Wiring a Sailplane

On Dec 11, 6:51 pm, toad wrote:
On Dec 11, 4:59 pm, Todd wrote:

Very Good suggestions. And while you are at it, be prepared to spend
some serious $$ on the proper tools. I use nothing but AMP PIDG
connectors crimped by a genuine APF PIDG Crimp tool. My tefzel wire
is stripped using the correct mil spec stripper( Ideal Industries
Custom Stripmaster(R) Wire Stripper 16-26 AWG wire Item ID:45-1987http://www.idealindustries.com). Probably near $300 worth of tools
there. Ideally, leave your soldering iron at home.

Oh, come on. Do you really think that the low temperature (compared
to near a running engine) and low vibration environment of a glider
requires such expensive connections ?

Todd
3S

Oh come on are you kidding? If you really don't know what you are
doing and don't have the right tools then go find a good A&P (or if
the aircraft is certified you'll need one to supervise and sign off
you work anyhow). I'd argue that doing things properly the first time
is not really expensive compared to the cost of downtime, time spend
chasing down problems and safety risks.

If I only I had a dollar for every mangled piece of glider wiring I've
seen... including do it yourself, or certain glider manufactures or
occasionally a clueless A&Ps (but most USA A&Ps I've run into seem to
have higher electrical wiring standards than many glider
manufactueres). Stand around a typical glider port for long enough and
you'll hear people complaining about radio reception, battery life,
transponder operation or some other electrical problems and when you
poke around inside their glider it is often not surprising why.

To start with if you are using those cheap single action crimp tools
you are probably wasting your time - yes it might work now but the
joints are likely not good quality. Crimp connectors need huge
pressure to work properly, think swaging metals together to form a
surface cold weld not just squeezing the connector enough to
mechanically hold onto the wire. You should be using good quality
ratcheting type crimpers with the correct die set to suit the
connector.

There are many reasons to use quality nylon jacketed crimp connectors
besides just heat exposure, they are much stronger and the jacket
resists slipping off better than with PVC jacketed connectors - and
usually the insulators slipping off is cause by damage during crimping
(improper/cheap crimp tools again) and/or excessive handling of the
wiring.

That proper crimp also totally seals the joint against moisture and
moisture related corrosion - that can be an issue in gliders stored in
humid trailers etc. And keep that soldering iron away from crimp
connectors, soldering after the crimp can do damage and pretinning the
wire before crimping is very bad. I completely agree on keeping the
soldering iron at home - as strange as it may seem at first but
properly done crimp connections are more reliable than solder
connections, and they are easier to do.

Like other have said I would not use anything but Tefzel wire
especially in potential abrasion areas such as harnesses that flex
when canopies with attached instrument panels move, etc. Tefzel wire
does require a special stripper for clean strips, you can get away
with a standard high quality stripper at times, but you might be able
to borrow Tefzel one from a friendly A&P. Another good source in the
USA of Tefzel wire is Stein Air http://www.steinair.com/wire.htm
Another reason to use Tefzel aviation wire is it is fully tinned and
much more resistant to corrosion than the usual untinned PVC coated
junk at hardware/auto parts stores.

Darryl

Good comments all around.

- Crimps - multi-action crimpers are better as they apply more
pressure. This goes for lugs as well as coax connectors.
- Solder - Is to be avoided in liu of crimp connectors. However,
sometimes you just can't avoid it.
- Lugs - Always use ring lugs, never spade lugs.
- Wire - Tefzel is the only choice. Why? As mentioned above,
abrasion resistant, fully tinned (so even if abraded there will be no
wire "hairs" to cause shorts), and (most importantly) doesn't give off
dangerous gasses when burning. Tefzel may seem expensive when looking
at $0.20/foot but if you go through 100 feet in a glider I would be
very much surprised. That's $20. Chicken feed.
- Gauges of wire - guidelines (larger is better)
12 to 14 gauge - Main power lead from battery to distribution block
16 to 18 gauge - Power lead from distribution block to individual
devices
18 to 20 gauge - Speaker wiring
20 to 26 gauge - Control wires such as push-to-talk, air brake
switch, etc
- Get you work inspected!



