Pilotage

A sunny afternoon prompted a thinly veiled excuse to go drill some holes in the sky: I needed to shoot a few landings to check a couple of things on the airplane. It sounded plausible enough to Stan, who enthusiastically accepted an invitation to come along. Stan is getting back into aviation after a 20-year-plus pause — so he, too, is keen on thinly veiled excuses.

At the airport we busied ourselves with unlocking, uncovering, untying, poking, prodding, and prepping the airplane. The gauges indicated low fuel, so I grabbed a calibrated tube and dipped it into each tank to confirm the quantity: 18 gallons total. More than enough for a few circuits.

Stan settled into the right seat. He's a big guy, and the two of us swallowed up every available inch of shoulder room. Even so, given the light fuel load and empty back seat and baggage area, I didn't give weight and balance much thought.

It was the hottest, stickiest part of a hot and humid day; climb rate would suffer. On the other hand, even with the mass in the front seats the airplane was relatively light, so perhaps the pluses and minuses would cancel out each other and the airplane would behave nicely as usual.

Wrong. It climbed miserably. When the Kansas City Downtown (MKC) tower controller issued a left turnout after departure from Runway 19, we had an eye-level view of the middle floors of K.C.'s modest skyscrapers.

On downwind, we were cleared for the touch-and-go. One of the most satisfying experiences in flying is executing a textbook approach and landing — making surgically precise power reductions, flap extensions, and trim adjustments at exactly the right moments so that you end up motoring down short final at target altitude, airspeed, pitch attitude, and power setting. All that's left is to squeeze off the last bit of power; gently arrest the descent; feel for the runway; and, finally, humbly acknowledge passengers' appreciative murmuring about the smooth, mains-first touchdown.

There would be no murmuring this day, at least not of the appreciative kind. My efforts at nailing the approach were subverted by thermal activity. Each time we overflew the Missouri River, which hooks across the approach end of MKC's Runway 19, the airplane would stop descending and begin to soar. This put us high on the glide path, which forced a steep descent on short final, which screwed up the power setting — in other words, the approach was totally out of spec. After flaring we sailed along just above the runway to bleed off speed, only to suffer the final and most embarrassing insult: A three-point — or worse yet, nosewheel-first — touchdown.

These were my worst landings in memory, and there was Stan observing it all from his front-row seat. He graciously nodded his head at all of the excuses I concocted. In truth, the experience buoyed his spirits because he realized that some of the misery he had been experiencing in his initial flying now had company.

I threw in the towel after four sloppy landings. On the drive home I tried to puzzle over the reasons for my inability to make even one acceptable touchdown. Sure, the thermals trashed the approach, but I should have been able to salvage the landing. Two days later my wife, son, and I took a weekend flight to visit friends camping in southwestern Missouri. The two landings I performed on the trip restored my confidence. They also spurred me to figure out why I had so much trouble that day with Stan aboard.

The answer materialized when I worked several weight-and-balance scenarios, including the just-completed family trip and the traumatic touch-and-go flight. According to my figures, the landing weights on those two occasions were within 15 pounds of each other. The difference was in the location of the center of gravity: 1.2 inches aft of midpoint for the family trip, and 2.25 inches ahead of midpoint for the pattern work flight. In each case, the CG was well within acceptable limits, yet the specific location of the CG with respect to the midpoint, or neutral position, had a telling effect on the airplane's handling at touchdown.

When CG is aft of neutral, pitch control is more sensitive and effective. With my featherweight son and me in the front and my wife and the bags to the rear, it was easy to exercise precise pitch control as the airplane settled to the runway. Not so with big-guy Stan and me in the front seats and a light fuel load. (On my airplane, the CG moves slightly forward as fuel is consumed.)

The pitch control problem was evident only at touchdown, because CG location has a more pronounced effect on handling at touchdown. Downwash on the horizontal stabilizer, which aids in pitch effectiveness, is much reduced just before touchdown because of ground effect and the fact that the propeller is idling rather than creating a strong slipstream.

What did I learn from the experience? A weight-and-balance calculation reveals much more than whether the CG is within legal limits. It also can function as a predictor of the airplane's landing demeanor. Forward of neutral point? Prepare for a more difficult exercise in keeping the nosewheel from prematurely touching down. The alternative? Stan gets to ride in back.