The Sparrow traces its origins back to the YD142-1 drone "technology demonstrator" prototype, which featured a box wing. Although it performed well in testing, I chose not to make an instructable for the YD142-1. Despite being several months old, the prototype remains airworthy. After the YD142-1 was designed, the Moth "double delta" drone was designed and published. The Moth featured two delta wings, one inverse delta and the other mounted conventionally below, like the RC airplane it was inspired by. Although the Moth was quite capable and successful, I did not feel designing biplanes was an idea worth investing in, due to their intricate nature, especially when installing the wings.
In early January 2012, I received a request for a miniature, realistic biplane paper airplane. To answer this, I looked back on the YD142-1 and the Moth. Quite quickly the delta wings of the Moth removed it from consideration. The YD142-1, although capable, had a chord of 2 boxes, making the mounting of the wing approximative. At this point, I decided to design a new aircraft, with some conceptual characteristics similar to the YD142-1 but with a somewhat different configuration.
After some design studies, I retained the similar Voyager's vertical and horizontal stabilizers. The wings and spars would be of entirely new design, however. Rather than have a box wing like the YD142-1, I decided the XD200-1 (which would later be named the Sparrow) would have a strut braced pair of wings. The required wing size was calculated from existing data from the Voyager paper airplane and the prototype was assembled. On its first flight, the Sparrow proved itself a worthy airplane, and it was given the slot for Instructable 155.
Some potential experiments and demonstrations possible with this airframe include:
- Glide ratio
- Weight and balance
- Hangtime versus other aircraft
- How surface inequality can affect aircraft (geometry/shape studies, flight dynamics)
- How each of Newton's three laws affect aircraft (a person acting as an external force on the airplane during launch and/or the air acting on the airplane as an external force characterized as drag (first law); the force of the airplane hitting something and transferring the force its built up with its mass and acceleration (second law); and lift versus gravity and thrust versus drag (third law))
- In a turn, circular motion is accomplished by lift directed toward the center of the turn.
TAA USAF Designation: D200-1
Step 1: Materials
1 Piece of 10.5 by 8 inch graph paper (4 boxes per inch)
Step 2: Begin Construction
After the fuselage is made, take another sheet of paper that is folded in half along the lines of boxes. Mark out two wings as shown (each 3 by 10 boxes). On one, mark a dotted line half a box in from the wingtips. Then mark out the horizontal stabilizers as 2 by 3, plus a swept portion with a sweep of 1 box of chord decaying every 3 boxes outwards from the wing root. Then cut it out.
Solid lines indicate places to cut. Dotted lines indicate fold lines.
Note: 1 box = 0.25 inches