Bill Crawford’s Flightlab Blog

I went a few months without posting my columns from the Atlantic Flyer. So here’s to catching up.

You’d think that an aerobatic maneuver as apparently straightforward as a loop would be a cinch to perform: Dive for speed, haul back on the stick, and then be patient until the world appears more or less as it was before. That’s certainly the core idea, but it’s not by itself a sufficient plan. We want a round loop, something Euclidian. And we want a loop in which the wings remain level with the horizon throughout the maneuver.

Roundness isn’t easy. It comes from flying a constant radius, which itself isn’t easy because the aircraft is busy changing speed and also its relationship to the pull of gravity. If you could hold your speed constant during a loop, roundness would be a matter of staring at the G-meter and adjusting your stick force to maintain a constant G value. The trouble is that speed doesn’t stay constant, but decreases in the climbing part and increases as you come back down. (Your exit speed, by the way, is always a bit lower than your entrance speed, due to the induced drag those Gs cost.) Because of the change in airspeed during the loop, you have to vary the G-force to maintain a constant radius. In practice, you pull pretty hard at the start because you’re going fast, ease up over the top because you’re slowing down, then start pulling hard again as the nose passes through vertical and comes back up to the horizon.

The problem with roundness is that as a pilot you can learn to infer it, but can’t actually see it. You are yourself within the phenomenon you’re trying to observe. To remove this epistemological roadblock you need help from an aerobatic coach on the ground, to see the loop for you and keep you apprised on the hand-held. If your coach radios “flat spot,” your pitch rate (thus G) was too low for your airspeed. If your coach says “pinched,” you pulled too hard—your pitch rate was too great for your airspeed. Eventually, if you have a good coach and aren’t a complete dullard, you learn to associate each part of the loop with its appropriate pitch rate—at least from a given starting speed, and at least in calm winds. When the wind is blowing you have to compensate by increasing your pitch rate if the wind is behind you in the loop, and by decreasing it if the wind is ahead. Windy conditions are a pain.

In an aerobatic competition, big loops tend to score badly because the judges can easily see variations in radii (flat spots and pinches). If you’ve got a fast airplane, you’ll have to pull pretty hard initially to keep the loop from getting too big. When I had my little Giles G-200, which was fast, I was pulling 6-G loop entries in an effort to keep them small. That was during my irresponsible period, but at least I slept well. Training in the Flightlab Zlin or Air Wolf, we pull about 3 G entering a loop, and maybe 0.5 G floating over the top.

Keeping the wings level with the horizon isn’t easy, either. Imagine you’re beginning a loop from a slight bank angle. Model this with your hand. As a banked aircraft pulls from level flight to vertical, one wing will end up lower than the other. In other words, after ninety degrees of pitch-up, an initial roll error becomes an error in yaw. If you just continue merrily along, that yaw error will again become a roll error, ninety degrees later, at the top of the loop. That roll error, in turn, becomes a yaw error as you head through vertical on the backside. Finally, as the nose returns to the horizon, the aircraft is again banked and you’re no longer headed in the direction in which you started.

All aerobatic maneuvers are extremely sensitive to initial conditions. In other words, if you screw things up at the start you have to work extra hard to make things come out happily in the end. Most beginning aerobatics students have a tough time keeping the wings level on the initial pull into a loop. With the right hand on the stick, there’s often a tendency to pull slightly to the right when pulling back. Sometimes it’s hard to track the resulting bank error, because the nose rises quickly above the horizon and the familiar roll references pass from view. In a loop, once you lose the horizon ahead, you look at the wingtip in order to judge attitude and position in the maneuver. If a wing is up or down when you hit vertical, a quick jab on the rudder can make things right. But it takes practice to learn where to look to identify errors, to recognize them, and then quickly to make the fix. Eventually, you pick up errors right as they begin. Then small, easy corrections are all you need.

I like to remind my sometimes-frustrated aerobatics students that you can’t learn to see errors unless you make errors. So lighten up. It’s all data, and it’s all useful if you’re willing to persist. I’ve noticed that good aerobatic learners take their mistakes more or less in stride. They don’t hurl a fit or have smoke come out of their ears. There’s no ego to nurse. They understand the relationship between making errors and making it to the next level.

