Not speaking for Phil, but there are multiple reasons. Here are just a few -
It is not compatible with many of the “standard” connectors, terminals, etc. because of dissimilar metal corrosion and/or loosening of the connection due to softness of the metal & thermal expansion & contraction. As a general rule, when it is used in home or commercial wiring a dielectric grease is usually used to seal the connections from air & moisture, and the wire is usually cleaned with a wire brush or something to remove the naturally occurring aluminum oxide, which is basically non-conductive, right before making the connection. Aluminum also has a higher coefficient of thermal expansion than copper. Aluminum is cheaper, and this is the main reason it was used in home wiring decades ago. Many home fires were attributed to it, and special receptacles & switches were eventually designed to be used with it. Many homes ended up being completely rewired.
John Evens
Arvada, CO
Kitfox SS7 N27JE
EAA Lifetime
Chap. 43 honorary Lifetime
Thanks John. I didn't have the time to get into the details earlier when I answered.
Phil Nelson
A&P-IA, Maintenance Instructor
KF 5 Outback, Cont. IO-240
Flying since 2016
The smaller EarthX batteries will have no trouble cranking any of the Rotax engines, but the -680 and -680C do not have the nameplate energy capacity specified by the 912iS and 915iS installation manuals. For a 912UL/ULS or 914 installation this wouldn't be as much of a concern, but the iS engines are dependent on electrical supply to continue running. Rotax specify a minimum battery capacity (16Ah, as I recall) to ensure that the engine will keep running in the event of both A and B alternator failures.
What we don't know is the length of time that Rotax believes the engine should continue to run in this scenario. Also, I'm unaware of any instrumented testing that shows current demand for an iS engine at typical cruise power settings, so calculating battery-only run time is very difficult.
The ETX-900 is packaged in the same case size as the -680 (the -680C is smaller) but has higher energy capacity and weighs very little more.
Eric Page
Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
Member: EAA Lifetime, AOPA, ALPA
ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
Map of Landings
Battery box is now complete. Running wires with new crimper tonight. Been working on multiple systems to make sure they all work together. Sent the firewall and electric service trays in to be powder coated. Heater is different than the factory in that it’s air flow is through tubes, blowing on the wind screen and the pilot and passenger. Direct flow of the heat on the skin makes the difference in how you feel, compared to indirect flow. Drove the cobra today to an event with 39 degrees out and felt warm with that and the seat heaters. Got my thermobob yesterday and was a bit dismayed in that I made the dash up thinking that I could put my heater valve in-line with the heater side but cannot with the thermobob. Perfect actually as the pull will just hook up to a valve I will need to make in the defrost vent. More flow to us instead when needed. Got all the panel material from aircraft spruce for more trays and servo mounts. Have to button up this fuselage in about two months to start painting. Cobra was awesome today and had fun with my cobra buddy going to Griots. Theme: super cars and was special for the large crowd that attended.
Starfox
Advanced Flight Systems made up my cables after my final measurements. Battery box is done. Just have to run the charger wire up into the dash.
Starfox
That's a really clean battery installation.
I wish I had known about the car show at Griot's. It's just across town from me and I last attended a German themed show back when we were allowed to go outside. I've even stumbled in there just to buy products and found this icon of motorsports:
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And just over a week ago I took my brother to the local car museum, which featured a lot of fantastic Alfas.
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Kitfox 5 (under construction)
Commercial SE/ME, CFII
Thanks Alex. Yes. These car gatherings around here are pretty amazing with all the tech companies and wealth it provides. My Seattle car club: Avants, has every car imaginable including Alfas. One guy in particular comes to mind. He maintains a past president of Microsoft's car collection. A big Alfa fan and has a lot of followers. One car in particular is the #12 prewar Alfa racecar that beat the Germans at the time. He can seem to go on for hours telling about it and other cars in that collection. I have been to the collection a couple of times and he lets you sit and be around the cars. I have had a lot of great times being around these collectors and their stories. Would not have been there if it wasn't for the cobra. Hope to do the same with my plane. Just getting out and seeing history and the stories behind it all. Looks like a nice collection of cars you saw over there!
Starfox
Beautiful autos guys. Cobras look like a blast on a sunny day.
DesertFox4
Admin.
7 Super Sport912 ULS Tri-gear
Working on the tail wheel. May have the wrong width one for this application. I see on the tundra lite website a 1.5” and a 1.25” listed. Almost fits with this bracket off. Could clean it out a bit to make it fit with the bracket off. Then it would fit. Mounted the lever as per the guy. That manufactured these with no bend in the wire. Just have to make a housing out of sheet metal and cover it. I like where it sits and up is locked, down is unlocked.
Starfox