22
$\begingroup$

How do military helicopters like the Blackhawk and CH-53, as well as the V-22 Osprey, perform mid-air refueling without their rotor blades (periodically and accidentally) contacting the drogue or fuel hose and causing a major accident?

Black Hawk refueling from a C-130

I imagine that if the rotor blades did make contact with the fuel hose, either the fuel would be released and be sparked and ignite, or ingested by the helicopter turbines, or the rotor would break, or all of the above! When a helicopter is refueling, its rotor is nearly above the fuel hose, or at the maximum, maybe 20 feet away? It's easy to imagine a bit of turbulence or a few centimeters of cyclic movement (a sneeze perhaps?) is all that it would take for the rotor to dip and come forward and contact the hose.

For the Osprey the propellers / rotors are behind the nose of the aircraft and thus farther away from the fuel hose, but still, like a helicopter the Osprey's rotors are very large, and are exposed as opposed to the concealed compressor blades of a jet turbine.

$\endgroup$
  • 1
    $\begingroup$ when an osprey would refuel in flight it would be in the level flight configuration (rotors pointing forward) $\endgroup$ – ratchet freak Jan 25 '15 at 13:38
  • 3
    $\begingroup$ You seems to be under the assumption that inflight refueling is safe. It is'nt. It's merely "safe enough" $\endgroup$ – Antzi Dec 7 '17 at 7:54
33
$\begingroup$

That photograph distorts the perspective. Just Google for "helicopter air-to-air refueling" and look at the image results. Many show other perspectives from which you can see that it is not possible for the blades to contact the hose or basket - the probe is longer than those on a fixed-wing craft for exactly that reason.

Better view of refueling probe


This video shows a CH-53E Super Stallion chopping off it's own probe through over-controlling the cyclic, but that particular mishap would be possible in other flight phases too.

$\endgroup$
  • 12
    $\begingroup$ woah crazy video. $\endgroup$ – Peter Jan 26 '15 at 3:37
  • 2
    $\begingroup$ It's pretty amazing to me that the rotor survived hitting the probe. You think they designed the probe to be easily broken in a case like that, so as not to break the rotor? $\endgroup$ – AllTradesJack Jan 28 '15 at 0:24
  • 6
    $\begingroup$ The probes are designed to snap easily if there is significant lateral or vertical force. For sure, the rotor would have been damaged and they would know all about the vibration but blades are tougher than you think. They can chop the tail clean off on some helicopters. $\endgroup$ – Simon Jan 28 '15 at 8:24
8
$\begingroup$

When fully extended the probe does extend past the rotor of the HH-60G; however, there is a potential for the probe not to extend. And in that case, the probe is well inside the rotor disc. Still, refueling can still be accomplished. Just like single-engine refueling, it takes more care but when you need fuel you do what you must. And in my 20 years flying the Pave Hawk I never found the switch for an IR sensor on the probe :) no such thing. Closest thing I can think of is using the probe light barely cracked on (it’s controlled by a rheostat) to cast a shadow on the drogue during NVG refueling but in a tactical environment even being that much of an emitter is unwise.

$\endgroup$
5
$\begingroup$

The probe is the furthest point forward on the Pave hawk helicopter. It also has an IR sensor to properly line up the boom(the female end). Obviously the procedure for approach is to come from behind to avoid such things from hitting the rotor blades.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.