Tonya Hodson has just become my go-to person whenever I need someone dumped from an airplane. I should clarify this: I mean the memorial dispersion of a loved one’s ashes, not the sudden disappearance of a business partner.

Unlike my male flying buddies, whose behavior is hard to predict, I trust Tonya to keep the mood solemn and appropriate. She was in the funeral business in Kansas for seven years (working the dry side, I believe), and so knows how to finesse the bereaved. She also owns a Stearman and flies formation at AirVenture. She recently won the Red Baron Memorial Scholarship for Aerobatic Training. Who better for the dispersal job?

An article by Tom Benenson, “Scattering Ashes,” in the October 2007 issue of Flying called these thoughts to mind. Benenson quotes from an account on the Internet that describes the basic problem: the somewhat lower pressure within the cabin, compared to outside, tends to suck the stuff back in. The typical narrative includes a lot of work with a vacuum cleaner. Airplanes are full of good places for ashes to hide. It may take several annuals and maybe an overhaul before the departed has truly done so.

Here’s Tonya’s response to my email inquiry as to whether she had ever dispersed ashes during her funeral parlor days, out there on the wide and rolling prairie.

“Yep, the first time was out of a Skyhawk. Dropped a preacher man over his church in the country with the congregation watching from below. Actually it was quite a moving experience. But aren’t all firsts?

“Next was out of the Stearman. A mother died of cancer and had pre-arranged the whole thing herself. We spread her ashes out in the Flint Hills about 25 miles east of Marion. Her husband and children were watching on top of the hill. We made a circle, and then dropped on the second pass. The air was really calm and the prop wash was well defined by the ashes. We got photos of the circular motion from the ground and the air on that one. Pretty cool.

“Her husband died about 10 months later and we dropped his ashes exactly one year later over the exact same location in the hills.

“Make sure the crematory runs the ‘cremains’ through the grinder at least twice; let them know they are to be dropped from the air and need to be extra fine. It costs a little more but it sure saves the paint on the plane.

“As far as I can tell, there is no way to keep the dust from settling on the side of the plane. I’ve heard of people running PVC pipe down the side of the plane. Never tried that.”

I hope Tonya can find the photographs showing the motion of the prop wash, as revealed by “cremains.” That would be educational, and also bizarre.

Wikipedia.org is full of information on the subject of cremation: Hindus swear by it, Roman Catholics often have mixed feelings. Zoroastrians prefer to expose the body to the elements. Most of the soft tissue turns to vapor and escapes through the crematory’s ventilation system. The ash that remains represents only about 3.5% percent of the body’s original mass. The mean yield in Florida is 5.3 pounds. If you leave a pacemaker inside the body, it explodes when the flames arrive. After the first time, apparently, this is no longer fun, and the originating funeral parlor gets in lots of trouble.

In her email, Tonya mentioned two trips through the grinder as a good idea, which is in conformity with industry recommendations for aerial dispersal. Wikipedia’s treatise contains a photograph of a grinder operator. He’s herding ashes down a hole in a sink. The apparatus looks suspiciously like a commercial kitchen garbage disposer. Even better, he’s wearing a Super Bowl XXXVII sweatshirt with the skull logo of the Tampa Bay Buccaneers. Even better than that, he’s smoking a cigarette. I don’t see an ashtray. Tonya says that when she got out of the business, around 2002, a second trip through the grinder cost the funeral parlor an additional $50. What a racket! It’s also the case that the grinder may not be perfectly cleaned of the previous set of remains before your party’s ashes go crunching on through. That means you may end up vacuuming a complete stranger out of the Cessna.

In a follow-up call, Tonya reaffirmed that residue is inevitable. Some ash is going to stick to the sides of the airplane, or to your delivery device, or to the inside of the ash container, no matter what. In the case of the airplane, this is just the nature of the boundary layer, in which the speed of the airflow becomes zero at the surface, and you can’t blow the dust (or Uncle Edgar) off, no matter how fast you fly. The only solution, according to Tonya, is discretion. Be prepared to keep the bereaved away from the airplane when you land. Only an amateur would promise airplane rides afterwards.

