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August 27, 2016

The Artificial Horizon and the Earth Path Indicator

Found at Frames Of Reference | The Arts Mechanical
When people first started to fly, an important question emerged.  The question was 'which way was up?' That seems like and easy question to answer, but when you are flying around in an airplane in a fog, it becomes more complicated.
a_artificalhorizon.jpeg

Artificial Horizon
An artificial, or gyro, horizon is the main instrument pilots use to fly through bad weather and low-visibility conditions. It indicates the aircraft's orientation relative to the earth, expressed as pitch, roll, and yaw. This is the first production model, the same type Doolittle used in his historic 1929 "blind flying" test.
a_earthpath.jpg

Record Earth Path Indicator, Mercury 4
The Mercury space capsule carried this device, designed by the Honeywell Corporation, which allowed the astronaut to see his orbital track and heading. For example, it indicated when the spacecraft was passing over a ground station or a landing site. The device was a simple globe, driven by a clockwork mechanism. Once in a stable orbit, the astronaut would wind up the clockwork, and set the position of a tiny scale model of the Mercury capsule, under which the globe would rotate.

Posted by gerardvanderleun at August 27, 2016 9:05 AM. This is an entry on the sideblog of American Digest: Check it out.

Your Say

So the artificial horizon has been around since 1929, and to this day there are pilots, generally dead ones, who haven't believed theirs was working.

Posted by: waltj [TypeKey Profile Page] at August 27, 2016 2:45 PM

JFK Jr. among them. His grandpa tried to sell out the Brits to the Nazis, his dad tried to fuck every woman he met and nearly got us all fried, his uncle was a fat drunk playboy pretending to be a statesman, and he himself didn't bother to actually learn to fly on instruments before trying it out at night. Fuck them all.

Posted by: DaveR [TypeKey Profile Page] at August 27, 2016 6:03 PM

One of the first things a pilot learns if they wish to remain alive is those instruments can be tumbled. They will straighten out. But you better believe them and not your ass. That is lying to you.

The rate of turn (Needle and ball) rate of climb and air speed indicator can and will keep your ass out of trouble.If your airspeed is increasing, you're going down and the rate of climb will tell you how fast.

Every new pilot should spend some time under the hood and have the plane put into all kinds of attitudes; they have to get themselves out just by those three instruments. the artificial horizon will tumble and cannot be relied on for any reading.

Posted by: Vermont Woodchuck [TypeKey Profile Page] at August 28, 2016 5:34 AM

Vermont - Right (as usual). Can't count the times I had to recage those old J8 attitude indicators after a turn. In the clouds, you get straight and level using needle-ball-airspeed, then check the AI. If it's not showing straight and level, you cage it (i.e. make it show straight and level). In USAF flight school '57-'58 we first learned needle-ball-airspeed in the Link, then perfected needle-ball-airspeed under the hood with the attitude indicator and ROC covered (you don't need the ROC either, but it's nice, just like the AI). Either you learned to stay right side up, fly straight and level, ascend, descend, and make turns precisely with just needle-ball-airspeed and the throttle, or you sought employment elsewhere (to put it politely). A fringe benefit of all this was you depended less on the ROC indicator on full instruments. It had a helluva lag, and untrained, or poorly trained pilots tended to chase it.

Posted by: BillH [TypeKey Profile Page] at August 28, 2016 7:13 AM

Back in 'those days' flying was fun. I learned from the farmer two farms away who also crop dusted. I spent most of my free time there (farm kids don't have much of that) helping him I started out picking up stuff and cleaning the planes (had two) a J-3 and a Stearman 75.

I learned about those planes from the cotter pins in the control surface hinges to the rivets in the bodies.

What was really funny was when I nearly got tossed out of flight school at Rucker for causing my IP to soil his shorts. I asked him if he knew how to crop dust. Then I showed him in that kite with wheels. Some people just don't have a sense of humor.

Posted by: Vermont Woodchuck [TypeKey Profile Page] at August 28, 2016 12:16 PM

Today they would spend a billion dollars and not get such an elegant and reliable instrument as that beautiful wind-up globe.

Posted by: StephenB [TypeKey Profile Page] at August 29, 2016 6:38 PM

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