adjusting for refraction, part I

re·frac·tion [rɪˈfrækʃən]. n.

1. Physics.

the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different.

2. Ophthalmology.

a. the ability of the eye to refract light that enters it so as to form an image on the retina. b. the determining of the refractive condition of the eye.

3. Astronomy.

a. Also called astronomical refraction. the amount, in angular measure, by which the altitude of a celestial body is increased by the refraction of its light in the earth's atmosphere, being zero at the zenith and a maximum at the horizon. b. the observed altered location, as seen from the earth, of another planet or the like due to diffraction by the atmosphere.

Here are some more tidbits about the job:

I have three bosses. They work and fly out of Apple Valley, but they all live elsewhere, like Nevada and southern Oregon. So they commute down here one week out of the month and fly with me, and rotate.

I'll call my first boss (the one I worked with last week) Mr. Mooney. That's not his real name, of course. It's the name of the plane we fly. His plane. It's a 1961 Mooney M20B. Doesn't look much different from any other small single-engine plane. Low wings, four seats, two-bladed propeller, and so on. It's radically different from the Cessna 172M I've been flying, though. There aren't any self-esteem issues among flying machines. Some airplanes are just better than others, period. And when they are, they say so, loudly. The Mooney M20 is what's known as a complex, high-performance airplane. In aviation parlance, "complex" equates with "bells 'n' whistles." Complex airplanes have extra goodies like retractable landing gear, specialized flaps, and variable-pitch propellers. If you want to know what a variable-pitch propeller is, you'll have to ask somebody else. I'm not really sure. I spent about 20 minutes this morning quizzing my second boss, Spud, what exactly the hell a variable-pitch propeller does. He explained it to me as best he could, he being a former Air Force jet pilot and me a dribbling halfwit student with only 40 flight-hours. I'm afraid I didn't understand most of it. The propeller hub is filled with oil, and has counterweights in it, which can be adjusted to tilt the blades about 30 degrees or so, to increase their efficiency in flight, which reduces unnecessary drag and saves fuel. That part I was okay with. But then we got into a big hairy discussion about mixture controls, and the vacuum pump, and manifold pressure...and visions of tiny dancing daisies began to spring unbidden to my mind. My brain, tired of jumping around trying to catch all the stuff that was flying over my head, was attempting to activate the screen saver. I found it most irritating, particularly when I was trying to comprehend how manifold pressure relates to throttle settings, and...

"High-performance" means that you have more than 150 horses under the cowl.

Mr. Mooney's Mooney (hereafter referred to by its model, Mooney, and its call sign, 17) has about 180 horsepower, retractable landing gear, cowl flaps, a variable-pitch propeller, an electric fuel pump, and a whole bunch of add-ons. It's painted white, with gray and aqua stripes. (The previous owner was a dentist. I assumed the aqua was some kind of toothpaste pitch, but I was mistaken. His wife just liked the color. Mr. Mooney hates it. My other two bosses, Spud and Dawg, continuously rib him about how awful it looks.)

Between Mr. Mooney's ready narration and the mere act of sitting in the plane, I have become rather familiar with Mooneys. They have lots of endearing little quirks. They're much more idiosyncratic than my friendly old Cessna, that's for dang sure.

My workday starts when I drive into the airport and up to Hangar Five. We go in through the little door, unlatch the big door, and open it. Mr. Mooney attaches a towbar to the front wheel, and I get behind the right wing. He pulls and I push. We roll the plane out of the hangar. It's usually nippy in the mornings this time of year. Mr. Mooney manually rotates the propeller a few times, just to loosen up the engine's innards. He makes sure that the master switch in the cockpit is off, though, before he does this. Otherwise the plane could start up unexpectedly, and he could "wind up" without arms.

