[simpits-tech] Aircraft power question

[Cris Harrison]

On 12/28/2013 06:47 PM, Matt Bailey wrote:
> 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).
> NO!!!! you can roach your cars electrics..
C. Harrison

> 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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>
>