Compass rose

[SkykingC310]

If anyone is interested in knowing when and how a compass must be swung, the procedure is defined in Advisory Circular 43:13-1B, chapter 12, section 3, paragraph 37. It lists ten occasions when a compass swing must be performed, five precautions when swinging the compass, and then six, time consuming steps, in order to accurately calibrate the instrument. I remeber having this as a project in A&P school. It was fun then, but not necessarily fun now. It's just a long process. And it's one thing to do it for a Cessna 150, but it's another thing to do it in an Embraer 135 regional jet.

 

[mikea]

The Compass Rose Deviation Calibration Department sends out a crew to swing the compass rose. Cut the pavement out to a depth of 8", re-align compass rose to magnetic north and replant the pavement.

Brought to you by the Department of Redundancy Department. Please submit all requests for "The Paperless Office" publication "PO-FairyTale-33.22.2159" via Document Request DPO.2380.AG.0192830 in triplicate. Electronic submissions will not be accepted.

I thought of that. That's how Chicaguh would handle the problem... wit da guys wit noses like dis gettin' da no bid contract for da concrete work... da same ones who got ta dig up Meigs at midnight on overtime.

Don't runways get renumbered in what, a 10 -20 year interval due to magnetic drift putting it off by than 5(?) degrees?

 

[TMetzinger]

Runway numbers can be significantly out of sync with magnetic north, since the pole wanders. Depending on the airport, it may be quite a while before the runways are renumbered, depending on how busy the airport is. It's been my experience that larger air carrier airports are renumbered more frequently than the smaller fields.

And as for Pontiac, I thought that looked familiar, although when I visit I rarely see the western end of the field, since I park at the western end.

Best wishes,

 

[fgcason]

Runway numbers can be significantly out of sync with magnetic north, since the pole wanders. Depending on the airport, it may be quite a while before the runways are renumbered, depending on how busy the airport is. It's been my experience that larger air carrier airports are renumbered more frequently than the smaller fields.

Don't forget that some runway numbers are deliberately not set to magnetic north to help keep everyone from smashing into each other when there are multiple parallels:

http://download.aopa.org/iap/20060216/SC-2/dfw_airport_diagram.pdf
17/35-L/C/R and 18/36-L/R = 174.3°/ 354.3°
http://download.aopa.org/iap/20060216/SW-1/den_airport_diagram.pdf
16/34-L/R and 17-35L/R = 169.8°/349.8°
08/26 and 07/25 = 079.8°/259.8°

A compass rose could be useful in such places.

 

[gismo]

The Compass Rose Deviation Calibration Department sends out a crew to swing the compass rose. Cut the pavement out to a depth of 8", re-align compass rose to magnetic north and replant the pavement.

Brought to you by the Department of Redundancy Department. Please submit all requests for "The Paperless Office" publication "PO-FairyTale-33.22.2159" via Document Request DPO.2380.AG.0192830 in triplicate. Electronic submissions will not be accepted.

Wouldn't it be simpler to plant a few strong magnets near the rose and move them as required?

 

[gkainz]

Wouldn't it be simpler to plant a few strong magnets near the rose and move them as required?

Aw geez...you'll have to ask the Magnet Planting Department and the Magnet Relocation Committee as well as the Relocation of Magnets Division Chief about that. Then of course, you will have to perform the Environmental Impact Study and file the appropriate Environmental Impact Statements to pull that one off!

 

[Anthony]

I thought of that. That's how Chicaguh would handle the problem... wit da guys wit noses like dis gettin' da no bid contract for da concrete work... da same ones who got ta dig up Meigs at midnight on overtime.

Daaa Bears.... Daaa Bears.....

 

[Anthony]

Aw geez...you'll have to ask the Magnet Planting Department and the Magnet Relocation Committee as well as the Relocation of Magnets Division Chief about that. Then of course, you will have to perform the Environmental Impact Study and file the appropriate Environmental Impact Statements to pull that one off!

Can't do it Greg. They have not yet received the form to order more forms to do the relo.

 

[gismo]

Aw geez...you'll have to ask the Magnet Planting Department and the Magnet Relocation Committee as well as the Relocation of Magnets Division Chief about that. Then of course, you will have to perform the Environmental Impact Study and file the appropriate Environmental Impact Statements to pull that one off!