Good luck.

On Dec 12, 11:51 am, ContestID67 wrote:
- Solder - Is to be avoided in liu of crimp connectors. However,
sometimes you just can't avoid it.

Why do you make this statement, John? I've dealt with tens of
thousands of cables professionally for over 35 years, and during that
experience I've found that if a connection is crimped, it's crap. By
that I mean it's highly likely to be either electrically noisy or
mechanically weak.

I did a Google search, and basically discovered that crimping vs
soldering discussions are, in some quarters, a quasi-religious war. I
don't want to add fuel to that fire, but are there authoritative,
unbiased studies (eg, not from connector manufacturers) that bear out
your assertion?

-John

On Dec 12, 11:04 am, jcarlyle wrote:
On Dec 12, 11:51 am, ContestID67 wrote:

- Solder - Is to be avoided in liu of crimp connectors. However,
sometimes you just can't avoid it.

Why do you make this statement, John? I've dealt with tens of
thousands of cables professionally for over 35 years, and during that
experience I've found that if a connection is crimped, it's crap. By
that I mean it's highly likely to be either electrically noisy or
mechanically weak.

I did a Google search, and basically discovered that crimping vs
soldering discussions are, in some quarters, a quasi-religious war. I
don't want to add fuel to that fire, but are there authoritative,
unbiased studies (eg, not from connector manufacturers) that bear out
your assertion?

-John

I'm not sure what sort of cable you are talking about. Some cables
e.g. professional audio cables are probably going to fail regardless
of how they are done just form the handling they get. Similarly I've
spent many hours repairing RF and microwave coax cables in research
labs and I'm sure most failere are from gross abuse (peopel pulling on
the cables etc.) and these have had all times of connections,
soldered, crimped, spot welded, exotic super conducting connections,
etc. For my money in my glider I'll take properly done crimp
connections.

There are quite a few research papers that demonstrate superiority of
crimp connectors in production environments - ie. where both solder
joints and crimp connections are performed properly. Even with good
control and technique solder suffers from dry joints and surface
contaminatation issues amongst others and in general take a lot more
skill to do properly than an equivalent crimp joint. Most of the
papers I recall are in IEEE publications not from vendors, if you are
an IEEE member or have access to their publications I'll try to find
them for you. Crimping may be faster and lower cost in production
environments but automotive and aerospace company also do not want to
pay for the cost of failed connections in the field - if soldering was
superior you would see it being used more in these applications.

It seems many people's experience with crimp connectors is using some
no brand PVC jacketed connector from the local hardware or auto parts
store with a cheap single action crimp tool. All bets are off if that
is the case.

Getting back to the original request, there are some interesting
articles on general aviation wiring etc. at http://www.aeroelectric.com/articles.html
I've not looked through them all but some seem to have a good
perspective from a professional A&P who does this stuff for a living.
He seems to have lots of practical examples of good tools and
workmanship, eg. -

http://www.aeroelectric.com/articles...rimptools.html
http://www.aeroelectric.com/articles.../shldwire.html
http://www.aeroelectric.com/articles/bnccrimp.pdf

Cheers


Darryl Ramm

I would suggest you take a look inside your car. You wont find
anything but crimped connectors EVERYWHERE. And the continue to
function even when corroded by the road salt the local highway
departments love to spread around here.

High quality connectors applied with the correct tool gives a very
reliable and repeatable connector. Look inside your next B787, you
wont find any soldered connectors there either. The technology is
quite well proven.

On Dec 12, 3:44 pm, Todd wrote:
I would suggest you take a look inside your car. You wont find
anything but crimped connectors EVERYWHERE.

High quality connectors applied with the correct tool gives a very
reliable and repeatable connector. Look inside your next B787, you
wont find any soldered connectors there either.

But if you look inside all the things that are connected together by
the crimped pin wiring harnesses you will find all the complex
electronics modules use surface mount soldered components!

