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Engine ground on RV 10

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planesmith(at)hotmail.com
Guest

Posted: Tue Feb 10, 2009 3:51 pm Post subject: Engine ground on RV 10

Hi All C

  

 I'm building an RV 10 with the 12v battery locally grounded and mounted in the tail. Where is a good place to locally ground the engine on the airframe? 

  

 Possible engine grounding options are:

  

 1. To a ground forest mounted on the stainless firewall. Q: Will the thin stainless handle the current during the starting of an IO 540?

  

 2. To one of the engine mount/airframe bolts.

  

 3. To the engine mount (Yes C I've read Bob's article against using this but through it in anyway.)

  

 3. Other options?

  

 I really don't want to run a negative cable back to the battery (~12 foot of #2 cable.) I have looked through the archives and this subject has been nibbled around both here and on the RV 10 list C but not hit square on the head. I look forward to you comments.

  

 Thanks C

  

 Vernon Smith (#324 RV 10 finishing)

Windows Live™: Keep your life in sync.  See how it works.  [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Feb 10, 2009 7:38 pm Post subject: Engine ground on RV 10

At 05:49 PM 2/10/2009, you wrote:

 	  Quote: 	
		  Hi All,



I'm building an RV 10 with the 12v battery locally grounded and 

mounted in the tail. Where is a good place to locally ground the 

engine on the airframe?



Possible engine grounding options are:



1. To a ground forest mounted on the stainless firewall. Q: Will the 

thin stainless handle the current during the starting of an IO 540?



2. To one of the engine mount/airframe bolts.



3. To the engine mount (Yes, I've read Bob's article against using 

this but through it in anyway.)



3. Other options?



I really don't want to run a negative cable back to the battery (~12 

foot of #2 cable.) I have looked through the archives and this 

subject has been nibbled around both here and on the RV 10 list, but 

not hit square on the head. I look forward to you comments.


	


   The big guys have been using airframes for cranking

   current grounds for many, many moons. In this case,

   ground crankcase to forest-of-tabs bolt with a braid

   strap -AND- it wouldn't hurt to add the jumper straps

   around the shock mounts like the big guys too . . .



   Bob . . .

planesmith(at)hotmail.com
Guest

Posted: Tue Feb 10, 2009 9:05 pm Post subject: Engine ground on RV 10

Bob C



Thanks for the response. Got it C two braided jumper straps. That's one less thing to obsess over!



Vern 



do not archive



[quote] Date: Tue C 10 Feb 2009 21:37:44 -0600

 To: aeroelectric-list(at)matronics.com

 From: nuckolls.bob(at)aeroelectric.com

 Subject: Re: Engine ground on RV 10

 

 --> AeroElectric-List message posted by: "Robert L. Nuckolls C III" <nuckolls.bob(at)aeroelectric.com>

 

 At 05:49 PM 2/10/2009 C you wrote:

 >Hi All C

 >

 >I'm building an RV 10 with the 12v battery locally grounded and 

 >mounted in the tail. Where is a good place to locally ground the 

 >engine on the airframe?

 >

 >Possible engine grounding options are:

 >

 >1. To a ground forest mounted on the stainless firewall. Q: Will the 

 >thin stainless handle the current during the starting of an IO 540?

 >

 >2. To one of the engine mount/airframe bolts.

 >

 >3. To the engine mount (Yes C I've read Bob's article against using 

 >this but through it in anyway.)

 >

 >3. Other options?

 >

 >I really don't want to run a negative cable back to the battery (~12 

 >foot of #2 cable.) I have looked through the archives and this 

 >subject has been nibbled around both here and on the RV 10 list C but 

 >not hit square on the head. I look forward to you comments.

 

    The big guys have been using airframes for cranking

    current grounds for many C many moons. In this case C

    ground crankcase to forest-of-tabs bolt with a braid

    strap -AND- it wouldn't hurt to add the jumper straps

    around the shock mounts like the big guys too . . .

 

    Bob . . . 

 

 

=========

 

 

 

Windows Live™: E-mail. Chat. Share. Get more ways to connect.  See how it works.   	  Quote: 	
		  [b]

rv9jim(at)juno.com
Guest

Posted: Wed Feb 11, 2009 6:16 am Post subject: Engine ground on RV 10

Vernan,

        Run a #6 wire from the forest of tabs directly to the battery

neg. term.  That gives you a good source of electrons for your equipment.

