Active Trailer gap for Tractor Trailers

[JSH]

Here is an interesting product from a company call Truck Wings. It is an active cab deflector that folds out at speed to close the cab to trailer gap and then folds again a low speeds so the truck can turn. They claim a 4% increase in fuel economy with is huge for a on-highway truck.

https://www.fleetowner.com/equipment...or-trailer-gap

[slowmover]

The savages allowed into this country always find a way to destroy stuff in new & imaginative ways. This wouldn’t be an exception unfortunately.

But I sure wish I’d had a gap closure system on the 579 Pete EPIQ a few days ago running out of ABQ thru OKC: 41,000-lbs in the box, all the way to the doors; had the tandems back a little farther than allowed; trailer has the full skirts & tails treatment. I keep the kingpin forward of center as the front axle rating isn’t taxed. 76,700-lbs. Gap is well under 30”.

Had my tail kicked the whole way in this new tractor (80k) by the crosswinds. Were the windmill gensets turning? Ha! Hardly.

I’d have been happy to have had that additional help. Stayed at 8.3-mpg with PACCAR 13L + 12-AMT at 66-mph. Reducing driver fatigue rates as high or higher than a few tenths. One wears down early in the day.

Now, if only the industry would develop & market a shock absorber that wasn’t gone by 30k. The gas charge is GONE by that point. Body roll and wind twitch gets real real old, real real quick. Boutique shocks ain’t gonna happen.

Thanks for posting.

.

[kach22i]

Looks interesting but wish there was a passive device that could net similar results.

UPS gets a lift as TruckWings eliminates the tractor-trailer gap
https://www.fleetowner.com/equipment...or-trailer-gap

The price for a single unit is approximately $4,000, with payback for a tractor traveling 80,000–100,000 miles a year pegged at 12-15 months. Earlier this year, XStream announced it secured $10.5 million in Series A funding, led by Autotech Ventures and Calibrate Ventures.

From the Random Aerodynamic Oddity Thread a week or two ago......

https://ecomodder.com/forum/showthre...-35653-41.html

Originally Posted by kach22i

FLOWBELOW WHEEL COVERS INCLUDED ON NEW ‘MPG PACKAGE’ FOR INTERNATIONAL LT SERIES TRUCKS
Posted on November 6, 2018
FLOWBELOW WHEEL COVERS INCLUDED ON NEW ‘MPG PACKAGE’ FOR INTERNATIONAL LT SERIES TRUCKS - NextTruck Blog & Industry News - Trucker Information




https://www.flowbelow.com/aerokit


https://www.flowbelow.com/trailer-aeroslider


February 27, 2017
by James Menzies
https://www.trucknews.com/equipment/...ne/1003077466/

I see this UPS truck in the original article is NOT outfitted with FLOWBELOW as part of the Aero-Package.

I wonder if there is any collaboration with Xstream Trucking as shown in the very first image in this thread. I do not see them listed as a partner.

FYI: Video below of the wings in action, looks very simple, easing any misforgivings I may have initially had.

XStream Trucking - TruckWings
https://www.youtube.com/watch?time_c...ature=emb_logo

Photos and videos of the TruckWings from XStream. For more info, visit www.xstreamtrucking.com

The butterfly roof portion is spectacular in my opinion, not just the sides.

[JSH]

XStream and Flow Below aren't connected that I know of. The only thing that concerns me about the Truck Wings is the use of air cylinders for activation. Yes, they are cheap but it is hard to keep multiple cylinders in time without constant fiddling.

The Flow Below product does work but the universal mounting kit is a bit of a pain. It is good to see they are offering some truck specific options.

[Hersbird]

Why can't a semi use a simple gap filler that goes a bit down the side of the trailer and be spring loaded so it flexes out in a turn and returns to center. You might have to also tie both sides together so the outside fairing also pulls away in a turn so it doesn't bind as the trailer comes into place. Basically like gills of a fish.

[slowmover]

Flow Below works well with vans. My company grown tired of repairing tails/skirts, but FB a priority.

