Treat each model as the sum of its total area and note its position, counting the midpoint of the wing chord as the location of that bit of area. Figure out the center of all the areas (a good guess will do). Measure the frontmost to rearmost area centers, and put the cg 10% of that distance ahead of the center. That should be a safe CG. I am sure you will find that you need the engine as a tractor on the front plane to achieve this.
As a final test, tie a string to the model at that point, if needed, steady it with a stick from one of the wings (rubber band everything together) and swing the thing around in the air. If it flies smoothly it is OK to fly, if it hunts or, worse, flops around, you need the CG farther forward.
I have successfully trimmed a variety of flying wings, including forward swept ones this way. Never a bit of damage on the first flights! And I do have a free-flight .010 formation of 4 Guillows gliders that flies just fine. The engine is on the front model, and ff models tend to balance more aft than c/l.
Topic: Skyray formation (Read 1249 times)