 Then, run a braided cable from the negative term of the battery directly

to the case of the engine.  This gives you two wires to hook up to the

negative terminal of the battery.  Basically, you have two wires from the

positive terminal.  One is the "keep alive" wire and the other is the

main wire to the starter solenoid ect.    Do not use the stainless steel

firewall as a current carrier.



Jim

____________________________________________________________

Need cash? Click to get a cash advance.

http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw1hEPyYtMguGP7lFk72hCWLzaeEGIu0lxdfvLA2mHoFbi7nb/

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Feb 11, 2009 6:50 am Post subject: Engine ground on RV 10

At 11:03 PM 2/10/2009, you wrote:

 	  Quote: 	
		  Bob,


	




 	  Quote: 	
		  Thanks for the response. Got it, two braided jumper straps. That's 

one less thing to obsess over!


	


    That's ONE braided jumper strap (or 2AWG welding cable

    with terminals and heat-shrink) and as many thin, flat, sheet

    metal bonding straps as you have shock mounts (usually

    4).

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

planesmith(at)hotmail.com
Guest

Posted: Wed Feb 11, 2009 8:06 am Post subject: Engine ground on RV 10

Bob C

  

 The RV-10 has a ground lug welded to the engine mount.

 Could I run one cable from the engine case to the this lug C and one cable from the engine case to the ground forest on the firewall? Thus eliminating the bonding straps around the lord mounts.

  

 Vern Smith



 	  Quote: 	
		   Date: Wed C 11 Feb 2009 08:47:29 -0600

 To: aeroelectric-list(at)matronics.com

 From: nuckolls.bob(at)aeroelectric.com

 Subject: RE: Engine ground on RV 10

 

 --> AeroElectric-List message posted by: "Robert L. Nuckolls C III" <nuckolls.bob(at)aeroelectric.com>

 

 At 11:03 PM 2/10/2009 C you wrote:

 >Bob C

 

 

 >Thanks for the response. Got it C two braided jumper straps. That's 

 >one less thing to obsess over!

 

 That's ONE braided jumper strap (or 2AWG welding cable

 with terminals and heat-shrink) and as many thin C flat C sheet

 metal bonding straps as you have shock mounts (usually

 4).

 

 

 Bob . . .

 

 ----------------------------------------)

 ( . . . a long habit of not thinking )

 ( a thing wrong C gives it a superficial )

 ( appearance of being right . . . )

 ( )

 ( -Thomas Paine 1776- )

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

 

 <=================

 

 

 


	


Windows Live™: Keep your life in sync.  Check it out.  [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Feb 11, 2009 8:24 am Post subject: Engine ground on RV 10

At 10:04 AM 2/11/2009, you wrote:

 	  Quote: 	
		  Bob,



The RV-10 has a ground lug welded to the engine mount.

Could I run one cable from the engine case to the this lug, and one 

cable from the engine case to the ground forest on the firewall? 

Thus eliminating the bonding straps around the lord mounts.


	


   About anything you want to do will function.

   We can argue/discuss a host of relatively

   small issues with equally small cause/effect

   scenarios.



   Bottom line is that hundreds of thousands of TC

   aircraft have used a variety of combinations

   for getting crankcases grounded. While the

   stainless firewall sheet is not a GOOD conductor,

   it's adequate for a very few accessories that

   depended on it for ground that includes things

   like contactors, voltage regulators, accessory

   control relays, etc. The notion of tying the

   forest of tabs to the crankcase with a fat

   wire is to GROUND the forest of tabs, not

   ground the engine.



   The minimum impedance path from crankcase

   to structure is through the engine mount

   bolts at the corners of the firewall.



   Since you've decided to use the fuselage

   as a battery return conductor, then our

   design goal might be to minimize current

   on across the firewall sheet.



   How about this? Leave the shock mounts alone

   and add a fat-wire jumper from the forest

   of tabs down to the most solid structure

   available under the floorboards. I think

   I like that better. This isn't going to

   reduce the firewall sheet currents to zero

   but they'll become a small fraction of the

   total during engine cranking.



        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

planesmith(at)hotmail.com
Guest

Posted: Wed Feb 11, 2009 8:57 am Post subject: Engine ground on RV 10

Thanks Bob C

  

 The extra information makes sense and helps greatly.