The avionics of the 787 or any other modern transport aircraft would
not be possible without thousands, if not millions, of soldered
connections.


Andy

Thank you, Darryl and Todd, for your replies. Thanks also to John for
his off-line message.

Darryl, my experience has been with coaxial cables having BNC, UHF,
microdot and LEMO connectors. It's interesting that one of the URLs
you provided, http://www.aeroelectric.com/articles/bnccrimp.pdf, shows
the exact BNC crimp connector that has proven most troublesome in the
field. I've seen many of these connectors be electrically noisy
straight from the factory. But also, there's no true strain relief on
this connector, so the ground braid tends to break in a completely
invisible manner. A soldered BNC connector (the type with the
compression nut on the bottom) doesn't seem to have this problem, and
especially so if it's been fitted with a strain relief boot.

I thank you for this URL, http://www.aeroelectric.com/articles.html. I
was aware of Mr. Nuckolls' site, but somehow I had missed this page.
He appears to be a no nonsense, practical man, and as far as I can
tell he doesn't have a preference for either solder or crimp - as long
as they are done properly, that is!

One thing he points out is not to tin a wire you'll use a crimp
connector on, nor should you solder a crimped connector. You shouldn't
do the second because it destroys the strain relief, and you shouldn't
do the first because the connection loosens over time. Very, very
interesting, because Tefzel wire is pre-tinned...

I'm not a member of IEEE, so references to their journal won't do me
any good. But I take the point that there are indeed unbiased studies
favorably comparing crimp to solder in a production environment.
Manufacturers of course care a lot about unskilled labor being able to
make quick connections, as it maximizes their profit. And I don't
doubt that connector manufacturers take considerable design care so
that their connectors can approach the reliability of a good solder
joint. But speed and skill isn't generally an issue when it comes to
you yourself wiring your own glider. Personally, I'll take the time to
make a good solder joint having proper strain relief. YMMV, but I've
seen too many bad crimp connections to rest easy with having them in
my own plane.

Todd, the fact that car and aircraft manufacturers use crimp
connectors doesn't really sway me. Look at Consumer Reports and you'll
see that the major source of complaints for reliability in cars is
electrical systems. And don't overlook the fact that the Space Shuttle
flight has just been scrubbed because of intermittent connections. As
I said above, I think manufacturers' prime motivation is assembly
speed using unskilled labor. Reliability is also important, don't get
me wrong, but I think they're more interested in minimizing their cost/
benefit ratio. And as Jerry Pournelle of Chaos Manor fame likes to
say, "better is the enemy of good enough".

-John

On Dec 12, 4:44 pm, "
wrote:
On Dec 12, 11:04 am, jcarlyle wrote:



On Dec 12, 11:51 am, ContestID67 wrote:

- Solder - Is to be avoided in liu of crimp connectors. However,
sometimes you just can't avoid it.

Why do you make this statement, John? I've dealt with tens of
thousands of cables professionally for over 35 years, and during that
experience I've found that if a connection is crimped, it's crap. By
that I mean it's highly likely to be either electrically noisy or
mechanically weak.

I did a Google search, and basically discovered that crimping vs
soldering discussions are, in some quarters, a quasi-religious war. I
don't want to add fuel to that fire, but are there authoritative,
unbiased studies (eg, not from connector manufacturers) that bear out
your assertion?

-John

I'm not sure what sort of cable you are talking about. Some cables
e.g. professional audio cables are probably going to fail regardless
of how they are done just form the handling they get. Similarly I've
spent many hours repairing RF and microwave coax cables in research
labs and I'm sure most failere are from gross abuse (peopel pulling on
the cables etc.) and these have had all times of connections,
soldered, crimped, spot welded, exotic super conducting connections,
etc. For my money in my glider I'll take properly done crimp
connections.

