What's All This Vice Versa Stuff, Anyhow?

Well, I always did want to write a column about vice-versa stuff. As my old friend Dave Ludwig likes to say, ''In this world, it's dog eat dog — or vice versa." As I already mentioned in my column about negative feedback, it's nearly impossible to ride a bicycle with your arms crossed, because the arms get their tasks all figured out one way and then you can’t tell them to do the job vice versa.

So I wanted to write a good column about other vice-versa stories, and along came Jack Fogarty, Darryl Phillips, Doug Grant, and Gunnar Englund, who beat meto the punch. At this point, there’s nothing I can do better than to shut up and let you read their letters:

Dear Mr. Pease:
Enjoyed your Jan. 9 column on negative feedback. Let me add one thing about crossed-arm bicycling.

If you try to balance a bicycle while rolling backwards, you'll crash. But, if you can cross your arms, hold them rigid and steer with your shoulders, you'll find you can balance — at least for a little while.
If you think about what you're doing, you'll crash, but if you let your automatic balance prevail, well, surprise! It works.

JACK FOGARTY
Professional Engineer
Columbia, MD
And I say, that's marvelous. I believe it. I haven’t tried it yet, but I will.

Next:

Hi Bob:
You sure hit a nerve with your mention of riding a bike with crossed hands. Of course you're right, and there are implications that go beyond a showoff stunt.
Probably more ingrained in our genetic servo wiring is control of our feet. From the first creatures, the left foot has pushed off to go right. This may actually be the reason the brain lobes are crossed.

We take walking so much for granted it’s difficult to even discuss the mechanics, so consider roller skating. You push with the foot opposite to the desired turn. It's equally true on other machines. Sit any kid on a sled, give him a start down the slope, and he will steer it fine with his feet. Push with the left foot to turn right. Can you think of an exception?

There is one. The airplane. The rudder pedals are hooked up "backwards" (you push left to turn left), and it causes the same cross-control problems you alluded to. One of my joys is giving first rides to kids, often in the 8- to 13-year-old group.

Most of them really take to flying, they do better than the typical adult. But taxiing for the first time is a nightmare. Invariably they go the wrong way, and make some comment that it's hard to steer with your feet. They're too overloaded by the unfamiliar surroundings to realize the obvious: the pedals are backwards.

Over the years. I've mentioned the problem to many pilots, and I've yet to find one that agrees. Usually they give me a look that says, "Well, buddy, I don't know about your rudder, but mine is hooked up just fine!"

The human is a very adaptable creature. We learn to fly and do okay most of the time. But within the brain, training is pulling one way and instinct the other. And when things suddenly come unglued — and millisecond response is needed — instinct sometimes wins and the wrong foot is used. It would be better to have the two forces aiding rather than opposing, but it’s hard to make the changeover. Anyway, I wanted to share this with someone who understands.

DARRYL PHILLIPS 
The Airsport Corp.
Sallisaw, Okla.

Now that’s a scary thought. Yes, a sled is easy to figure out how to steer. And yes, an airplane is feasible to control, and many people figure out how to fly it quite easily, after you think about it a little. But I never thought of its controls as being backwards or vice versa....

Now let's go on to a story about British Flying Officer H. M. Schofield, who was a pilot for racing seaplanes in 1927: "He took the Shoit-Bristol 'Crusader' out for a trial flight on Sunday the 11th. No sooner had he lifted off the water when he did a jerky half-roll and slammed back into the sea again. The impact tore the aircraft to bits and ripped off most of Schofield's clothing, smashing his goggles against his forehead. Bewildered, half-drowned, and infuriated, he was carried off to the nearby Italian Naval Hospital. When his aircraft had been reclaimed, it was found that the aileron control cables had been reversed! The best-laid plans...." *

So, just as George Philbrick pointed out that it was impossible for the automatic or "computerized" controllers of his day to accommodate a reversal of polarity —you can be completely gefoozled, even as a skilled human, if somebody springs a surprise change on you. As the seaplane's airspeed began to rise, the pilot saw the right wing dropping. When he moved the stick to the left to try to bring the wing up, things got worse so fast he never had time to realize that the controls were reversed. Now there’s positive feedback for you!

It’s the same situation as the technician who was trying to mount a gyroscope on the bulkhead of a missile. It was kind of inconvenient to get it bolted down, so he decided to mount it on the other side of the bulkhead — it fit much better using the same mounting holes.

