Message-ID: <19981006221359.6830.qmail@www04.netaddress.usa.net>
Date: Tue, 06 Oct 1998 22:13:58
From: Dan Schaefer <dfschaefer@usa.net>
To: lancair.list@olsusa.com
Subject: More wire termination, NavAid tracking, Imron
Mime-Version: 1.0

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To David Buckwalter, totally agree with your advice to use a proper
crimping tool - I was remiss in not mentioning that in the earlier
post. Unfortunately, I took it for granted that such things are just
known (that's an OOPS!). The proper crimping tools are not the types 
available from the auto parts store - those are fine for smashing a
terminal, but are bad for crimping a reliable connection. Generally,
the type of tools needed are those that have either changeable or 
multiple dies sized for the terminal and wire size being crimped.
The most common, and easiest to use, also control the amount of 
squeeze you can put on a crimp as too much muscle is just as bad as too little. Don't settle for anything less if you are crimping.

By the way, if you're soldering your connections, you sure better
be using "Tefzel" insulated wire (or at least, Teflon) because to
get things hot enough to make a good solder joint, you'll destroy
other kinds of insulation - like any of the PVC's, etc. Most all
of the older or auto type wire has the wrong kind of insulation
for aircraft use. Tefzel meets Mil Spec MIL-W-22759/16 for stranded
unshielded wire and is rated for 150 C max. This stuff feels "waxy"
similar to Teflon but it has a much higher resistance to cold-flow
and cut-through if, for example, it's rested on or pulled around a
sharp edge like a bracket or sheet metal corner.

Gerald Cerchio asked about pro's 'n con's of flying in prime and also 
about Imron. If you can be absolutely sure that whoever does the 
final prep for painting (either you or the paint shop) gets every
trace of oil, exhaust residue, bug guts and etc. off the prime, then
it's no big deal. However, I've seen the results on a friend's plane
where the painter was less than thorough in cleaning and some of 
the paint, in spots, didn't stick well enough to survive being rubbed
out - some large patches came off on the bottom of the fuselage. You 
just have to be very finicky about the final cleaning, or paint first.
Since you seem to be in the San Francisco area, check out the Calif.
regulations about Imron if you're going to do the painting yourself.
Imron is considered (for very good reason) very toxic in it's un-
cured form - if you are planning to paint your plane yourself, don't
use it. The shops that shoot it have to have some pretty sophisticated
equipment to handle the toxicity. You could end up with severe, and 
permanent nerve damage - the proud owner of a beautiful, shiny air-
plane which you will be too screwed up to fly! Further, I was told by
the folks where I bought my paint that Imron, once cured, doesn't 
touch-up well because Imron cures by what's known as cross-linking 
within the curing layer and won't link to a new application once 
cured. A touch-up will stick pretty well mechanically, but doesn't 
really become one with previously cured surface. The paint folks 
recommended Delthane catalyzed acrylic, which comes out nearly as 
"wet look" as Imron, with none of the drawbacks. I used it, I've had 
to do some minor touch-up and I like it.

Bob Belshe brought up a question about the Nav Aid autopilot tracking
a KLX135 GPS. As I noted in my last post, they seem to get along OK
but often settle down tracking parallel to the desired course with a 
1 (or more) mile offset. Appparently the Nav Aid requires a minimum
amount of error signal to lock on the course. I'm not sure, but I 
think it's because the error signal vs offset is linear and may 
account for the insensitivity around zero error (offset). This is the
reason you need to crank in some a/p trim to fly the course center
line - that actually moves your desired track a ways left or right
while the Nav Aid is still happily flying with the original offset.
I'm not too comfortable with this so I'm building a error signal 
amplifier with selectable gain and transfer function (gain rate curve)
as an experiment and will report on howgozit if it works out. May be 
a while as I'm getting ready to retire after 30 years at the "Bomber
Factory" (or as some wags have put it, "B-1's are us") plus moving
out of Lala Land. Not sure where we're going to land but it's gotta
be outa California and in the Northwest somewhere. My wife likes
the Corvallis area of Oregon - anybody up there in on this forum? 
What's the airport and flying weather situation up in that part of 
the country?

Cheers,

Dan Schaefer


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