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EarthX and composite prop?

Rick RV-4

Well Known Member
I have a long way to go on my RV-10, but I am working on the fuselage so need to start making some decisions. Mike Newall's "a better battery" thread got me thinking, but I did not want to hijack his thread.

Lighter is better, but CG is critical too. I've been thinking of going the EarthX route, but worry about the CG issue of losing weight in the back. To counter the loss of junk in the trunk, I then thought about going with a composite prop (such as the WhirlWind) to balance out the battery exchange.

Any thoughts on this plan, or can anyone comment on this based on experience? Being an RV-4 builder/owner, I'm much more familiar with the weight and balance issues on that plane vs. the RV-10, so I'm happy to learn from those who have dealt with these issues.

Fire away!

Rick
RV-4 N999XS
 
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W/B

I made a W/B diagram for my plane using Excel.
Then you can see exactly what happens if you add or remove weight
at a certain station. If you are familiar working with Excel, it`s easy.
Also you can try to search for W/B diagram for RV-4 and insert your data.
Good Luck :)
 
I have a Hartzell 3-blade and use an EarthX battery. I have a mess of glass and a backup battery under my panel. So my plane in nose heavy empty and with my 200... err 210 lb frame up front.

Flying solo I throw a 24 pack of water in the baggage. It's not that big of a deal, I flew off phase I with it being nose heavy and no weight in the back... just kept my speed up.
 
W & B

I have a -10 that has the MT prop and two EarthX batteries.

I used the MTV-9 prop instead of the MTV-12 that Vans recommends because my engine is making just under 300 HP and 300 HP is the max limit on the MTV-12.

The MTV-9 prop is about 11 lbs heavier than the MTV-12.

I built a spreadsheet to play around with the numbers and I can tell you that a 135 lb solo pilot and 30 gallons of gas will require 25 lb ballast in the cargo area to get to the forward CG limit.

I have been test flying the plane using the APP limitation, so I have two pilots on board...the CG was about 1 1/2" aft of the forward CG limit. After speaking with several transition training guys, I chose to put 75 lbs of ballast in the baggage area to move the CG closer to the midpoint.

Just some data points...
 
I have a long way to go on my RV-10, but I am working on the fuselage so need to start making some decisions. Mike Newall's "a better battery" thread got me thinking, but I did not want to hijack his thread.

Lighter is better, but CG is critical too. I've been thinking of going the EarthX route, but worry about the CG issue of losing weight in the back. To counter the loss of junk in the trunk, I then thought about going with a composite prop (such as the WhirlWind) to balance out the battery exchange.

Any thoughts on this plan, or can anyone comment on this based on experience? Being an RV-4 builder/owner, I'm much more familiar with the weight and balance issues on that plane vs. the RV-10, so I'm happy to learn from those who have dealt with these issues.

Fire away!

Rick
RV-4 N999XS

I have the Hartzell 2 blade composite 8301 blades (11-14 pounds lighter than the BA aluminum versions), and the battery (earth-X) on the firewall. No regrets at all:). This has me towards the forward limit solo and low fuel, but I always carry a 10 pound tool bag with me everywhere I go, so no worries. This also allowed me to get rid of the big 2 ought run power cable to the back. Would do it again in a heartbeat.
 
I was also a little nose heavy on my RV-10 and with short legs I flew with the pilot seat full forward compounding that issue. I was thankful that I had the weight of dual PC 680 Odyssey’s behind the baggage bulkhead. It seams that a lot of RV-10 owners need ballast weight so I see no benefit in using the EarthX batteries for weight savings.
 
I have the Hartzell 2 blade composite 8301 blades (11-14 pounds lighter than the BA aluminum versions), and the battery (earth-X) on the firewall. No regrets at all:). This has me towards the forward limit solo and low fuel, but I always carry a 10 pound tool bag with me everywhere I go, so no worries. This also allowed me to get rid of the big 2 ought run power cable to the back. Would do it again in a heartbeat.

Hi Larry, I’m curious about your battery mount on the firewall. I’m in the early stages of construction and if it were easy to go the Cessna route vs Piper in the back I’d be interested. How much extra work was it? Are you able to post pictures of the install?

