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-   -   W&B with Earth X battery (http://www.vansairforce.com/community/showthread.php?t=146304)

togaflyer 02-02-2017 12:39 PM

W&B with Earth X battery
 
The Earth X shaves around 21 lbs off compared to the Odyssey battery. That is a significant weight change at the battery station. Up front I have an IO 540 with mags, MT prop, and a Plane Power backup alternator. How does this impact the CG of the -10. Will the plane have a significant forward CG. Will I need to keep some weight in the baggage area to compensate for forward CG.

Guy Prevost 02-02-2017 01:47 PM

Possibly. I have two Earth X batteries on the firewall and a lightweight prop. I've purposely kept the plane light with a forward CG. I keep two 25lb shot bags in the baggage compartment when lightly loaded so I can trim on final. I consider this the best case scenario. With a more aft CG I wouldn't be able to fill the airplane without getting the CG too far aft. This way I move two small canvas bags and can carry over 1100 lbs!

Some people call the 10 nose heavy--I believe that's the design intent to allow the plane to carry a load when required. Vans keeps shot bags in theirs for demo flights too.

Paddy 02-02-2017 02:26 PM

EarthX Battery
 
I too have dual alternators and mags but with the heavier Hartzell prop. With a remote transponder and dual batteries/contactors behind the baggage bulkhead and I was worried about shifting the CG too far back, so I switched out a PC-925 for an ETX-900. I calculated that those 21 lbs at an arm of 183.5" was worth almost an inch in empty CG placement. Result is that I need ballast when solo, but can load to max gross comfortably without worrying about getting the CG too far aft, even with minimum fuel. My plane feels very similar in balance to the factory -10 in which I did my transition training with Mike Seager, who also used ballast in the baggage area during training. That EarthX battery spins the IO540 like a car and with the Slickstart module, it fires up within a few blades both cold and even after a hot soak.

Bill.Peyton 02-02-2017 02:52 PM

Rich,
As an example, I just calculated my new CG assuming that I used two earth-x batteries in place of the two odyssey batteries I have now. (Both of my batteries are located directly behind the baggage bulkhead.) This would yield a weight reduction of 32.6 lbs. The Vans specification for the forward CG limit is 107.8. ( I have a Hartzell prop)

Currently the CG with 15 gallons of fuel (min reserve for me) the CG is 108.3, and with pilot only @180lbs, the CG moves to 108.9.

With two Earth-x batteries and 15 gallons of fuel, the CG goes to 107.4, and with one 180lb pilot is moves to 108.1.

Hope this helps your thought process...

vic syracuse 02-02-2017 05:23 PM

My RV-10 has an MT 3 blade prop and an Earthx 1200 battery.
I also have tip tanks. I fly a lot solo, with full tanks, including the tips, and the usually 10 lbs of "stuff" in the baggage compartment. I never feel a need to add ballast. It lands very nicely and never runs out of trim for landing.

Vic

majuro15 02-03-2017 06:46 AM

Guy, do you have any pictures or details on mounting the dual batteries on the firewall? I'm curious and couldn't find any on your build log.

Strasnuts 02-03-2017 08:59 AM

Quote:

Originally Posted by Guy Prevost (Post 1146968)
Possibly. I have two Earth X batteries on the firewall and a lightweight prop. I've purposely kept the plane light with a forward CG. I keep two 25lb shot bags in the baggage compartment when lightly loaded so I can trim on final. I consider this the best case scenario. With a more aft CG I wouldn't be able to fill the airplane without getting the CG too far aft. This way I move two small canvas bags and can carry over 1100 lbs!

Some people call the 10 nose heavy--I believe that's the design intent to allow the plane to carry a load when required. Vans keeps shot bags in theirs for demo flights too.

I like GUYS setup and if I had to do it again I would go this direction. I have a 925 in the back and a two blade blended hartzell up front. I also have a heavy engine, a dash N1A5. I use half flaps when I'm alone if runway permits. I can go full flaps but use a lot of trim. Mine is on the fwd cg when I'm alone.

togaflyer 02-03-2017 11:43 AM

Thanks for the input. With the minimal weight of the Earth X, I can see installing it FWF without much CG impact, but I wonder how the environmental conditions FWF would affect the battery's longevity.

Guy Prevost 02-03-2017 04:37 PM

Quote:

Originally Posted by majuro15 (Post 1147154)
Guy, do you have any pictures or details on mounting the dual batteries on the firewall? I'm curious and couldn't find any on your build log.

Apparently I don't. I'll take some next oil change. I have both batteries near the right side of the firewall with the contactors just to the right of them.

ppilotmike 02-10-2017 09:42 AM

Quote:

Originally Posted by Guy Prevost (Post 1147331)
Apparently I don't. I'll take some next oil change. I have both batteries near the right side of the firewall with the contactors just to the right of them.

I'd like some pictures too. How are they holding up in the engine compartment. I would think the heat would affect things negatively and potentially shorten the life of the batteries..


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