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  #1  
Old 12-24-2006, 09:45 AM
Paul "OX" Harder Paul "OX" Harder is offline
 
Join Date: Dec 2006
Location: Windsor, Colorado
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Question Battery Location for RV-8

First just want to wish everyone a Merry Christmas and a very happy (get to fly lots of hours in an RV!) New Year. Now here is my question with a little background info. Our -8 will have a Grove landing gear, a glass cockpit and an IO-360 with a Hartzell Blended Airfoil prop. The rest of the Aircraft will be built basically as per plans. We will save maybe 15 lbs. with the gear and glass cockpit, but will gain 30 lbs. or so with the engine/prop combo, so with these parameters (rough I know) can we put the battery (Oddysee brand) and associated hardware on the firewall and not run into foward CG problems?
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  #2  
Old 12-24-2006, 10:31 AM
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13brv3 13brv3 is offline
 
Join Date: Nov 2005
Location: Tellico Plains, TN
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Hi Paul,

While battery location is a pretty hot debate, if you're talking about an angle valve IO-360, then I'd bet the universal answer will be to put the battery in the aft location. The Grove gear will help, but since the location of the gear legs isn't that far forward, it won't help much.

I've had two O-360 RV-8's now. The first had a Sensenich prop (not much lighter than a Harzell), inverted oil system, and a big Concorde battery in the aft location. It was great for solo and aerobatics, but you could easily exceed the aft CG with heavy passengers or aft baggage.

The current plane has a blended airfoil Harzell, no inverted oil, and an Odyssey on the firewall. This puts it right at the forward CG limit when solo, but you can put any size passenger and baggage up to the max gross weight, without quite exceeding the aft CG. This plane will be a bit better off when painted, since paint tends to shift the CG aft a bit.

Often, the "best" location boils down to the mission you have in mind. If you lean toward nose heavy, then you have more capacity for heavy passengers, and bags. Leaning toward aft makes for a better flying solo configuration, but you have to be careful with aft loading.

Cheers,
Rusty
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  #3  
Old 12-24-2006, 07:40 PM
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chrispratt chrispratt is offline
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Default Battery location

Put it in the back.

Chris
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  #4  
Old 12-24-2006, 09:10 PM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
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Hi Paul,

I've got the "light" O-360, Hartzell BA prop, rear Odyssey battery, and glass cockpit. With pilot and full fuel, I am right at the forward CG limit. To be honest, the Odyssey is pretty light, but I think that anything aft will help. I can put a HUGE guy in the back seat and still be in limits....

Just one more datapoint for you.

Paul
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  #5  
Old 12-25-2006, 08:47 AM
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DanH DanH is online now
 
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<<Our -8 will have a Grove landing gear, a glass cockpit and an IO-360 with a Hartzell Blended Airfoil prop. The rest of the Aircraft will be built basically as per plans.>>

Paul, I'm building the same configuration (well, IO-390 rather than IO-360). I'm going with an Odessey in the back, with the battery box configuration such that I can go to a heaver Concorde if desired later. Previous experience with an 8A convinced me the airplane feels a lot better when the CG is not against the forward limit.
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