Rotorcraft tankers

[Ian Corrigible]

With the Marine Corps reportedly (http://www.janes.com/article/58270/v-22-aerial-refueling-system-nears-contract-decision-with-additional-upgrades-pending) on the verge of signing a production contract for the V-22 Aerial Refueling System first tested in August 2013 (http://www.pprune.org/rotorheads/490255-v22-osprey-discussion-thread-mk-ii-20.html#post8034717), the question comes to mind: what preceded the Osprey as the first rotorcraft AAR/IFR tanker?

The CH/MH-47 Fat Cow (http://www.boeing.com/chinooknews/2009/issue_01/field_s5_p3.html) has the refueling element down pat, but only on the ground.

An AStar was used for an in-flight refueling of a microlight during a trans-Mediterranean flight in 1984, albeit with a less-than-stellar transfer rate (37 gal tanked in 8½ minutes):

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(Jump to time index 10 min 44 sec)

Any others?

I/C

[Ascend Charlie]

Lots of Navy choppers refuel in the air, but only by hoisting a hose up from a ship while they hover overhead.

[Um... lifting...]

I think he meant t'other way around, where the helicopter delivers the fuel, which in my view would be a rather rash thing to do. Inflight, anyway.

But if not, C-130 tankers quite commonly deliver fuel inflight to helicopters of many types. KC-135s have done it as well, though that's a bit dodgier operation due to the typical speed disparity. C-130 overwing kits are used at remote island areas to extend helicopter range. I think I used one once, ever.

HIFR is a bit of a sketchy operation, as you have to pump the fuel UP to the aircraft, so to get adequate flow rate at your typical hover height, you need a great deal of pump pressure at the ship just to get it to the nozzle. I never liked doing it even one bit, but did it enough to develop a healthy distrust for it. I know of a crewman who had a seeping leak in the HIFR rig, and rather than hand signal for pump stoppage, shut off the valve in the rig... that little error raised the hose pressure to the point where atomized fuel sprayed under his helmet visor blinding him, all over the aircraft cabin, and could have gone in the engine intakes had not an alert deck crew stopped the pump. Nope, never liked HIFR one bit.

[Ian Corrigible]

Yes, I was thinking of tankers not receivers, so HIFR will only apply if there's been a mix-up with transfer pump's polarity.

Given the wealth of concepts on the Secret Projects (www.secretprojects.co.uk) forum, I was surprised not to find any tanker proposals for the H-53, Mi-6 or FTR/AMT/JTR/JHL (http://www.pprune.org/rotorheads/191164-super-heavy-lift-coaxial-helicopter.html), etc.

I/C

[Um... lifting...]

Just back of the envelope of course, but I should imagine there'd be all manner of nasty aerodynamic effects upon the hose / drogue for helicopters of whatever type, not to mention that pesky tail rotor on the lead ship.

Helicopters in formation typically fly with step-up as opposed to step-down as do the planks for just that reason (also it's easier to look downward in most helicopters than in most planks due to the positioning of the glazing). I see little advantage over using a C-130 or other turboprop where there's all sorts of room for tanks & other machinery and plumbing. Most tankers have a lot more range than what they are fueling (I except carrier-based tankers) and far greater fuel capacity.

Rotor downwash on the hose and on one's own rotor while bringing the hose under one's own rotor... I shan't sleep tonight for thinking about it.

[Ascend Charlie]

Then again there was that Yoochoob video of the Jolly Green receiving fuel from the Herc, got a little oscillation going, went high on the drogue, and when he pushed forward on the cyclic to come back down, he chopped off his own fuel probe. Lucky the jolt didn't shake off his tailboom or wreck the rotor - he just sort of slid back a bit and thought about it a little.

[rotorfan]

AC~

I watched that video in disbelief, as in "holy $hit!". I kept rewatching until it truly was disbelief: I'm confident it's an animation, likely from a flight sim program. It just doesn't look detailed enough for reality. I must admit it got me the first time.

[OvertHawk]

Rotorfan

I can't comment on the video you actually saw since I don't know for sure which one it was, but, be assured - there is a video of the incident described and it is 100% genuine!

OH

[Um... lifting...]

I considered mentioning that video, but as I had thought it rather well known, I didn't. It is indeed genuine.

What I have never heard nor seen regarding that video is what happened on the other end of the hose after the rotor blades cut through.

I would assume there was a bit of flailing since the drogue was no longer stabilizing the hose and the tanker either reeled in what was left or had some means of jettison. Either way, I'd not be surprised to learn there was a little damage to the trailing edge of the wing. I might be wrong of course.

Now imagine an un-streamlined hose end flailing around near a tail rotor. That is what would keep me up nights.

[Bravo73]

https://youtu.be/VAdpKpppZiA

VAdpKpppZiA

[PDR1]

I can remember seeing that film clip way back in the early 1990s when the animation technology simply didn't exist, so I'm fairly sure it's genuine.

But tanking a heli from a fixed wing tanker isn't that unusual is it? I mean it took about five seconds to find lots of photos like this:

https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Helicopter_aerial_refueling.jpg/220px-Helicopter_aerial_refueling.jpg

PDR

[sandiego89]

PDR, yep there are lots of those photos (I like the ones showing two CH-53's with slung loads taking gas from a single KC-130) but the purpose of this thread was to talk about rotorcraft PASSING fuel to another aircraft in flight: ie being the donor aircraft. The Osprey is the only one I am aware of passing gas in the air (not counting the A-star)