The Birdyglider can be built in one of four different tail configurations such as the classic tail (above left). The T-tail (above center), the U or dual rudder tail
(above right) and the V-tail (below left). All tail configurations are included on the plans.
lage top where it sits. In the first place, it is not easy to get the same exact curvature every time (unless you build a device for that purpose). In the second place it would be dif- ficult to always get the same wing incidence angle. In the third place, you would have to cut the fuselage wing seating tab in many smaller tabs that follow the curbing. Lucki- ly, the cardstock has a slight natural curv- ing tendency that will take shape as a cam- ber when the wing is built.
alignment is not okay, you are in for a night- mare! Rather, build yourself another T-tail Birdy.
What didn’t work (and a couple of solutions)
Of course there were many other ideas that I tried during the process, most of which were goofs, from building up a lami- nated airfoil wing, which made the plane glide like a brick, up to a thinner fuselage waist, which resulted in the fuselage ba- nanaing at the first launch.
After trials, I found it was preferable not to add camber to the wing and to the fuse-
In an attempt to “fence” the airflow under the wing, I bent the wing tips down at a 90- degree angle and at an approximate 70-de- gree angle at the wing tips. I have realized that this certainly makes the glide more steady direction wise, but this also dimin- ishes the flight distance by diminishing the wing area, therefore augmenting the wing load ratio. Also, I tried wing tips up, which enhances stability, but again,
decreases
flight distance. On the other hand, bending the wing tips horizontally resulted in better (longer) glides.
I tried the revolutionary “blown flaps” brought into the world of paper airplanes by Peter Vollheim. This works pretty well in the classic A4 paper airplane (the type chil- dren fold, no offense), preventing stall and yielding a longer glide. It was not the case with this type of laminated paper glider, be- cause it diminished the glide ratio. Cutting an elliptical hole in the fuselage around the c.g. shaved out only 0.2 grams of
weight at the most, but it weakened the overall structure of the body for catapult launching. However, I admit that for hand launching and for competition, every bit of weight you can shake off is a blessing. Covering the glider with methylcellulose and commercial paper coating sprays in or- der to make the paper impervious or at least stronger always warped the paper. If you find a suitable coating, pass on the recipe (
german_tapia@hotmail.com); I’ll send you a glider.
Further ideas
Of course, there is always a way to im- prove an airplane, and the Birdy is no excep- tion. Indeed, experimenting may be the meat of the hamburger, mostly if you consid- er that the Birdy is really inexpensive and quickly built, so… why not try something new?
I have had nice surprises by building the
Birdy in balsa and in balsa and styrofoam (from party trays). The all styrofoam version didn’t work quite well for catapult launching (the fuselage was too weak). These materi- als certainly made better flyers, and you can certainly try them or other materials. You may be surprised.
Anyway, I don’t want to lose sight of my first purpose: an all paper catapult glider. Thanks to Mardi, Max and Jeff from M&M Hobby Center for their support with this project.
When constructed per the plans, the wing (above left) will receive a camber naturally. In further flight tests, Jose found that the wingtips bent horizontally
FLYING MODELS
(above right) helped improved the Birdy’sglide. It is easy to experiment with the Birdythanks to its ease of construction and low cost of material.
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