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battery cables & Relays - Now G's

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FLYaDIVE(at)aol.com
Guest

Posted: Sun Oct 01, 2006 6:09 am Post subject: battery cables & Relays - Now G's

In a message dated 9/30/06 1:59:19 PM Eastern Daylight Time, 

robert.mccallum2(at)sympatico.ca writes:



 	  Quote: 	
		   The "G" forces required to open a closed contactor are generally not

  survivable. (or at least very close to it). I don't have quantitative

  numbers, but I have tried pulling one open and the force required is VERY

  significant. Many, many times that required to close it.

  

  Bob McC

==========================
	


Dave & Bob:



UhmpTeen years ago I had access to a laboratory of test equipment.  And did 

some pretty weird tests ... Mostly for the government ... Figures ... They are 

TOTALLY WEIRD!  And useless I might add.

Anyway ... How many 'g's' do you think it takes to pop on a Bic Pen cap, you 

know the old style Bic Pen that had the clear barrel and the blue removable 

snap on cap?

The procedure was to LIGHTLY place the cap on the tip of the pen.

Hold the pen in a vertical position with the cap and point facing UP.

Then drop the pen on the other end.

The drop (KE) with the sudden stop would pop the cap onto the pen.

The height was increased until the cap was fully seated.

If I recall the height was somewhere around 4 or 5 feet onto a steel 

accelerometer surface.

So how many 'g's' do you think?



Remember the height was ONLY 4 to 5 feet.

Barry

"Chop'd Liver"

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Sun Oct 01, 2006 6:40 am Post subject: battery cables & Relays - Now G's

Interesting test, but not really valid here...



You "Bic pen" test measured essentially two things:



Friction



Sealing



These are the two factor that determine the ease (or lack thereof) with

which the cap can be seated on the pen.



Gravity would have been a negligible factor in this type of test.



With a contactor, you are dealing with a solenoid, which is designed and

constructed to provide a given, and measurable, amount of "pull in" force.

You can also simply weigh the object being pulled in.



Just as a hypothetical...note that I am neither a scientist nor an engineer,

so if I'm "terminology deficient" please try to let it slide.



Assume that, if operated vertically, the solenoid can lift a 15 lb weight.

Also assume that the movable contactor portion of the device weighs 1 lb.

Obviously, it would take a gravitational force of greater than 15 g's to

open the contactor.



Note that it was only "static" gravity being considered in the above

hypothetical.



In an aircraft flying aerobatics, such factors as acceleration would also

play a part in the equation...



--

N6030X(at)DaveMorris.com
Guest

Posted: Sun Oct 01, 2006 6:57 am Post subject: battery cables & Relays - Now G's

Barry, I think that would depend on whether it was a girl's BIC pen 

or a guy's.  (Girls tend to chew on the caps and then a higher force 

is required to re-cap them).

I give up, how many g's?

Dave Morris

At 09:07 AM 10/1/2006, you wrote:

 	  Quote: 	

In a message dated 9/30/06 1:59:19 PM Eastern Daylight Time,

robert.mccallum2(at)sympatico.ca writes:

 > The "G" forces required to open a closed contactor are generally not

 >  survivable. (or at least very close to it). I don't have quantitative

 >  numbers, but I have tried pulling one open and the force required is VERY

 >  significant. Many, many times that required to close it.

 >

 >  Bob McC

==========================

Dave & Bob:

UhmpTeen years ago I had access to a laboratory of test equipment.  And did

some pretty weird tests ... Mostly for the government ... Figures 

... They are

TOTALLY WEIRD!  And useless I might add.

Anyway ... How many 'g's' do you think it takes to pop on a Bic Pen cap, you

know the old style Bic Pen that had the clear barrel and the blue removable

snap on cap?

The procedure was to LIGHTLY place the cap on the tip of the pen.

Hold the pen in a vertical position with the cap and point facing UP.

Then drop the pen on the other end.

The drop (KE) with the sudden stop would pop the cap onto the pen.

The height was increased until the cap was fully seated.

If I recall the height was somewhere around 4 or 5 feet onto a steel

accelerometer surface.

So how many 'g's' do you think?

Remember the height was ONLY 4 to 5 feet.

Barry

"Chop'd Liver"

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sun Oct 01, 2006 7:34 am Post subject: battery cables & Relays - Now G's

Bill;



---

_________________
Bob McC
Falco #908
(just starting)

khorton01(at)rogers.com
Guest

Posted: Sun Oct 01, 2006 7:34 am Post subject: battery cables & Relays - Now G's

On 1 Oct 2006, at 10:07, FLYaDIVE(at)aol.com wrote:

 	  Quote: 	

 In a message dated 9/30/06 1:59:19 PM Eastern Daylight Time,

 robert.mccallum2(at)sympatico.ca writes:

> The "G" forces required to open a closed contactor are generally not

>  survivable. (or at least very close to it). I don't have  

> quantitative

>  numbers, but I have tried pulling one open and the force required  

> is VERY

>  significant. Many, many times that required to close it.