After we preflight M17, we climb in. We have to actually climb up on the wing to get inside. Mooneys, oddly, have only one door, on the right side. So Mr. Mooney gets in first, slides himself over into the left seat, and then I get in. It's a tight fit. Both of us are about six feet tall, and broad-shouldered. Mr. Mooney scoots up close to the controls, and I sit back. I close and latch the door. It's strange. Forward visibility is more restricted, thanks to the two-part windscreen. The Mooney is a low-wing aircraft, meaning I can't look out the side window and see the ground anymore. There are a few more knobs and switches in the Mooney than I'm used to: controls for the variable-pitch propeller, for example. There's also an enormous gray lever extending up from the middle of the floor, just underneath the control panel. It looks like a thick gearshift. It's called a Johnson bar, and it operates the landing gear. Instead of flipping a tiny switch, Mr. Mooney grasps this bar with his right hand and wrenches it backward and down, latching it to the floor between the seats. I have learned to scrunch myself against the door and keep my elbows and shoulders out of the way, or else. Then the gear goes up. To put it back down, Mr. Mooney reaches down, grabs the bar, and yanks it back up, locking it into place under the control panel. Gear down.

Needless to say, I was rather impressed with this mechanism. I've heard of hand-cranked landing gear, requiring 33 turns of a little metal wheel, but this Johnson bar takes the biscuit. Mr. Mooney tells me it's far more reliable than any switch or button. That's true, I reckon, but neither switches nor buttons require biceps to operate.

The Mooney is a zippy little plane, though, and has enough horsepower to stay well abreast of the UAV. In fact, the UAV doesn't go that fast. In the air, we have to weave behind it to keep ourselves from shooting past. Mr. Mooney starts the engines while I hook up the GPS and the TKAS systems. The GPS is a Garmin 396, a good basic mid-range navigational aid. "TKAS" stands for...um, stands for...uh...

It's a collision avoidance system. It's a squat gray box with a low-bit screen on the front. It's attached with Velcro to a little platform we've rigged up for it, and hooks up to the GPS with a cord. The data from the TKAS is displayed on the GPS as a small black screen, inset over the main display. It has two little concentric circles on it, representing one-mile and three-mile radii from the plane. As we fly, I keep my eyes glued to the GPS, the TKAS, the UAV and the skies nearby, to make sure nothing out there smacks into anything else. I'm an extra set of eyes. In fact, that is my technical job description. I am the observer.

Mr. Mooney and I take off from the Apple Valley airfield and swing west to head to Victorville, about ten miles away. Barely a minute in the air, and we're inside their airspace. Mr. Mooney swings north so we can get behind the UAV—a gray speck on taxiway B—as it takes off to the south.

On the first day, takeoff went perfectly. We followed the UAV out to the test site, a 20-minute flight or so. It was tough to see the little spindly-winged bird until it climbed above the horizon and was silhouetted against the bright sky. Mr. Mooney and I came back to Apple Valley and twiddled our thumbs for six hours until the afternoon flight, when we jumped back into M17, took off for the test site, and caught the UAV as it flew out. (I actually spotted it first; Mr. Mooney congratulated me heartily, saying "I'd earned my pay.") We escorted it back, handed it off to the ground controllers, landed at Apple Valley, and went home.

The second day was a bit weird. It was windy, which meant things were quite bumpy aloft. There were a few minor technical difficulties to sort out, which meant that Mr. Mooney and I had to land at Victorville and spend twenty minutes chilling in the FBO. (Fortunately, they had free popcorn and bottled water.) We flew a quick local mission and then went home.

This week I'm flying with Boss #2, Spud. Spud barely made it down from Nevada in the company Mooney, Sierra Hotel (a 1964 M20E, named for the last two letters of its call sign). There's a high-pressure system down the hill in the L.A. Basin. Conditions up here, then, are ridiculously blustery: 25-30 miles an hour sustained, gusting to 50. It's been that way for the last couple of days. Spud was getting severely tossed around, coming down through the Owens Valley. On top of that, the governor on the variable-pitch propeller was acting up, too. But he made it.

It's so windy, however, that flights have been canceled today and tomorrow. Spud and I spent the morning helping the mechanic down at the airport investigate that misbehaving governor. I'll tell you some more about that next time, I reckon. Let me fly an actual mission with Spud and then I'll get back to you. I can't wait until this spring weather clears up and we can start flying...

Oh yeah...and I'll tell you, in my usual roundabout way, why the word "refraction" is so important to what I'm writing about.