Thanks

Keith
 
...with an Earth X battery up on the firewall. If it helps in the decision process, I'm 175 pounds.

And for those who have gone this route, any pics of the battery install on the firewall would be great!

Just putting this out there as something you might want to research; I have no personal experience but in speaking with an RV-10 owner at Sun 'n Fun, it was mentioned that they had repeated EarthX failures with the battery mounted on the firewall.

It was determined that excessive heat was the culprit and the (EarthX) battery was moved to the aft fuselage with no further issue.
 
I will research that. I certainly do not want issues due to heat, and I was wondering if that was an issue with putting the battery up there.

Thanks,

- Rick
 
Just putting this out there as something you might want to research; I have no personal experience but in speaking with an RV-10 owner at Sun 'n Fun, it was mentioned that they had repeated EarthX failures with the battery mounted on the firewall.

It was determined that excessive heat was the culprit and the (EarthX) battery was moved to the aft fuselage with no further issue.

I mounted my Earth-X on the firewall. Initially it would get too hot in the summer and give me the warning of overheating (make sure you wire the status indicator light). I ended up putting a heat shield under the bottom of the battery box to protect the case bottom from convection heating after shutdown from the exhaust pipe. I also mounted a shroud around the top and sides of the box and piped plenum air to the top to keep the electronics in the battery top cool and happy. I also added a heat shield to the exhaust pipe that's directly below the box. No issues since then at all. I think having the battery on the firewall and a lighter composite prop has many advantages over the standard set up. Here are some pictures of what I did. Feel free to call me for any more information. Cell 317 407 8479.
 

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RV-10 EarthX batteries and WW 77HRT 2 blade prop

I have just started flying my RV-10 with dual electrical systems (dual EarthX batteries, dual alternators, and a crossover solenoid). My original configuration was an ETX900 in the normal battery location behind the baggage bulkhead, an ETX680C on the firewall up as high as I could get it with EarthX's mirrored/insulated battery box, and the crossover solenoid with wiring on the firewall.

My W&B was such that I had to carry about 40# in the baggage area but I do not have interior panels and carpet installed yet so I expected that number to drop a little. No big deal because I always carry tools, extra oil, plugs, tow bar, cabin cover, etc in the back which will reduce any extra weight I have to carry for CG.

However.... during the first several flights the ETX680C would overheat (slow blinking warning light), even in its insulated box. The temps under the cowling were just too high for the battery to stay cool without extra cooling similar to what others in this thread have done.

Given the need for weight in the baggage area and the heat under the cowl I opted to move my ETX680C aft to sit beside the ETX900. I also moved the BU master solenoid, XC solenoid, and associated wire back there. No more heat problem and my CG is almost perfect now.

If you look carefully at the picture below you can see the ETX680C in its mirrored box on the firewall (left center of the picture) during construction.
https://1.bp.blogspot.com/-QvtVgyz7Jwo/YDHR-6RzRTI/AAAAAAAAHqU/PRhIZhKapkQNq_yzpJngxDMnlmnMAwfvgCLcBGAsYHQ/s2048/20210214_234140009_iOS.jpg
 
I have just started flying my RV-10 with dual electrical systems (dual EarthX batteries, dual alternators, and a crossover solenoid). My original configuration was an ETX900 in the normal battery location behind the baggage bulkhead, an ETX680C on the firewall up as high as I could get it with EarthX's mirrored/insulated battery box, and the crossover solenoid with wiring on the firewall.

My W&B was such that I had to carry about 40# in the baggage area but I do not have interior panels and carpet installed yet so I expected that number to drop a little. No big deal because I always carry tools, extra oil, plugs, tow bar, cabin cover, etc in the back which will reduce any extra weight I have to carry for CG.

However.... during the first several flights the ETX680C would overheat (slow blinking warning light), even in its insulated box. The temps under the cowling were just too high for the battery to stay cool without extra cooling similar to what others in this thread have done.

Given the need for weight in the baggage area and the heat under the cowl I opted to move my ETX680C aft to sit beside the ETX900. I also moved the BU master solenoid, XC solenoid, and associated wire back there. No more heat problem and my CG is almost perfect now.