There are quite a few research papers that demonstrate superiority of
crimp connectors in production environments - ie. where both solder
joints and crimp connections are performed properly. Even with good
control and technique solder suffers from dry joints and surface
contaminatation issues amongst others and in general take a lot more
skill to do properly than an equivalent crimp joint. Most of the
papers I recall are in IEEE publications not from vendors, if you are
an IEEE member or have access to their publications I'll try to find
them for you. Crimping may be faster and lower cost in production
environments but automotive and aerospace company also do not want to
pay for the cost of failed connections in the field - if soldering was
superior you would see it being used more in these applications.

It seems many people's experience with crimp connectors is using some
no brand PVC jacketed connector from the local hardware or auto parts
store with a cheap single action crimp tool. All bets are off if that
is the case.

Getting back to the original request, there are some interesting
articles on general aviation wiring etc. athttp://www.aeroelectric.com/articles.html
I've not looked through them all but some seem to have a good
perspective from a professional A&P who does this stuff for a living.
He seems to have lots of practical examples of good tools and
workmanship, eg. -

http://www.aeroelectric.com/articles...s/bnccrimp.pdf

Cheers

Darryl Ramm



On Dec 12, 5:44 pm, Todd wrote:
I would suggest you take a look inside your car. You wont find
anything but crimped connectors EVERYWHERE. And the continue to
function even when corroded by the road salt the local highway
departments love to spread around here.

High quality connectors applied with the correct tool gives a very
reliable and repeatable connector. Look inside your next B787, you
wont find any soldered connectors there either. The technology is
quite well proven.

On Dec 13, 6:53 am, jcarlyle wrote:
[snip]
One thing he points out is not to tin a wire you'll use a crimp
connector on, nor should you solder a crimped connector. You shouldn't
do the second because it destroys the strain relief, and you shouldn't
do the first because the connection loosens over time. Very, very
interesting, because Tefzel wire is pre-tinned...

Apples and oranges. Tefzel and many other wires are pre-tinned,
covered with a thin hard coat of tin or similar metals. You are
confusing this with the completely different process of "tinning" with
solder. Different chemicals, different processes, different thickness,
etc. etc.

Darryl

On Thu, 13 Dec 2007 06:53:03 -0800 (PST), jcarlyle
wrote:

One thing he points out is not to tin a wire you'll use a crimp
connector on, nor should you solder a crimped connector. You shouldn't
do the second because it destroys the strain relief, and you shouldn't
do the first because the connection loosens over time. Very, very
interesting, because Tefzel wire is pre-tinned...

Pretinned and "bunch tinned" as we used to call it are different; the
pretinned has each strand tinned. Bunch tinned has the group of
strands "glued" together with tinning or solder. Which is Tefzel
aircraft wire?

Aside ... back in the 1970's, the best wiring for boats was considered
to be the bunch tinned; a combination of good vibration resistance and
corrosion protection according to the wire salesmen calling on us
trying to get our chief engineer to use it on mobile radios. It was
said to be formable to a path but resistant to fatigue failure.

I AM NOT STATING THAT AS FACT, rather as what we were told.

George, I don't know. Until I read Darryl's message, I didn't know
that wire was sometimes tin plated. To me, the word "tinned" meant
that it had solder applied to it.

-John

GeorgeB wrote:
On Thu, 13 Dec 2007 06:53:03 -0800 (PST), jcarlyle
wrote:

One thing he points out is not to tin a wire you'll use a crimp
connector on, nor should you solder a crimped connector. You shouldn't
do the second because it destroys the strain relief, and you shouldn't
do the first because the connection loosens over time. Very, very
interesting, because Tefzel wire is pre-tinned...

Pretinned and "bunch tinned" as we used to call it are different; the
pretinned has each strand tinned. Bunch tinned has the group of
strands "glued" together with tinning or solder. Which is Tefzel
aircraft wire?

Aside ... back in the 1970's, the best wiring for boats was considered
to be the bunch tinned; a combination of good vibration resistance and
corrosion protection according to the wire salesmen calling on us
trying to get our chief engineer to use it on mobile radios. It was
said to be formable to a path but resistant to fatigue failure.

I AM NOT STATING THAT AS FACT, rather as what we were told.