Vasily  Pilipchuk  

 
THE AERODYNAMIC BRAKE
 
for baitcasting and centerpin reels
 
 
At an initial stage we accelerate a bait up to some speed and release a spool. A bait accelerates a spool, and itself loses the velocity. There occurs the moment, when speed of a bait and peripheral speed of an upper turn of line on a spool become equal. It is initial velocity of alone casting.
 
In the moment, when speeds of a bait and upper turn became equal, it is began a stage of flight of a bait as the body, casted in bevel way to horizon. From all forces, braking a bait, we detail three: friction of line about a rings, gravity and resistance force of air. These forces results in moderation of the bait's fly speed.
To prevent tangling of line and to obtain a maximum range of casting, it is necessary to agree gyration of a spool and movement of a bait. The best system for braking a spool - the thumb of the master. But to become the wizard of casting the long-lived practice and perseverance is indispensable.
To facilitate the spool control procedure and to make it accessible for beginners, the baitcasting reels are equipped with the brake of different types.
 
First - axial frictional. It allows to compensate the effect of gravity and friction of a line about the rings, because it is possible to consider the value of action of these forces on a phase of trajectory from a beginning up to vertex as a stationary value.
But to balance force of an aerodynamic resistance without losses of range so simply it will be not possible. A reason in following.
 
If the speed will be diminished twice, the environmental resistance will be diminished in four times. Such dependence is named square-law (graphically it is a parabola). Therefore, to brake a spool it is necessary under the square-law way. By the analysis or intuitively Gett Borgstrem has applied the centrifugal brake, but he, that is named, has got exactly. The force, with which one the centrifugal brake acts on a spool, too quadratically depends on speed.
Due to this property of the centrifugal brake there is a possibility to agree running speeds of a spool and bait on a uprising phase of trajectory. We consider a uprising phase of trajectory because after passing a vertex the bait again starts to be accelerated. And farther, up to the splashdown of a bait, to brake a spool is harmfully. And just before the splashdown the spool should be stopped.
The conditions of optimum casting "in general" are those. But nevertheless it is most important to automate the braking just on a uprising stage, because further it is much easier "to help" by the thumb.
 
Alongside with dignities proved to perennial practice, the centrifugal brake has a number of faults, namely:
  •  As a rule, it is adjusted by degrees, that does not allow to attune a reel in the best way.
  •  As a rule, for adjustment of the brake the spool should be opened. That to do under a rain or in darkness not only is inconvenient, but also is harmful for mechanism - inside the body can get sand and moisture, which one subsequently will give in failure of a reel.
  •  The value of a braking force hardly depends on a condition of the surface, on which one the braking pins slips. The hit in a place of friction of a moisture or oil results in failure of the centrifugal brake and, as a consequent, it results in line tangling.
     
    Except for mechanical and centrifugal, now are used a number of diverse braking systems. They have dignities and imperfections, but the comparative analysis of all systems leaves for frameworks of the given article. As of today centrifugal-mechanical system:  a) is closest under the characteristics to square-law;  b) is widely applied, - therefore we have considered it as alternate variant to our  aerodynamic brake.
     
    As spoke ancients: "Similar recovers similar". To balance the resistance force of air, acting on a bait, it is possible to brake a spool too by air resistance. For realization of this method of inhibiting action it is necessary to cause a spool to spin the turbine. Then the airflow, produced by the turbine, will take away the energy of a spool and by that to brake it. And under the demanded square-law principle. How to tune such brake? - It is necessary to adjust stream on an entrance or exit of the turbine by the shutter. That's all.
     
    Structurally device consists of three details: the impeller, coherent with a spool, and two disks with viaholes (there are possible also other solutions). One of disks is turned regarding other by the handle, placed outside the reel body, thus changing a sectional area, through which one transits an airflow. And there is a set-up of the brake.
     
    Alone brake is small-size, ight-weight and simple, it can be built-in in any baitcasting or centerpin reel without significant changes of its construction. The details of the brake can be produced from thermoplastics, the qualities of a material here are unessential.
     
    Let's consider briefly the general principles of constructioning and operation of the aerodynamic brake.
     
    The device includes bound among themselves:  a) an element given in gyration by a spool and creating at gyration an airflow, and  b) the means of creation of variable resistance to the indicated airflow. Structurally these details can be executed variously.
    As one of preferential variants of an element, creating an airflow, there can be an aggregate of blades, supported on the common disk, given in gyration by a spool. The blades create an airflow, oriented basically in a plane of gyration, therefore such construction it is possible to name "a centrifugal impeller".
     
    Other optional version of fulfilment of an element, creating an airflow, is the aggregate of blades by the way of air propeller - "propeller". The airflow, established by the propeller, is oriented predominantly in bridge spin axes of the propeller.
    The form of fulfilment of means, creating variable resistance to an airflow, also can be miscellaneous. Compulsory condition is the availability of a moved or slewing shutter, arranged on path of stream. The shutter can be arranged in an arbitrary place of stream.
    The airflow can be open, that is to arrive from an atmosphere and to be reset in it, or to circulate inside a housing, covering a decelerator.
     
    In figures the "open" variant with the propeller is rotined.
    The device consists of an element, creating an airflow, by the way of propeller 1, coherent by common shaft with a spool 2, and means of creation of a resistance to an airflow, executed by the way of a cylindrical body 3 with cross-hatchings 4 and turned around of an axis of disk 5 with cross-hatchings 6. By rotational displacement of the disk 5 concerning a body 3 change square of an overlap of cross-hatchings 6 and 4, owing to what the change of a resistance to an airflow 7 and, accordingly, change of the form of a parabola in dependence of a braking force of a spool on speed of its gyration.
     
    Patent RU 2265329.
     

     
     
     
     

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    Published 28.04.07

     
     
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