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Best Practices for Reliable Electronic Deployment
#11
I still have these lying about from my R/C days.. :-)

http://www3.towerhobbies.com/cgi-bin/wti...XHGL9&P=ML

But I've been using servo connectors (and omitting one of the three wires) for my charges so that I can remove the bulkheads from the bay without any tools.

I plan on a complete redesign of my alt bays this spring. Right now things have been hectic for me.

Walsh
I like rockets!
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#12
These are the type I am referring to:

http://www3.towerhobbies.com/cgi-bin/wti...LXDKA3&P=7

for two wires or if you are setting up wiring for two charges, these which have 4 wires:

http://www3.towerhobbies.com/cgi-bin/wti...LXDKA7&P=7

I do not use the larger ones as they have a tendency to pull on the wires (weight wise) if you are using smaller wire. These connectors are used for the critical connections for batteries, etc. The problem with using servo connectors is there is always a possibility of it momentarily coming apart (happens all the time in R/C) which is something you do not want to leave to chance in this application.

They are available in red and black and I use the color coding so there is no way I can hook up my charges wrong ( drogue / main) after setting up the altimeter.

David
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#13
The one DD failure I had last year was due to a wire being pulled from the altimeter. I solved that with a couple changes.

1. I now use 4-flat wire instead of speaker wire or equivalent. If 4 wires are connected to individual terminals and one comes loose, the other 3 will at least hold the wire in place and possibly preserve your connection. With speaker wire, if one comes loose it is more likely to break away.

2. I run wires from the altimeters to terminal strips, then connect the charges and battery wires to the terminal strips. This to prevent the wire from being pulled from the altimeter. The terminal strips tend to have a better hold than the wire connection posts on the altimeters. You can also more safely use solid wire from your altimeter, which gives you a better connection than with braided wire and also eliminates the need for terminal connectors, which can come apart.

I have not had a problem using solid wire and prefer it because I use screws with the heads cut off them as terminal posts through the bulkheads. The screws are held in place with nuts, tightened and epoxied into place. Then a second set of nuts hold the solid wire in place on both sides.

My fundamental thought in doing all this is that a solid wire, wrapped around a terminal, then tightened down is the best electrical connection you can have short of soldering.
Evan Brown
NAR# 92851
Level 2
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#14
Very good comments.  We will summarize the wiring topic before moving on to batteries which is next.

Again this is an industry best practices thread, anyone can chose to do less.

In summary:

Stranded wire is a more robust solution than solid core ONLY if properly terminated.

The proper way to terminate stranded wire is a properly crimped on ferrule for screw down terminals or crimped spade lugs for terminal blocks.
Solid wire is self terminating for terminal blocks.

Solid core wire will break easily if nicked.  It is almost impossible for an amateur to strip a solid core wire without nicking it. If using solid core wire use shooters wire or doorbell wire the insultion is designed to be stripped by fingernail.  Your fingernail cannot nick copper.

Here is what the military requires for stripping solid core wiring..
http://www.hmcelectronics.com/product/St...leshopping

However there are many more failures of stranded wire pulling out of connectors or a stray strand shorting than solid wire breaking during a flight.
John Derimiggio
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#15
Thanks Mike, David, Evan and John!  Smile
David- I could not find what gauge wire is recommended for use with those microconnectors. Since the end pins that will be soldered to seem to be solid, the limitation would appear to be the pin spacing, so it appears 20/22 gauge would work out fine.
While we are talking about wiring I am concerned somewhat about current flow limitations in smaller gauge wiring in the lengths I will be using (2 feet or so between the altimeter and the terminal strip on the charge side of the bulkheads). What gauge do folks use for reliable ematch (or if I can't get them the Quest Q2C2s) ignition?
Greg
Greg Young - L3
NAR #42065
TRA #00234
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#16
(03-20-2013, 07:36 PM)gyoung link Wrote:Thanks Mike, David, Evan and John!  Smile
David- I could not find what gauge wire is recommended for use with those microconnectors. Since the end pins that will be soldered to seem to be solid, the limitation would appear to be the pin spacing, so it appears 20/22 gauge would work out fine.
While we are talking about wiring I am concerned somewhat about current flow limitations in smaller gauge wiring in the lengths I will be using (2 feet or so between the altimeter and the terminal strip on the charge side of the bulkheads). What gauge do folks use for reliable ematch (or if I can't get them the Quest Q2C2s) ignition?
Greg

By the time you get into current carrying concerns you selected a wire that is too fragile to strip easily. For this reason i would go with 22 or 24 ga.  24ga has a continous current rating of 3.5A for chassis wiring applications.
John Derimiggio
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#17
That sounds good, thanks John!
I haven't had previous experience using ignitors to detonate charges powered by 9 volt batteries, and I tend to overbuild my electronics a bit. Given 24 gauge works for folks, I'll rewire using either that or 22 gauge, once you have received those 22 gauge ferrules you have coming and can ascertain whether or not they will fit the terminals on the MARSA4.
Greg
Greg Young - L3
NAR #42065
TRA #00234
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#18
I ordered a bag of 500, I'll give them away to anyone who wants some.
John Derimiggio
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#19
I use 24 AWG, but 20AWG would be the largest (overkill) for this application.

David
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#20
I'm not sure whether the 18 ga. properly seats in the altimeter connectors. I imagine it will, but I tend to use 22-24 ga. Beyond the fact that they can do the job, it is easier to compress them into a 2.5" dia. av bay.
Evan Brown
NAR# 92851
Level 2
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