Need Advice from Design Wizards

[aggie79]

My wife and I are considering building a standy TTT because an internal porta-potti is a necessity at this stage of our life. We like the outside galley of Andrew's Midget, but prefer the extra bit of interior room in his Widget design. Weather down here is not much of an issue, so the galley could be inside or out.

From a towing perspective only, does the further rearward axle placement of an outside galley due to its center of gravity result in better towing?

[mikeschn]

Check out the ET here...

http://tnttt.com/viewto ... c&start=75

Mike...

[Chaotica]

From a towing perspective only, does the further rearward axle placement of an outside galley due to its center of gravity result in better towing?

Axel placement is based on total trailer weight and a percentge of tongue weight, usually around 10-15%.

You can learn about trailer balance here.

http://www.angib.pwp.blueyonder.co.uk/t ... tear81.htm

[aggie79]

Thanks. I've been following the ET with great interest. It is very close to what we have in mind. And, I have downloaded Andrew's spreadsheet on weight distribution.

Because I've never had a boat or travel trailer, I was looking for some practical experience/advice on how a TTT would would tow. Without calculating Cg for each, and all things being equal (over length, tongue weight, etc.), the axle placement for a TTT with the galley located at the front of the trailer (toward the hitch) would be closer to the tow vehicle than a mirror image of the same TTT with the galley at the rear of the vehicle.

From what I gather on the forum, a trailer will tow better with a more rearward placement of the axle which would seem to imply a rear galley is better from a towing perspective. Have a lost my mind or am I overthinking this?

[angib]

If the galley is at the back and is heavy, the axle needs to be positioned well back so that the tongue weight is still sufficient.

With a heavy galley at the front, it already gives a higher tongue weight and there is no need to move the axle back to get a good tongue weight.

Providing the tongue weight is right, I don't think there's anything to choose between the aft galley/rearward axle or the front galley/middling axle, at least for ease of towing.

Andrew

[aggie79]

Thanks again for everyone's insight. Your advice has been helpful and is appreciated.

Although I am comfortable with woodworking and basic auto mechanics, and have the tools, trailer construction is new ground for me. We are just trying to figure out what we want to build (at least for our first project.)

[coal_burner]

The further back you put your axle, the easier it will be to tow.
There are two good things about a far aft axle.
The first: when backing up the trailer, the further the axle is from the hitch, the slower the trailer will turn and jacknife. My neighbor backs his 17 foot boat trailer into his driveway twice a weekend without any problems. When he borrowed my 5x8 utility trailer, it took him about 10 tries to back into his driveway, because the trailer was too sensitive to his steering inputs.
The second thing: when driving at freeway speeds there is much less sway due to aerodynamic forces when the axle is far back.
lets say, that a semi passes you at 80 mph, and the wash from that attempts to push the trailer sideways. the trailer will act as A giant lever, with the hitch as your fulcrum, and the effort provided by your tires trying to grip the road surface.
If the axle is far back, the trailer will act as a second class lever where more of a side load will be required to overcome the tires' effort to not skid sideways.
If the axle is far forward, the trailer may actually act as a third class lever, and a very small side load will be required to overcome your tires' aversion to skidding sideways.
My father built A large trailer several years back, with An ultra heavy duty axle that was given to him for free. he placed the axle in the very middle of a trailer box that was about 20 ft long(He could haul a full sized car in this trailer with only 300 lbs of tongue weight). Everytime A semi passed us, the trailer swayed side to side about 2 ft.
The next year, we moved the axle back about 3 ft. and the swaying problem almost completely disappeared.