Master Contacter

Discussion of aircraft electrical system design, construction, and problems.

Re: Master Contacter

Postby Bryan Cotton » Tue Apr 11, 2017 10:38 pm

Bob,
Thanks for that info. Not a bad option.

Here is a picture of my steel key to replace the red plastic key. It started out as a tube. I found a bolt that fit snugly in the tube. There is a short piece of bolt inserted and a hole drilled through tube and bolt hunk. This hole is a light press fit for an AN3 bolt shank.
Image

The switch and steel key weigh 4 oz. An aluminum tube to rivet to the steel key adds 2 oz. Add rivets, handle, and brackets will probably be another 2 oz to the assembly - one half lb. I am curious what a contactor weighs. Anybody?
Image
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Re: Master Contacter

Postby gammaxy » Tue Apr 11, 2017 11:16 pm

Chris Madsen
Aerovee Sonex N256CM
Flying since September 2014
Build log: http://chrismadsen.org
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Re: Master Contacter

Postby Bryan Cotton » Wed Apr 12, 2017 9:14 am

Thanks Chris! Seems like a good trade.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Bryan Cotton
 
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Joined: Mon Jul 01, 2013 9:54 pm
Location: C77

Re: Master Contactor

Postby Bryan Cotton » Wed Apr 12, 2017 7:18 pm

Here I am engineering by making parts over and over until they come out right:
Image

On the final bracket I'll have nutplates for AN3 bolts.
Image

The brackets are offset 30 degrees so I can run my pushrod horizontal from the subpanel.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Bryan Cotton
 
Posts: 4954
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Location: C77

Re: Master Contacter

Postby n982sx » Thu Apr 13, 2017 11:42 pm

When I started to make a few custom parts, I saw that Bob Mika used paper models. I did that for all of my Sonex custom pieces and it worked well. Saved on aluminum.
Bob Meyers

Built and Flying Sonex N982SX http://n982sx.com
Built and Flying RV-14 N626KM http://n626km.com
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Re: Master Contacter

Postby racaldwell » Fri Nov 03, 2017 4:21 pm

Hi Bryan,

How does the shaft for the battery switch get around the fuel tank? I don't have a front fuselage yet so I can't see for myself. I am contemplating the Flaming River battery switch that comes with an extension handle. But I already have a Sky Tek master contactor in the hangar that I am tempted to use out of simplicity sake. The one in my RV-6 has been holding up for almost 18 yrs & 960 hrs.

Still trying to finalize my power circuit.

Rick
Xenos 0057
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Re: Master Contacter

Postby Bryan Cotton » Fri Nov 03, 2017 5:32 pm

Rick,
I have not finalized it yet, but it is to the left and underneath. The handle will be on my subpanel.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
User avatar
Bryan Cotton
 
Posts: 4954
Joined: Mon Jul 01, 2013 9:54 pm
Location: C77

Re: Master Contacter

Postby lutorm » Sat Oct 20, 2018 7:14 pm

I'd also like to stop wasting 1 out of my 10 precious alternator amps on the master contactor. There are solid state "relays" that use essentially no current, something like https://www.mouser.com/ProductDetail/Cr ... 7kvuhYo%3d. Anyone tried this route?

The thing you have to watch for with solid state devices is that they're sufficiently protected from voltage spikes, these have maximum ratings of at least 50Vdc, but it would be possible to add an extra overvoltage protection on top.
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Re: Master Contacter

Postby Bryan Cotton » Sat Oct 20, 2018 10:06 pm

Here are a few pictures. First one is the mechanical switch.
image015.jpg
Master sw

Here is the switch mechanism in the off position.
image017.png
Off

And again in the on position.
image016.png
On


I sacrificed a 1/4" drive u-joint from my socket set to make this work.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
User avatar
Bryan Cotton
 
Posts: 4954
Joined: Mon Jul 01, 2013 9:54 pm
Location: C77

Re: Master Contacter

Postby Bryan Cotton » Sun Oct 21, 2018 12:48 am

A couple more pictures. Here is my u-joint welded to my steel key. The plastic key is shown for comparison.
u-joint and key.jpg

Here is the handle I welded up. The guide is a loose fit, it keeps the tube from flopping on the floor. It bolts to the vertical extrusion that is in line with the instrument panel.
master handle.jpg

Weight is 10.5 oz missing the mounting bolt for the guide and 4 rivets. The 13 oz for the electric contactor would not include the master switch and associated wire. So the weight is close, the current draw is infinitely better.

Edit: there are two small firewall penetration guards I have to weigh too. So weight is very close to dead even.

Edit again: the electrical master will also need a penetration but you could argue it shares one with other wires.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
User avatar
Bryan Cotton
 
Posts: 4954
Joined: Mon Jul 01, 2013 9:54 pm
Location: C77

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