  

 Vern

  

 do not archive



 	  Quote: 	
		   Date: Wed C 11 Feb 2009 10:23:44 -0600

 To: aeroelectric-list(at)matronics.com

 From: nuckolls.bob(at)aeroelectric.com

 Subject: RE: Engine ground on RV 10

 

 --> AeroElectric-List message posted by: "Robert L. Nuckolls C III" <nuckolls.bob(at)aeroelectric.com>

 

 At 10:04 AM 2/11/2009 C you wrote:

 >Bob C

 >

 >The RV-10 has a ground lug welded to the engine mount.

 >Could I run one cable from the engine case to the this lug C and one 

 >cable from the engine case to the ground forest on the firewall? 

 >Thus eliminating the bonding straps around the lord mounts.

 

 About anything you want to do will function.

 We can argue/discuss a host of relatively

 small issues with equally small cause/effect

 scenarios.

 

 Bottom line is that hundreds of thousands of TC

 aircraft have used a variety of combinations

 for getting crankcases grounded. While the

 stainless firewall sheet is not a GOOD conductor C

 it's adequate for a very few accessories that

 depended on it for ground that includes things

 like contactors C voltage regulators C accessory

 control relays C etc. The notion of tying the

 forest of tabs to the crankcase with a fat

 wire is to GROUND the forest of tabs C not

 ground the engine.

 

 The minimum impedance path from crankcase

 to structure is through the engine mount

 bolts at the corners of the firewall.

 

 Since you've decided to use the fuselage

 as a battery return conductor C then our

 design goal might be to minimize current

 on across the firewall sheet.

 

 How about this? Leave the shock mounts alone

 and add a fat-wire jumper from the forest

 of tabs down to the most solid structure

 available under the floorboards. I think

 I like that better. This isn't going to

 reduce the firewall sheet currents to zero

 but they'll become a small fraction of the

 total during engine cranking.

 

 

 

 Bob . . .

 

 ----------------------------------------)

 ( . . . a long habit of not thinking )

 ( a thing wrong C gives it a superficial )

 ( appearance of being right . . . )

 ( )

 ( -Thomas Paine 1776- )

 ------------==========

 

 

 


	


Windows Live™: E-mail. Chat. Share. Get more ways to connect.  Check it out.  [quote][b]

BRogers(at)fdic.gov
Guest

Posted: Wed Feb 11, 2009 12:12 pm Post subject: Engine ground on RV 10

Bob Nuckolls,



You said below that stainless firewall sheet is not a GOOD conductor.

Will you please quantify that statement?  How much worse is it than

2024-T3 aluminum?



I have a battery in the tail of my airplane that is grounded through the

airframe, but the forest of ground tabs is on the stainless steel

firewall.  Does that mean that I need to run a fat wire from the forest

of tabs attach bolt on the stainless steel firewall to some portion of

the aluminum airframe?



Thanks,



Bob J. Rogers



--

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 12, 2009 5:22 am Post subject: Engine ground on RV 10

At 02:06 PM 2/11/2009, you wrote:

 	  Quote: 	
		  



Bob Nuckolls,



You said below that stainless firewall sheet is not a GOOD conductor.

Will you please quantify that statement?  How much worse is it than

2024-T3 aluminum?



I have a battery in the tail of my airplane that is grounded through the

airframe, but the forest of ground tabs is on the stainless steel

firewall.  Does that mean that I need to run a fat wire from the forest

of tabs attach bolt on the stainless steel firewall to some portion of

the aluminum airframe?


	


   It wouldn't hurt.



   The simple answer to your question is that stainless steels are

   between 10 and 30% as good a conductor of electron flow as

   annealed copper. That sounds worse than it is in this case

   because we're not dealing with a long, thin conductor between

   point A (your battery ground) and point B (your forest-of-tabs).



   Imagine if you will 1,000,000 conductors between A and B. Each conductor

   is made of aluminum (A-to edge of firewall) where a piece of

   stainless wire is spliced on (edge of firewall to B). While the

   addition of the stainless might make the over all path resistance

   of any one conductor jump by a factor of 3 to perhaps even

   10x, the PARALLELED value of all those conductors is still

   a rather low number.



