Cargo Trailer Aerodynamics
- Thread starter ITTOG
- Start date
dreadlocks
Well-known member
Nice and legal..
How much is it gonna cost to cover your legal defense after your insurance refuses to be liable for the damage your aero rig did to some innocent bystanders.
How much is it gonna cost to cover your legal defense after your insurance refuses to be liable for the damage your aero rig did to some innocent bystanders.
Void warranties on what? Lots of axles are spring under axle. It only depends on where you weld the perches.
Your gearmotor idea is overthought yet under considered to the point of dangerous. What will hold the tension while towing? A nut? 2 nuts? Not under torque. Where will the receiver pin go?
If you want to have a telescopic tongue, drill it in multiple places for receiver pins, but by all means, please use a receiver pin.
And safety chains!
Your gearmotor idea is overthought yet under considered to the point of dangerous. What will hold the tension while towing? A nut? 2 nuts? Not under torque. Where will the receiver pin go?
If you want to have a telescopic tongue, drill it in multiple places for receiver pins, but by all means, please use a receiver pin.
And safety chains!
What holds the tension? the gear-motor and the 3/4 inch all-thread. The gear-motor is reduced to 6 RPM, and turning that from the all-thread should be VERY difficult. If the trailer somehow manages to creep backwards, there is a stop on the all-thread. The ball mount has a receiver pin. The tongue has chains.
dreadlocks
Well-known member
great, your safety chains will hold onto whats left of your tongue while rest of trailer flies off a cliff.. so your replacing your hardened steel receiver pin and hitch, with a $56 gear motor as far as weak links.. also whats going to automatically extend it when you turn? if you have to make evasive maneuvers your gonna impact your tow vehicle.
I assume that you came here asking advice in good faith. I believe that advice has been presented the same way. If you are only here to tell us that we are all wrong in comparison to you, have fun.
What you are proposing to do is possible, but not a good idea.
The same thing can be accomplished by simply drilling a number of cross holes for a pin in the tongue. Maybe every 4 or 6”. Manually push the trailer into position and put a receiver pin or bolt through the holes. Simple, cheap, effective. You can see many instances here of people building similar adjustable tongues on trailers.
This is very similar to the way semi-trailers reposition the axles, although with larger pins.
It looks like you have a long cross country trip planned. You mentioned staying in KOA facilities. Given their cost, have you considered taking less stuff, no trailer, and staying in cheap motels? Have you simply considered taking less stuff? 300 lbs seems to be a lot of gear.
I did come here for guidance, but I don't think I'm communicating my wishes very well. Yes, I could use a ball mount with a long receiver shank and drill a second hole for the pin, but I don't want to stop the car to go from in town to close coupled for the interstate. I'm trying to build a way to make that change on the move. It seems I'm being told my design won't work, but not from someone who has tried it. The main thought seems to be that the screw won't hold once the motor is turned off. What if I use a spring loaded solenoid activated pin to lock the tubes in forward or rearward length. Would that be as safe as getting out and moving the ball mount manually?
I'm traveling with my wife, who packs heavy, and she is very loathe to sleep in bargain hotels. 300 lbs is a maximum guess. could be 200.
Years ago, I built a reverse wedge low cargo trailer that tapered to license plate height at the rear, and added 5 MPG to the Accord I was towing with. I'm hoping to gain a few MPG over the bluff Prius rear by keeping the airflow headed towards a smaller point of departure at the rear of the carrier.
I'm going on this trip with the fixed tongue that this trailer comes with. Maybe I won't need to pull the trailer up tight. Just trying out some ideas, just in case.
I'm traveling with my wife, who packs heavy, and she is very loathe to sleep in bargain hotels. 300 lbs is a maximum guess. could be 200.
Years ago, I built a reverse wedge low cargo trailer that tapered to license plate height at the rear, and added 5 MPG to the Accord I was towing with. I'm hoping to gain a few MPG over the bluff Prius rear by keeping the airflow headed towards a smaller point of departure at the rear of the carrier.
I'm going on this trip with the fixed tongue that this trailer comes with. Maybe I won't need to pull the trailer up tight. Just trying out some ideas, just in case.
dreadlocks
Well-known member
drive more, engineer less.. is this really just a one time trip? get a friggin hitch cargo rack and call it a day.
The concern is not the screw backing off, although that might happen. The concern is that the screw is not strong enough, nor are your “safety stops” for towing a trailer, even at the lower DOT class levels. In addition the cornering force on something that is slack enough to get a gear motor to push it back and forth will bend and bind it in no time. Plus, normal screw thread just isn’t made for that. What you are describing is essentially a linear actuator. A ball screw would be a good idea. Lots of people make these. Tell any of them that you are going to build it into the tongue of a trailer (BTW, your first sketch showed it under the car, not the trailer) and see what their attorneys and engineers say. If you are up for thousands in machining costs, you might make something strong and precise enough to move back and forth like you want. It will be expensive, heavy, and a huge diminishing return. All so you can push a button to make your trailer longer? You are the only one who will be impressed by this. Just make a short trailer if that is what you want. The limitation on turning will not impact you in almost any normal paved road situation. The main issue will be seeing it. Put an antenna on the rear of the trailer.
Experience is not the sole purveyor of knowledge. Just because none of us have done this before doesn’t mean we aren’t looking out for your best interests, and those of the public. Personally, I’ve never contracted Ebola before. I still feel confident in stating it isn’t a good thing to do.
Experience is not the sole purveyor of knowledge. Just because none of us have done this before doesn’t mean we aren’t looking out for your best interests, and those of the public. Personally, I’ve never contracted Ebola before. I still feel confident in stating it isn’t a good thing to do.
mikeyb1976
Member
Only as far as ground clearance, tire clearance, center of gravity, approach/departure angle (think pulling into parking lots and the dips that occur there), and possibly aerodynamics (based on height) is concerned
There's a reason why travel trailers/5th wheels have a service called "axle flip." Sometimes the trailer ends up sitting too low, so the axle gets taken off the top and put back on underneath. It's done all the time.
Regarding the collapsing tongue (urban dictionary thing?), the one question I ask is, outside of dump truck trailers, do you see that application anywhere else? If not, there's probably a very good reason why.
You'd likely be better off putting solar-powered wheels on the trailer to maximize eMPG.
source: Worked at a trailer hitch place for the summer; family member owned similar business 10+ years.
So, my next question (NO MORE TELESCOPING!) is this:
With the Ironton 40 x 48 trailer the length from coupler to axle is 59.8 inches with a rear overhang of 19.2 inches of frame. I have the option of putting the tongue on the other end, and flipping the trailer around giving a coupler to axle length of 50.2 inches, with a rear overhang of 28.8 inches of frame. My car has a 106 inch wheelbase, and rear axle to ball would be about 34 inches. The reason I might do this is that I may be able to move the load box forward, and would need to move the wheels forward to balance the combo. How would this change the trailing dynamics?
Also, how do I start a new thread?
With the Ironton 40 x 48 trailer the length from coupler to axle is 59.8 inches with a rear overhang of 19.2 inches of frame. I have the option of putting the tongue on the other end, and flipping the trailer around giving a coupler to axle length of 50.2 inches, with a rear overhang of 28.8 inches of frame. My car has a 106 inch wheelbase, and rear axle to ball would be about 34 inches. The reason I might do this is that I may be able to move the load box forward, and would need to move the wheels forward to balance the combo. How would this change the trailing dynamics?
Also, how do I start a new thread?