PPL exam compass errors
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Thread starter probably wondering why he asked the question now. He got a satisfactory answer after two replies, then the thread drifts all over the place even to carb ice. It would be great if we all understood every technicality of every aircraft subpart but we dont as we are all still learning. Brilliant piece by Keith Williams, I wonder how many ATPL`s could recite that.
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I suggest that mach jump goes and gets himself an Airpath brand Aircraft compass and pulls it apart.
some people only ever learn by having the evidence in front of them.
some people only ever learn by having the evidence in front of them.
I suggest that mach jump goes and gets himself an Airpath brand Aircraft compass and pulls it apart.
some people only ever learn by having the evidence in front of them.
some people only ever learn by having the evidence in front of them.
MJ
I couldn't find an Airpath compass to dismantle, so I Wrote to Airpath and asked the question. Here is their reply.
Sorry, dubbleyew eight, you are right.
MJ
I don't know if this will settle your argument, but basically you are both correct. The card assembly is balanced for the vertical component of the earth's flux lines based upon the surveyed strength by NOAA for a given latitude and hemisphere. A small weight is applied to level the display level, non-accelerated flight. The pendular design of the card assembly helps minimize (but not eliminate) the dip errors when turning and accel/decal environments. Hope this helps.
Gil Stone
President
Airpath Instrument Company
Gil Stone
President
Airpath Instrument Company
MJ
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Thanks to MJ for that and well done to Airpath for responding
Interestingly, it implies that compasses sold at different latitudes therefore should have different counterweights. Which makes sense but is not something I think would have been practically possible or commercially desirable. A compass made for Florida will be a nuisance in Scandinavia and vice versa!
B.
Interestingly, it implies that compasses sold at different latitudes therefore should have different counterweights. Which makes sense but is not something I think would have been practically possible or commercially desirable. A compass made for Florida will be a nuisance in Scandinavia and vice versa!
B.
Last edited by Baikonour; 5th Aug 2014 at 16:17. Reason: typo
Interestingly, it implies that compasses sold at different latitudes therefore should have different counterweights. Which makes sense but is not something I think would have been practically possible or commercially desirable. A compass made for Florida will be a nuisance in Scandinavia and vice versa!
It looks like anyone thinking of flying from London to Capetown will have to consider the need to change the compass half way.
MJ
Yes. I believed that the whole point of the pendular suspension of the compass card was to eliminate the need for balance weights, so that the compass could be used anywhere in the world.
It looks like anyone thinking of flying from London to Capetown will have to consider the need to change the compass half way.
It looks like anyone thinking of flying from London to Capetown will have to consider the need to change the compass half way.
Only if airplane was moving base from north to south would there be any noticeable difference and any compass will function in any location. Static balance would be slightly off (1-3 degrees) but design incorporates 18 degrees of tilt/turn.
GS
GS
MJ
Last edited by Mach Jump; 5th Aug 2014 at 20:40.
Since the magnetic dip is 60 odd degress+ in the uk, and 60 odd degrees- in South Africa, I'm more confused than ever now!
Not so sure this is correct.
The pendular design of the card assembly helps minimize (but not eliminate) the dip errors when turning and accel/decal environments.
Confused?