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Old 01-28-2015, 01:50 PM   #15
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It occurs to me that if you duplicate the factory spec tongue weight you will be pretty good.
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Old 01-28-2015, 01:57 PM   #16
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Try to duplicate factory spec for tongue weight.

A Sherline scale will be exactly what you need.

http://www.sherline.com/lm.htm
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Old 01-28-2015, 03:32 PM   #17
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Have you thought of placing the batteries under the refrigerator? This would:
1. Raise the refrigerator up so you don't have to bend over to get stuff out of the bottom shelf (as done on later model AS's).
2. Move the weight forward directly over the front axle.
3. Still have storage under the refrigerator toward the front.
Also: Use AGM battries:
1. Cost the same per year (they last longer).
2. No fumes to worry about - no 'battery box' or outside venting with it's ducking.
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Old 01-28-2015, 08:46 PM   #18
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Quote:
Originally Posted by Silver Hawk View Post
Have you thought of placing the batteries under the refrigerator? This would:
1. Raise the refrigerator up so you don't have to bend over to get stuff out of the bottom shelf (as done on later model AS's).
2. Move the weight forward directly over the front axle.
3. Still have storage under the refrigerator toward the front.
This is a great idea in my situation; I hadn't even considered that but it makes perfect sense to put the batteries and inverter under the fridge. I already have the lifted fridge in my design plans (see attached image) so all I have to do is run the wiring where it comes up from the floor behind the axels to the front of the axels where the fridge is located.

Thanks for the idea Silver Hawk!

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Old 01-28-2015, 09:14 PM   #19
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But what will you place across from that to offset?

In mine the reefer is starboard atop the furnace and across from the washer/dryer plus pantry. Just off axle dead center. The reefer and W/D each weigh 120-lbs and the pantry weight plus goods easily offsets the furnace weight.
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Old 01-28-2015, 11:05 PM   #20
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My 30ft Flying Cloud is set up with 4 Lifeline 6 volt AGMS batteries, total amps:880, total weight: 264#, no venting needed! I have a Magnum MS 2000 Inverter. I haveThese GPL-4CT batteries will last years verses the old style! Another issues is to keep the inverter and batteries as close together as possible,more efficient, less loss of voltage. Most of the installation I've seen, including my trailer with a forward couch or bed is to place the system underneath, then run shore power to the inverter and then back to the distribution( breakers, fuses)point. This setup keeps all the weight forward of the axles, yet 4ft to 10ft behind the hitch, centered left to right and easily accessible. This setup tows great. I also use a Hensley Hitch. You also have room for a solar panel controller.
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Old 01-28-2015, 11:13 PM   #21
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One way to get help locating the various weights is to use center of gravity calculations similar to those used for aircraft or ships. You can google for details or visit a local airport and ask a pilot to explain it.
Basically, establish a point (datum) to measure distances (called arms) to the weights you'll locate. Each distance multiplied by the object's weight gives a moment. The total moment (possibly made up of both + and - moments depending on whether they are forward of or behind the datum) divided by the total weight gives the center of gravity (CG).
I'd recommend deciding on the needed tongue weight and achieve it with weight forward added or removed to get it, first. The CG with that tongue weight is the one to maintain as you place the other weights.
As others have suggested, it's more than a front to rear balance game empty weight, max weight, useful load and lateral balance will influence how it travels.
Good luck with your project.
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Old 01-28-2015, 11:31 PM   #22
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NWClassic beat me to it, but anyway, here goes:

You also need to consider the weight of the trailer itself, but that works in your favor since a majority of the trailer structure is forward of the axles.

As for estimating the tongue weight, the physics of this is pretty straightforward if we ignore the fact that you have dual axles and a suspension. These are reasonable assumptions to estimate tongue weight since, for ideal towing, the trailer would be level and the load on the axles the same. You need to measure the distance from the center of the axles to each of your loads including the trailer structure and the coupler. Call every distance forward of the center of the axles positive and every distance aft of the center of the axles negative. Weights of the trailer are forces down - call them positive. For each load, multiply the weight by the distance, letting the weight of the coupler be T, for Tongue weight. The sum of all these (moments) must be zero.