>

>  Bob McC

 ==========================

 Dave & Bob:

 UhmpTeen years ago I had access to a laboratory of test equipment.   

 And did

 some pretty weird tests ... Mostly for the government ...  

 Figures ... They are

 TOTALLY WEIRD!  And useless I might add.

 Anyway ... How many 'g's' do you think it takes to pop on a Bic Pen  

 cap, you

 know the old style Bic Pen that had the clear barrel and the blue  

 removable

 snap on cap?

 The procedure was to LIGHTLY place the cap on the tip of the pen.

 Hold the pen in a vertical position with the cap and point facing UP.

 Then drop the pen on the other end.

 The drop (KE) with the sudden stop would pop the cap onto the pen.

 The height was increased until the cap was fully seated.

 If I recall the height was somewhere around 4 or 5 feet onto a steel

 accelerometer surface.

 So how many 'g's' do you think?

 Remember the height was ONLY 4 to 5 feet.

How did you determine the relationship between the reading on  

accelerometer when the pen landed on it and the acceleration that the  

pen cap was subjected to?

If the accelerometer wasn't mounted on the pen cap, I'm not really  

sure what you were measuring.

Kevin Horton

Ottawa, Canada

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sun Oct 01, 2006 7:54 am Post subject: battery cables & Relays - Now G's

Barry;

  

 I don't know, but it's going to be pretty high as  the deceleration distance is extremely small, and you have to provide enough  force to overcome distorting the plastic past the detents. The weight of the cap  is tiny, the force required a few ounces, so the G's will be extreme. (now  there's a quantified term for you )

  

 Bob McC

  

 DO NOT ARCHIVE

  

  

 [b]---

_________________
Bob McC
Falco #908
(just starting)

N6030X(at)DaveMorris.com
Guest

Posted: Sun Oct 01, 2006 8:55 am Post subject: battery cables & Relays - Now G's

Barry, I think when I worked in a government lab I must have had more 

fun than you.  We were shooting down missiles using an airborne laser 

in a KC-135.  You should see what a gigawatt pulsed CO2 laser does to 

a BIC cap, or a chunk of asbestos concrete.







Dave Morris

 	  Quote: 	
		  UhmpTeen years ago I had access to a laboratory of test equipment.  And did

some pretty weird tests ... Mostly for the government ... Figures 

... They are

TOTALLY WEIRD!  And useless I might add.

nuckollsr(at)cox.net
Guest

Posted: Sun Oct 01, 2006 12:37 pm Post subject: battery cables & Relays - Now G's

At 11:33 AM 10/1/2006 -0400, you wrote:



 	  Quote: 	
		  



On 1 Oct 2006, at 10:07, FLYaDIVE(at)aol.com wrote:



>

>

>In a message dated 9/30/06 1:59:19 PM Eastern Daylight Time,

>robert.mccallum2(at)sympatico.ca writes:

>

>>The "G" forces required to open a closed contactor are generally not

>>  survivable. (or at least very close to it). I don't have

>>quantitative

>>  numbers, but I have tried pulling one open and the force required

>>is VERY

>>  significant. Many, many times that required to close it.

>>

>>  Bob McC

>==========================

>Dave & Bob:

>

>UhmpTeen years ago I had access to a laboratory of test equipment.

>And did

>some pretty weird tests ... Mostly for the government ...

>Figures ... They are

>TOTALLY WEIRD!  And useless I might add.

>Anyway ... How many 'g's' do you think it takes to pop on a Bic Pen

>cap, you

>know the old style Bic Pen that had the clear barrel and the blue

>removable

>snap on cap?

>The procedure was to LIGHTLY place the cap on the tip of the pen.

>Hold the pen in a vertical position with the cap and point facing UP.

>Then drop the pen on the other end.

>The drop (KE) with the sudden stop would pop the cap onto the pen.

>The height was increased until the cap was fully seated.

>If I recall the height was somewhere around 4 or 5 feet onto a steel

>accelerometer surface.

>So how many 'g's' do you think?

>

>Remember the height was ONLY 4 to 5 feet.



How did you determine the relationship between the reading on

accelerometer when the pen landed on it and the acceleration that the

pen cap was subjected to?



If the accelerometer wasn't mounted on the pen cap, I'm not really

sure what you were measuring.


	


   I'm having trouble visualizing it too. The acceleration imparted

   on the cap was a function of change in velocity and

   time over which the change takes place.  Acceleration =

   delta velocity / t.  Terminal velocity on a 5 foot

   fall at 32.16 f/s/s is 18 feet/second.