If you look carefully at the picture below you can see the ETX680C in its mirrored box on the firewall (left center of the picture) during construction.
https://1.bp.blogspot.com/-QvtVgyz7Jwo/YDHR-6RzRTI/AAAAAAAAHqU/PRhIZhKapkQNq_yzpJngxDMnlmnMAwfvgCLcBGAsYHQ/s2048/20210214_234140009_iOS.jpg


If you put Earth-X on the firewall in a 10, you have to shroud it and provide ambient air for cooling. The electronics that manages the battery is located on the top inside the molded case. The design of the 10 is that the heat valves dumps the heated air right under the cowling, instead of overboard when not used, which makes it quite hot under the cowl always. A lot of certified planes have a blast tube pointing at the (non Earth-X) battery, so us building a shroud is not out of the ordinary at all.

By having my battery on the firewall, I get a farther forward CG (less chance of having the plane fall on it's tail with big back seaters loaded first), a short run for power to get to the starter (better cranking), the battery is forward of the stainless firewall (if something really bad happens), and I got rid of a few extra pounds from not running the big 2 ought wire run all the way to the back tray. I also think that cruise speeds are a little faster when the CG is further forward:)......
 
When fully loaded (e.g., 4 people plus bags in the back) most of the -10’s I’ve seen tend to run out of aft cg before going overweight (note: check cg at landing weight, it is worse than at takeoff), so I think it is desirable to need 25 pounds or so of water in the baggage area for solo flying. This gives flexibility for full-load situations.
 
Thanks all,

I think for now I'll stick to keeping the battery(ies) in the back. Too bad there's not a decent way to put it in the back (passenger side) of the firewall.

Cheers,

Rick
 
W&B RV-10's out there

Well time to start calculations on predicted W&B so I thought I would start with an "average" number of people who have posted. (Averaging Arm and Weights) What I am seeing is most W&B's work out fine no passengers and a small amount of baggage. (water bottles, tools etc.) What I am seeing is once you add 2 small children (Or 2 folding bikes) and baggage the CG does not come out. Most if not all are aft heavy. (Using low fuel worse case) What am I doing wrong? I wanted to start "adjusting" the W&B for my set-up but need to get the "average" numbers correct first. Below is my calculations which could be in error. Let me know how yours came out and I'd be glad to insert into my xls or send me your completed W&B with passengers and baggage.
 

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Well time to start calculations on predicted W&B so I thought I would start with an "average" number of people who have posted. (Averaging Arm and Weights) What I am seeing is most W&B's work out fine no passengers and a small amount of baggage. (water bottles, tools etc.) What I am seeing is once you add 2 small children (Or 2 folding bikes) and baggage the CG does not come out. Most if not all are aft heavy. (Using low fuel worse case) What am I doing wrong? I wanted to start "adjusting" the W&B for my set-up but need to get the "average" numbers correct first. Below is my calculations which could be in error. Let me know how yours came out and I'd be glad to insert into my xls or send me your completed W&B with passengers and baggage.

Well, for starters, your rear passengers appear to have ZERO moment arm (blank entry in the right hand column)
 
Well time to start calculations on predicted W&B so I thought I would start with an "average" number of people who have posted. (Averaging Arm and Weights) What I am seeing is most W&B's work out fine no passengers and a small amount of baggage. (water bottles, tools etc.)

I had 75 pounds of bags and 290 pounds of people in the back on the way to Oshkosh in addition to 430 pounds of people up front. Even with zero fuel, I would have just touched the aft limit.

The airplane has the standard 2 blade Hartzell BA prop and an Odyssey battery in the normal location. It does not have a spiffy (i.e. heavy) interior.
 
Bob Turner, thanks

Well I knew something was wrong. I used my RV-14 W&B and added a line for passengers in the rear and did not populate the XLS correctly. Numbers make a little more since. I'll review and plug on.
 

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Seems W&B OK now

Even with passengers and baggage the numbers now make since. Thanks, been a long day......
 

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Anything more

You mentioned for starters and would like to understand anything more you want to add. Insight is always welcome.
 
I only meant that I saw the missing entry and stopped looking for anything else. I agree, numbers look about right now. As you see, if you burn off the last ten gal, the cg moves further aft, which is why it’s important to always check your expected landing cg.
 
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