Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Contrary to popular belief

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


                                 

Overhead Air-to-Air Refuelling

Fly the hose above the tanker
  (+3)
(+3)
  [vote for,
against]

All air-to-air refuelling systems appear to use either a hose or a boom that extends below and behind the tanker aircraft. This poses many problems due to wash from the wings and engines/props. I notice that they have said that the A400M will never be able to refuel helicopters inflight (one, if not the most important, of its designed roles) because helicopters find it too difficult to maintain stable flight in the turbulent air behind and below the tanker.

There’s much cleaner air above the wing of the tanker – engines and propellers are predominantly below the wing, and I have a feeling (very technical I know) that lift induced turbulence is probably worse below the wing. Why not have small wings (computer and gyroscopically stabilized) on the trailing drogue that lift the hose and drogue like a kite into the cleaner air above the tanker? As helicopters have their rotors on top, the rotor would be even further away from the turbulence.

I know the Americans use a rigid flying boom but this also unimaginatively extends below the tanker.

In the A400M’s case, the enormous T- tail might pose a problem but it would just need a longer hose and more lift from the drogue's wings to give a bit more vertical separation.

Gordon Comstock, Dec 17 2015

Here's a problem http://aviationweek...ow-research-project
Airbus Defense and Space’s military aircraft division says that the aerial refueling of helicopters by the company’s A400M airlifter is now the subject of a research project after admitting it will be impossible to achieve in the aircraft’s current configuration. [Gordon Comstock, Dec 17 2015]

Warthogs don't go fast. https://www.youtube...watch?v=DCVmPffxDkU
[Voice, Dec 18 2015]

[link]






       Pretty sure the booms extend well below any turbulance caused by the tanker.   

       Structurally speaking, hanging a lightweight hose is much easier than extending a rigid support member upwards.
doctorremulac3, Dec 17 2015
  

       //Structurally speaking, hanging a lightweight hose is much easier than extending a rigid support member upwards// - said the actress to the bishop
hippo, Dec 17 2015
  

       ////Structurally speaking, hanging a lightweight hose is much easier than extending a rigid support member upwards// - said the actress to the bishop// Thank you Finbarr.   

       But this would not be extending a rigid support member upwards. The bell-shaped end of the hose would have wings and would be flying and would support the weight itself like a kite does its string.
Gordon Comstock, Dec 17 2015
  

       Not a free ride. The wing would lift the hose using angle of attack which would cause drag. The heavier the member, the more drag. Not a factor with a gravity positioned hose.   

       I would guess the additional "weight" of that drag, that is, workload imposed on the tanker aircraft would be much more than just having a lightweight aluminum crane arm hold the hose upwards.   

       Additionally, the stability imparted to the hanging hose from its weight is gone in the one that you're flying like a kite.   

       That being said, your idea might be worth the additional load if it's the only way to clear the rotors. I know they currently refuel helicopters with extended fuel booms at the front of the helicopter. Do you know whey they can't do that in this case? Just extending the hose as low as you have to go to avoid the turbulence?
doctorremulac3, Dec 17 2015
  

       //Pretty sure the booms extend well below any turbulance caused by the tanker.//   

       Actually no, according to an airman friend of mine, this is a scary harrowing pain in the ass.   

       It seems to me that having the hose try and 'fly' would make it terribly difficult to connect due to lack of controllability. Try hooking up to a kite which is dancing in the wind.   

       I suppose you could make the hose an extension of the copter, but the weight of it might not be ideal.   

       It seems to me that whichever aircraft is on top also has to be out in front. This makes it the aircraft in the back's responsibility to try and hook up, simply for vision's sake. But that's far too impractical to expect the tanker to bob and weave to connect to the smaller craft.   

