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  #11  
Old 05-29-2017, 08:25 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
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Quote:
Originally Posted by Nukeflyboy View Post
My empty CG is 107.82 with design range of 107.84 to 116.24.
Front seat passengers and fuel sit close to the CG making most RV10's nose heavy, not tail heavy. If you put back seat passengers and baggage the CG moves appropriately aft.

My a/c is stock with a 2-blade Hartzell.

With only front seat passengers and no ballast there is not enough trim authority to flare and land, hence the weight needed in the baggage compartment.
If you really mean that with a forward cg that there is not enough trim authority to flare and land using only the trim, you are correct. But, I doubt you need 40 lbs to bring it within the forward limit. Does it flare easier with ballast? Absolutely.
I'd say your cg is about perfect. When solo and low gas, you can afford a bit of ballast (but again, my empty cg is forward of yours, I sit forward, and only need 20 lbs). But if your really put heavy people/things in the rear seat and, especially, the baggage area, you'll be glad your empty cg is where it is. I've seen a fair number of RV-10s where it is limited by aft cg, when carrying a full load.
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  #12  
Old 05-29-2017, 09:06 PM
sritchie sritchie is offline
 
Join Date: Jun 2015
Location: Boulder, CO
Posts: 130
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Thanks for the responses, all. I'm going with the whirlwind prop, so I think I actually might want to mount both batteries on the firewall. Each ETX900 weighs 4.9 pounds, and if I recall the difference between the whirlwind prop and the stock hartzell is ~20 pounds. Giving that up means that I'll probably want some more weight up front.

Does this seem reasonable? Would love reactions, and maybe a photo from anyone who's seen or has a great dual battery firewall setup!
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  #13  
Old 05-30-2017, 07:09 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by sjhurlbut View Post
You live in Colorado so one thing I would consider is preheating the engine compartment. I live in Canada so battery in engine compartment is preferred because when you preheat engine for winter ops the batteries get some residual heat as well.

Very curious about the forward CofG on mentioned RV10. So far I've heard everything opposite which is another reason I'm going battery on firewall.
Assuming you are using an IO-540 and Hartzell BA prop, the RV-10 needs the battery(s) mounted aft for W&B.

Check flying RV-10 W&B data and decide for yourself. Send me your email in a PM and I'll send you mine.

Carl
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  #14  
Old 05-30-2017, 09:35 AM
Pukauma Pukauma is offline
 
Join Date: Jul 2014
Location: West Covina, Ca
Posts: 51
Default My version....

This is my version of dual batteries. Two (2) EarthX 1200's still are less weight than a single lead acid. Just modified the existing structure.

I hope this picture things works....

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  #15  
Old 05-30-2017, 09:39 AM
Pukauma Pukauma is offline
 
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Location: West Covina, Ca
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Default My version....

****. I think I have it this time......

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  #16  
Old 05-30-2017, 09:53 AM
sritchie sritchie is offline
 
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Location: Boulder, CO
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Quote:
Originally Posted by Carl Froehlich View Post
Assuming you are using an IO-540 and Hartzell BA prop, the RV-10 needs the battery(s) mounted aft for W&B.

Check flying RV-10 W&B data and decide for yourself. Send me your email in a PM and I'll send you mine.

Carl
Hey Carl, I'm actually using a whirlwind prop, which is about 20 pounds lighter up front. I'll PM you my email. Thanks!
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  #17  
Old 05-30-2017, 04:54 PM
Nukeflyboy Nukeflyboy is offline
 
Join Date: Aug 2007
Location: Granbury, TX
Posts: 96
Default Dual battery location for RV10

I would not put the batteries forward of the firewall, it will only make your CG worse and the temperature will accelerate its degradation.

Bob - you are correct, the 10 lands just fine without the ballast but the trim authority is insufficient to fully compensate and you need a lot of backpressure on the stick.

My sandbag weighed 40 lbs and it was convenient. My trim is still full against the stops when I land.
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  #18  
Old 05-30-2017, 07:14 PM
AviatorJ AviatorJ is offline
 
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Location: Oklahoma City
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Dual earthX batteries. I sort of like that idea....
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  #19  
Old 05-31-2017, 09:20 AM
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Guy Prevost Guy Prevost is offline
 
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I have a lightweight whirlwind prop and dual EarthX batteries on the firewall. I'm happy with my configuration.

I don't have to, but I typically carry 2ea 25lb sand bags in back when lightly loaded. The plane just flies a little better when it's not close to the forward limit. The real advantage is I can load up the plane without the sandbags and have no CG issues.

I was able to go from one PC680 on the firewall and a single alternator to two EarthX batteries, two alternators, and 3 contactors for a net weight gain of 1lb. The 1lb was basically from the additional large cables. Note that the original battery was already small and light for a 10.

Guy
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Last edited by Guy Prevost : 05-31-2017 at 09:22 AM.
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  #20  
Old 05-31-2017, 09:25 AM
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Auburntsts Auburntsts is offline
 
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Location: Tampa, FL
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Quote:
Originally Posted by Guy Prevost View Post
I don't have to, but I typically carry 2ea 25lb sand bags in back when lightly loaded. The plane just flies a little better when it's not close to the forward limit. The real advantage is I can load up the plane without the sandbags and have no CG issues.

Guy
I do the same thing except I use a 5-gal collapsible water container. That way I can easily dump water if I fly out light but come back heavy with pax/cargo.
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