Spaceman wrote:I'm sure you're right I'm just not electrically fluent enough yet to sketch that out! So far I've been looking for the simplest possible way!
lakespookie wrote:Other things to note my planned electrical system includes 3 servos, I want to do long leg cross countries so I want to throw in a yaw damper if possible although I suspect that either that wont be possible or I wont find an elegant mounting point for the YD servo so that would improve power budget.
Spaceman wrote:The power stabilizer seems very simple to plan and install and it costs $250. Perhaps I could do a backup battery system for less than that, I just don't know yet how to wire that off the top of my head.
N190YX wrote:When you operate the starter, you have crazy amperage spikes resulting in voltage spikes up and down as the starter is actuated, and then lugs down a little on each compression stroke as it slows down with the load on the compression stroke, using more amperage, and eases up while the engine is not on a compression stroke and turns more easily. I damaged the gas discharge numbers on a KX155 by accidentally starting my engine with the avionics turned on after the engine stalled on a landing roll out. Should have turned the avionics off before using the starter. I recommend turning everything off while using the starter! Those avionics are expensive, to purchase, and to repair!
sonex1374 wrote:lakespookie wrote:Other things to note my planned electrical system includes 3 servos, I want to do long leg cross countries so I want to throw in a yaw damper if possible although I suspect that either that wont be possible or I wont find an elegant mounting point for the YD servo so that would improve power budget.
A yaw dampener (or autopilot servo) isn't really needed on the rudder. The plane does not wander at all in yaw, and when a fixed rudder trim tab is adjusted properly the plane will have no yawing tendency at cruise speed. You might need some rudder input at slower speeds, but that's not a problem, nor is that a time when you'd be flying under the autopilot. It's not even worth fabricating an adjustable rudder trim tab.... just not something to worry about.
My advice is to skip the 3rd servo. You'll never miss it.
Jeff
sonex1374 wrote:Spaceman wrote:The power stabilizer seems very simple to plan and install and it costs $250. Perhaps I could do a backup battery system for less than that, I just don't know yet how to wire that off the top of my head.
Chris,
The folks over at the AeroElectric Connection have been kicking around several ideas for a short-term boost of voltage during cranking that would prevent the voltage sag to the EFIS while the starter is cranking. One solution has been to install a booster transformer that only kicks in when cranking the engine. This would take something like 11 volts and boost it to 14 volts (example....don't know that exact voltages or have a part number). I'm sure you could contact them for specifics, or research your own based on your system's average bus voltage while cranking your starter.
The linked drawing shows how this would be wired in (the section in blue labeled "Brown-out Booster"). http://www.aeroelectric.com/PPS/Adobe_A ... /Z01P3.pdf
Here's a recent message in this thread to get you started. http://www.matronics.com/digest/digestv ... c#MESSAGE1
gammaxy wrote:Wish I knew what happened in your case. What I measure on my Main/Avionics bus doesn't have any dangerous transients during engine start.
lakespookie wrote:Spaceman, wiring the second bus just entails driving a second pair of power wires to the units. Garmin already has the units, so you would need on switch to send power from the battery to the bus 2 power and a second switch to enable charging of the battery, Normal startup you power the avionics from the backup avionics power with the charge cuircuit open, then once you have stable power kick on the full avionics bus disconnect the backup power, or leave it on up to you, then activate backup avionics charging. note you will have to send power to both your G3X and the Engine interface unit but pretty much all the garmin avionics support dual bus power so in theory you could fully power all your avionics via the back ups but I feel like that's a bit much and not worth all the extra wiring. you really only care about the efis and the engine interface unit. If you look at the interconnect drawings it should be clearly labeled.
Spaceman wrote:That's a handy graphic to refer to. None of your instruments have trouble with that drop to like less than 8.5 volts? I'll have to dig through the Garmin encyclopedia later and see if there's a specified minimum.
14. TO MINIMIZE THE CHANCE OF THE SYSTEM RESETTING DURING ENGINE CRANKING, THE OPTIONAL REDUNDANT (DIODE OR'D) POWER INPUTS MAY BE CONNECTED TO AN AUXILIARY BATTERY (SUCH AS THE TCW TECHNOLOGIES INTEGRATED BACK-UP BATTERY SYSTEM) OR STABILIZED POWER INPUT (SUCH AS THE TCW TECHNOLOGIES INTELLIGENT POWER STABILIZER IPS-12V-8A) TO MAINTAIN THE NECESSARY LRU MINIMUM INPUT VOLTAGE. HAVING A STABLIZED SOURCE OF POWER DURING ENGINE CRANKING SHOULD ALLOW THE SYSTEM TO PROVIDE CONTINUOUS ENGINE INDICATING SYSTEM (EIS) OPERATION DURING ENGINE START AND MAINTAIN ANY DESIRED PRE-FLIGHT SYSTEM SETUP OR FLIGHT PLANNING THAT WAS ACCOMPLISHED PRIOR TO ENGINE START. VISIT
http://WWW.TCWTECH.COM
Spaceman wrote:That's a handy graphic to refer to. None of your instruments have trouble with that drop to like less than 8.5 volts? I'll have to dig through the Garmin encyclopedia later and see if there's a specified minimum.
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