As a simple example consider a trailer with the dry weight of the trailer centered on the trailer and say that center is 5 feet forward of the axles, and the dry weight is 5000#. The coupler is 15 feet from the axles. There is a load of 200# 2 feet forward of the axles and another load of 500# 10 feet behind the axles. Then starting from the rear:
500x(-10)+200x(2)+5000x(5)+Tx(15)=0
-5000+400+25000+15T=0
20400=-15T
T=-1360
The significance of the negative sign is that there must be a force upward on the tongue of 1360# to balance the weight of the trailer and its contents.

A simple example, and one with too much tongue weight, but hopefully you get the idea.

Al
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Old 01-30-2015, 05:26 AM   #23
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Quote:
Originally Posted by Earthcreeper View Post
Try to duplicate factory spec for tongue weight.

A Sherline scale will be exactly what you need.

http://www.sherline.com/lm.htm

Thanks for the link, just ordered it!

Quote:
Originally Posted by nwclassic View Post
One way to get help locating the various weights is to use center of gravity calculations similar to those used for aircraft or ships. You can google for details or visit a local airport and ask a pilot to explain it.

Basically, establish a point (datum) to measure distances (called arms) to the weights you'll locate. Each distance multiplied by the object's weight gives a moment. The total moment (possibly made up of both + and - moments depending on whether they are forward of or behind the datum) divided by the total weight gives the center of gravity (CG).

I'd recommend deciding on the needed tongue weight and achieve it with weight forward added or removed to get it, first. The CG with that tongue weight is the one to maintain as you place the other weights.

As others have suggested, it's more than a front to rear balance game empty weight, max weight, useful load and lateral balance will influence how it travels.

Good luck with your project.

Thanks! This is really helpful!

Quote:
Originally Posted by Al and Missy View Post
NWClassic beat me to it, but anyway, here goes:

You also need to consider the weight of the trailer itself, but that works in your favor since a majority of the trailer structure is forward of the axles.

As for estimating the tongue weight, the physics of this is pretty straightforward if we ignore the fact that you have dual axles and a suspension. These are reasonable assumptions to estimate tongue weight since, for ideal towing, the trailer would be level and the load on the axles the same. You need to measure the distance from the center of the axles to each of your loads including the trailer structure and the coupler. Call every distance forward of the center of the axles positive and every distance aft of the center of the axles negative. Weights of the trailer are forces down - call them positive. For each load, multiply the weight by the distance, letting the weight of the coupler be T, for Tongue weight. The sum of all these (moments) must be zero.

As a simple example consider a trailer with the dry weight of the trailer centered on the trailer and say that center is 5 feet forward of the axles, and the dry weight is 5000#. The coupler is 15 feet from the axles. There is a load of 200# 2 feet forward of the axles and another load of 500# 10 feet behind the axles. Then starting from the rear:
500x(-10)+200x(2)+5000x(5)+Tx(15)=0
-5000+400+25000+15T=0
20400=-15T
T=-1360
The significance of the negative sign is that there must be a force upward on the tongue of 1360# to balance the weight of the trailer and its contents.

A simple example, and one with too much tongue weight, but hopefully you get the idea.

Al

Thank you Al, I'm a visual learner so seeing your example really connected the dots for me.
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Old 01-30-2015, 06:04 AM   #24
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Quote:
Originally Posted by TommieDee View Post
My 30ft Flying Cloud is set up with 4 Lifeline 6 volt AGMS batteries, total amps:880, total weight: 264#, no venting needed! I have a Magnum MS 2000 Inverter. I haveThese GPL-4CT batteries will last years verses the old style! Another issues is to keep the inverter and batteries as close together as possible,more efficient, less loss of voltage. Most of the installation I've seen, including my trailer with a forward couch or bed is to place the system underneath, then run shore power to the inverter and then back to the distribution( breakers, fuses)point. This setup keeps all the weight forward of the axles, yet 4ft to 10ft behind the hitch, centered left to right and easily accessible. This setup tows great. I also use a Hensley Hitch. You also have room for a solar panel controller.
Tommie,

Just a quick note;

Your lifeline GPL-4CT batteries are 6VDC and 220 amp/hours, so you have 2 in series pairs to make 12VDC and then paralleled. Your total capacity is 440 amp/hours, not 880.
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