Weighty options

I let go of the yoke. One heart beat… Two heart beats…

The horizon rises in the windshield. Slowly at first, then faster. Up. Up. Up. Faster and faster still. The whisper of the wind turns into a roar. Then a howl. Twin tails rising high into the air, Tess nose-dives toward the earth like a Stuka dive bomber.

stuka

The wind resistance tugs at the prop, red-lining the tachometer.  The vertical speed indictor shows 800 feet per minute down… 900 feet per minute… 1,000 feet… 1,200… The airspeed indictor snaps to the yellow line. I lose my nerve. My hand back on the yoke, I pull back. Gently. Firmly. The horizon, now above my head, slowly slides across the roof of the canopy, down the windshield, below the nose. We are straight and level again.

I turn to Lisa, who’s sitting calmly in the right seat, pencil poised over her knee board. “Well,” I say, “that wasn’t encouraging.” Clearly the new trim is not working right.

So much for a trouble-free return to service.

We return to the field, land, and my mechanics make an adjustment. Back to the designated practice area. Back up to 8,500 feet. Again, the Stuka dive.

stuka

We return to the field a second time, land, and my mechanics make another adjustment. Back to the designated practice area. Back up to 8,500 feet. Again, the Stuka dive.

stuka

On the third try, we’ve run out of trim. It’s deployed 45 degrees into the slipstream, and still the elevator can’t hold the plane in level hands-off flight. Something is seriously amiss. Tessie has become mysteriously nose-heavy. Like our engine mystery of two summers ago, there’s no satisfactory and satisfying answer as to why this is so. But cause aside, we need a solution. And one solution to a nose-heavy airplane is to simply add some weight to the other end. And as the tail is much farther behind the center of gravity—that magic balancing point an aircraft in flight rests on and rotates around—than the nose is forward of the center of gravity, a little weight should go a long way.

Or so we thought.

Funny how many of the things we think  should work simply don’t with this stubborn little airplane.

I won’t bore you with all the details of the testing plan. Or with the details of the flights, one after another, after another, after another, after another. For most of a day. But we started by securing one-pound bags of “Sea Pearls” in Tessie’s tail. The bags are designed for scuba diver belts. They are small, flat, full of tiny lead shot, and surprisingly heavy for their size.

IMG_1947

Based on the weight and balance sheets, it shouldn’t have taken too many bags to get Tessie to fly right. The weights were placed 180 inches behind Tess’s center of gravity. One hundred and eighty inches is a loooooong lever with which to raise the nose. Or so we all thought.

But it was not the case. Seventy-five dollars’ worth of Sea Pearls later, I still had a plane the Luftwaffe would have been proud to deploy. With the maximum amount of added weight that my maintenance team felt was safe, we still couldn’t fly level. Oh, sure. It was better. The dives were slower. Less aggressive with each bag of Sea Pearls. But anything like level flight with neutral trim eluded us.

It was time for Plan B. Which was four washers installed along the bolts that secure Tess’s tail to her fuselage. Yep. We shimmed her tail. Then I went up to test fly.

No more Stuka.

But were the weights still needed? There was only one way to find out. Take some out, test fly, and see how many, if any, were needed with the shimming of the tail feathers. Again, I won’t bore you with the details of the flights. One after another, after another, after…

But in end, there were no Sea Pearls in Tessie’s tail and she flew true.

In fact, she’s never flown better.

Now, if we can just figure out why her brand-new attitude indictor is spinning like a top, and why her compass points the wrong way…

 

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