05 March, 2006

Day 11 with the Tern: Renewed Fire

Well, maybe not fire, but at least I could work on it again.

I finished the center wing for the most part today. I realized that the cutout in the center rib and the hatch were holding the spoiler servo well enough, and I actually didn't need to screw it to anything. I may add a couple more bracing blocks on the hatch, but that will be easy before covering. After sheeting and cap stripping the center wing, I finished sanding the leading edge of the left wing and rounded the left wingtip. They both came out really well. With the dihegral, the final span should be just over 76 inches.

As you can tell from the picture, the sweep on the outer wing panel is quite large (14.5%). My calculations show that I will have plenty of lift, and the sweep will add a lot of stability, but it will really help the Tern get up to high speed during penetration flight.

I did a quick weight check. My target weight for the model, balanced, was 32 oz, which would have given a wing loading of just a touch under 8 oz/sqft. Covered, with radio and battery, the fuse weighs right at 11 oz. The center wing with servo weighs 3.5 oz, and the left wing weighs 2 oz. With another 2 oz for the right wing and then 25% addition to the total wing weight for covering, spoilers and joining, that brings the estimated weight of the plane to 20.5 oz before balancing. If I can't balance this thing with 12 oz of lead, we are in trouble.

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In fact, I just got off the treadmill...