Getting ready to race

“One minute out,” said Lisa.

“45 seconds out,” said Lisa.

“30 seconds out,” said Lisa.

I griped the yoke horn firmly with my left hand, and wrapped my right hand around the throttle.

“15 seconds out,” said Lisa.

“Now,” said Lisa.

I snapped the yoke to the left and down. The horizon cartwheeled to the right. We rolled.

Ten degrees.

Fifteen degrees.

Twenty degrees.

Thirty degrees. I started pulling back to hold Tessie’s nose on the horizon.

Forty-five degrees. The controls began to get heavy.

Sixty degrees. A quick glace left. The ground seemed straight below, spinning around the wing tip. The airspeed began to fall off. The G-forces started pushing me back in my seat.

“Roll out!” commanded Lisa.

I spun the yoke back to the right, pushing forward at the same time, and the horizon dropped back to straight and level like the falling curtain at the theatre. The G-forces relaxed their grip. The airspeed began to recover.

“Crap,” said Lisa. We’re waaaay off again.”

So much for science. And technology had failed us twenty minutes earlier.

Lisa and I are trying to perfect the perfect race turn. Having received the official racecourse for the third SARL race of the season, we now know we need to make a pair of 120-degree heading changes on the roughly triangular racecourse. Figuring out that the heading changes were 120 degrees took us more time than it should have, especially considering that Lisa is an honest-to-God college professor. Of course, she’s a biologist, not a mathematician. In the end we ditched the calculus and laid a kindergarten protractor over the flight chart to determine how many degrees we had to turn through to get from one heading to the next.

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Smart people often over-think things. Often the simplest solutions are the best. This would also prove true of the current problem Lisa and I were trying to over-think at 7,000 feet above the New Mexico desert.

Now, as you already know, there is no book called Air Racing For Dummies, and our competition is hardly going to share their secrets, so we are on our own to develop a plan to win. Because we are handicapped as air racers by having a slow plane, we are always looking for ways to gain seconds over the competition. One bright idea I had was to make our turns sharp. A plane making a “standard” turn takes two minutes to traverse a circle. A steeper bank drops that time. It also cuts the turn radius, the amount of real estate over the ground that the plane uses up making the turn. So a steep turn should keep us tighter to the course and give us an advantage over a plane making a more shallow turn. The downside is that air speed drops in steep turns, so it may be a wash, but steep turns are fun, and we got into this whole race business in the first place to have fun.

We originally played with 45-degree bank turns, but we’ve now upped the ante to 60-degrees of bank. It’s only 25 percent more angle, but it’s twice the fun. Oh. Right. And it should also cut the turn radius even more. Of course, the steeper the turn, the more it slows the airspeed, so it may be academic, but, again, I point you to the fun factor.

The angle of bank part of the plan is going fine, but we needed a way to know when to rollout of the turn. We’d tried eyeballing it on the Flight Pad (my iPad Mini streaming a Garmin GPS) but it updates too slowly and we lacked precision. Sometimes we rolled out early, other times late. I did some research and re-learned the forgotten rule of thumb that you should “lead” your rollout by half your bank angle. For a 60-degree bank, you’d roll the plane out when it’s 30-degress from its intended heading. When I read this, I realized at once that my otherwise useless-in-the-modern-world Directional Gyro (DG) all of a sudden had a new lease on life.

The DG is a descendant of the compass. Because compasses misbehave under a number of circumstances, and most especially in turns, the DG tracks and reports an airplane’s heading to help make course changes more precise. It’s a 360-degree ring, much like our kindergarten protractor, that rotates as the plane turns. Back in the days before GPS and moving maps on tablet computers, the DG was a key instrument in cross country flight.

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I think you can see where this is going.

Yes. The plan was to set the DG to zero as we approached the turn, and use it to track how many degrees we’d turned, and then roll out smack on course.

It didn’t play out that way.

The first failure was the whole-set-to-zero thing. Due to the nature of gyroscopes, friction, and the fact that the stupid planet is rotating, DGs suffer from something called precession, which means they don’t hold their settings very well over time, creeping about 15 degrees per hour from their set course. Back in the day, we’d just periodically correct them using the compass. But as Lisa and I approached our first turn, the precession wasn’t 15-degrees per hour. It was more like 15 degrees per minute. Probably worse. We could see it moving, like the sped-up clock in the intro sequence of the old black and white Twilight Zone episodes.

Clearly our DG had a mechanical issue. Serves me right for buying a rebuilt one to save money.

The second failure was that the gyro, that wouldn’t stay still on a straight course like it’s supposed to, froze solid in a turn, now refusing to move when it should be. It was doing the exact opposite of what it was designed to do. To say I was frustrated would be an understatement. We flew along in silence for long minutes. Each brainstorming in silence.

Finally, Lisa said, “Let’s use time instead.”

And so we started experimenting. It was like an airborne version of Goldilocks and the Three Bears. First we tried 10 seconds, but it was too hot and we overshot. Next we tried eight seconds. Still too much. Then five seconds. Not enough turn. Finally six seconds was just right.

But how to track time in the cockpit during a solo race, while managing the steep turn and all that goes with it? A dash mounted timer? Some sort of metronome? Remembering the protractor, we decided to test the simplest solution:

“One minute out,” said Lisa.

“45 seconds out,” said Lisa.

“30 seconds out,” said Lisa.

I griped the yoke horn firmly with my left hand, and wrapped my right hand around the throttle.

“15 seconds out,” said Lisa.

“Now,” said Lisa.

I snapped the yoke to the left and down. The horizon cartwheeled to the right. We rolled.

“One-one thousand,” I said out loud, “two-one thousand, three-one thousand, four-one thousand, five-one thousand, six-one thousand.”

I spun the yoke back to the right, pushing forward at the same time, and the horizon dropped back to straight and level like the falling curtain at the theatre.

I held course and let the data from the GPS catch up. The map on the touch screen jerked, flashed, then settled down.

And we were dead on course.

 

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