Aerodynamic vehicle towing a non-aerodynamic trailer...

[gone-ot]

...just think of that U-HAUL trailer as an aero anchor or aluminum parachute (wink,wink)!

[BamZipPow]

Picked up a 4x8 trailer this time around...only small stuff on this trip.

Configured the hatch to provide some air diversion over the trailer. Since my hitch has the trailer tilted towards the rear, I've set my hatch to have the air meet just at the top of the trailer. We'll see how this goes.



My supports (1x2 wood strips) are bolted to the hatch and my aero cap main rails. Since this will be my first time traveling at highway speeds with the hatch propped open, it will be interesting to see how well the supports hold up.

I wonder how much of a hit I will take if I don't close up the gaps between the aero cap and the hatch in this configuration?

[BamZipPow]

Originally Posted by botsapper

We like recycling...
http://ecomodder.com/forum/showthrea...tml#post236561

Botsapper...what were the numbers using this setup? Or is this all photoshopped and no real data available?

[BamZipPow]

Installed a Gurney flap on the end of the hatch. Not sure if it will do anything or not.

[BamZipPow]

Got an indicated 20.2mpg on arrival. Nothing fell apart or fell off. Supports held up great.

Dropped off the trailer and reinstalled my lower grill blocks. The only change on this return trip will be the Gurney flap.

[slowmover]

Get that trailer level, or barely nose down, friend. The config shown in the pic above makes for low tongue weight = propensity for trailer sway. At the least, that trailer will be moving around more than need be, calling for more steering corrections per 100-miles. Tire load is also off from FF to RR (braking).

And, from perspective around here, that flat plane of the trailer underside is like an airplane wing gaining lift. Towing rather comes down to tow vehicle rear axle traction, so a trailer moving side-to-side and light on its feet, so to speak, has not an attitude conducive to lane-centered stability.

Masterlock Adjustable Height Ball Mount

I paid about $50 at a U-Haul store years ago. Uses a wrench to move up and down.

FWIW I don't ever trust the U-Haul management to have their techs make sure that:

tire pressure
lug nut torque
surge brake actuation
lighting

is fully operable and meeting spec according to their own guidelines. U-Haul specialzies in out-of-court settlements which do not disclose liability. Dumb renters, sure . . poorly-maintained equipment, bet on it. Their stuff is made well, but any of it can fall between the cracks.

Pleased you hit 20. Whats the percentage drop from solo, now? And over what terrain and distance? Any idea of total weight versus scale weight (payload)?

.

[Grant-53]

The ideal is to have the whole rig follow the smooth C template.

[aerohead]

Originally Posted by BamZipPow

Picked up a 4x8 trailer this time around...only small stuff on this trip.

Configured the hatch to provide some air diversion over the trailer. Since my hitch has the trailer tilted towards the rear, I've set my hatch to have the air meet just at the top of the trailer. We'll see how this goes.



My supports (1x2 wood strips) are bolted to the hatch and my aero cap main rails. Since this will be my first time traveling at highway speeds with the hatch propped open, it will be interesting to see how well the supports hold up.

I wonder how much of a hit I will take if I don't close up the gaps between the aero cap and the hatch in this configuration?

We'd have to test it both ways to really know.
With the opening,this is where the airflow will begin to shred.But the turbulence should basically be contained within the footprint of the cap/lid,so by the time it makes it to the U-Haul it might be a wash.
I agree with Frank Lee that having the trailer hide behind the full 'outline' of theT-100 will be better than with the lid down,and airflow crashing into the nose of the trailer.
Except for the U-Haul's fender area,the air should reattach before it finally separates for the last time at the back.
Hope you get some weights!
Thanks for the data!'n happy trails!

[BamZipPow]

I got just under 24mpg coming back home before traffic came to a standstill on I-45. Not sure if the Gurney flap is doing more harm than good. It might keep the rain from coming off the edge of the aero cap and not gitting me soaked when I tuck up under the back end. I'll keep it on fer my local runs and see if it makes a difference or not. If it doesn't, then I'll probably take it off and see what happens the next time I make more runs to College Station.

Looks like my combined mileage is just over 20mpg. Still not too bad. I might git a few more chances to pull another trailer or two up to College Station. I'll do more data collection at that time and what changes I make to my truck.

I know I don't have a baseline...but there wasn't a normal trip pattern to develop before these runs came up. I just have to work with what I have.

[slowmover]

We'll look forward to what the weight differences were from solo (if you have a chance to scale it), and the percentage changes as recorded.