[simpits-tech] Aircraft power question

[Matt Bailey]

Good point about the buses. Am I correct that a huge batch of terminal
blocks would be considered a bus? Or are we talking about something a
little fancier? (I have very little experience poking around the
innards of aircraft in any detail). I *do* see some odd rectangular
looking relays in the nose. On the back of the cockpit, there are over a
dozen individual terminal blocks. There are several big wire bundles
coming off them and going aft, which of course are just cut off now.
Unfortunately, a bunch of wires also go back into the cockpit, and they
got cut because they are right along the inside of the outer skin. I am
worried that power delivery for the cockpit goes up to that bunch of
terminal blocks for organization purposes. Does this make sense? Or
perhaps I am just not getting the right relays energized to tie
everything into power....

I still have two of the three "big" inverters in the nose, as the
previous owner was unable to figure out how to remove those. That
leaves me with inverter #1 and a "750va" inverter (not sure what that
monster is for).

I played with it today. I figured out some of the power delivery stuff
for the #1 and #2 inverters. My problem right now is I don't have a good
28v DC power source. I series'd two 12v batteries together and was able
to power up inverter #1 for a few minutes. It appears to work (and
makes quite an intimidating sound!), but I got absolutely no reaction
inside the cockpit. Even the load/volt/CPS indicators did not budge.
Then I tried tying the power lead that is supposed to go to inverter
#1, into my 24v battery rig also. There were some interesting noises
inside the cockpit, but then my little batteries wore out (this thing
draws a TON of current). I am HOPING this means that I just have to
have the 28v supply leads connected to power to engage some relays or
something to tie in all the necessary buses, but I won't know for sure
until I work out a better DC power source (I am actually thinking of
using a couple of my cars in series with jumper cables and the engines
running).

Interestingly, there don't seem to be any bus tie-in controls in the
cockpit. I guess it all happens "under the hood".

Matt

On Fri, 27 Dec 2013 15:05:47 +0000
Roy Coates <roy at flightlab.liv.ac.uk> wrote:

> Remember that there will be multiple buses which can be shed or
> cross-linked.  I know zip about the Sabreliner but even our baby J41
> has 5 (maybe 6?) buses. A very basic 737 has eleven.  So, the wiring
> won't be as simple as you might like.
> 
> >From my limited experience - the battery master does indeed operate
> >a relay
> but then the battery power is fed to the bus controller which is
> likely another box full of relays hidden away somewhere.
> 
> Also, not all the gubbins in the cockpit will be fed from the same
> bus. Essential vs Non-Essential items, left or right side, there are
> many permutations.
> 
> Test meter out... and lots of patience!
> 
> Roy.
> 
> 
> 
> On 27 December 2013 04:59, Matt Bailey <dabigboy at cox.net> wrote:
> 
> > I got a chance to poke around the Sabreliner a little bit with a
> > multimeter and a cable checker/sound'r-out'r and tried figuring out
> > the wire routing for cockpit power. I am a little perplexed...as
> > far as I can tell, none of the wires going to the battery master
> > actually exit the cockpit directly. Do aircraft normally have only
> > a relay connected to the battery master switch? I would think that
> > at least the common lead should trace out to the wire going to the
> > negative terminal of the aircraft's batteries. I assume I need to
> > dig in the forward nose/avionics bay some more for relays or
> > terminal blocks.
> >
> > I want to use as much of the plane's original wiring as possible.
> > Any particular pointers you guys could offer in tracking down the
> > power delivery circuits to the cockpit? The wiring diagram for the
> > entire plane from Sabreliner Corp is over $700.....a little more
> > than I can spend when I am trying to save up to build a shop for
> > this thing this summer!
> >
> > --
> > Matt Bailey
> >
> > Keeping It Real:
> > Sabreliner 60 Flight Simulator
> > Serial # 306-61 - N1JX
> > http://sabrelinersim.com
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> >



-- 
Matt Bailey

Keeping It Real:
Sabreliner 60 Flight Simulator
Serial # 306-61 - N1JX
http://sabrelinersim.com