[slowmover]

Originally Posted by Hersbird

Why can't a semi use a simple gap filler that goes a bit down the side of the trailer and be spring loaded so it flexes out in a turn and returns to center. You might have to also tie both sides together so the outside fairing also pulls away in a turn so it doesn't bind as the trailer comes into place. Basically like gills of a fish.

I’ll start an answer with: the forces involved in deployment are against huge loads. Pressures on either side vary greatly no matter what winds present. IT ISN’T EQUAL.

As a note, too many of y’all have the wrong idea about aero. Straight-ahead forces are almost self-equalizing. Not that important compared to crosswinds. A tall vehicle with high COG and enormous sail area (the trailer skin is larger than your house) has other worries.

Straight ahead is easy. Any vehicle.

Now, ask a pilot about crosswind landings.

.

[JSH]

Originally Posted by Hersbird

Why can't a semi use a simple gap filler that goes a bit down the side of the trailer and be spring loaded so it flexes out in a turn and returns to center. You might have to also tie both sides together so the outside fairing also pulls away in a turn so it doesn't bind as the trailer comes into place. Basically like gills of a fish.

It could work for an operation where the tractor and trailer are owned by the same company and they are willing to make modifications to the trailer. (Like using welded corners on the front of the box instead of rivets that could snag on the cab extender. The geometry could also get tricky because the 5th wheel moves fore and aft so the driver can balance the axle weights so it would have to work with the complete range of trailer gaps. You would also need to be OK with the extender rubbing on the trailer and damaging the paint on both.

A big issue for aero on tractor trailers is that most of the time the tractor and trailer aren’t owned by the same company. The trailer owner has little incentive to spend money to reduce someone else’s fuel bill. They just want a cheap generic box trailer that any tractor can transport. Likewise a truck owner can’t make mods that limit the types of trailers he can tow.

Edit: The truck also can’t be more than 102 inches wide and trailers are already that wide on the outside. Your typical trailer is 99 inches wide inside so you can put two 48 inch pallets side by side. That leaves an inch on each side and an inch between pallets for room to maneuver them.

[aerohead]

Originally Posted by Hersbird

Why can't a semi use a simple gap filler that goes a bit down the side of the trailer and be spring loaded so it flexes out in a turn and returns to center. You might have to also tie both sides together so the outside fairing also pulls away in a turn so it doesn't bind as the trailer comes into place. Basically like gills of a fish.

NASA did just this back in the 1980s.Pictures are online.'Project Shoebox',at Edwards AFB,California.

[kach22i]

Originally Posted by aerohead

NASA did just this back in the 1980s.Pictures are online.'Project Shoebox',at Edwards AFB,California.

I did a search on that and found the strangest thing by accident - and in our expanded topic zone I'm hoping.


MIT and NASA engineers demonstrate a new kind of airplane wing
Assembled from tiny identical pieces, the wing could enable lighter, more energy-efficient aircraft designs.
David L. Chandler | MIT News Office
March 31, 2019
MIT and NASA engineers demonstrate a new kind of airplane wing | MIT News

While it would be possible to include motors and cables to produce the forces needed to deform the wings, the team has taken this a step further and designed a system that automatically responds to changes in its aerodynamic loading conditions by shifting its shape — a sort of self-adjusting, passive wing-reconfiguration process.

“We’re able to gain efficiency by matching the shape to the loads at different angles of attack,” says Cramer, the paper’s lead author. “We’re able to produce the exact same behavior you would do actively, but we did it passively.”

This is all accomplished by the careful design of the relative positions of struts with different amounts of flexibility or stiffness, designed so that the wing, or sections of it, bend in specific ways in response to particular kinds of stresses.

The resulting lattice, he says, has a density of 5.6 kilograms per cubic meter. By way of comparison, rubber has a density of about 1,500 kilograms per cubic meter. “They have the same stiffness, but ours has less than roughly one-thousandth of the density,” Jenett says.

Earlier I expressed interest in a passive wing or filler between cab and trailer, and the MIT article seems to be applicable - but not just yet.