       Perhaps a vision system aid for the aircraft in front might make it workable with enough training. But it still would be tricky as the connection point would essentially become at the tanker, and not at the aircraft.
RayfordSteele, Dec 17 2015
  

       //It seems to me that having the hose try and 'fly' would make it terribly difficult to connect due to lack of controllability. Try hooking up to a kite which is dancing in the wind.//   

       And try flying that kite in the downwash of a helicopter.
doctorremulac3, Dec 17 2015
  

       I think this is a good idea. Not all kites are unstable, and if you had an over-sized kite with computer controlled surfaces it could be made to be very stable. Seems to me it should be the responsibility of the hose to hook up with the helicopter. Neither the tanker nor helicopter should weave around to catch the hose. Both should fly straight and level. The house should adjust length altitude and side-to-side position to catch the inlet on the helicopter.   

       One problem could be the weight of the hose full of fuel.   

       Or maybe the helicopter or jet should just land on top of the tanker. Imagine the 747 carrying the space shuttle, but with mid-air docking. That way you can change out the pilots as well if needed.
scad mientist, Dec 17 2015
  

       //How about a system that simply dumps fuel in mid- air? The aircraft requiring the fuel has the responsibility to grow the necessary techniques and apparatus to scoot around and catch all the falling fuel before it goes too far. A big sponge, for example.//   

       I had actually started to post that then erased it.   

       My idea was a funnel on the trailing aircraft with a vacuum to suck it into the fuel tank. Problem is, you miss and get that fuel trail into the turbines of the trailing aircraft, you've got issues. Plus a spark turns that well aerated fuel stream into a flame thrower.
doctorremulac3, Dec 17 2015
  

       There's a couple of different turbulences (turbuli?) in play here. The wingtip vortices, and that from the engines. Normally the receiving aircraft is below these, not by much. Big receiving aircraft can get their empennage involved easily. I was talking to a hog driver (A10 pilot) last Christmas who said one of the only legitimate criticisms of the A10 is that it's a pig to refuel... when loaded, it's only just able to keep up with faster tankers. So the tanker obliges and slows down, they have to put out some flaps to stay in the air, now there are wake vortices trailing behind the flaps and the A10 is right on the limit. Anyhow, from turboprops I'd imagine the prop wash is a major concern, maybe some added flap vortices from the heavy plane having to slow down to helicopter speeds. Anyhow, I think the principle here is workable, maybe have the probe extending back from the top of the vertical stabilizer? oh this gives me an idea.
bs0u0155, Dec 17 2015
  

       I think the "kite" idea is potentially excellent. Note also that the idea suggests a "stabilized" drogue, which ought to be doable. Depending on the length of the fuel line, the drogue could be dynamically stable against deflections of at least a few metres (including downwash from the helicopter). Then the helicopter pilot only has to compensate for his own aircraft's movement.   

       In fact, why not make the drogue smarter? Given some sort of communication between tanker and helicopter, the flyable drogue should be able to compensate for small movements of both aircraft - in effect flying itself to the nozzle of the helicopter. The drogue should be much more maneuverable, over small distances, than either of the aircraft.
MaxwellBuchanan, Dec 17 2015
  

       // But this would not be extending a rigid support member upwards. The bell-shaped end of the hose would have wings and would be flying and would support the weight itself //   

       Hur, hur, hur, wink wink, nudge nudge, say no more, say no more !   

       Oh ... that's not a double-entendre, then ... ?   

       Sorry. As you were ...
8th of 7, Dec 17 2015
  

       Why not use an upward boom with a trailing hose and drogue? Then you can bin the computer and fancy auto-magic fins.
the porpoise, Dec 17 2015
  

       //In fact, why not make the drogue smarter? Given some sort of communication between tanker and helicopter, the flyable drogue should be able to compensate for small movements of both aircraft - in effect flying itself to the nozzle of the helicopter. The drogue should be much more maneuverable, over small distances, than either of the aircraft.//   

       I have just written that up....   

       //Why not use an upward boom with a trailing hose and drogue?// They put drogues on the end of probes for reasons of versatility, slow, and they have to land to change them back.   

       // Then you can bin the computer and fancy auto-magic fins.//   

       You're no fun.
bs0u0155, Dec 17 2015
  

       How does it deal with the getting the bugs off the windscreen?
not_morrison_rm, Dec 17 2015
  
      
[annotate]
  


 

back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle