Ground Reference, Part 2
We're in the middle of our third lesson. We've flown along a power line and learned to set up a crab to compensate for wind drift, flown a rectangular pattern around a field, and just finished doing turns around two big water towers.
1. Speed, a Trick, and the Yaw String
“Hey Walt, this is my first landing on a grass strip. It's kinda neat. I didn't know you could land an airplane in a place like this.”
Says Walt, the old timer, “Heck, this is a big field. And it's flat and fairly smooth. You should see some of the strips people fly ultralights out of around here. They're short, narrow, up and down hill, and some have ruts and holes you have to dodge. Shucks, people fly real airplanes in and out of here all the time.”
“Let me ask you, why did it look like we were going so fast on final and while we were getting ready to touch down? We were really moving on!”
“Nah, not all that much. On final, we had the tailwind pushing us along. Our ground speed was airspeed plus the speed of the wind, so we would've been doing about 60 mph ground speed. But, that's 20 percent faster than our airspeed of 50.
“What's important is that you use your airspeed indicator to judge your speed rather than to look outside. If you slow down until things on the ground pass by at what seems to be a normal speed, your airspeed will be way too low and you could tear something up. That's one of the few times when it's better to read a gauge than to look outside the plane.
“Now when we got near the ground, the wind speed was practically nothing. See, there's very little wind blowing here on the ground. But go up 50 or a 100 feet and it's a different story.
“The extra sensation of speed near the ground is an optical illusion. On that big, paved runway across the hill, there's not much to look at in the way of detail. But here on the grass, we see weeds, clumps of dried grass, ruts, and tracks, all whizzing by, and that gives us the impression of going faster. You'll get accustomed to it in short order. And the trees are closer as well!”
“Yeah, Walt, now one other thing. That trick you showed me about being sure you're going to clear the tree ... Will that work on any tree, or just that one out there?”
“Heh heh heh ... It'll work for any tree, or anything else you're trying to get across. Just look at the highest point of the obstacle, whatever it is, and see where it falls this side of the runway. That is, if you shined a light from the plane, where would the shadow of the highest part of the obstacle fall?
“Then watch that point. If it moves upward, that's a sign that you're moving downward. At the same time, the tip of the tree, or whatever, will appear to be moving upward. When you see that, you ain't gonna make it. You need to add power.
“But if the point moves downward, or the tip of the tree seems to move downward, you're too high and need to reduce power. And it goes without saying that when you get real close to the tree, the tip of the tree needs to be moving downward. ... heh heh heh ... Otherwise, it would hit you square between the eyes!”
At this point, Walt pulls something out of his shirt pocket and walks around to the front of the plane. “Forgot to put the yaw string on before we took off.”
He has a short piece of red yarn about 4 or 5 inches long with a Velcro tab on one end. And down near the bottom of the windshield, there is another Velcro tab glued right to the center of the lexan. He sticks the yarn onto the windshield.
“You know what this is, don't you?”
“Yeah, I've read something about it and heard people talk about it, but I've never flown with one. I know it shows the direction the wind is blowing across the windshield.”
“That's all you need to know right now,” says Walt. We'll see what it does once we get in the air. You ready to do some more flying?”
2. Takeoff and S-Turns across a Pipeline
We climb back into the Challenger, fire up the 503, and after it warms up a bit, taxi out across the grass to the end of the strip. On the way out, Walt describes the takeoff procedure: full power, back stick to take the weight off the nosewheel, be alert with the rudder to keep the plane straight; at 35 mph raise the nose slightly, and get a definite liftoff by the time the airspeed reaches 40 mph.
Once off the ground, release backpressure just a bit to let the airspeed build up, but don't let it settle back to the ground. And whatever you do, don't PUSH the stick forward ... just let off on some of the backpressure. You can wreck if you push the stick forward because that would make the plane dive back to the ground.
We point the nose of the Challenger down the center of the field. Hold the brakes and run it up to 3400 RPM for a mag check. Throttle back. Everything looks good to go.
Walt says, “Let 'er rip!”
We release the brakes and push the throttle forward smoothly. The nose starts to the left, but we catch it with right rudder. The plane accelerates rapidly, bumping along over the grass, which is not as smooth as a paved runway. The airspeed indicator comes alive. At about 20 mph, we pull back on the stick just to take some weight off the nosewheel. At 30, the nosewheel is off the ground.
When the airspeed indicates 35, we give a definite backwards nudge of the stick. The nose rises, and the Challenger climbs into the air with a considerable nose-up attitude. After it is up to a height of maybe 3 or 4 feet, we relax the backpressure on the stick and let the nose come back down a bit, but it remains nose-high. The airspeed is now up to 45 and rising, ... then 50, ... then 55.
When the airspeed gets to 55 mph, we increase the backpressure on the stick to keep the airspeed from going higher. We climb out at 55 mph. The Challenger climbs at a steep angle because of the headwind. Soon we're 300 feet or more above the ground.
“Very good takeoff,” says Walt. “Now do a climbing turn to your left and circle back over the field. Level off at 1300 feet on your altimeter. Take up a compass heading of 330 degrees.”
Let's see now .... climbing turns are supposed to be shallow. And you MUST watch your airspeed. OK. Bank to the left about 10 degrees, which is not steep at all. Keep the ball centered with the rudder ... Have to release backpressure just a bit to maintain 55 mph.
Now we're approaching 1300 feet while still in the turn. Lower the nose in order to level off. Airspeed begins to build up, passing through 60. As it nears 65, we reduce the power to give 5700 RPM. We've now turned through a little over 180 degrees and are headed back, straight across the field. We level the wings and fly straight ahead.
After maybe 15 or 20 seconds, the compass settles down to about 345 degrees. Now, just a bit of a turn on to the left brings the plane to a heading of 330 degrees. We're straight and level. Everything seems to be in order.
In a bit, Walt says, “In a mile or so, you should see a long, straight path cut through the woods that goes for miles. That's the gas pipeline. You'll be flying almost straight across it. When you get there, turn left and follow it for a while.”
Golly GeeWhiz! We're flying this thing! Walt said the takeoff was good! Maybe this flying business is not as hard as I thought. Now if I can just find that pipeline. He said “long straight path through the woods ...” Don't see it yet.
Altitude 1350 ... bit high. Airspeed 67 ... close enough. Compass heading ... thing is oscillating back and forth between 325 and 340. Maybe come to the left just a little ... RPM is 5750. Back it off just a tad. Lot of trees down there. Hope this motor don't quit. Don't see that pipeline.
“Hey Walt, help me out. Are we close to the pipeline yet?”
“Should be getting close now. I'll give you a hint ... look out to the side instead of always straight ahead. It may be easier to spot that way.”
We look to the left, then to the right. Nothing. Keep on going. Then suddenly, there it is. A big wide swath cut through the forest that goes as far as the eye can see. We bank into a left turn to fly along it. Overshoot it a bit, but after a bit of “coming back,” we're directly over it and lined up with it.
But the plane starts drifting to the right. That's the wind from the south blowing us to the right. Set up a crab of a few degrees ... the plane actually points to the left of the pipeline, but we track right down it. Piece of cake!
“OK, what I want you to do now is to do a series of turns back and forth across the pipeline. Make a track like a snake crawling along the pipeline. Keep the turns centered on the pipeline, equal on the left and right. This is what we call S-turns.”
We begin with a shallow bank to the left and turn away from the pipeline. When we're a few hundred yards to the left of it, we roll out of the left bank and roll into one to the right. The plane turns back toward the pipeline, and quite soon is directly over it again. Now the next turn to the left ... but the plane swings way out to the right of the pipeline, much farther than what we were on the left.
OK. Steepen the bank a little to get back, which seems to take a long time. Then, a shallow right turn as we cross over to the other side of the pipeline and start the turn in the other direction.
Finally, a comment from the back, “Have you been watching the yaw string?”
“Yeah, it keeps swinging from side to side.”
“That's showing you that you're not perfectly coordinated with the rudder and stick. The string is much more sensitive than the ball.”
Half way through the turn, now on the left of the pipeline, we can see the plane already drifting to the right even though it's pointed parallel to the pipeline. The wind is tending to blow us back across it. As we come on around, we start moving to the other side in a hurry.
As we cross over, we set up a fairly steep bank for the turn on the downwind side of the line to keep from being blown over into the next county, as Walt says. This seems to work. We turn fairly quickly and soon are headed upwind again. At this point, we reduce the angle of bank and much more slowly work our way back to the other side.
After two more passes back and forth across the pipeline, Walt comes on from the back seat, “Now make the turns more pronounced. Make a full half circle on each side of the line, and try to cross the line going at right angles to it.”
This is hard to do at first. Without the wind, it would be easy, but the wind is always blowing us to the right so the angle of bank you need is constantly changing. Then a little light comes on ... Talley Ho!
When we're going with the wind at a high ground speed, we need steep angles of bank to turn quickly. Going upwind at a lower ground speed, we need a shallower angle of bank. With this idea, it's not so bad, but it's still hard to get the turns just right so we pass over the pipeline at right angles to it.
3. Flying in the Beans
“See the river up ahead? That's the Yadkin river. Let's go down a little and make a right turn where the pipeline crosses the river, and fly up the river about a hundred feet above the treetops. Reduce your power a little to get down a bit quicker.”
We straighten out above the pipeline and throttle back to about 5000 RPM. We let the nose go forward, and we start going down at what seems to be a pretty good clip.
“Walt, we're going down fast! Is this OK?”
“Yeah, you're OK. We're fairly low already and you can see changes in altitude a lot better when you're down like this. You can raise the nose a little as you start to make your turn. Don't forget to put the power back in it.”
As we approach the river, we bank to the right and come around directly above it. We roll out, increase the power and level off. Boy, you can really see the treetops and things on the ground now!
“You're still a bit high. Take it on down.”
“Walt, are you sure about this?”
Easing the stick forward ever so slightly lets the plane settle on down closer to the trees. Finally, Walt says, “This is good right here. Now follow the river for a while.”
The river is fairly straight in this section, so there's not much to do in the way of turns. But we seem to be going really fast! Airspeed is 65, which is normal, but we're going with the wind, and we're close to the trees. We can see the speed.
Uh oh. The river makes a left turn up here. This ought to be interesting.
As we approach the turn, we bank quickly to the left, and give it too much rudder. The plane skids to the right. Shallow the bank; ease off the rudder. Now we're not turning fast enough, drifting over to the right of the river. Steepen the bank ... and finally get back above the river as it straightens out again. Oh boy.
Long straight section ahead of us now. Thank goodness. No comment from the back. Whew! Somebody's down there fishing. Wonder what they must think! We fly along for a minute or so, and the river turns back to the right.
This time, we bank more gradually, judging the bank needed by how the plane responds. And we go easy on the rudder. That skid back there was not pleasant. We make it around the turn and roll out into another long straight section.
Walt comes on the intercom, “Let me have the plane for a minute. I want to show you something. See that big field of soybeans over to our right? Let's go over there and see if there's any bugs on them.”
Walt takes the plane, reduces power a little, and then turns across the line of trees beside the river. As we cross the trees, he noses down in a bank to the left, and goes right down in the field.
“Walt, we're below the trees over here!”
“Yeah, but the trees are tall.” He puts the power back in, and we fly along the rows of beans about 10 feet above them. Smooth and steady. This sure is a big long field!
“Is this safe, Walt? How do you know there's not a power line or something going across here?”
“I think it's OK. If we have an engine problem, we'll just land in the beans. And I've flown down here a hundred times, at least, and I already know that there are no power lines crossing the river in this section. Nobody lives around here either.”
“Walt! Up ahead ... there's a line of trees going across the field!”
“Where? Are you sure? I don't remember any trees going across here.”
And we go barreling down the bean rows at 65 mph headed straight for the trees. Hope Walt is just kidding! We're way below the tops of those trees.
As the Challenger seems destined to crash into the trees, we feel Walt lift the nose, and amazingly, the plane rises smoothly up and over the trees. And on the other side, another big long field of beans. The plane settles back down, but not quite as close to the beans as before.
“You wanta try it now? Go ahead. Just don't shove that stick forward ... heh heh heh ... !”
Here we go. Plane stays level for a few seconds, then starts to climb. We nudge the stick forward a little and the climb stops, but it won't go back down.
Walt says, “You're up too high. I'm getting hypoxia. Get it back down a bit.”
“It won't go down, Walt!”
“ ... heh heh heh ... Sure it will. It's not the plane ... it's YOU! You're afraid of the ground. That's why it climbed up with you. You were pulling back on the stick without realizing it. Now ease it back down ... easy, please.”
A conscious effort is required to push the stick forward and let the plane settle toward the beans. Wow! This is a trip! Level off now. Oops, climbing again. Stick forward just a tad. Whoa! Headed toward the beans in a hurry ! !! Pull it up ... now way too high. Stick forward to get back down ... sinking too fast ... pull up ...
“I've got it,” says Walt from the back as the plane suddenly stops it's bucking bronco routine. “You're overcontrolling. Take it easy. Straight and level 10 feet above the beans is no different from straight and level at 5,000 feet. Let's trim it out.”
Walt tweaks the trim wheel a tad, then fiddles with it a bit more ...
“Now look. It's flying all by itself, right above the beans!”
“Walt, there's some more trees up ahead.”
“Yeah, I see 'em. You've got the plane.”
As the trees approach, we hold off until the last minute, then pull back on the stick. The Challenger literally jumps straight up ... way before we get to the trees.
“Bit heavy on the backpressure, weren't you? Continue your climb this time. Let's go back up a couple of hundred feet.”
As we cross the trees, we see that there is a solid stretch of woods for a mile or so, and the river turns to the right, fairly sharply.
“Stay with the river.”
We turn right, following the river for a short distance, and then it turns to the left, abruptly. We roll into a steep bank to the left, trying to stay directly above the river.
“Airspeed ... Add power!”
Oh boy. Forgot about adding power in a steep turn. We shove the throttle forward quickly and roll the wings back toward level. River sails off to the left!
“Sorry about that, Walt.”
“Well, I would tell you not to worry about it, but when you're low like this, you can't afford to mess up. A rule of thumb is, when you bank to make a turn, you add power. Better to add it when you don't need it than to need it and not have it. Now, see if you can find the river again. Back off the power now. Your recovery was good, but you flunked following the river.”
A gentle left turn brings us back over the river just as it makes another turn to the right. Roll to the right, gently, then another straight stretch before it turns to the left again.
“At this next turn, fly on past the river and then make a turn to the left down a long field of corn. Take it down a bit when you get to the big long fields.”
OK. Here we go. The river turns left, but we stay straight, a hundred feet or so above the trees. And there are the fields of corn. We make a gradual left turn and head straight down the middle of the fields. Ever so slowly, we let the Challenger settle down toward the corn. Try not to overcontrol. Easy, easy.
4. Flying the Yaw String
We fly along the corn briefly, and then Walt says, “Now watch the yaw string. Just touch the rudder pedals lightly, left, then right, and see what the string does. Keep your wings level.”
OK. A nudge of the left rudder pedal and the top of the string slides off to the left as the nose of the plane swings to the left a little. We're now a bit sideways to the corn but still traveling in about the same direction down the long rows. Then, a touch on the right pedal and the top of the string swings to the right.
“See what the string is doing?”
“Yeah, it always points down the rows of corn. It shows you where 'straight ahead' is.”
“Well, yes it does,” says Walt. “Shucks, I'd never noticed that. The way I think of it is that the top of the string points to the side where you have too much rudder. Or, the bottom points toward the side where you need more rudder. It amounts to the same thing. Now try it again. Push it sideways then see what the string tells you that you need to do to get the plane back straight.
“Oh, by the way, you've got a line of trees up ahead.”
GoodGaudAmighty! How could we not notice those trees? Gentle backpressure on the stick and we rise over them, nice and smooth, and then settle back to another long field on the other side. Now back to the string.
With the wings level, pushing the right rudder, when you don't need it, causes the top of the string to move to the right, showing where you don't need the rudder. Or, the bottom points to the left, showing where you do need it. Simple, and it works.
“Hey Walt, you can really see the plane skid to the side when you give it the rudder it doesn't need. It'll move across a dozen rows of corn in a heartbeat.
“Hey Walt! The whole field curves around to the right. What do I do?”
“My suggestion would be to make a turn to the right.”
So here we go, ... roll into a turn to the right and add a little power, staying in the middle of the field, not more than 20 feet above the corn. Playing with the rudder keeps the yaw string smack dab in the center. This little ol' Challenger swings right around, as smooth as silk! And, it seems like if you don't worry about the altitude so much, or the lack of it, it's a lot easier to control. Amazing!
“When you get to the end of the field, pull up a couple hundred feet. We've got a bunch of woods coming up.”
When we climb up above the trees at the end of the field, we see another huge field up ahead that must be a half a mile in diameter. And the river crosses underneath us.
Walt says, “Let's circle around that field and head back down the river. You can drop down a tad if you wish, but don't get too low because that field ain't exactly level. It rises on the other side over there.”
We drop down a bit and start a smooth circle around the field. We can tell the wind is blowing us along a bit, so we steepen the turn as we start running downwind.
“Hey Walt, look down there! There's a field full of deer! A whole herd of them.”
“Yeah, we see them a lot out here in the open country. Watch your altitude!”
Oops! Got to looking at the deer ... Wow! ... Was slipping right toward the ground! Good grief ... roll the wings back level and pull the nose up to get us back up out of the weeds!
After circling the field, we head back down the river, flying over the river and ducking over into the fields when we come to them. The yaw string is tricky, but it really helps to keep the Challenger feeling “smooth” in the turns. In a short while, we come back to where the pipeline crosses the river.
“Let's climb up to altitude now and head back to the airport,” says Walt. “It'll soon be time for lunch.”
We start a full-power climb by first raising the nose and then adding power as the airspeed drops to 55. We remember making a right turn to go up the river, so we begin a very shallow climbing turn to the left.
As we gain altitude, we spot the Churchland twin towers over to the left, and we can see the headwaters of the lake way down on the right. We head off in a direction between the towers and the lake. Can't see the airport yet.
“How high shall we go, Walt?”
“Go up to about 1500 feet. That's pattern altitude back at the airport, so we might as well get set up to enter the pattern.”
In five minutes or so, we spot the big plant south of the airport, and then recognize the big hangar up on the hill. Piece of cake! We turn to the right a bit, and head straight for it.
5. Landing in a Crosswind
“Davidson County Unicom, Challenger niner Whisky Bravo, 4 miles to the northwest at 1500, active and reported, please?”
And back over the radio, “Hey Walt, thought you'd got lost! Isn't it about time for your nap? No reported, but the wind has swapped around and is now favoring Runway 6. Showing 11 mph out of 140.”
“Thanks, Charlie. We'll give it a try on 6.”
“Hey Walt, is it legal to talk like that over the radio? I thought it was supposed to be strictly business.”
“Well, it's not illegal, and I guess we really shouldn't, but there's not much going on today, and ol' Charlie gets bored. Most people aren't flying because of the wind.”
“Turn slightly to the right now, and when you get in line with the runway, turn back to the left and track straight toward it. You'll need a crab to the right.”
After turning right, and then back left, we're in line with the runway. Altitude is still 1500 feet. We look around for other planes but don't see any. For the first time, we become aware that the plane is bumping around a bit in the thermals that are now developing. Funny how you get used to them.
“Davidson County traffic, Challenger niner Whisky Bravo, straight in on Runway 6, three mile final, Davidson County.”
“Pull the power back to about 5000 RPM now and slow us down to an approach speed of about 50 mph. Hold this speed, and control the descent with the throttle.”
So here we are on final. Crabbing to the right so that we're heading toward the runway sort of sideways. We seem to be getting a bit low, so we add a little power. The thermals make it hard to hold a smooth descent.
About a half mile out from the runway, ... “Davidson Country traffic, Challenger niner Whisky Bravo, short final, Runway 6, Davidson County.”
We're getting closer to the ground now, and the air seems to be getting rougher. Airspeed is 50, or pretty close, ... it waggles up and down with the bumps.
“Walt, is this gonna be OK? Seems sort of rough.”
“Well, you never know. Hold what you got and work it on down. Keep the power in to control the rate of descent ... we've got a pretty good headwind. Usually, it will smooth out when we get down next to the runway. We can always hope.”
We were wishing for a more confident response from Walt, but still holding the crab and with a bit of power still in it, we fly across the interstate and cross the end of the runway at maybe 50 feet above it.
“OK, I'll take it now,” says Walt. “Good deal,” we say, with a bit of relief.
But he doesn't do anything any different. The plane flies on down the runway at the same rate of descent, still in the crab to the right. When we're just off the pavement by a few feet, Walt reduces the power, gives it left rudder to swing the nose around so that it points straight down the runway, and lowers the right wing.
We touch down on one wheel! Only after the plane is down and rolling out does the left wheel drop, and then, in short order, the nosewheel touches. We feel Walt working the rudder pedals rather smartly, and then he gets on the brakes. The Challenger slows to a crawl just short of the midfield turn off.
“Hey Walt, that was pretty good!”
“I'll take it,” says Walt. “It's always good to be down when the wind is blowing like this because you never know when a gust will hit you and send you off into the weeds. You always gotta be ready for that gust, but always hoping it doesn't show up.
“Ok. You can taxi us back to the hangar, but keep it slow. That wind will whip you around in a heartbeat if you don't watch it.”
We taxi back to the hangar and shut down the 503. As we roll the plane into the hangar, Walt says, “Hey, what's wrong with your face? All I can see is teeth!”
“Yeah, Walt, that was great. That wind will really blow you around won't it, but flying down next to the beans, ... that was something else ... and those turns over the river ... and there was a bunch of deer out there ...“
“Yeah, I get the picture,” says Walt. “But let me tell you something. After you solo and get to flying by yourself, don't you even think about going out there and doing that for a long, long time. It's not hard, but it's critical. If you get distracted for just an instant when you're that low, you can mess up big time and wreck an airplane. And it's always a shame to wreck a nice, pretty airplane.”
“Yeah, Walt, I understand. But it was still great. And I won't.”
“I think you figured out that wind business. When you're going with the wind, you're moving faster over the ground and you've gotta turn sharper to make your track good. Against the wind, it's just the opposite.
“But you've gotta always remember, ... beware of steep turns, especially at low altitude. Turn steep, add power. Now today, we were doing ground reference and it helps to be close to the ground so you can see what is going on. But normally, we don't do stuff like that, especially on windy days.”
And Walt suddenly grins, as if he just remembered something good. “Let me tell you one about talking trash over the radio ... heh heh heh ...
“One day a month or so ago, the wind was blowing directly across the runway, 15 steady, gusting to 20 or more. Nobody, but nobody, flying, except one of the hotshot corporate pilots from up on the hill coming in on 24 in one of those big twins.
“He'd called in several times asking about the winds, and Charlie would read him the numbers, which was not good news. Finally, he gets over the runway, and the wind is blowing him around all over the place, but he finally gets it down about midfield, touching down on one wheel . Then it's hard braking to get stopped because he was carrying a bit of “extra” airspeed.
“So after he gets down and is rolling out, trying to get stopped and keep that thing on the runway, ol' Charlie, who is not a pilot and who never flies, gets on the radio and says, “See there, you done landed that entire big ol' airplane on one wheel and only needed half the runway. What's the problem!”
“The silence on the radio was loud and clear! Ha ha ha... Love it!”
“Walt, you mean the wind blows those big airplanes around too?”
“You'd better believe it. The only difference is that you can tear up a lot more stuff in a lot less time in one of the big ones.
“Lunch time! See you again Saturday, right?”
“Yeah, Walt, thanks a bunch. I'll be here!”
Author: Doc Green