How to calculate turn radius of fifth wheel for new driveway

[howardwheeler]

I am putting in a new drive so that I can pull out my 37 foot Alpenlite rather than having to back it out (I know that’s extremely lazy but I have the opportunity because we must put in a completely new drive anyway and want to take advantage of it). Because of trees it would be nice to know what the sharpest turn can be knowing that the trailer will track inside the truck’s track. I will make the drive wider at the point of the turn to accommodate the trailer tracking inside the truck path, but since you pay for additional materials, it would be nice to figure out the minimum needed. I would take my trailer out in a parking lot and simply do some trial runs but I can’t move it before my friends will be here with the equipment to put in my main drive. I thought some here might have some formula for radius’s and how to determine how far inside the trailer will track from the truck. Thanks

[howardwheeler]

Thanks everyone. I’ll let you know what I come up with.

[Hammerboy]

You got to think like Red Green or "how would Red Green do this?" All you need is some inverted spray paint and of course duct tape.

What you do is go to your favorite parking lot and duct tape on for the outside radius of your fifth wheel rear bumper a orange inverted spray can and that would show your tail swing. On the inside radius of your circle tape a inverted yellow on the front corner of your fifth wheel and then a inverted red on your front bumper of your truck on the inside radius also. Use a little duct tape to hold the spray paint open and start driving circles.

Disclaimer: This was a joke for those that don't know better.

Seriously either a scale model with all the measurements including wheelbase, overhangs on truck and trailer, etc. or go to a parking lot with some orange cones to drive thru. And bring a 100' tape with you

Dan

[howardwheeler]

And you’re right about a scale model as a possibility. One of my grandkids no doubt has a truck and trailer toy that I might be able to use. I think this calculator on the Truck Science site is the ticket—if I indeed can use it once for free. Or even once for cheap. Otherwise I know the best thing is to try turning in a parking lot, but I don’t think I can do it before my friends get here with their equipment and materials. They do road work and are squeezing me into their schedule for just materials cost. I’m very appreciative and don’t want to hang them up. It’s a real opportunity.

[howardwheeler]

The Truck Science link appears to be exactly what I’m looking for. It has a complete set of tools to determine track of truck and trailer with any wheel bases you choose for truck and trailer. Thank you very much. It says I can use it for free but you subscribe to their products. I’m trying to see if I can use it for free once because I have no ongoing need to calculate.

[noteven]

Make a simple scale model?

[4x4ord]

Your best option is definitely to follow SAR Tracker's advice and measure it out in a big parking lot. I would think you should be able to turn it around inside a 55 foot circle.

[valhalla360]

Mandalay Parr wrote:
I’m an engineer and not aware of any such formula.

I'm a traffic engineer and yes we have software (autoturn) to do this but not convenient for a layperson to obtain. You could go to a local engineering firm but it likely doesn't make financial sense unless it's a buddy who will run it for you.

If you google "turning templates", you can pull up pre-made ones for various design vehicles that will give you a good idea of what to consider but we don't normally design for RV's (to many variations).

The idea to find an empty parking lot and then simulate the turn while marking it out is a good option. Make sure to add a little extra width as you won't hit the curve exactly down to the nearest inch every time. The outside sweep of the rear overhang doesn't need to be paved, just clear of trees and other obstructions.

One complication to consider: Is it a simple single turn? Or do you have to turn left off the road and then almost immediately turn right? If, yes, when you go out to the parking lot, make sure to simulate the entrance and exit maneuvers.

[ford_truck_guy]

howardwheeler wrote:
I’m also concerned about how the tail swings out, but I guess I’m going to have to just guesstimate.

You will need to watch that...

I was going camping for the weekend and had stopped at the travel plaza on the PA Pike for a break. When walking back to my rig, there was a couple driving the wrong way with a NEW rig trying to find a parking spot between the trucks, he was hugging the barrier. I knew what he was doing, so I started jogging ( as best as this fat ARSE could ) to get to him but was too late.... He cut a hard left turn and scrapped the rear curb side of the trailer , tore the corner edge off and the bumper....

Know your swings ! ! ! !

[hammer55]

or look on you tube and put in trailer tracking

[bucky]

click here for link

tippytoe wrote:
This might help: https://truckscience.com/turning-circle-calculator/?gclid=EAIaIQobChMIn8jTmIKj3AIVA8-yCh2yPgI8EAMYASAAEgJNnfD_BwE

[tippytoe]

This might help: https://truckscience.com/turning-circle-calculator/?gclid=EAIaIQobChMIn8jTmIKj3AIVA8-yCh2yPgI8EAMYASAAEgJNnfD_BwE

[howardwheeler]

I’m also concerned about how the tail swings out, but I guess I’m going to have to just guesstimate.

[Mandalay_Parr]

I’m an engineer and not aware of any such formula.

[SAR_Tracker]

Go to a big parking lot in the middle of the night, and measure it.