're that close, you'll immediately identify references on the back of the trailer that you can use to stop your movement relative to the trailer. If it moves left, you'll immediately want to correct to the left, etc. IT will move, to be sure - - and you'll move - - at that distance the airflow around the trailer will make your vehicle do things you're not familiar with. OH, and you'll want to keep the brake lights in your peripheral vision and your toe near the brake pedal just in case. This will give you a slight appreciation for A/R from a two-dimensional perspective. Add in the third dimension (up and down) and quadruple the speed, and you'll be in the right neighborhood.


NO, NO, NO, NO ! Don't do that - - do NOT tailgate the 18-wheeler. It's dangerous!

Oh, which reminds me of a WARNING in the flight manual - - flying in close vertical proximity to another aircraft is HAZARDOUS!


Duh.

Living on the edge Tony!

 

[minitour]

...1. When getting gas, you will be IMC. Every time.
...

well that was one of my questions...thanks

the other ones:

1 Doesn't that really f*ck with weight and ballance of both planes? One is getting heavier while the other is getting lighter...so wouldn't that also f*ck with airspeed, stall speed, power settings (you'd have to adjust to stay in the right place?), etc???

2 Doesn't the wake from that KC135 royally screw with the smaller jets???

Good stuff here guys...awesome.

 

[MachPi]

When you're refueling in the envelope, you're always making tiny corrections of your power, attitude, blah blah blah. I suppose if the tanker flew perfectly, the weather was perfect, and the stars aligned, you might notice the subtle overall increase in power you'd need to keep up with the tanker in your now heavier plane. But really, with all the minute corrections you make during receiver AR, the weight and balance becomes lost in the effort.

The only time I recall it ever being something you needed to attend to was when you were refueling to max weight, and I mean max weight. Above 580k or so in the -10, the FE kept an eye on the thrust settings to make sure we didn't overboost. It wasn't a giant deal if you did go over, but you didn't want to sit on the other side of MCT redline forever without knowing about it.

 

[Sarka]

well that was one of my questions...thanks

the other ones:

1 Doesn't that really f*ck with weight and ballance of both planes? One is getting heavier while the other is getting lighter...so wouldn't that also f*ck with airspeed, stall speed, power settings (you'd have to adjust to stay in the right place?), etc???

2 Doesn't the wake from that KC135 royally screw with the smaller jets???

Good stuff here guys...awesome.

1. Yes. The CG of both a/c will change which cause continual adjustments, but you really have to pass alot of gas (pun intended) to make significant changes.

2. I've always been on the leading side, not the trailing side. Although, when refueling helo's you can really feel the rotor beat throughout the entire a/c. In a 130, we were at max-get-it to refuel jets and the jets were near stall speed. When tanking helo's, it was just the opposite. We'd be just above stall and the helo would be at max speed.

 

[TonyC]

well that was one of my questions...thanks

the other ones:

1 Doesn't that really f*ck with weight and ballance of both planes? One is getting heavier while the other is getting lighter...so wouldn't that also f*ck with airspeed, stall speed, power settings (you'd have to adjust to stay in the right place?), etc???

2 Doesn't the wake from that KC135 royally screw with the smaller jets???

Good stuff here guys...awesome.

He was being facetious about always being IMC on the boom.

From the perspective of both the tanker and the receiver - - CG has to be monitored and controlled. The tanker plans which tanks to offload the gas from, and has to keep CG within limits. The receiver plans which tanks to put the gas in to keep his CG within limits. The AR is usually planned at a constant airspeed. In order to maintain the constant airspeed, the tanker gradually reduces power, and the receiver has to gradually increase power. Sometimes, at higher altitudes, hotter temperatures, heavier weights, we would request the tanker leave the power set and allow the formation to accelerate - - little better throttle response at the higher airspeeds when we were close to the limits. Stall speeds -- yes, they changed, but we weren't anywhere close, so that was never a factor.


The wake turbulance from the KC-135 had a big effect on large airplanes. The vortices from the wingtips were directly in line with the wingtips of other -135s. Maintaining level flight just a few feet off centerline required a significant yoke input. Ironically, the phenomenon was not nearly as noticeable behind a KC-10 - - the wingtips were farther away. The same vortices would have been barely noticeable to a fighter.

 

[Eagleflip]

The same vortices would have been barely noticeable to a fighter.

Unless you were just a smidge high coming off the boom and returning to the wing. Had it happen one day when I was flying a three tanked Eagle and managed to catch the wake. Heard a couple of yaw warning beeps from the jet before it settled out--not a good thing when flying that configuration.

And yes, I was being facetious about always being IMC on the boom.

Unless you're doing an ocean crossing, that is!

Day VMC tankers were normally a blast. I was just recounting to one of my fellow pilots the joys of doing my first day A/R over northern Arizona. I could barely keep the tanker in view because I was looking at the massively beautiful terrain near Sedona.

 

[GasPasser]

perspective

While many of the aspects have been covered in answering the original question, one that was not mentioned was the effect that the position of the photo ship and the camera angle can have to the viewer of the photo. The photo ship can be below, above, behind, or beside the tanker, basiclly anywhere. The A/R formation could be straight and level, yet the photo could give the viewer the impression that they are in a turn, in a climb, or both. Great question, thanks for asking!