   When the pen hits the hard stop, we don't know what

   time interval elapses between first contact and zero

   velocity . . . i.e. time to bring to rest. The smaller

   the number, the higher the acceleration. I suspect the

   accelerometer was used as a timing device . . . I.e,

   measurement of the force interval for stopping the

   pen's fall, not as a direct measurement of acceleration.



   In any case, numbers in the hundreds of g's would not

   surprise me.



   Bob . . .

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Sun Oct 01, 2006 7:15 pm Post subject: battery cables & Relays - Now G's

Man, you sure can tell it's the weekend...

  

 do not archive

  [quote][b]

_________________
From The PossumWorks...

FLYaDIVE(at)aol.com
Guest

Posted: Mon Oct 02, 2006 4:13 am Post subject: battery cables & Relays - Now G's

In a message dated 10/1/06 11:58:27 AM Eastern Daylight Time, 

robert.mccallum2(at)sympatico.ca writes:



 	  Quote: 	
		   Barry;

  

  I don't know, but it's going to be pretty high as the deceleration 

distance 
	


 	  Quote: 	
		   is extremely small, and you have to provide enough force to overcome 

 distorting the plastic past the detents. The weight of the cap is tiny, the 

 force required a few ounces, so the G's will be extreme. (now there's a 

 quantified term for you )

  

  Bob McC

================================
	


EXCELLENT Bob, EXCELLENT!



Now I know this is going to sound really crazy but ...

It averaged 200 g's

g's can be measure in either acceleration or deceleration and as the joke 

goes ... It is not the fall that kills you, it is the sudden stop.

Barry

"Chop'd Liver"

FLYaDIVE(at)aol.com
Guest

Posted: Mon Oct 02, 2006 4:14 am Post subject: battery cables & Relays - Now G's

Hi Bill:

- Bill's thoughts - 

Interesting test, but not really valid here...



You "Bic pen" test measured essentially two things:

Friction

Sealing

These are the two factor that determine the ease (or lack thereof) with

which the cap can be seated on the pen.

Gravity would have been a negligible factor in this type of test.



[Barry] -

Friction - YES

Sealing - NO

The test does not care if the cap seals, all it cares about is overcoming 

friction and moving the cap to is closed position.

Other factors is the weight of the pen, weight of the cap and distance 

dropped, velocity of the objects before stopping and force absorption on the objects 

and impact surface.  KE = 1/2 M x V2

But, take a guess on how many 'g's' were developed?

- - - - - - - - - - - - - - - - - - - - -

- Bill's thoughts - 

Assume that, if operated vertically, the solenoid can lift a 15 lb weight.

Also assume that the movable contactor portion of the device weighs 1 lb.

Obviously, it would take a gravitational force of greater than 15 g's to

open the contactor.



[Barry] - Good analogy, but what happened to the FRICTION, if it is part of 

the pen it is part of the solenoid. And there is also the constant opposite 

pull of the coil/solenoid for as long as power is applied.

- - - - - - - - - - - - - - - - - - - - - - 

- Bill's thoughts - 

In an aircraft flying aerobatics, such factors as acceleration would also

play a part in the equation...



[Barry] - And when would acceleration be encountered?  Especially at Max 

acceleration?  

NOT in straight and level flight! For the only acceleration then would be 

Rearward. Not pulling down on the plunger of the solenoid. (Vertically mounted 

relay)

If you consider the acceleration {But it really isn't, it is the g force you 

are feeling} when you pull out of a dive ... That is a change in velocity 

which equates to g forces.

When you pull out of a dive the plane slows down, it does not increase in 

speed.  It is only the g force you feel that gives that impression.



There is a difference between Velocity and Speed.  



Questions:

If you point the nose of the plane down, say 3 degrees and the prop RPM is 

fixed will the plane increase in speed until it hits something?

 

If you feel the g force (greater than 1 g) only during acceleration why can 

you feel the g force in a centrifuge at a constant speed?



If you point the nose of the plane down, say 3 degrees and the prop RPM is 

fixed will there be an increase in g force until it hits something?



Ain't physics grand?  An Exlax a day keeps everybody away.



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

FLYaDIVE(at)aol.com
Guest

Posted: Mon Oct 02, 2006 4:31 am Post subject: battery cables & Relays - Now G's

In a message dated 10/1/06 12:58:53 PM Eastern Daylight Time, 

N6030X(at)DaveMorris.com writes:



 	  Quote: 	
		   Barry, I think when I worked in a government lab I must have had more 

  fun than you.  We were shooting down missiles using an airborne laser 

  in a KC-135.  You should see what a gigawatt pulsed CO2 laser does to 

  a BIC cap, or a chunk of asbestos concrete.

