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Sherlock Ohms

Lightning Knocks Out Aircraft's Compass

Dan Clark
11/20/2012  
27 comments
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OLD_CURMUDGEON
User Rank
Platinum
LIGHTNING!
OLD_CURMUDGEON   11/21/2012 9:50:17 AM
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1)  The PINTO wasn't a "bright star" in the heavens for FORD!  I'm surprised that these maladies were the only ones with that vehicle!

2)  IF y'all wanna see some KC-135 tanker planes, take a trip to Tampa, FL and visit MacDILL AFB.  You'll see MORE of them than you can count on your fingers & toes!

3)  VERY god point about the new "compoosites" being used for vehicle bodies.  But, maybe they'll add some carbon fibre or lampblack to keep the Faraday Cage effect alive.

ssco00
User Rank
Silver
Re: Redundancy
ssco00   11/21/2012 10:04:57 AM
Actually, the KC-135 had three double airline-type seats and, across the aisle, some fold down bunks to accomodate a second crew for very long missions.  Also there was a freezer, refrigerator, and microwave oven for the in-flight meals.  In addition, there were some fold down troop transport type seats.  There were windows in the escape doors above the wings.

 I had a long ride in such an aircraft at AFROTC summer camp in 1963.  We got to watch refueling of a B-47 from the boom operator's compartment in the tanker.

 

Stuart S

Critic
User Rank
Platinum
Degaussing
Critic   11/21/2012 10:22:51 AM
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Some ships and submarines have on-board magnetism-control equipment.  The magnetic signature of the vessel can be adjusted to help avoid magnetic detection and ensure proper operation of magnetically-sensitive equipment. 

The KC-135 has been in service for a long time (over 50 years), so it is not surprising that some of its design features are not too clever by today's standards.  Placing a large piece of steel near compasses in an aircraft just isn't smart at all.  There are other (non-magnetic) materials that could have been used instead.

Fortunately, with modern electronic navigation equipment, it is not absolutely necessary to rely heavily on a compass for navigation anymore.

Steel-hulled ships have used compasses for a long time.  Compasses can be compensated (historically using obvious compensating balls) for the hull magnetism, and must be adjusted periodically if accuracy is important.

Larry M
User Rank
Platinum
Re: Degaussing
Larry M   11/21/2012 10:40:14 AM
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Several effects cause ship hulls to become magnetic. Some occur at construction time, like hammering and riveting of hull plates.

Others occur in operation including cables carrying DC currents, wave motion lapping at the hull, and even the motion of the ship through the earth's magnetic field. These are compensated by running calibrated DC currents through cables provided on the hull for this purpose.

bob from maine
User Rank
Platinum
Re: Degaussing
bob from maine   11/21/2012 10:48:43 AM
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The US Navy used to have a destroyer degaussing site in Newport R.I. Periodically the destroyers would steam to this site and slowly maneuver through the range. As I remember, most radio and radar was turned-off and occasionally there were some eddy-current issues that created some interesting folklore. I've seen several boats struck by lightening and while some had obvious physical damage from both the heat of the lightening and the heat of the current flowing through stainless rigging, others had no damage at all. Every single electronic component that I found damaged as a result of a lightening strike on the water was from current coming up through the negative (ground) and overstressing protection as well as parasitic diodes. Making the engine block and the entire negative side of the electrical system charged to several hundred/thousand volts cause all kinds of damage, some of which didn't appear for several months after the final insurance check had been cashed. Airplanes and cars really appear as conductive air and the current usually just passes through the skin and out the opposite side. BTW car tires are not a very good insulator (the black part of the tire is mostly carbon) and you can see photo's of cars that had energized high-tension lines draped across them where the tires are on fire.

JimT@Future-Product-Innovations
User Rank
Blogger
Real or just Hollywood?
JimT@Future-Product-Innovations   11/21/2012 1:07:50 PM
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Ever see the movie "Sweet Home Alabama"-?  Reese Witherspoon and Josh Lucas's characters put steel rods (like 10' rebar) standing upright in the sand on the beach before a lightning storm.  The result was a twisted root-like structure of glass resulting from the instant crystallization of the sand.  I always wondered if that was real or just Hollywood.

bobjengr
User Rank
Platinum
LIGHTNING
bobjengr   11/22/2012 11:58:37 AM
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Dan--Very interesting post.  Several years ago my wife and I were coming back from a visit to a friend of ours now living in Spain.   We were in-bound over the Atlantic, about 45 or 50 minutes from NY, when our 747 was struck by lightning.  The pilot indicated we had just experienced a "static discharge" and there were no issues with arriving safely.   The sudden "hit" sounded like cannon had gone off inside the cabin and there was a tremendous flash that illuminated the entire right wing. After 30 minutes, the captain came on line and told us we had been cleared for immediate landing and would be on the ground in15 minutes.  I always wondered what, if any, damage had been done to the instruments and the air frame.  Of course the airlines would never let you know but it was an interesting moment. 

Dan Clark AJ4AH
User Rank
Iron
Re: LIGHTNING
Dan Clark AJ4AH   11/24/2012 1:09:22 PM
NO RATINGS
You were on an international flight, which means all systems must work 100% including the duplicate backup systems or you land and have them repaired immediately. I could imagine a wing strike might have affected the fuel guage readings from that wing, engines readings or even the compass.

Hopefully that was just a precaution, to declare a lightning strike and get pushed to the front of the line for the landing. In any case you are safe and sound and I can relate to that!

Dan Clark

Dan Clark AJ4AH
User Rank
Iron
Re: Real or just Hollywood?
Dan Clark AJ4AH   11/24/2012 1:23:56 PM
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Hi Jim T@Future-Products-Innovations

That's one of my wifes favorite shows. It is definitely for real! I have a couple of websites for you to check out.

The first is from The University of Florida's Lightning Research Group and the other will give you an idea of how rare they are in by their price.

http://www.lightning.ece.ufl.edu

http://www.minresco.com/fulgurites/fulgurites.htm

 

Dan Clark AJ4AH
User Rank
Iron
Re: Redundancy
Dan Clark AJ4AH   11/24/2012 4:48:38 PM
NO RATINGS
Hi Richnass,

The Airforce KC-135 is a version of a Boeing 707 passenger plane. Neither are being manufactured any longer. The KC abreviation is the Airforce initals for an in-air-refueling plane. It mostly carrys cargo but the ones I worked on also had hammocks strapped to the walls for hitchikers. I would imagine it's still in service at a very greatful general. We had originally thought it might be removed from service till a fix had been found.

 

 

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