   As an example, I think I heard a number offered in a meeting

   on lightning issues that the resistance of a Model 400 Beechjet

   from nose to tail was on the order of 1 milliohm. Pretty low

   as far as cranking engines was concerned (assuming that you

   ran cranking current the length of the airplane!). In terms

   of 100,000 amp lightning strikes, that 1 milliohm was quite

   significant for other concerns.



   If you visualize your point A to point B conduction pathway

   as a wire frame made up of many paralleled paths of connected

   airframe components, the whole thing is still pretty good

   (with "pretty" being "terribly" non-quantified . . . terribly

   isn't well quantified either).



   The point is that while the stainless steel as a single entity

   in a huge array of entities doesn't cause the cranking current

   pathway to become useless. The concerns come with ageing

   of the airframe where new rivets that were swelled up in tight

   holes become less conductive with time in service and

   environmental effects.



   It would be interesting to get a conductivity measurement

   between the center of the firewall sheet and the battery (-)

   terminal of your airplane before and after adding a

   fat-wire jumper.  I did have occasion to measure the

   battery(-) to crankcase resistance on a wrecked 172. See



   http://www.aeroelectric.com/articles/grnding.pdf



   Even in the bent state, the resistance was just

   under 3 milliohms. Know too that the majority

   of that resistance came from wire and joints in

   wires use to complete the chain. The airframe

   would have been a small fraction of the total.



   If this sounds like an indefinite answer as to the

   value of adding the jumper wire, you're right. Your

   brand new airplane as-assembled will probably not

   show the effects of less-than-the-best grounding.

   But as a matter of experience and good practice let

   me offer that I try to avoid using the firewall sheet

   (indeed other parts of the airframe) as the universal

   ground conductor.



   This is discussed in the 'Connection and in Figure Z-15.

   Adding the jumper now and then using the airframe for

   grounding ONLY a few remote accessories is a good

   thing to do for the owner-operator that's going to

   be flying this airplane 20 years from now . . . hopefully

   that's you.



   Bob . . .

rparigor(at)SUFFOLK.LIB.N
Guest

Posted: Thu Feb 12, 2009 12:26 pm Post subject: Engine ground on RV 10

Hi Bob"The simple answer to your question is that stainless steels are > between 10 and 30% as good a conductor of electron flow as > annealed copper. "Did you add a decimal place stating between 10 and 30% and mean 1 and 3%??According to this table:http://www.ndt-ed.org/GeneralResources/MaterialProperties/ET/ET_matlprop_Iron-Based.htmbetween 1 + 3% is more accurate??Ron ParigorisJust as a reference annealed copper is 100% and silver 106%:http://www.wisetool.com/designation/cond.htm   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 12, 2009 3:11 pm Post subject: Engine ground on RV 10

At 02:23 PM 2/12/2009, you wrote:

  	  Quote: 	
		  Hi Bob



 "The simple answer to your question is that stainless steels are 

 > between 10 and 30% as good a conductor of electron flow as 

 > annealed copper. "



 Did you add a decimal place stating between 10 and 30% and mean 1 and 3%??



 According to this table:



  http://www.ndt-ed.org/GeneralResources/MaterialProperties/ET/ET_matlprop_Iron-Based.htm 



 between 1 + 3% is more accurate?? 	




   Good eye! I tried to do conductance values to

   percentages of resistance . . . Thanks!



   Bob . . .



     [quote][b]

MauleDriver(at)nc.rr.com
Guest

Posted: Thu Feb 12, 2009 5:03 pm Post subject: Engine ground on RV 10

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		      That's ONE braided jumper strap (or 2AWG welding cable

    with terminals and heat-shrink) and as many thin, flat, sheet

    metal bonding straps as you have shock mounts (usually

    4).

Bob, I want to do that on my RV10.  I have the forest of tabs on the 
	


firewall which has an 8AWG wire running back to the battery.  I'll run a 

braided jumper strap from the bolt on the forest of tabs  to wherever 

it's best connect it to the IO540 crankcase.  And I understand it 

doesen't really ground the engine as much as it grounds the forest of tabs.



But what do the 4 "thin flat sheet metal bonding straps" look like?  I'm 

imagining something forming an arc around the non-conductive shock 

mounts but I've never seen this and can't find a reference.  Can you 

elaborate a bit here or point me to the photos you probably have out on 

your site?  Is this something I fabricate or buy?