  

  

  

  Dave Morris

======================
	


Dave:



You are a sick puppy ... But I like the way you think!  (Punch line taken 

from a joke)



I don't know who had more fun, but it sure was interesting.  So, do we use 

LASER cannons today?  Where can I get one?  Are they small enough to mount on my 

car?

Probably too expensive ... Just send me the schematic, I'll build one.



Barry

"Chop'd Liver"

FLYaDIVE(at)aol.com
Guest

Posted: Mon Oct 02, 2006 4:39 am Post subject: battery cables & Relays - Now G's

In a message dated 10/1/06 11:37:26 AM Eastern Daylight Time, 

khorton01(at)rogers.com writes:



 	  Quote: 	
		   How did you determine the relationship between the reading on  

  accelerometer when the pen landed on it and the acceleration that the  

  pen cap was subjected to?

  

  If the accelerometer wasn't mounted on the pen cap, I'm not really  

  sure what you were measuring.

  

  Kevin Horton

  Ottawa, Canada


	




Hi Kevin:



By starting off in low increments of height and dropping the pen; at some 

height the cap would snap onto the barrel.  Since all parts were falling as one 

unit the acceleration was the same for both the cap and the barrel.  The 

accelerometer just read of the force of the impact in g's.



Sort of like the egg drop experiment but in reverse.  We did not want to 

preserve the egg   

We were making egg salad  .



Barry

"Chop'd Liver"

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Mon Oct 02, 2006 4:41 am Post subject: battery cables & Relays - Now G's

Just for fun, a couple of points...



I threw in "sealing" in the Bic pen discussion to deal with the air trapped

in the cap. Given sufficient sealing, you would never be able to get the cap

farther down than the compressibility of air would permit.



I ignored friction in the solenoid as it would actually increase the force

required to open the contacts.



Interesting discussion...

--

FLYaDIVE(at)aol.com
Guest

Posted: Mon Oct 02, 2006 5:09 am Post subject: battery cables & Relays - Now G's

In a message dated 10/1/06 11:19:07 PM Eastern Daylight Time, 

Fiveonepw(at)aol.com writes:



 	  Quote: 	
		   Man, you sure can tell it's the weekend...

==============
	


And a RAINY one here in the Mid Atlantic - NJ

FLYaDIVE(at)aol.com
Guest

Posted: Mon Oct 02, 2006 5:16 am Post subject: battery cables & Relays - Now G's

In a message dated 10/1/06 4:41:52 PM Eastern Daylight Time, 

nuckollsr(at)cox.net writes:



 	  Quote: 	
		   I suspect the

     accelerometer was used as a timing device . . . I.e,

     measurement of the force interval for stopping the

     pen's fall, not as a direct measurement of acceleration.

  

     In any case, numbers in the hundreds of g's would not

     surprise me.

  

     Bob . . .

========================
	


Righty O! Bob ...



Averaged 200 g's



The accelerometer read out in g's and the output was also shown on an 

O'scope.  There was also other numbers, I don't recall, probably Newtons.



Barry

"Chop'd Liver"

nuckollsr(at)cox.net
Guest

Posted: Mon Oct 02, 2006 6:20 am Post subject: battery cables & Relays - Now G's

At 08:38 AM 10/2/2006 -0400, you wrote:

 	  Quote: 	

In a message dated 10/1/06 11:37:26 AM Eastern Daylight Time,

khorton01(at)rogers.com writes:

 > How did you determine the relationship between the reading on

 >  accelerometer when the pen landed on it and the acceleration that the

 >  pen cap was subjected to?

 >

 >  If the accelerometer wasn't mounted on the pen cap, I'm not really

 >  sure what you were measuring.

 >

 >  Kevin Horton

 >  Ottawa, Canada

Hi Kevin:

By starting off in low increments of height and dropping the pen; at some

height the cap would snap onto the barrel.  Since all parts were falling 

as one

unit the acceleration was the same for both the cap and the barrel.  The

accelerometer just read of the force of the impact in g's.

Sort of like the egg drop experiment but in reverse.  We did not want to

preserve the egg 

   Yeah, but if the accelerometer were stationary on

   the 'floor' then it's already at-rest when the pen

   hits it. The only data one might expect from the accelerometer

   is duration of the deceleration event, not its magnitude

   but I've not convinced myself that would work either.

   Accelerometers are sensitive to delta-v. If the critter

   is stuck to a relatively rigid surface like a concrete

   floor, whacking it with a falling pen would impart no

   motion.

   I think Gilles' suggestion for calculating the ratio

   of seating force to cap mass would yield the most

   meaningful result.

   Bob . . .

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