But when the missile was launched, the controls went "haywire,” and of course, it also crashed, with controls full-over against the stops. Both of these cases are just like the next story, which you can appreciate without being an airplane pilot.

Dear Bob:
Your column on “Negative Feedback” reminded me of a real-life example of positive feedback described by one of my profs at Northeastern.
The example deals with a dual-control electric blanket, where the controls have ended up on the wrong side of the bed. From any initial condition (for example, both set at “5”), the system soon goes unstable. The husband is too cold so he turns “his” control up. The wife, of course, gets too hot and turns “her” control down. This makes the husband colder, so he turns his side up more, causing her to turn hers down. Eventually, both controls end up at the stops and the humans end up at each other’s throats.

DOUG GRANT
Wilmington, Mass.

Exactly! Now I'll finish up with a letter about a ship that was moving MUCH slower than 100 mph, when it crashed, and crashed... and crashed repeatedly.

Dear Bob:

It’s kind of a privilege to have an opportunity to write to you. I look forward to some day passing the casual remark to my grandchildren, “...and then I told Bob Pease...”

This brings me a little bit closer to the subject. When I was a child myself, me and my friends did just that — bicycling on a lawn with our arms crossed. You are right, it is very difficult and it hurts, too. Some of us got rather good at it, and I recall that the girls adapted faster than the boys. Is there a lesson to be learned?

The experiment has been repeated here in Sweden recently. Or rather between Sweden and Denmark, on the water separating Swedish Helsingborg from Danish Elsinore. Remember Hamlet?

A clever person decided to make the new ferry more efficient by allowing it to go both ways, without having to turn around each time. The idea isn’t very new, but this time the clever person decided to save some money by using the same steering wheel for both Denmark-bound and Sweden-bound traffic. A steering wheel and an old-fashioned machine telegraph seemed to be a bad idea, so the two were combined into one joystick.

Now there was some real confusion: The difference between starboard and backboard is tricky enough, but now you also had to separate Swedish and Danish starboard and backboard. If that’s not enough, it seems there were different forwards and backwards as well. One set for Sweden and one set for Denmark.

All good experiments have results. In this experiment, we use the word “consequence” instead. The consequences were: heavy damage to both harbors, heavy damage to the ferry (both ends), damage to cars, and people injured. The experiment went on for some time. Obviously, the experimenters were anxious to rule out random and systematic errors. After some time, with consistent results, the experiment was evaluated. We’re still waiting for the report.

Moral: Know your polarities, and stick to one set of definitions.
For someone who knows anything about northern Europe, astronomy, and folklore, it comes as no surprise that the name of the ferry is Tycho Brahe.

GUNNAR ENGLUND 
Granbergsdal, Sweden

Well, Mr. Englund, some skiers and some drivers are just “an accident looking for a place to happen,” and that ferry boat was, too. Note, Mr. Englund observed that it was appropriate for the ferry to be named after the great 16th-century Danish astronomer Tycho Brahe. Brahe published a list of “bad-luck” days — the “Tycho Brahe days” — when a great project or journey should not be initiated, because it will come to a bad end. 

Mr. Englund did confirm that no correlation had been found between the Brahe days and the ferry accidents or the boat’s launching date. Perhaps the people who designed the control system for the ferry will propose a U-lane vehicular tunnel between England and France — with no center divider. So, where do the drivers change over from driving on the left to driving on the right? Any time they want to! — whenever the mood strikes them! Now there’s a vice-versa situation!

All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
Address:
Mail Stop C2500A
National Semiconductor
P.O. Box 58090
Santa Clara, CA 95052-8090

Excerpted from The Great Air Races by Don Vorderman, Bantam Books.

BOB’S MAILBOX

Dear Bob:

Thank you for writing all of those very informative and enlightening articles. They are both educational and bring back memories of my forty years in electronics. I have clipped every one to date for further reference. I believe I have a very good source for high-isolation power transformers, both linear and switching types, for Mr. Neal Iverson of the Boeing Co. His letter was in the February 20 issue. The company is: Glen Magnetics Inc., Third Avenue, Alpha, NJ 08865; tel: (201) 454-3717; fax: (201) 454-2702.

Mr. Iverson should contact Mr. Emil Badway, who is the vice president of engineering. They have made many extremely critical transformers for companies I have been employed by.

GLENNA THOMPSON
Penn Yan, NY.

Thanks for the info.—RAP