Blanik L-13 tow release

Discussion in 'Soaring' started by Hot Wings, May 29, 2019.

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  1. May 29, 2019 #1

    Hot Wings

    Hot Wings

    Hot Wings

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    Doe anyone have a picture if this tow release mechanism, from the other side? Or a good description of it's mechanism?
    [​IMG]

    Or a diagram of a similar glider bridle release? I'd rather not reinvent the wheel.
    Maybe even a used part off a timed out glider?
     

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    Last edited: May 29, 2019
  2. May 29, 2019 #2

    hugomeiland

    hugomeiland

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  3. May 29, 2019 #3

    Hot Wings

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    Yes, that is where I got the picture. ;)

    The factory parts catalogue drawing doesn't detail the cam mechanism. Designing one that releases from the cockpit is rather trivial but the back release, with a single spring, looks like some clever design that I'm not seeing.
     
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  4. May 29, 2019 #4

    Victor Bravo

    Victor Bravo

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    There is a company who advertises on Barnstormers all the time, who is always selling Blanik parts, Blanik fuselage sections, etc. Last name is Petkov, he's in Bulgaria I believe. He should be able to walk outside to one of his wrecked Blaniks and take as many photos as you want.
     
  5. May 29, 2019 #5

    Hot Wings

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    Or even sell me a complete right and left unit.
    Thanks for the lead!

    If there were enough old Blanik parts around maybe there would be enough of them to supply my builders with parts rather than make new?
     
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  6. May 29, 2019 #6

    Victor Bravo

    Victor Bravo

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    The Blanik is a sad story. There were some wing failures and they grounded one of the greatest gliders ever designed. Truly a wonderful flying airplane. What do you mean "your builders"?
     
  7. May 29, 2019 #7

    BoKu

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    Based on that cross-section, I'd guess that the actuation arm on the inside of the fuselage engages a pair of helical slots in a cylindrical barrel. Pulling the release knob rotates the central pin on its axis and pulls the actuation arm through the slots, retracting the pin inward and releasing the bridle hook.

    I'd guess that the clock spring depicted in the cross-section does double duty; one end is anchored against that lug at the 7-o'clock position (port side; 5-o'clock starboard), and the other end is anchored on the platform for the central pin. The former prevents the bridle hook from just falling out of the release due to gravity when the tow line is slack, and the latter forces the pin to its extended position unless the release knob is pulled. This particular combination of functional complexity with mechanical simplicity has Kalashnikov written all over it.
     
  8. May 29, 2019 #8

    Hot Wings

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    :cool::rolleyes:
     
  9. May 30, 2019 #9

    Hot Wings

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    After some more thought I'm wondering if I have/had a fundamental misunderstanding of how this mechanism works.
    I assumed that the back release was a combination of the little tang on the underside retracting the pin as it was dragged back by the winch rope.

    If all the back release tang does is hold the tow rope hook horizontal and in place with spring tension on the ground and simply allows the link to disconnect when the winch rope angle is near vertical then the mechanism is much simpler.

    Maybe someone that has actually hooked up an L-13 can enlighten me?
     
  10. May 30, 2019 #10

    Victor Bravo

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    Have a look at how Marske does it on the Pioneer. The older one I saw used two standard glider tow releases mounted in the lower wing roots. So a bridle would auto release at the top of a winch launch, or you could aero tow it.
     
  11. May 30, 2019 #11

    Hot Wings

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    That is how the older version of this plane was done except they were pretty wide - around 2 meters. Marske's looks to be just a bit wider than the fuselage.
    Moving them to the wings, but closer together, might be an option. It would require some revised linkage and number crunching.
     
  12. Jun 2, 2019 #12

    proppastie

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    Simple Carbon Dragon Tow Release, will automatic release on winch or car tow if you forget. Will not work with very high load bungee launch at tail (According to Phil Lander)
     

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  13. Jun 2, 2019 #13

    Hot Wings

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    Thanks!
    I'd not seen this one before ... and I have original CD plans. :oops: The simplicity of the Schweizer but it back releases. Just might work if I can figure out how to structurally plant it in the "D" cell.
     
  14. Jun 2, 2019 #14

    simflyer

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    All about grounding of Blaniks was started by some lack of discipline, when Blaniks was used to unapproved aerobatics and wingspar hinge was broken. Exist possibility to repair problematic wing spar hinges - actualy offered by two firms I think.

    Actually only L13AC (aerobatic version) and L23 Super Blanik are approved to fly. Maybe Blaniks NG would be produced.
    I flew Blaniks few years and it have single lower hook for aerotow and pair of two side hooks for winch start, which could release by hand or aautomaticaly, when rope hook turns by rope holded down to winch. I think, it is possible to do photos of Blanik mechanism or maybe find drawings.
     

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