This is a picture of the flying model you will be making.
Monday, August 4, 2008
Part 1: Building the wing and stabilizer
Building the wing. A piece of foam plastic is used as a building board. The parts are held in place by pins, but the pins are never pushed through the parts themselves, as that would unduly weaken them. Instead, balsa and carton pieces are pinned next to the spars to support them. Note the use of long carton pieces as rulers to support the spars and ensure that they stay straight.
The wing is covered with lightweight mylar. This extremely thin plastic film can be very difficult to handle due to its fragility and static cling. There are a number of different techniques to cover the wing. The simplest is simply to flatten out the film on plane surface and drop the pre-glued wing frame onto the covering. The works well with flat wing, but is more difficult for wings with a curved profile. To make the covering process easier, Torstensson uses this "cradle" made of hardwood, with balsa rails to fix the film onto.
When the cradle has been adjusted, it is time to attach the wing frame to the covering. The wing frame is first sprayed with 3M 77 spray-mount glue. It doesn't take much glue, a quick spray from about 3 feet away is sufficient. Note liberal protection of the floor with newspapers, spray glue tends to stick everywhere
The left wing should be washed in. That means that at the wing tip, the leading edge should be higher than the trailing edge. The left wing tip thus gets a hinger angle of attack, increasing lift and drag and helping to keep the left wing up as the model turns left.The leading edge is cracked and glued, the trailing edge pinned down while the leading edge is supported with balsa blocks of correct height, and the wing is again left to dry.
Part 2: Fuselage
Tissue tubes are used to mount the wing on the fuselage (motor stick). Tissue tubes are made by rolling tissue paper on a round former (in this case a drill). The candle is used to rub the former with, to coat it with a thin layer of stearin, which prevents the tubes from getting stuck on the former. A nail polish bottle can be used to store diluted glue in, and has the bonus that it comes with a convenient brush.
Friday, August 1, 2008
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