I’m not finished complaining. Last month the gripe was airshow jingoism. (One email in support, one righteously aghast.) This time it’s the editorial overuse of the phrase “the dream of flight” and its related constructions.

For example, the sentence “As a boy in Kansas, Edgar was seized by the dream of flight, believing that one day he too would soar….” Or maybe something like “For thousands of years, mankind gazed upwards, watching the birds follow their long, lonely track across the sky, and dreamt the dream of flight, until finally two brothers….” That sort of overly lofty stuff is what I’m complaining about now. The phrase “dream of flight” has a definite annual cycle, like ragweed, peaking with the advent of AirVenture every summer, which is why I’m irritable. Read EAA’s Sport Aviation and all the Oshkosh hype. You’ll see.

(I suppose you think I could come up with something less arcane and more compelling—or actually informative—to write about, since it’s only twelve times a year. I won’t disagree. Unfortunately, the grease-stained muse of aviation prose takes August off and I’m pretty much out of Schlitz, inspiration-wise. I don’t know how the other guys do it. Better column next month, I promise. But please continue.)

Beyond our well-founded objections to the relentless use of cliché, we complain that what’s usually being described is actually mere daydreaming. The kid in the cornfield, the upwardly gazing caveman, or perhaps the fellow who is thinking about building an RV-6 or resuscitating a Cub are all daydreaming. They’re not on a vision quest, or achieving Nirvana, or making a solemn pact with future generations. We just don’t want to use the phrase “daydreaming of flight” because it sounds too much like lollygagging, which reflects badly on the pilot population in general. A daydream suggests slacking off—in the sense that maybe it would be far more productive to mow the lawn or fix the roof than to build an airplane. A true “visionary dream,” however, transcends such mundane projects with utopian ambition beneficial to all. Think of Dr. Martin Luther King. There’s a Dream, capital D. He wasn’t just lollygagging, or drooling over a rivet-gun catalog, and Coretta certainly wasn’t yelling at him to get all that airplane crap out of the garage. Note the difference?

Also make the distinction between the cliché “dream of flight” and the much more interesting “flying dream.” In a flying dream, meaning the kind that usually happens at night, you might be copying an endless clearance from ATC in what sounds like Medieval Lithuanian, or flying like a bird yourself, or scrambling to jump clear of the Hindenburg. In an aviation daydream you are mostly in the world, and only a little bit out. You are held responsible for your actions and are expected to be at least marginally rational. In a “flying dream” you are irresponsibly zonkers and editorially unrestrained. My wife tells me that over the last year or so I’ve become an extreme, physically active dreamer. (“You’re thoroughly obnoxious,” was one way she put it.) I wake up screaming, “The bunny rabbit, where’s the bunny rabbit?” I live in Boston; a bunny would get mugged. My wife fears for her safety and longs for a little more REM sleep. She believes that my dreams are largely aviation related, but the connection is difficult to confirm, because they usually vanish when she wakes me up. Yet sometimes I do remember. My favorite is the repeater that started in childhood, in which I stand in the back yard, look up, and they’re holding an amazing old-time airshow, apparently just for me.

Here’s an aviation dream that survived the dawn. It belongs to a distinguished author (“Astonishing … A breathtaking performance” – Washington Post.) who is also a pilot. We turned off the gyros and flew aerobatics together recently. He had the following dream that night. Here’s the extract from his email:

“I can’t sign off without telling you about the dream I had last night. I was flying along while lying back on what seemed an awful lot to me like a mattress, and a phone rang. I answered it to find that it was “Sherry, from across the street.” I have no idea who “Sherry, from across the street” is, but I said it was good to hear from her, and that if she would hold on a second, I would pull back the throttle to reduce the engine noise so I could hear her better. As soon as I did this, the nose of the mattress turned straight down, and I found myself in clouds, very aware that the gyros of the attitude indicator were caged. I told Sherry VERY quickly that I would have to call her back, and then I began monkeying with the controls to try righting myself. That was the end of the dream, or at least all I remember.

“Gee, I wonder where the idea of pointing straight down, and having caged gyros on the attitude indicator could have come from?”

