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-   -   Electrical System Design and Build (https://vansairforce.net/community/showthread.php?t=152279)

FlyinTiger 01-19-2022 08:32 PM

Thank you
 
Leok, that is a lot of work and posting it all for us to digest is a thankless and time consuming task.

For now I'm learning about the VPX system and will be putting one in my RV-7 as I take it all apart and put it back together with a new panel, engine and prop.

Thank you. I found your build log and like your set up. I'll likely be going a very similary direction with my RV-10 build that will start in the near future. :cool:

leok 01-21-2022 04:09 PM

Updated Link to the PPt file
 
I think this is a new link to the file and should work without an email to me. Enjoy the process!

https://docs.google.com/presentation...f=true&sd=true

If you have any problems downloading the files, shoot me a PM with your email and I will send you the files.

claycookiemonster 02-03-2022 07:19 PM

Redundency, or load sharing?
 
I am WAY behind you in this, but the thinking is beginning. As to the two alternators; one 60a and the other 30a: what is the total expected electrical load in your aircraft? I'm asking because I'm considering a back-up alternator too. Do you plan for the primary 60a alternator to be able to carry the entire load? Is the back-up really a back-up, or is it carrying a part of the system all the time?
I'm thinking about the early light twins that had two engines, but neither of them was really capable of powering the ship alone.

leok 02-04-2022 06:12 AM

Typical load and back up alternator
 
If I add every load maxed out in the ship I would need 85 amps. That would include transmitting on every radio at the same time, seat heaters on, and heated pitot on, as well as every light and running the flap motor, which will never happen.

My typical load in flight is less than 15 amps. That is with all of the exterior and interior lights on as well as the avionics. If I add the 10 amps in for the heated pitot that is still less than 30 amps.

I have actually used the back up alternator one time when the field plug in the primary came loose. No issues. I flew home like nothing happened where I could trouble shoot in comfort. The only difference I see is a slightly lower buss voltage than normal as the regulator is set slightly lower.

Leo

claycookiemonster 02-04-2022 01:18 PM

Ok, thanks.

There are interesting design philosophies in operation here. In a related, but unrelated vein, all current Boeing jets have a single rudder surface with multiple actuators, except the 777, which has a split rudder with separate actuators. So, which contingency makes you lose more sleep: one rudder actuator fails and locks the entire rudder so the other actuator can't move it, or one actuator fails and now you only have half a rudder? You can thought experiment this all night long, though I'm sure Boeing has data.

As to modeling an electrical system, is it worth carrying a back-up alternator when the primary can carry the entire load? Or, if your max anticipated load is, say 80a, then why not carry two 40a alternators and split your devices so either half can get the job done?

I'm not sure there is any one ultimately right answer. Thanks for all your schematics. May your back-up be forever superfluous.


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