Other Projects
Hobby Bench Buddy
Copyright © 2003-2009 [BetterFly Crafts]. All rights reserved.
The Ductling D-I
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.
In my archives You will see the concept evolving with drawings using the FACETMOBILE
as the base design. Interestingly there is a prototype undergoing development that
is looking similar to my 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 centre 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.
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"x 3/32" and 3/16"x 1/4" 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 mould 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.
The Facetmobile into the Ductling
The reason for the Ductling borrowing from the Facetmobile technologies is based on the lifting body technology and I though this would be an interesting concept to introduce to the Duct-tail. I first played with CAD drawing building from the original model, then I began to introduce an electric power plant. As you can see I also began to change the wing configuration, then I began to think about fan units. I built my versions with the modifications, and this is what came out. As a glider it preformed well.
After playing around with the configuration, I doodled in a dream state and sketched the Idea of the Ductling. I tried reworking the details with the Facetmobile modifications in mind, then some static models where built out of 1/16” balsa frame and covered with ordinary paper. This gave me something to think about. Originally the SeaHawk was the concept I was developing, now with a twist, a new tail the Duct-tail, hence the Ductling.
A gap between the wings at the trailing edge in one of the models is for the DUCT-TAIL (fan unit) Similar to the first model with the wings expanded some more. I felt this did not work well. In developing shapes, it helps to have a physical object to view it. The model was improved for lift, by creating a better body profile of an airfoil. This worked well. The D-WAV is prominent here.
