Matronics Email Lists :: View topic - Connectors and factories

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Connectors and factories

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

dlj04(at)josephson.com
Guest

Posted: Thu Feb 06, 2014 5:41 pm Post subject: Connectors and factories

Bob,



As someone who runs a small electronics factory I can sympathize with 

your decision not to continue doing that. There are a thousand trivial 

things you have to do every day that impact your bottom line, your 

ability to sleep well, and in the OBAM business, more serious consequences.



I'm building a CH750 and just this week have been pondering the problem 

mentioned with the Ray Allen trim servo wires. There are other 

disassembly points too like lights and gauge senders in the wing, so I 

would like to choose one type and stick to it. Maybe we can kick this 

around for a bit.



While I would like to use a standard connector, preferably mil standard 

like the old MIL-DTL-5015 ("MS connector") they are just too bulky and 

heavy. I really would rather not use a proprietary sole-source connector 

like the Switchcraft EN but if I'm going to choose something sole source 

I would want one that's in common use.



I'm considering two connector families. One is weatherproof automotive 

connectors like the Delphi Weather Pack. The other is a lightweight 

plastic variant of a military round connector, like the AMP CPC series. 

Weather Pack is available in 1 to 6 and 22 contacts, and seems to be a 

well proven system, but seems a little bulky.



Comments?

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Feb 07, 2014 6:12 am Post subject: Connectors and factories

At 07:39 PM 2/6/2014, you wrote:

 --> AeroElectric-List message posted by: dlj04 <dlj04(at)josephson.com>



 Bob,



 As someone who runs a small electronics factory I can sympathize with your decision not to continue doing that. There are a thousand trivial things you have to do every day that impact your bottom line, your ability to sleep well, and in the OBAM business, more serious consequences.



    Agreed . . . but it's not that the production tasks were

    demeaning or debilitating. It wasn't even a decision

    driven so much by economics . . . had my product flow

    been say 100x larger and I was running a profitable

    factory, it still wouldn't have made much sense.



    I've been reviewing the ideas offered by the likes of

    Adam Smith who spoke of the value and 'rightness' of

    division of labor and spontaneous organization. An

    economist Leonard Read spoke to these ideas most

    elegantly in his essay "I Pencil" about 60 years

    ago:



  http://tinyurl.com/me3q3hj



  http://tinyurl.com/mmlbv8p 



    The point I have belatedly acknowledged that in spite

    of all the hats I can wear, it makes best sense

    to take on those efforts where my time and talents

    move the project along most efficiently. I.e. it

    makes no sense for the cobbler to raise corn,

    feed cattle, butcher them for hides and tan the

    leather to make shoes. There are people who

    do these ancillary tasks better than he can

    and he doesn't even need to supervise them!



    So my quest is to seek out a combination of

    wearers of hats that compliment each other.



 

 I'm building a CH750 and just this week have been pondering the problem mentioned with the Ray Allen trim servo wires. There are other disassembly points too like lights and gauge senders in the wing, so I would like to choose one type and stick to it. Maybe we can kick this around for a bit.



 While I would like to use a standard connector, preferably mil standard like the old MIL-DTL-5015 ("MS connector") they are just too bulky and heavy. I really would rather not use a proprietary sole-source connector like the Switchcraft EN but if I'm going to choose something sole source I would want one that's in common use.



 I'm considering two connector families. One is weatherproof automotive connectors like the Delphi Weather Pack. The other is a lightweight plastic variant of a military round connector, like the AMP CPC series. Weather Pack is available in 1 to 6 and 22 contacts, and seems to be a well proven system, but seems a little bulky



 

    Your perceptions are correct but lets consider

    the return on investment for the 'ideal solution'.

    There are some folks who make very rugged yet

    tiny connectors suited to the task. One in 

    particular is LEMO



 [img]cid:.0[/img]



 



   who joins up bundles of wires in a rugged,

   water tight connector about 1/2" in diameter.

   I've seen these in the catalogs for years but

   didn't cross swords with one until a couple

   years ago when a device I had to talk to

   came already fitted with a LEMO connector.



   We had to come up with a mate and get it

   installed on the end of a 4-wire bundle. By

   the time we tracked down sources for and

   purchased the mating connector and tools,

   we probably had 2,000 dollars of labor

   and purchases invested in the task. Too

   late in a meeting weeks before first flight

   I blurted out, "Lets cut the damned thing

   off, go to the warehouse and get $50 worth

   of connectors out of stock that install with

   tools we already have!"



   Everybody smiled and nodded except the program

   manager who had already expended the $2K

   and wasn't willing to pitch it in favor of

   moving the project forward by about a week.



   This is a prime example for loss of spontaneous

   organization and focus on design goals. 



   What are your concerns for mating those itty-

   bitty actuator wires to the ship's systems?

   What are the consequences for say, inadvertent

   disconnect on a dark-n-stormy night flight

   over Mount Doom?



   Is the airplane likely to be stuck in a condition

   so far out of trim that it's un-manageable with

   elevated risks to aluminum and bone?



   How many times over the lifetime of the airplane

   do you expect to open this connection for maintenance

   or replacement of the actuator? By what

   percentage of total task would labor go up if

   those wires were simply soldered together and

   heat-shrinked?



   I think well considered answers to those 

   questions will form the basis for a practical

   selection of a connector for the task.



   I used to commiserated with my chief scientist

   at Beech about 'thousand dollar meetings' . . .

