Question

[gareth lacey]

To the avionics guru,s out there ,i have 8 panel switches powering from 8 thermal overload switches, can you loop ground to all switches and have 1 main ground to ground block or individual grounds to block

Thanks gareth 

[danny_galaga]

If you  mean can you daisy chain them, I don't see why not. But make sure the total current draw of all the loads doesn't exceed what the ground return wire can handle. 

[old man emu]

39 minutes ago, danny_galaga said:

If you  mean can you daisy chain them, I don't see why not. But make sure the total current draw of all the loads doesn't exceed what the ground return wire can handle. 

More than half the electrical problems with any vehicle are caused by poor ground return wiring. As Danny says, if you use one wire going back to the ground block from many individual points, use a lot thicker wire. Don't scrimp on the thickness of earth wires.

[skippydiesel]

As has been covered many times in the is Forum, 12 volt systems require very good earth return, if you want best performance from & longevity in, components. Airframe  returns are just not sufficient over the long term. Dedicated earth return circuit/wire all the way back to the negative terminal on the eatery is very much recommend.

[gareth lacey]

My main earth block is direct to battery, also will do ground to frame ,but all switches will now go to ground block as will all lights, gauges, actuators plus will ground to frame

 

[old man emu]

I reckon Kyle can answer this best.

 

If a current is moving through a conductor, doesn't it create a magnetic field?

If a compass is affected by magnetic fields, wouldn't the flow of current through a metal airframe cause an error on the compass? 

If the airframe was excluded from the circuit by the use of a dedicated return cable, would the compass be affected?

 

[Yenn]

OME that is the reason we have to swing the compass and that swing has nothing to do with centrifugal force.

[old man emu]

Is that why I had the shite ripped out of me by a LAME when I took a compass out of a plane and was whirling it around my head on a length of safety wire? Well, he told me to go out and swing it, didn't he?

[old man emu]

2 hours ago, Yenn said:

swing has nothing to do with centrifugal force

It's CENTRIPETAL! CENTRIPETAL! CENTRIPETAL!

[tillmanr]

Wouldn’t it experience both centripetal as well as centrifugal forces?

[old man emu]

2 hours ago, tillmanr said:

Wouldn’t it experience both centripetal as well as centrifugal forces?

Jeremiah 5:21 ('Hear now this, O foolish people, and without understanding; which have eyes, and see not; which have ears, and hear not').

[skippydiesel]

8 hours ago, old man emu said:

I reckon Kyle can answer this best.

 

If a current is moving through a conductor, doesn't it create a magnetic field?

If a compass is affected by magnetic fields, wouldn't the flow of current through a metal airframe cause an error on the compass? 

If the airframe was excluded from the circuit by the use of a dedicated return cable, would the compass be affected?

 

Not sure I would suggest excluding the air frame - I think supplementing any existing airframe connections, with a dedicated earth return circuit (connected to the airframe at variose points ) would be a better way to put it. The aim is to ensure a good earth return via a reliable rout/wire.

[tillmanr]

19 hours ago, old man emu said:

Is that why I had the shite ripped out of me by a LAME when I took a compass out of a plane and was whirling it around my head on a length of safety wire? Well, he told me to go out and swing it, didn't he?

When you swung the compass on the line the compass would have come towards your hand due to centripetal force but however it didn’t due to centrifugal force. Centripetal means toward the centre does it not?

[old man emu]

1. Centripetal: (adj) moving or tending to move towards a centre.

2. Centripetal Force:  the force that is necessary to keep an object moving in a curved path and that is directed inward toward the center of rotation.

3. Centrifugal Force:  the apparent force that is felt by an object moving in a curved path that acts outwardly away from the center of rotation.

 

Centripetal Force is an actual force, Centrifugal Force is an apparent force. In other words, when twirling a mass on a string, the string exerts an inward centripetal force on the mass, while mass appears to exert an outward centrifugal force on the string. 

