trailer aero

[skyking]

Originally Posted by KamperBob

Aero wise that rounded nose left from the horse trailer is about as good a start as you can get. You could build sides up to template. I'm not sure of the trip purpose or how much weight goes on that trailer. Seems like a lot of tongue weight. If one set of axles would suffice maybe remove the rear one for the trip. That would bring tongue weigh down. With a template shaped profile there would be more cargo space up front so the hitch might not be overloaded. Hard to say really. I feel like I'm missing a lot of context...

great idea Bob, or even better, remove the tires only. This will help shift weight off the tongue.

[trooper Tdiesel]

i have thought about pulling one hole axil, but this thing was made to have a steel roof its hole life, and not have the frame take all the stress.
i think it would be like bending a pace of tin back and forth, sooner or later it will give....

some photos of when i made it a cargo trailer. starting 2/3 of the way down the page....
IsuzuPup.com • View topic - any intrest in parts at East Coast meet ?
i wanted to leave the sides at 3 foot all around it, but the sides made the trailer twist, shake, vibrate quite badly, so i lessened them.


its common for me to carry super local hay loads, so i have been toying with adding maybe 5 feet to the rear of the trailer.
to lessen the tunge load and make less trips....

also this would let me get a home made title for it, since i would have papers showing i had put steel in to it. and more or less reconstructed it in a manner of speaking.
a legal way to make a trailer home built in OR state.

its a deal where 3+ people have had the thing thru the years but no one transfers the title.
it has never been registered in my state, thus i can not apply for a lost title.
when i got it it was a rusting heap of junk that the guy wanted gone NOW!!!
i made him sell it for $1.00....so when dealing with WA state they could account for the 0.07c tax other wize it would have been FREE

i just got the trip permits to day for the drive, LOL the DMV is like wow what on earth are we going to do LOL

[euromodder]

Originally Posted by skyking

great idea Bob, or even better, remove the tires only. This will help shift weight off the tongue.

Why would it ?
The trailer tilts around its front axle.
Removing anything from behind the front axle, will increase tongue weight.


If the intended load allows for it, move the fuel tank aft over the wheels.
If possible at all, move it to be near the rear axle.

[euromodder]

Originally Posted by trooper Tdiesel

i have thought about pulling one hole axil, but this thing was made to have a steel roof its hole life, and not have the frame take all the stress.

Looking at the trailer pics in that thread, run a continuous beam down the centerline, and put a diagonal brace in either of the squares that you have made this way.



I hope the beams on the left and right that make up the towing tongue / triangle, are running aft for the entire length of the trailer ?

If you want to lengthen it - and carry more weight - why not double up the lengthwise beams while you're at it ?

[trooper Tdiesel]

yes the steel runs all the way from the tung to back to the front of the tires.

just ran it over the plug and play scales on the high way with no real load.
1,600lb trailer and 150lb tung load.

but with some where around 160 gal of cooking oil, it was 2,900lbs on the trailer and 4,800 on the trooper.
a staggering 600lbs tung load, sence the trooper is 4,200lbs with a full tank and me in it.
the load transfer bars put best i can guess 150lbs+/- of that on the front axil of the tow auto...

that was with two full drums in line with the frunt axil, and two half full drums just in front of them, looking at that photo, two drums are right behind and two are right in frunt of the steel cross peace that was the wall divider for the horse area, and 20gal in plastic jugs up in the aro nose

any way the moral of this is, it gives me a good base line as to how to load it for the long drive.

the scale runs on 50lb jumps so if it was 2,949lbs it would read 2,900
at least that's what i under stand.

[skyking]

Originally Posted by euromodder

Why would it ?
The trailer tilts around its front axle.
Removing anything from behind the front axle, will increase tongue weight.


If the intended load allows for it, move the fuel tank aft over the wheels.
If possible at all, move it to be near the rear axle.

taking rear tires off removes that force upward there. pivoting around the remaining axle, this acts to remove tongue weight. Leaving the rear axle in place without tires, removes even more tongue weight.
This of course lowers the carrying capacity, and might induce less than friendly tracking, bounce in the bumps, etc.
Typically, two axles track nicer, have less tendency to bounce, less tendency to lift and lower the tow vehicle (TV) because the tongue weight is more stable. Downside, more parts to replace, tires, scrubbing during tight maneuvering.

[drmiller100]

horsetrailers OFTEN use the sides of the trailer for strength. I'm not very impressed by the "frame rails" which run fore and aft. If it were mine, I'd add something, or put some sides back on.

600 pounds tongue weight is not that much. The hitch and truck should be just fine with that much.

a MINIMUM of 10 percent of the trailers weight needs to be tongue weight. A MAXIMUM of 20 percent is recommended.

You are within those guidelines.

Not enough tongue weight leads to trailer whipping and someone dead. Too much makes your truck squat, but it takes a LOT of tongue weight to affect the handling.

[KamperBob]

Given more context I hereby withdraw my suggestion to remove rear wheels. (It's actually an advanced move given leaf spring equalizer pivot mechanism.)

Tangent on tongue weight. The ad-hoc 10% rule in the US is less (5-7%) overseas. Hucho's section on caravans touches on tongue weight. One explanation is typical trailer geometry when nose/tail pressure effects are taken into account. Think about it. If surface normals intersect the axle pivot then tongue weight stays constant; whereas with boxy trailers front push and back pull takes weight off the tongue as speed increases.

[euromodder]

Originally Posted by skyking

taking rear tires off removes that force upward there. pivoting around the remaining axle, this acts to remove tongue weight.
Leaving the rear axle in place without tires, removes even more tongue weight.

Sorry, but it doesn't.
The trailer is already front-heavy as it is.
So it pivots around the front axle.
Anything behind the front axle is acting as a balancing weight, so removing it puts more weight on the tongue.

Being so front heavy, 600lbs on the tongue means it's unloading the rear axle, and putting a lot more strain on the front axle. What's the use of a double axle then ?

This trailer was obviously designed with the weight of the horses in mind - that's a lot of weight, but they were situated right over the wheels.

I'm always surprised by statements like

600 pounds tongue weight is not that much. The hitch and truck should be just fine with that much.

600 lbs on the tongue is a lot.
Sure it's a 4x4, but still.


On this side of the Atlantic, most passenger cars allow with 100-150 lbs, some 200lbs on the hitch. We don't use special sway gear, or special bars to move some of that weight forward on the tow vehicle, and yet we tow more trailer weight with passengers cars than what's allowed in the US.

While a positive downforce on the tongue is good to control the tow, and keep it from unloading the rear axle of the towing vehicle, there's no need for excessive tongue weights.

[skyking]

draw a force diagram. put 2200 pounds on both axles. Remove back axle. Moves force forward. reduces tongue weight. I will devote no more to this post than this post. If you are unable to see that I cannot help you further.
Edit: the weight of the tires and axle rest on the ground. Now that axle hangs off the frame too. See where this is going?