The above is a great example of how dreams process, and mangle, the events of the day. Elaborate dreaming is actually quite common after the first aerobatic flight. And I also like it when mysterious women show up in the neighborhood. Did this Sherry person leave a number?

I’ve never been to an airshow outside the United States, so I can only imagine what it might be like elsewhere on the planet. In the U.S., at least, major airshows tend to involve patriotic themes. This is especially the case at airbases or when there’s otherwise a strong military presence. But even when the Thunderbirds or the Blue Angels aren’t around, the Flag usually gets waved pretty hard.

Which happens in both literal and symbolic terms. I can’t remember an airshow that didn’t begin with skydivers descending with an American Flag. Taking symbolism to the limit, airshow performer Julie Clark calls her “Mopar T-34” the Free Spirit. It makes red, white, and blue smoke; the aircraft, in effect, becoming the Flag. The imagery is potent. Aerobatic flight represents physical freedom of the highest order, and it’s popularly thought to demand physical courage. Stick them together and you have America’s fundamental notion of itself—the land of the free and the home of the brave. Clark’s aircraft is even painted with a nod toward “Air Force One.” Plus, as she flies, Neil Diamond’s “Coming to America” blares dramatically from the sound system. When Clark lands and taxis back in, she waves an American Flag out the canopy. There’s nothing subtle (or new) about the appropriation of the national identity by a performer working the emotions of a crowd. There’s nothing subtle about the national identity it projects, either. Then again, what could be more boring than a subtle airshow?

I’m a child of the political ‘60s, so you have to be cautious around me and not expect to pluck my heartstrings. I think listening to anything sung by Neil Diamond is like eating lard. Having already been told to “love it or leave it,” I’m wary of those whose patriotism is either aggressively simple-minded or just a ploy to get me to agree with a bad idea—or maybe to buy a certain brand of auto parts.

As a result, I sometimes miss out on the fun. The pilot in me loves it when an F-18 pulls so hard you can see water vapor condense over the wings. But then the cautious patriot in me remembers that the aircraft is, in its brutal reality, a killing machine. I can accept the need for such a machine, but I can’t stop worrying about its misuse. I can admire those Americans and others who are fighting now in Iraq and Afghanistan, and thank them. But I can’t feel as I might have if the war—in Iraq, at least—had not been such a duplicitous blunder. I feel the troops need my apology more than my thanks. A bad world became worse because we refused to examine our presumptions, and servicemen and women and their families have taken the brunt. We abused their patriotism. Maybe we should re-question the meaning of our own—not to lose love of country but to see things with more critical, less-misty eyes, and minus the soundtrack.

Patriotic enthusiasm comes easier to me, without ambivalence, when I’m watching World War II warbirds, defenders of liberty against outright aggression, pure and simple. The older warbirds at airshows bring to mind Hollywood scenes of fighter pilots in individual combat or bomber crews with the wise guy from the Bronx and the kid from Nebraska battling through the flack and the Messerschmitts. And the World War II machines, now antiques, refer us back to what really were simpler times, when enemies were bordered nation states with aircraft of their own, and we could harness our industrial might to pummel them in a standup fight, toe to toe. We didn’t have to win hearts and minds afterwards, or keep the fanatics apart. We didn’t have to deal house to house with vicious sectarian and tribal resentments many times older than our own country. Victory was absolute. Maybe those were the days. Then again, be careful what you wish for. Not much stays simple anymore.

I keep promising not to tell flying stories, but the spirit is weak. This month I want to write about the aerobatic maneuver called the hammerhead, yet am drawn by strange alien forces to the subject of swimming pools. There’s a lot you can tell about the tenor of a community by flying around and checking out its backyard swimming pools. If you know anything about pools—or ever had an ambivalent dominion over one, as I have—you know that the natural tendency of small, self-contained bodies of water is to become vile. Rather than signaling moral failure on the part of the man of the house, as my wife once suggested, a green, algae-rich pool actually reveals conformity with nature’s plan: that the fittest slime should take control. Obviously, pool water that’s transparent and sparkling means the presence of folks to whom nature’s wishes carry little weight. These are the same people who deny global warming. They believe the universe is 6,237 years old, at most, despite the fossils dug up when the pool was installed. More about swimming pools in a bit.

