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Moving the battery aft- CG issues

P

pnassar

Member
My RV7 has the 200hp A1B6 IO360, Sam James cowl, and the required 2 inch prop extension. All of the above left with an aft CG of 76.89. Plane flies a little nose heavy..controls are a little heavy, lots of up trim on final, and possibly a little extra fall off passing inverted on ballistic rolls. Thought I would start by moving the 15lb PC680 from Firewall to just behind the rear baggage compartment. That will move the CG about 1" aft. Any suggestions on other changes ? What is the safest and best mounting technique for the new location ?

Thanks for the thoughts !

Pete
N267RV RV7
 
I had a dual electrical system auto engine conversion in the past. I placed one of the batteries right under the vertical stab to get CG where I wanted it. Kind of extreme and the long cable run was not ideal for starting but it worked. Before making that change both batteries were under the baggage area floor. PC680s fit between those stiffeners just right:).

Randall
 
An option may be to replace the battery with a lightweight Lithium Iron Phosphate battery. A saving of up to 11 LB (over the PC680) and no additional wire weight or battery location change required.

Bob Nuckolls is doing an excellent job researching and testing the details of this new technology. Lots of discussion on his forum.

Bevan
 
Thanks for the input. Spoke to Vans today. They have drawing available detailing the rear placement of the battery. I think this is the first step.
Thanks !!
 
Thanks Joe,
I received OP16 from Vans today. It is going to be a pain to run the wires and penetrate the firewall but probably worth the effort. I did consider the lipo suggestion. However, need the weight in the back and was somewhat scared away by the article of the in flight aerovoltz fire.
 
Before you move the battery, it is possible to change the prop and put a composite one up front?

Other options include putting the lightest starter you can find and replacing your mags with P-mags. The P-mag swap alone will remove 3 lbs up front. Changing the battery, as already mentioned, will also save you a lot of weight.

The good thing, all these changes are positive and will lighten the entire airplane. Moving the battery aft, will add weight and complexity.

Just my $.02.
 
Much easier than moving the battery would be to go with a much lighter battery up front and putting some weight (less than was saved by the lighter battery) all the way in the tail for the long arm benefit.
 
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