Having followed various discussions on the merits of the Stratospool kite winder on the Kite Aerial Photography Forum (http://arch.ced.berkeley.edu/kap/discuss/ ) I decided to make my own.
Click on the image to enlarge
The real catalyst was a recent visit to my in-laws. The house next door is being renovated and the builders had just broken up and thrown out a load of built in cupboards made of plywood. They kindly allowed me to help myself to whatever I wanted. Yay free stuff!!!
The build was fairly straight forward with the dimensions more rule of thumb than copying existing designs. The stratospool consists of two parts that I will call the reel, that’s the part with the line on, and the frame, which is the bit that the reel is attached to.
The reel incorporating the handle was drawn at 1:1 in inkscape and then printed and stuck onto the wood to provide a cutting and drilling template. The core of the reel is solid, made by cutting several circles out of the plywood and then gluing them together, before shaping them so that they were round. To do this I drilled the centre hole and inserted a long bolt and attached a washer and nut to keep the core segments together. The end of the bolt was then placed in the chuck of my pillar drill and with the use of a rasp this was used as a makeshift lathe.
To make the winding handle I cut out a number of rounds with a hole saw. These were then glued and also held together with a nut and bolt while the glue dried. The length of the handle was designed to fit my hand. Just one of the bespoke measurements that I expect make the difference between a good winder and a great winder. Currently this design has only one handle for winding. Others have placed another one closer to the centre for fast reeling and it remains to be seen if I will later follow suit.
Click on the image to enlarge
The sides of the reel are not glued to the core, but held in place with round head roofing bolts that go through the core. These are attached to tee nuts that pull the sides tight against the core. The bolts are countersunk into the side of the reel that is against the frame. Having them flush with the surface prevents them interfering with the fame and braking. The handle is also bolted on. Using washers and a nylon insert nut, not quite fully tightened up, allows the handle to stay still in the hand while the reel is rotating.
The frame length was decided on after testing the reel with a temporary frame made to allow me to see how the reel and brake preformed under load. This also allowed me to understand how the design could be refined and made more comfortable to use. This is where personal preference took over and where my design differs a little to others.
I found that holding the frame at the end pushed it back against my body. Making this an asymmetric tee allows me to hook my thumb underneath and fingers over the top, making my grip more secure. Just having a handle on one side as some other designs have, I felt, may need more pressure to keep the frame in line with the body as it would also tend to pull the whole winder to one side, unless you kept your grip very close to the frame. This tee also has a screw ring in the end as a line guide. During testing I saw that this can be a point of stress and so added a steel bracket underneath. This was cut down on one side in order to fit and is secured with screws. From my research I had seen that some people rest the frame against their stomach and others against the top of their thigh. I found that I preferred the latter and therefore added only a small tee piece to the bottom of the frame. This has proved to be just right for me. The other key dimension determined by the test flight was the position of the hole for the bolt that attaches the reel to the frame. Once in the right position for my arm length, reeling in became a smoother operation and everything feels more balanced.
Unlike others I chose to have a brake handle that is only tapered at one end. I felt that for me I only needed the brake to be effective closest to the frame handle. The brake is ingenuous and very effective once you have it tuned up. Two leather pads are attached to the side of the frame adjacent to the side of the reel. When the brake is depressed it moves the reel slightly off centre so that the side rubs against the pads. This effect can also be achieved by pulling the handle away from the frame. This is actually more effective at stopping the reel but does place more strain on the brake lever. I am currently thinking about how the brake could be improved. I have found that, as well as stopping the reel, braking can be useful to control the speed when letting out line. The bolt attaching the reel to the frame needs to be just tight enough to still allow the reel to rotate but not so tight that it binds against the brake pads. Equally if it is too loose the brake will not work at all. Two nylon insert bolts have been used to maintain the correct tightness, although more field testing is needed to see if that is the best option. The spacing of the various components attached to the bolt is achieved using washers, which also help to keep the reel off the brake pads.
Click on the image to enlarge
The final addition was a shackle from a chandlers. This is fixed through the frame and allows me to attach a climbers sling with a carabiner. This can be used to attach the winder to a fixed object like a fence , a bench or a tree. Passing the sling around my body attaches it to me, allowing me to walk around with the kite in the air. Having a double loop allows me to have one loop around my waist and the other slipped down behind my thighs, therefore sharing the load like a climbing harness. A second shorter sling can be either worn as a neck strap, to share the load with the waist strap, or to lock off the reel.
I am currently conducting field tests and will add more to this post as I tune and refine the winder.
Get a SketchUp model of the reel here
Variations on the stratospool design
Demo of statospool by Jim “Windwatcher” Powers
Various discussion on the KAP Forum
Also search Flickr for images of stratospool reels.