Joy of Stick, Love of Yoke

By Dave Matheny, EAA 184186

There used to be an aerospace writer at my newspaper, the Star Tribune of Minneapolis, whose sphere never included anything as simple and insignificant as the types of aircraft that I flew, from ultralights to single-engine Cessnas and Pipers. He mostly did space stuff, which of course is fascinating in its own right, but is not the full spectrum of flying — as we EAAers know.

One day I overheard him telling a couple of staffers excitedly about this new breakthrough at Airbus, where they were putting the stick to one side of the cockpit, decluttering the area in front of the pilot, where old-fashioned airliners still had a yoke, or “wheel,” as he called it. He made it sound as if the side-stick had never been done before. (And that the yoke was obsolete, which it isn’t, but that’s another matter.)

Choosing my moment, I commented that I had been flying a side-mounted stick for years on my Quicksilver MX Sprint. He was so disconcerted at hearing this loony, and in his opinion probably false, information that he missed my explanation that I wasn’t claiming to have a fancy fly-by-wire system, just a simple connection of stick to push-pull tube to tail, located on the side because that made the whole arrangement simpler.

Choices

An awful lot of considerations go into the designer’s choice of stick or yoke beyond its location. Side-stick, yoke (or wheel), center stick — what’s your preference as a pilot? I delight in them all, but it was not always so. Long before I ever got my first flying machine, I thought a stick would be much cooler than a yoke. Fighter pilots had sticks. But I was a kid, and influenced by wanting to fly a fighter rather than a bomber or transport.

It was ironic justice, in a “serves you right, you little snob” sense, that my first aircraft’s hand control was neither stick nor yolk, but something resembling bicycle handlebars. That particular flying machine, an American Aerolights Eagle ultralight, was a hybrid: a flying wing with tip rudders plus a canard out front for pitch control. The handlebars were connected to the tip rudders and worked surprisingly well, banking and turning the aircraft very effectively.

But, seriously — handlebars? That seems so bush league. Well, equipment should be judged according to functionality. Does it do the job? Is it convenient and reliable? Does it suit the pilot and the aircraft? The pilot’s connection through hands and feet to the aircraft is such an intimate part of the union with it that all of these things matter.

So here is a quick look at the two main kinds of hand controls, partly for the benefit of newcomers to flying, partly because some pilots have never flown anything but a stick or a yoke, and partly to review some of the virtues and drawbacks inherent in each. This is not a comprehensive compare-and-contrast between stick and yoke, just a close look at the two.

The Stick

The stick is a simple device, and wonderful because of that. It’s as intuitive as anything ever was. A Cro-Magnon man would grasp its operation in about four seconds. (Push stalagmite left, cave tilts left. Push forward, cave tilts forward. Got it.) A flying friend, Mark Weinrich, a former airline pilot, said the sticks on his biplanes lend themselves to a more natural coordination of bank and pitch in the turn than the yokes he had in airliners and his current Bonanza. In a turn, drawing the stick back and to the side becomes one smooth motion; doing the same with a yoke is two motions, although of course time and practice smooth the operation.

One minor disadvantage of the stick is that it can make it somewhat awkward to get into the cockpit. Professional aircrew could be expected to handle the simple task of snaking a leg around the stick to sit down, but as airplanes got more family-friendly in the late 1940s, the yoke became far more common.

You can add anything you want to a stick. They tend to sprout buttons, triggers, and wheels to bring such things as trim and push-to-talk switches under the pilot’s hand. (These get really convenient once you get used to which does what.) Sticks also go beyond a simple pole and are sometimes divided at the top into two parallel short sticks, as in the F-102. Then there’s the Spitfire’s “spade grip,” a circle on top of the basic stick that enables two-handed grasping, and also provides a place for the monster-sized push-button gun trigger.

I mention the F-102’s split-top stick and the Spitfire’s spade grip because each acknowledges the yoke’s virtues. That split top enables use of either hand while the other is busy, and the spade grip allows considerable two-handed force to be used when maneuvering, as Spitfires would need in combat.

The Yoke

The yoke can take many shapes, from the half-circle of the B-17 (and my Ercoupe, for that matter), to a pair of parentheses as seen on Cessnas, to the spread-wide M shape of the Concorde, which, come to think of it, is a lot like handlebars.

One of the yoke’s advantages is that the pilot can use a lot of force on it if the need arises, and it may arise. Remember the old movie cliché where the pilot yells to the co-pilot, “Help me pull ’er out of this dive.” That can actually happen. The B-17, for example, had only a mechanical connection between yoke and control surfaces. With an engine or two gone, and other grave wounds to the airframe, human strength was all that was available to keep the big bomber going straight and level.

In general, if there are a lot of buttons and triggers needed, the stick will share them with the throttle, but in the usual GA aircraft with a yoke, the push-pull throttle has no room for buttons and the like.

Much was made of the Ercoupe’s wheel-like yoke when it was first introduced in the late 1930s, how it enhanced the feeling that steering the airplane was as easy as steering a car. Most large airplanes had wheel-like yokes, so they weren’t exactly revolutionary, though, and the similarity to car steering evaporated at takeoff. Cars don’t go up when you pull back on the wheel. (And purely as an aside, pilots don’t much care for being patted on the knee and told, “You won’t need to use those skills anymore.”)

The yoke also becomes a kind of desk for the pilot, with lots of stuff mounted on the central portion, from GPS to timers to checklists.

Left to Right, Right to Left

Anyone transitioning from stick to yoke needs to adapt to a change from left to right — that is, left hand on throttle (usually) to right hand on throttle, and right hand on flight control (usually) to left hand on flight control. Yoke to stick means just the opposite. Is the transition a big problem? Not huge, but I know that whenever I make as big a transition as this, I pause to reflect on what I am doing. During the pre-takeoff runup might be a good time. “I have the throttle in my right hand, the yoke in my left. Got it.”

Although a buyer might prefer a stick to a yoke, or vice versa, in practice there is not much choice. The aircraft you have in mind has one or the other, and conversions are vanishingly rare. Before I grew to love the yoke in my Quicksilver GT400 — in fact, before I even bought the airplane — I thought up ways to convert the yoke to a stick. Working out the conversion with pencil and paper, I realized how much I didn’t know and how difficult it would be. You don’t just go to Sticks ’R’ Us and get the blister pack, peel off the backing, pop out the antiquated old yoke, and plug the stick in its place. Nobody makes such a thing, which is good, because there would be a lot of failures. Anyway, in time, I learned the virtues of the yoke.

So: When choosing between the two, I recommend following the wisdom of Yogi Berra: “When you come to a fork in the road, take it.”

Post Comments

comments

Artikel ini diambil dari http://inspire.eaa.org/2019/02/01/joy-of-stick-love-of-yoke/

, ,

Leave a Reply

Your email address will not be published. Required fields are marked *