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Power Kite Quick Release

Page history last edited by Stephen M. 14 years, 1 month ago




For spring 2009 this group (McKinley, Murphy, Beladi) was assigned a project to invent a quick release system for kiting.  The device was required to be very light and small while maintaining enough strength to quickly release up to 800 lbs. under load.  After market research and brainstorming, we selected a design that functioned on an over center hinge that, when opened, would part two halves of a pulley and allow the control strop to escape from the harness.  The final design also features a method for automatically closing the device without using your hands as well as a means for pushing the strop out of the device in case of any adverse conditions.  The Quick release also features an a set screw that allows adjustment of the central axis which makes opening the device easier or harder as desired. The entire quick release used only approximately $30 worth of materials and could be sold for up to $100 according to the customer surveys.  The device is compatible with all kiting harnesses that use a spreader bar and can be adapted for use in the rest of the market by adding a carabeiner.


Prior Work:

  The Captive Method

The first method of attachment is the captive method which connects the kite to the user with a spreader bar and hook.  In some instances of this design, the hook is replaced by a pulley that allows greater maneuverability of the kite.  The disadvantages of this system is that while under load, the one must pull the strop towards the body in order to release it from the hook or pulley.  The advantage to this system is that the user will be able to lift the kite into the air and maneuver it into a holding pattern before easily inserting it into the spreader bar hook or pulley.


Non-Captive Release

            The second method of attachment involves a quick release system typically employing a winchard hook or other similar maritime releases.  With this system, the kite strop is held by a pulley that is attached to the winchard hook  The winchard hook is then attached to a carabeiner that is attached to the harness.  By pulling the release for the winchard hook (yellow ball connected to red string below) the hook releases the pulley and strop in an emergency.  The advantage to this system is that it adds a quick release element.  The disadvantages of this system are that once released, the pulley on the end of the strop becomes a hazard that is now released with velocity after being held under great tension.  This method makes initially raising the kite harder because the kite must be attached to the winchard hook before it can be raised.  Also, because of the long combined length of the elements to this system the total possible length of the strop (limited by length of arms and attachment method) is reduced.  The shorter the strop is, the harder and more hazardous he kite will be to control.



After reviewing the customers needs and determining the rough specifications and requirements the group sat down and began the tedious task of brainstorming.  Concept generation was accomplished through brainstorming in a group and as individuals. Each idea was discussed and drawn up; the potential of each drawing was to be assessed later on in the process.  Early on in the design process we decided to focus on two main groups of releases.  The first was designed to release on the handles that controlled the kite.  These designs would sever connection with the power lines thus applying full breaks to the kite.  The second group of designs would release from the connection point to the harness.  The final design was in this category.  The main difficulty was designing something that did not release any components of itself along with the kite.


The final design depended on an over center hinge to open a bisecting pulley that would allow the rope to slip through.  The design was drawn in CAD (Pro E) and fabricated by hand in the machine shop.  The pulley, because of its complexity was milled by our university's CNC technician.


A working lego model created to test the concept of the over center hinge.



Before commencing machining of the prototype, critical areas of the design were scrutinized to demonstrate proper action and strength.

Seen above at left is the set screw that allows for adjustment of the locking angle.  A maximum of 2 degrees was allowed, corresponding to a 1lb release force for a hanging load of 1000 lbs.  This screw can be adjusted to allow any amount of sensitivity in releasing the mechanism.


Five specific areas on the part were identified as critical areas; these were analyzed to determine the load on the pulleys corresponding to failure.


Additional Pictures:











Special thanks to Rick Winn (UMass Undergraduate Machine Shop Director) and Michael McKinley (Course TA, MIE 213)









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