Battery location

[praterdj]

I am currently working on the empennage for my RV-8 and during the time when I am unable to build I find that I am constantly planning for later phases.

My question revolves around battery location. As mentioned I am building the 8 (tandem seating) and C.G. is an issue. I am not a small person (6?5? and 250#), I am looking at either the new IO-390 or an IO-360, and a constant speed propeller.

I know this is not an uncommon situation but I would like to build the plane as light as possible. The question is that since I?m going to use one of the light batteries (12 pounds?) and a sky tech starter, do I need to put the battery in the back?

Another location I am considering is in the front baggage compartment. My only reluctance for a rear battery location would be running the battery cables through so many structures as well as the additional weight of the longer cables.

Any suggestions?

Thanks,

Donald

[tonyjohnson]

Donald,

I had the same decision to make. It is very tempting to put the battery, especially the light one, in the front baggage compartment. I used the w&B spreadsheet that another 8 builder shared with me to determine the differnence.

I did the numbers with the battery in the back, and with it in the front baggage compartment. There was more of a difference that I would have thought given the light weight of the battery. With the battery in the front, I was within about 4% of the forward CG with me in the pilot seat. I weight about 200 lbs. I am planning for the catto prop (18 lbs.). With the C/S prop, there is no question that I would put the battery in the rear even with the longer cable runs.

I wish that I had a different answer for you. I would love to put the battery in the front baggage compartment for simplicity of wiring.

Tony

[Kahuna]

Originally Posted by praterdj

My question revolves around battery location. As mentioned I am building the 8 (tandem seating) and C.G. is an issue. I am not a small person (6?5? and 250#), I am looking at either the new IO-390 or an IO-360, and a constant speed propeller.

Donald

You MUST put it in the back with this config.
Maybe further back than design given its light weight

Kahuna

[praterdj]

Thanks guys for the input. I've pretty much come to the same conclusion but it helps to hear it from someone else.

I might even decide not to go with the lighter battery so that I can use the additional ballast to my advantage.

I'm trying to diet as well but considering how that's going I might need to use a big truck battery for balance.

[osxuser]

Originally Posted by praterdj

Thanks guys for the input. I've pretty much come to the same conclusion but it helps to hear it from someone else.

I might even decide not to go with the lighter battery so that I can use the additional ballast to my advantage.

I'm trying to diet as well but considering how that's going I might need to use a big truck battery for balance.

Gill G-35's are pretty heavy