Wait! I've got the solution: Magnetic paint!

 

[cherokeeflyboy]

Wait! I've got the solution: Magnetic paint!

Is that the stuff they paint treadmills with to prevent premature takeoff??

 

[Frank Browne]

Re: Compass rose...HUMOR!

Good navigating. So, where am I?

HR

Looking at this photo kinda got me wondering...How can the excitement level of General Aviation be elevated? That's what GA needs. A certain excitement element in order to attract the more...um...risk tolerant people. So to that end, I have redesigned the standard compass rose. Instead of the compass rose being painted on the tarmac surface, it will be mounted on a pedestal with a mechanism not unlike that of a childs pinwheel. The idea is, whenever a compass is swung, the A&P will give the thing a twirl kinda like the contestants on Wheel of Fortune do. Where ever the rose stops, that will be the guide for calibrating the aircraft compass. In addition to alleviating the bordom that sometimes occurs during cross country flights, it will also reduce congestion at the busier airports.

 

[fgcason]

Re: Compass rose...HUMOR!

Looking at this photo kinda got me wondering...How can the excitement level of General Aviation be elevated? That's what GA needs. A certain excitement element in order to attract the more...um...risk tolerant people. So to that end, I have redesigned the standard compass rose. Instead of the compass rose being painted on the tarmac surface, it will be mounted on a pedestal with a mechanism not unlike that of a childs pinwheel. The idea is, whenever a compass is swung, the A&P will give the thing a twirl kinda like the contestants on Wheel of Fortune do. Where ever the rose stops, that will be the guide for calibrating the aircraft compass. In addition to alleviating the bordom that sometimes occurs during cross country flights, it will also reduce congestion at the busier airports.

Can I go first?!

 

[gismo]

Re: Compass rose...HUMOR!

In addition to alleviating the bordom that sometimes occurs during cross country flights...

Not to mention the challenge of landing on that raised platform!

 

[gkainz]

So, if you landed a helo on that compass rose, would the helo body begin to rotate counter to the blade rotation, similar to the "airplane on a conveyer belt" problem?

 

[fgcason]

So, if you landed a helo on that compass rose, would the helo body begin to rotate counter to the blade rotation, similar to the "airplane on a conveyer belt" problem?

My scientific opinion:
Air has a much lower coefficient of friction than a mechanical bearing in such situations. The rose itself has inertia to resist turning. Therefore..
(a) If a helicopter pilot was flying, it probably wouldn't rotate too much if at all.
(b) If I was at the controls, it'd spin like a top until the helicopter toppled off and threw blades everywhere.

Hmmm... How much anti-torque is available from the tail rotor as the main rotors slow while shutting down? With some good bearings the compass rose is very likely to spin around some and maybe a lot depending on the unknown variables...but not as much as it would if I was playing with the pedals.


A better question to stir the pot: Can a helicopter take off on a rotating platform?

 

[gismo]

My scientific opinion:
Air has a much lower coefficient of friction than a mechanical bearing in such situations. The rose itself has inertia to resist turning. Therefore..
(a) If a helicopter pilot was flying, it probably wouldn't rotate too much if at all.
(b) If I was at the controls, it'd spin like a top until the helicopter toppled off and threw blades everywhere.

Hmmm... How much anti-torque is available from the tail rotor as the main rotors slow while shutting down? With some good bearings the compass rose is very likely to spin around some and maybe a lot depending on the unknown variables...but not as much as it would if I was playing with the pedals.


A better question to stir the pot: Can a helicopter take off on a rotating platform?

If the platform was rotating fast it would depend significantly on what the direction of rotation was. That's of course assuming the pilot doesn't get dizzy and the tail doesn't fall off.

 

[gkainz]

I think the scenario is more along the lines of "could a helicopter take off from a platform mounted on a spindle and bearings, which was free to rotate?" still following the "airplane on a conveyer belt" thread? Correct?

 

[fgcason]

I think the scenario is more along the lines of "could a helicopter take off from a platform mounted on a spindle and bearings, which was free to rotate?" still following the "airplane on a conveyer belt" thread? Correct?