   10 people sitting around a table for an hour

   to arrive at some decision . . . and then 

   walking out of the meeting no closer to a

   solution than when we walked in . . . or

   perhaps having burdened our work order with

   a $1000 decision on a $50 part.



   How can we free up some hours for our readers

   to go buck a few more rivets as opposed to

   getting wrapped around the decision axle on

   the particular harness connector?



   Adam Smith would approve . . .



 

   Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

3c4b778d.jpg

Description:

Filesize:

14.67 KB

Viewed:

2429 Time(s)

dlj04(at)josephson.com
Guest

Posted: Sat Feb 08, 2014 9:30 am Post subject: Connectors and factories

On 2/7/14 11:58 PM, AeroElectric-List Digest Server wrote:

 	  Quote: 	
		   *



      There are some folks who make very rugged yet

      tiny connectors suited to the task. One in

      particular is LEMO

Ha! Yes, we are at the moment wrestling with a LEMO for a multichannel 
	


audio application. Some air carrier headsets also use LEMO. Remember, 

those connectors are made in the same region of Switzerland where they 

make watches. Very pretty and clever, but overkill for this.

 	  Quote: 	
		       Is the airplane likely to be stuck in a condition

     so far out of trim that it's un-manageable with

     elevated risks to aluminum and bone?

I don't know that yet.
	


 	  Quote: 	
		  

     How many times over the lifetime of the airplane

     do you expect to open this connection for maintenance

     or replacement of the actuator?

There will be some configuration changes in the tail that may require a 
	


few removal/install cycles, and the tail trim is not the only place 

where this is needed.

 	  Quote: 	
		   By what

     percentage of total task would labor go up if

     those wires were simply soldered together and

     heat-shrinked?

That's the default, of course. One other alternative, that I have used 
	


in certificated aircraft projects over the years, is to use a PIDG knife 

disconnect connector per wire, each one in a vinyl sleeve and laced 

together.

 	  Quote: 	
		  

     How can we free up some hours for our readers

     to go buck a few more rivets as opposed to

     getting wrapped around the decision axle on

     the particular harness connector?

I asked for discussion about the more general case of the several 
	


few-conductor breakaways in a small OBAM plane, such as for wing and 

cowling removal. I don't think it's necessary to get wrapped around any 

axle as many solutions will work, but thought there might be a consensus 

or a better idea than the ones I've had. Never mind, dlj04 out.

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Feb 09, 2014 4:38 am Post subject: Connectors and factories

 	  Quote: 	
		  I asked for discussion about the more general case of the several 

few-conductor breakaways in a small OBAM plane, such as for wing and 

cowling removal. I don't think it's necessary to get wrapped around 

any axle as many solutions will work, but thought there might be a 

consensus or a better idea than the ones I've had. Never mind, dlj04 out.


	


   I'm sorry you didn't receive the response you were

   seeking . . . but I don't think there's any 'axle

   wrapping' going on here either.



   Trim systems are, as a general rule, simply a convenience

   to the pilot. I flew an ultra-light hangared at our

   airport back about 1990. Fun machine. But I was initially

   appalled at the forces I had to hold on the controls to

   maintain the desired approach configuration for landing.

   Inputs were light in 'cruise' but it took quite a bit

   of stick and rudder input to put the little machine down

   where I intended.



   I asked the owner if there were any instructions for

   'trimming' the airplane for better handling qualities

   and he was surprised. The 'out of trim' condition of

   his particular choice of flying enjoyment was transparent

   to him . . . he had learned how to make the airplane

   do what he wanted and the awareness of demands on him

   as a pilot disappeared into automatic responses.



   So in the grand scheme of things, the value of a trim

   system for any axis goes to reducing pilot workloads

   to free up concentration on other things. Except for

   the risks posed by a runaway trim system that has

   too much aerodynamic authority, those little plastic

   boxes with motors in them do not warrant great

   concern for system reliability. Should a trim actuator

   become inoperative during some phase of otherwise

   controlled and trimmed flight, loss of said actuator

   does not represent a significant threat to aluminum and

   bones.



   This is generally a design goal for TC aircraft that

   must be demonstrated during qualification. The Beechjet

   was demonstrated to be manageable all the way to

   the runway with the trim system stuck at full

   nose down trim (general position for cruise

   a Mach airspeeds and altitudes).



   We can use that information to guide decisions

   in the selection of components for those little

   black plastic boxes. The generally controlling desire

   for most installations has been compactness. The

   wires need to route though small holes in structure.

   There's also been no demonstrated need for

   environmental robustness. Consider the

   manner in which these actuators are built.

   The connectors need be no more robust

   than the actuator on the other end of a 6-inch

   wire bundle.



   With the above points in mind, we can begin

   to consider connector styles and methods. It

   appears that this thread has run the spectrum

   of choices . . . as it has on several other

   occasions over the years. The only really

   elegant, small and robust connectors identified

   to date are Lemo products. At the same time,

   our conversation has failed to identify any

   operational or risk-reducing need to do anything

   fancier than 'lectric Bob's chopped down

   d-sub or even knife-splices under heat-shrink.



   It is useful to review these questions in open

   forum from time to time. Newcomers haven't

   participated or read past discussions and they

   just may be aware of an alternative, heretofore

   un-known solution. The electronics business is

   dynamic and it's quite likely that any new

   and exciting solution will be tossed in from

   out in left field by someone who may be surprised

   at how exciting his/her contribution is to the

   rest of us.



   Old timers on the List may fine these repeats

   boring but this is a class-room with a constantly

   rotating clientele. Let us be mindful of our

   role as teachers.

   Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum