interest of an open throat

Discussion in 'Classic Racquet Talk' started by baggiot, Jul 18, 2014.

  1. baggiot

    baggiot New User

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    Hello everyone,
    I have a question about the open throat of a tennis racket.
    I'd like to know what are the physical justifications and more precisely the mechanical explanations about the passage from the totally straight racket handle to the open throat and specifically the Y shape.. I only found general informations about this evolution on the internet, like " it gives a better stability" or "you have a better control of off centered balls" and I need an explanation a bit more scientific!
    Thank you for your future answers :)
     
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  2. joe sch

    joe sch Hall of Fame

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    The open throat design does provide improved stability, control, and feel. Probably the most important benefit is more power since this design helps provide a stiffer frame. The racket evolution has been mostly about more power going from wood to stiffer composites. If you want to get some "scientific" details then just measure the stiffness of a standard Wilson JK woody compared to the open throat Head Vilas of the same era. Use a Babolat RDC Racquet Diagnostic Centre Machine which many good tennis shops carry.
     
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  3. baggiot

    baggiot New User

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    Thank you for your answer joe sch.
    Unfortunately, I need mechanical explanations ( like why the Y shape gives more stability that straight handle, which stresses in the material of the racket are decreasing , beyond the fact that we use another material..) exclusively linked to the Y shape..
     
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  4. joe sch

    joe sch Hall of Fame

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    You should be able to uncover these details from the patent. You will need to do some research at the patent website. Please feedback your answers after you complete this action.
     
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  5. Sanglier

    Sanglier Rookie

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    Are you writing a report on tennis racquet designs and evolution, baggiot? If so, Joe is absolutely right, there are tons of interesting information of this nature that you can glean from even a cursory patent search.

    In this specific instance, the patent you should look up (assuming you are limiting your searches to US patents only) is 2109525, authored by the legendary innovator Frank Donisthorpe for the famed Hazells company, in which he described the mechanical rationale behind his revolutionary "Streamline" design.

    While some of the terms he used, such as "drive", may not be sufficiently scientific for what you are trying to put together, they are more than adequate to serve as the starting point for you to dig deeper into the subject.

    In a nutshell: An open throat racquet does not behave significantly differently from a closed throat design unless it is much wider than the latter. Indeed, if you hit dead center on the sweet spot on every stroke, you may not experience any difference at all between an open throat frame and a closed throat frame of similar specs. It's only when the point of impact shifts away from the length axis that differences may emerge.

    Namely, a wide open throat design places the mass towards the periphery of the frame relative to the length axis; which increases the polar moment of inertia in the 'twist' orientation (i.e., twist weight), making the frame more stable during off-axis impact (i.e., by slowing down the twist speed, the same way that a spinning figure skater or gymnast can slow down the spin by extending out his/her limbs in a direction perpendicular to that of the spin axis). A more stable frame provides more accuracy during off-axis impact, hence more "control".

    Odd-looking frames such as the Chris and Spalding Orbitech are examples where this theoretical benefit of the open throat design is explored to its practical limit. As stability comes at the expense of maneuverability, and most racquet designs aim to appeal to as many different types of players as possible, much of what we see now represents a happy median between stability and maneuverability; which is probably why so may modern racquets look alike.

    Another 'possible' benefit of the open throat design that is virtually never mentioned is its inherent vibration dampening qualities: In a mono-shaft design, every bit of frame vibration is transmitted to the handle at the frequency generated at the head. In an open throat design, on the other hand, the vibration frequencies traveling down the two shafts 'may' not necessarily be in phase with one another. If and when the two out-of-phase vibrations encounter one another as they reach the grip, they might cancel each other out to some degree, the same way that noise-canceling headphones work, or at least disrupt each other enough that the shock to the player's arm may be reduced. As I understand it, this was the principle behind a couple of the PK Asymmetric designs, but it was put to maximum use in the Rossignol DV that I posted here a while back: http://tt.tennis-warehouse.com/showthread.php?t=411822&page=2. I am not aware of any other instance where a designer had tested this theory to such a degree. My own feeling is that the practical benefit of going to this extreme was in fact quite negligible (as two similarly-sized shafts can already deliver more or less all the vibration-dampening quality there was to achieve via the open throat design); which might explain why it didn't catch on.

    Good luck with your project! If you are interested in the physics of tennis, by all means get a copy of "The Physics and Technology of Tennis" by Brody, Cross and Lindsey. I bought one after reading about it on Joe Sch's website. It's the best (only?) reference of its kind and an indispensable 'mythbuster'.


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    Last edited: Jul 21, 2014
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