Couple of interesting web links

Discussion in 'Aviation' started by meridian, Jan 9, 2009.

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  1. meridian

    meridian LE Good Egg (charities)

  2. Mmmm, rather like the Attack version of the X2.

    Can we have 70 of them please?

    [​IMG]
     
  3. meridian

    meridian LE Good Egg (charities)

    So is the contra rotating thing the way of the future then?
     
  4. Depends what you want to use it for. It will give a higher performance and a greater lift capacity of an equivalent powered and sized aircraft but has a few cons that mean, at present, it won't replace the current configuration of main rotor and anti torque tail rotor aircraft.
     
  5. meridian

    meridian LE Good Egg (charities)

    Interesting that the Russians have stayed with the concept and now Sikorsky is coming back to it, perhaps it is one of those technologies that requires the very latest in materials and design to make doable. Is it the same basic principal that makes the Chinook so fast, all the power goes into lift and thrust rather than anti torque.

    I had a look at the stats for one of those Kamov Helix types and I couldnt believe the capacity and lift for such a compact (although very tall) design. I expect they wear out and are very maintenance intensive.

    All very interesting though
     
  6. Pretty much.

    Are you thinking of the Kaman K-Max (with inter meshing blades) as opposed to the Russian Helix (with contra blades)? The K-Max is the skinny ugly thing that has a huge lift capacity for its weight.
     
  7. meridian

    meridian LE Good Egg (charities)

    Fascinating stuff.

    Am I mixing my names. I looked at both, the meshing Kaman one is the one they use for logging and pylons in place isn't it. The one I couldnt believe was the Russian (or is it Ukranian now) Helix, it can lift 16 people or 4-5 tonnes in less length than a Lynx. I don't doubt there is more to it than that but bugger me, thats very impressive.

    Wonder if we could buy them at less than a FLynx :D
     

  8. We could buy an Aston Martin Vanquish for every member of the AAC for less than FLynx....and you can fit more people in an Aston.
     
  9. meridian

    meridian LE Good Egg (charities)

    Stop talking common sense
     
  10. The South Koreans like them too.

    [​IMG]
     
  11. Dammed with faint praise?
     
  12. That X2 thing reminds me of the old AH56.

    [​IMG]
     
  13. Did they put the tail on upside down deliberately? :?
     
  14. Probably done at 657, gash fcukers!!!
     
  15. The AH56 was an altogether bizarre design. Very cutting edge in its time. You may notice that it has not only an anti-torque tail rotor but also a pusher prop too. Its classified as a compound helicopter.

    The good points:

    1. The pusher prop in combination with the winglets and a rigid rotor head meant for a high top speed.

    2. Due to having a gucci pusher prop, it meant the aircraft could accelerate and decelerate without pitching down or pitching up. This meant that weapons systems would have a more stable platform throughout the speed range. It could also pitch up and down in the hover without moving forward or backwards.

    3. The gunners position (front) moved with the weapon system in its own cupola (inside the cockpit). He had a little periscope that looked wherever the gun looked.

    4. It never went into production.


    The bad points:

    1. The main rotor blades are considered to be unique in the helicopter world in that the blade had positive camber. Usually a helicopter blade is symmetrical if viewed from its end (top half is the same profile as the bottom half). Producing lift is achieved by altering the pitch angle of the blade by way of pivoting the blade along its length. The AH56 already had pitch on the blade even if the collective lever was at zero. This along with it having a rigid rotor head (very stiff due to having no hinges to flap and drag) threw up a few undesirable handling qualities. One of those being the retreating blade had a violent tendency to sweep down. Or even the advancing blade sweeping down. It pretty much did its own thing in a very unpredictable manner. One aircraft crashed due to the main rotor sweeping down and extracting the pilot.

    2. Due to the above, (not withstanding the pilot extraction) huge vibrations were caused by the rotor set up. Handling was considered to be unacceptable through most flight regimes from hover to fast forward flight. It was less stable than a crack cocaine addict.

    3. NASA stuck one in a wind tunnel to explore the vibration issues and that too dismantled itself when the main rotor struck the tail.

    4. Subsequent prototypes were fitted with a downward firing ejection seat (fuck that at low level!!).

    5. Due to the ridiculous handing properties, varies 'fixes' were sought by sticking automatic flight control systems, hydraulic dampers and various other devices to try and just control the main rotor head. You cant polish a turd.

    6. It was pants.


    Why is the vertical fin below? Dunno but a guess would be that the tail is quite short (look at side views) and the main blades over hang the empennage. Sticking the fin below means it could keep the tail boom shorter (certainly not making handling any better!)