Friday, September 5, 2008

No Mere Knob


I began having profound thoughts the other day about...let the bugles flourish...the landing gear knob. What goes through engineers' minds when they design something so simple as a knob? Maybe more than we think. The knob on the end of the landing gear handle is, I kid you not, shaped like a tire complete with treads. Why, we ponder, would the engineers design this thing with such a shape? Some possibilities:

First, the designers might think we pilots are exceedingly stupid, an allegation that is not always defensible. Maybe they're afraid we might forget what the handle is for. In such a case a quick visual affirmation could be helpful. For example, if the captain ordered the gear extended and the co-pilot experienced a brain fart--say, forgetting where the handle is located--the day is saved. There! Oh yes, that must be it, the one with the tire on the end of it.

Second, and the most plausible (but barely) engineers know a plane can loose all electrical power at night. The battery will provide limited lighting for about half an hour, but suppose the battery cashes-in for the night before we land. We have flashlights in case that happens. But based on the old proverb that captains’ flashlights are nothing more than containers for the storage of dead batteries, aircraft designers guessed they needed to give us an extra hedge. Thus they gave the gear handle knob a unique and familiar shape to the touch—a tire with threads. This theory assumes the designers used human engineering considerations—doubtful. But if that’s true then they also did this with the flap handle. Located on the center console between us, it’s shaped like an airfoil—a wing. No problem identifying that in the dark, either.

Then the third possibility for making a tire at the end of the handle is they feared the plane might need to be landed by a non-pilot. Imagine the pilots are dead or unconscious, Joe Passenger at the controls, people behind him screaming and praying, sweat cascading down his chin, the runway getting bigger, fast. He thinks: Wheels? Where? Ahh, the knob shaped like a tire.
But not all gear handles on all planes have tire shapes. The Airbus 320, a French product, has a yo-yo shaped gear knob. Ponder on that.

Now for the winner of the bug contest (see Aug 28 post):

Bob Schneeflock
is runner-up with a guess of 115 knots.
Mike Epsman hit it on the nose at 110 knots but he hedged with a "+/-" therefore I must disqualify him.
Larry Parker is the proud winner at 110 knots.

Pic of the trip:
Massive glaciers east of Anchorage. I interrupted the movie and told the passengers they might want to lift their window shades and take a peek.

4 comments:

bradcockrell said...

There is a "Far Side" joke in there somewhere!

fatquiver said...

In studying carbon-fiber, Luke stated that the new Boeing 787 Dreamliner is made of 100% synthetic material. He said that the stuff is 100x stronger than steel and 1/6 the weight. Went on to mention that the cabin pressure can stay at a more desirable level, it saves fuel due to less weight, and, yeah...very cool. He likes the Manta wings. Maybe a future pilot here? Do you fly these?

Alan Cockrell said...

The Dreamliner is still in development and testing. I'll probably retire before it becomes fully operational and if my airline buys it, which so far they have not. I wish I could get Luke up in my Yak-52.

Alan Cockrell said...

George Myers via e-mail:
I'm not much older than you but there was a big debate back in the 50's about the landing gear handle. Some planes, like the early Beech Bonanza had toggle switches, side by side, for the flaps and landing gear. Others had various levers and handles. Pilots made the obvious mistake and landed gear up thinking that they had it down. I suspect that non-professionals made the mistake more than others. I think that somewhere along the line that the FAA mandated a separation between the two handles and also that the landing gear switch be shaped like a wheel and the flap handle be shaped like an airfoil. It could be interesting to research that sometime.