 

[Swede]

Tanking can be fun, or it can suck royally, depending upon weather, what tanker (KC10 vs KC135) turbulence, etc. Falling off the boom is always good for a laugh when it's not you, humiliating when it is. Usually good for a round of beers later. It is initially a totally unnatural act to make physical contact with another aircraft. The F15 had the worst possible boom inlet, behind the pilot and to the left, requiring liberal use of the rear-view mirror to help with positioning and boom extension once contacted. Once contact is made, a series of guide lights (like a fancy PAPI) helps you maintain an optimum position, although as other guys mentioned, positional cues relative to the tanker work best.

One of the BIG steps in a fighter-pilot's career is the dreaded 4-ship night tanker mission as part of a flight-lead upgrade. Often the hardest part of the mission is the rendezvous. The tanker flies a racetrack pattern, and as flight lead you need to create the intercept by usually calling for the tanker to turn, which he will do, hopefully rolling out in front of you. The altitudes are deconflicted until visual or good radar contact is made. A bad rendezvous will be with the flight in a multi-mile tailchase (more beers to buy), or worse, if the tanker rolls out BEHIND you on the track.

A quick story to end a long post, and probably one of the hairiest tanker stories I'm aware of. A good buddy was in Hawaii, enroute to Japan. A KC10 was making the run, and he recieved permission to fly with the tanker and thus make it in one leg. The distance required a large number of refuelings.

The fighter was an F15C. Well on his way, things went to $hit quickly. The first thing that went wrong was his inertial dumped, eliminating his INS and his radar as well. A partial electrical fault eliminated his TACAN. This guy had no way to navigate, no HF radio, no way to remain "tied" via radar to the KC10. Of course, at that point they hit a line of solid wx, requiring my bud to join on the tankers wing in hard and turbulent IMC. For FOUR HOURS. Going lost wingman almost guaranteed he'd end up in the water. Talk about motivation to maintain formation! Anyone who's flown close formation in IMC knows that it is challenging at the best of times due to spatial D. This guy's vestibular went bat-$hit. He felt that they were inverted, pointed straight down, etc, at various times over that hideous 4-hour span. He was totally strung-out after landing.

 

[dtfl]

In the 130 - the FE dumps the fuel into the mains because they take gas faster - but the CG isn't that critical - cargo is - and that's not moving. Your trim changes as you get heavier and your deck angle increases..and then comes the point where you do not have enough power to stay in so you toboggan - 300 fpm descent while tanking. I always enjoyed that ...tanker autopilot on, that is.

talking about Murphy's law - I can add a couple -
in combat your latches will always fail or your hyd will go out so you have to fly stiff boom....or your electrics dork up so you have to use manual disconnect procedures....those are what always happened to me. Never failed!! But combat=get it done.

 

[sandman2122]

The most fun (and work) you'll have!

Ahhhh yes, AR!

So there I was, just finished "First Pilot" school for the C-141 at Altus AFB, OK with @ 5 flights under my belt and they send me (and my buddy Brian W.) immediately to Air Refueling school.

It was probably one of the most demanding "stick & rudder" checkrides for me in the AF. Brand new to the Lizard, doing a night, IMC, heavy-weight rendezvous (sp) to a KC-135 - also from Altus. Talk about bull***t, we closed in on this guy to 1 mile, didn't see anything because it's night and we're IMC. Then my checkpilot tells the -135 to "turn on your strobes". We see a flash above and ahead of us and my EP says, "go get 'em". WTF! So there I go after his freakin strobes in the weather, until he materilized at the pre-contact position........pretty cool though. After getting my time on the boom autopilot on we got to do some autopilot off - which turned out to be vertical S alpha's +/- 500 fpm - niiiiiice. Left my seat pretty wet from sweat!

Awesome flying to get to do AR.

 

[MooseTrax]

I can assure you there is not a scarier job in the heavy training business than schoolhouse AR instructor.......well maybe assault landings too! And I completely understand what Swede is talking about being spatial D trying to get the gas in the weather, in the turn........It was fun (or should I say a challenge), but I don't miss it!

 

[dtfl]

Refueling - both of you blacked out and you on NVGs.

 

[MooseTrax]

WOW---even more fun! Take the field of view down to 40 degrees, no peripheral vision........can I get some weather and some turns please? No thanks!

 

[Swede]

I'm curious, those of you who have gassed via both boom (Af) and basket (Navy/Marines) which was more challenging?

The difference between the KC10 and the KC135 was striking. Besides having lighting like the Mother Ship from Close Encounters, the 10 had a very powerful boom. In other words, once contact was made, at least for a fighter, it felt like a giant had you in some kung-fu grip. The 135 had a puny boom, and if position wasn't maintained, you'd fall off pretty easily.

The guy operating the boom had a LOT to do with the tanking. Experienced boom operators would weild the boom like a big Zulu spear... you get within range and he stabs you. Other guys, well, we've all heard stuff like this:


BOOMER
"Forward 2..."
"Forward 2..."
"Forward 1..."
"Up 1..."
"Forward 1..."
"Down 1..."
"Back 1..."

RECIPIENT
"G.D. it, plug me NOW!!!!!!"

(THUNK) "Err, contact"

"Thanks A-hole"