Last month I wrote about my first encounter with a Pitts S1S—a little trouble steering on the ground combined with a little trouble making the smoke system stop. Yet I grew to love that airplane, and more importantly, I learned to land it. Come to think of it, I destroyed my first prop in that Pitts, actually a loaner prop from my buddy Hans—a man of serene forbearance, fortunately. Plymouth Airport threatened to but never billed me for the taxi light that was also destroyed, a fact (assuming that a statute of limitations applies) I now feel comfortable flaunting in front of management.

Anyway, a Pitts does a fine hammerhead. In this maneuver, for reminders, you pull to the vertical, slow down almost to a stop, and then kick left rudder. The airplane yaws 180 degrees and heads back down toward the dirt. Before it hits the dirt, of course, you pull back to level flight. I’m going to reconstruct the most satisfying Pitts hammerhead I ever flew. But first a more specific description of how the maneuver is performed.

A hammerhead either requires lots of entry speed in order to gain altitude during the initial vertical line, or should be started high enough so that altitude is irrelevant. The problem is that you slow down to almost nothing at the top of the maneuver. So when you come back down, you have to generate sufficient airspeed to pull the Gs necessary for recovery. That means trading potential energy (altitude) for the kinetic kind (airspeed). An airshow pilot starting a hammerhead at low altitude and low airspeed might not be able to gain the altitude necessary for recovery. Pilots have died this way. My little S1S required an entry speed around 140 mph to drive the vertical line high enough so that recovery at or above entry altitude was guaranteed.

So now we are in the vertical line, with plenty of altitude beneath. As the aircraft slows, slipstream effects increase and cause the nose to yaw to the left. Consequently, a gradual increase in right rudder is needed to keep the flight path vertical. In fact, if we just left our feet flat on the floor, the aircraft would slowly yaw around in a lazy arc and head back down on its own.

At the same time, as we climb and lose airspeed, the torque generated by the prop becomes more apparent. The aircraft starts to roll to the left, against the prop’s rotation to the right. Right aileron may be necessary to counteract torque. If so, aileron deflection will have to increase as airspeed drops and the control surfaces become less effective.

Learning when to kick left rudder takes practice. We go to the left to take advantage of the leftward yawing tendency generated by the slipstream. Kick too soon and the aircraft flies around in an arc, with the pivot point somewhere beyond the wingtip. Wait too long and the aircraft will pivot around its center of gravity, while the center of gravity itself begins to sink. A pivot point somewhere within the span of the left wing usually gives a good-looking turn around. Aesthetics matter.

As the aircraft yaws around the top, the right wing goes faster than the left and tends to produce more lift. Compensating right aileron is necessary to keep the aircraft from rolling. Some of the rolling tendency is still due to torque effect, however, and if the ailerons are giving up the ghost it may be necessary to pull the power back to reduce the torque.

Now that we’ve kicked and are headed back down, the subject of swimming pools returns. My best ever hammerhead happened one hot, summer afternoon, when I pivoted around the top and headed vertically down exactly centered on a circular, above-ground swimming pool. “Dude, way cool!” I thought. This was over a sparsely settled, less fashionable outskirt of Taunton, Massachusetts—a town not fashionable to begin with. There was a mobile home, and cars and pickups scattered around the yard. Clearly a redneck enclave. Perfect!

In my experience, folks with above-ground pools and redneck landscaping invariably fit the airshow attendance profile. They’re what make airshows such classy affairs. This isn’t snobbishness; it’s simply the truth. So I gave them a four-point roll on the down line. On the first point, I must have gotten their attention. By the second point, I bet they were questioning the future. By the third point, at least four individuals could be seen climbing out of the pool and heading off in all directions. The fourth point probably went unobserved by the runners below. Aerobatics doesn’t get any better! In fact, life doesn’t get any better.

The regulations prohibit aerobatics over an open-air assembly of individuals. Do four excitable rednecks swilling Budweiser in an above-ground pool constitute an open-air assembly? Of course I recovered above 1,500 feet AGL, as required by FAA regulations. I will take a polygraph, if necessary, to confirm the entire story.