 

The difference between Centripetal and Centrifugal Force has to do with different 'frames of reference,' that is, different viewpoints from which you measure something. "Centripetal Force and Centrifugal Force are really the exact same force, just in opposite directions because they're experienced from different frames of reference. If you are observing a rotating system from the outside, ( watching someone whirl an object around their head), you see an inward centripetal force acting to constrain the rotating body to a circular path. However, if you are part of the rotating system (the thing being whirled), you experience an apparent centrifugal force pushing you away from the center of the circle, even though what you are actually feeling is the inward centripetal force that is keeping you from literally going off on a tangent.

 

 

[danny_galaga]

Is there a lot of centripetal force in an earth lead?

[Yenn]

Centrifugal force may be an apparent force, but if you swing a heavy weight around your head and the thin cord you are using to swing it, breaks, then that apparent force becomes a real force.

It is much like someone saying you don't suck through a straw but air pressure pushes the drink up it. Air pressure didn't move it until you sucked.

[old man emu]

Can we get off this Centripetal/Centrifugal Force thing? It's obvious that nobody is willing to try to understand it and it is not getting an answer to the original question

 

On 19/01/2021 at 4:16 PM, gareth lacey said:

To the avionics guru,s out there ,i have 8 panel switches powering from 8 thermal overload switches, can you loop ground to all switches and have 1 main ground to ground block or individual grounds to block

Thanks gareth 

 

[APenNameAndThatA]

19 hours ago, old man emu said:

Can we get off this Centripetal/Centrifugal Force thing? It's obvious that nobody is willing to try to understand it and it is not getting an answer to the original question

 

 

This is a pattern. When people disagree with you, you assume that they are dumb. Centrifugal force is apparent, but it is also real. Let me explain. Centripital force and centrifugal force act in opposite directions. If you have a rock tied to the end of a string and swing it around your head, the string goes tight. String can only go tight if it is under tension. A piece of string can only be under tension if it is being pulled from *both* ends in *both* directions. The apparent part of centrifugal force is not that it does not exist, but that if you let go of a string, the stone flys forward and not straight out. 

 

You still have not learnt after you said that centrifugal force in the propeller diagram was there in error. It was not there in error. Someone smart enough to create a propeller diagram will be smart enough to know the nature of centrifugal force. 

Edited February 12, 2021 by APenNameAndThatA

[gareth lacey]

I asked a simple question and got a bunch of useless replies .Sheesh ( apologies to the ones that did answer my question and thank you

 

[old man emu]

Sorry, Gareth.

I posted this as an attempt at humour.

 

On 10/02/2021 at 5:10 PM, old man emu said:

Is that why I had the shite ripped out of me by a LAME when I took a compass out of a plane and was whirling it around my head on a length of safety wire? Well, he told me to go out and swing it, didn't he?

Yenn dragged us into the forces discussion.

 

I'm still waiting for Kyle to answer my question here about magnetic fields generated by electrical currents., for which I apologise for pointing to a sidetrack.

4 hours ago, APenNameAndThatA said:

you assume that they are dumb

I don't assume people are dumb. Someone, sometime in the distant past, got the idea all wrong and published an incorrect explanation which has become a physics myth. 

4 hours ago, APenNameAndThatA said:

A piece of string can only be under tension if it is being pulled from *both* ends in *both* directions

I agree with that, and it makes explaining the forces involved in the circular motion of a mass connected to a fixed point a bit easier.

 

I invite you to follow me over to the sister site where this discussion can be continued.

[APenNameAndThatA]

Discussing things with you one one site is plenty, thank you. 

Edited February 12, 2021 by APenNameAndThatA

[skippydiesel]

Gentlemen! the tone of this exchange seems to have become a tad acrimonious. I much preferer friendly/respectful disagreement/debate . Anything less does us all a disservice.

[old man emu]

33 minutes ago, APenNameAndThatA said:

Discussing things with you one one site is plenty, thank you. 

Geez, It's bloody impossible to be nice to you. If I agree with something you say, you find fault with something else. 

[skippydiesel]

9 hours ago, old man emu said:

Geez, It's bloody impossible to be nice to you. If I agree with something you say, you find fault with something else. 

Not sure of my definition here  but is this not a "troll"/"trolling" ??

[Jabiru7252]

starts in games, ends in tears...