If anyone can help me identify the ground lug on the RV10 engine mount 

or the best place to attach a ground on the crankcase, I'd appreciate it.



Thanks.



Bill "ready to hang the engine" Watson

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 12, 2009 7:56 pm Post subject: Engine ground on RV 10

At 06:59 PM 2/12/2009, you wrote:

 	  Quote: 	
		  

<MauleDriver(at)nc.rr.com>



Robert L. Nuckolls, III wrote:

>    That's ONE braided jumper strap (or 2AWG welding cable

>    with terminals and heat-shrink) and as many thin, flat, sheet

>    metal bonding straps as you have shock mounts (usually

>    4).

Bob, I want to do that on my RV10.  I have the forest of tabs on the 

firewall which has an 8AWG wire running back to the battery.


	


     Eliminate this dude. It's contribution is too

     tiny to measure much less observe. Ground battery

     through 4AWG welding cable to the same class of

     structure as cited below . . .

 	  Quote: 	
		     I'll run a braided jumper strap from the bolt on the forest of 

 tabs  to wherever it's best connect it to the IO540 crankcase.  And 

 I understand it doesen't really ground the engine as much as it 

 grounds the forest of tabs.


	


     Okay, add another fat-wire jumper from forest

     of tabs to structure right behind the firewall.

     Anyone out there got a picture of the heavy

     metal under the floorboards between the rudder

     pedals?

 	  Quote: 	
		  But what do the 4 "thin flat sheet metal bonding straps" look 

like?  I'm imagining something forming an arc around the 

non-conductive shock mounts but I've never seen this and can't find 

a reference.  Can you elaborate a bit here or point me to the photos 

you probably have out on your site?  Is this something I fabricate or buy?


	


     Leave those off. We distilled this process down

     a bit from the first thought about using the

     shock-mount straps. It's STILL a good idea not

     to use the engine mount for anything other

     than holding the engine on the airplane.

 	  Quote: 	
		  If anyone can help me identify the ground lug on the RV10 engine 

mount or the best place to attach a ground on the crankcase, I'd appreciate it.


	




        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

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

planesmith(at)hotmail.com
Guest

Posted: Sat Feb 14, 2009 7:45 pm Post subject: Engine ground on RV 10

Bob C



You asked for some pictures of the RV 10 floor boards. 



Just a note C In one of the photos there is a nice heavy 3/4" angle that runs in the side wall of the aircraft for the full length (there is a splice in it back behind the baggage door.) Van's has said not to drill any additional holes in this piece C however there is a plate mount with three AN 3 bolts that hold the rudder pedal blocks (it's visible in the photo labeled SYS 010.) Maybe this would be a good place to ground the firewall ground forest?



Of course C I though about this after pulling a #2 ground up from the battery yesterday! 



Hope this is of help C



Vern Smith ( #324 RV-10 finishing) 



 	  Quote: 	
		   Date: Thu C 12 Feb 2009 21:54:08 -0600

 To: aeroelectric-list(at)matronics.com

 From: nuckolls.bob(at)aeroelectric.com

 Subject: Re: Engine ground on RV 10

      

Okay C add another fat-wire jumper from forest
	


 	  Quote: 	
		        of tabs to structure right behind the firewall.

      Anyone out there got a picture of the heavy

      metal under the floorboards between the rudder

      pedals?

 

 

 >But what do the 4 "thin flat sheet metal bonding straps" look 

 >like?  I'm imagining something forming an arc around the 

 >non-conductive shock mounts but I've never seen this and can't find 

 >a reference.  Can you elaborate a bit here or point me to the photos 

 >you probably have out on your site?  Is this something I fabricate or buy?

 

      Leave those off. We distilled this process down

      a bit from the first thought about using the

      shock-mount straps. It's STILL a good idea not

      to use the engine mount for anything other

      than holding the engine on the airplane.

 

 

 >If anyone can help me identify the ground lug on the RV10 engine 

 >mount or the best place to attach a ground on the crankcase C I'd appreciate it.

 

 

         Bob . . .

 

         ----------------------------------------)

         ( . . .  a long habit of not thinking   )

         ( a thing wrong C gives it a superficial )

         ( appearance of being right . . .       )

         (                                       )

         (                  -Thomas Paine 1776-  )

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

========================Windows Live™: Keep your life in sync.  See how it works.

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