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The Ductling D-I is a concept that evolve from several idea, primarily to make use of the DUCT-TAIL.

This craft was a design in July 2003 based on the FACETMOBILE, a lifting body design. Interestingly there is a prototype undergoing development that is looking similar to this design, where wings are evident. This is crossing over to a Blended Wing Body (BWB) design. The structure is simple and geometrical making this for an interesting shape.  My problem is finding the center of gravity, I'm guessing at this point. Before I began on this design, I built a scale mode of the FACETMOBILE I found in and article by Ken Johnson in MODEL BUILDER October 1995 issue.  See drawings in my archives. The Facetmobile intrigue me with it's unique look, no wings. A lifting body, does it fly? was my first question. So I had to build one for myself to prove the point and study this concept. The model flew.... and so my modifications began. However this modification is more of a challenge since this is my first duct fan power plant. The Duct-tail concept is based on vector thrusting with the tail rudder inside the shroud I cal it the Duct-Tail. In building this model I have learned several do and don'ts.  I feel there is room for improvement in reducing weight and increasing surface controls. My maiden flight was at best trying. The launching process was awkward and proved to degrade the proper conditions to take flight. Also, the fact that the C.G. need to be identified for proper weight distribution to assist in the take off. I plan in changing the choice of material for building the Duct-tail shroud. Instead of fiber glass I plan 1/64 plywood or foam. This may give a better finish shape and less weight. The way the rudder is controlled need to be managed differently to allow better handling for launching the craft.  I plan to make this a successful flying machine, surely.

     
 
 

   
 
 

Building the fuselage

After working out the CAD drawings the parts where cut and built for assembly. The basic parts are laid out for fit. Two boards where placed underneath each side of the fan unit allowing the fan sit properly in the bulkhead, ready for assembly of frame work. Construction of the frame work was done with 5/8"x3/32" and 3/16"x1/4" strapping. In order to build light the skeleton is kept simple. Using plastic pop bottle material for the intake manifold, helped with improvising the proper shape needed and keeping the weight down. Looking at the fan shroud bulkhead is a build up of several layers like plywood to strengthen the joining wings.  A view of the boards underneath is shown more clearly to allow the shroud to fit.

The Duct-Tail

Making the mold for the Duct-Tail, I used the general shape caved out of foam and covered it with balsa to protect it from the fiber glass resin. The frame work was completed with capping the frames using 1/2 x 1/16 " ribbon strips.  This would reinforce the frame and provide a surface for the covering.  The Duct-Tail is fitted for assessing mounting detail at the tail end exhaust, and a simple solution is determined in fixing the mount for the Duct-Tail.  A clever seat was devised to catch the shroud and mounting it in position. This will also provide as a guide for the rudder assembly. The configuration is taking shape. The wiring is fitted through the shroud crisscrossing inside and aligned with the fins to minimize turbulence.  A rib is added top and bottom of the shroud to strengthen it and give shape for the outer skin of the Duct-Tail.  The rib provides a locking mechanism for the fan shroud to hold it in place at the bulkhead.  The rudder is assembled and fitted for detail assessment on control access.  A wire frame is added to help maintain the shape of the exhaust in the tail.  A rear view of the Duct-Tail shows the details of the clever set-up.   A servo is mounted on the bottom for the rudder control. It was determine that a servo would be places underneath the inlet spoon and on either side of the rib the control rods are attached to the rudder by means of a push/pull horn system.  With receiver, battery and servos in placed. 18 oz.  Painted and covered, ready to go.

A preview of the next revolution, a twin fan V configuration.

 

 

 


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