Easy trailer front-end improvement

[aerohead]

Originally Posted by oldtamiyaphile

You don't have to enclose the sides, an open sided half pipe will work nearly as well. There's a company actually making and selling them like that.

[aerohead]

If the top of the trailer is taller than the tow vehicle the splitter could create some positive lift,especially in a crosswind.
The air won't be able to bleed 'up',and as the dynamic pressure acts on the underside of the splitter it will be pushing upwards,affecting tongue weight,stability.
Something more stable,would be to split a 8" PVC pipe and attach the halves to the upper edges of the trailer face.This would be incapable of generating lift.

[oldtamiyaphile]

Also, Hucho suggests that a vehicle mounted deflector is worth more than re-profiling the top of the trailer. This could be roof mounted on a removable roof rack. He shows a fast back vehicle towing a caravan, with a large roof mounted deflector showing the lowest drag.

[freebeard]

This puts me in mind of the Triceratops...

https://en.wikipedia.org/wiki/Triceratops#Growth_and_ontogeny

Juvenile Triceratops has an epoccipital fringe (that disappeared in the adults) similar to the serrations on modern turbojets used to suppress noise.



...on the back of a 1948 Cadillac Sedanette.

[aerohead]

Originally Posted by oldtamiyaphile

Also, Hucho suggests that a vehicle mounted deflector is worth more than re-profiling the top of the trailer. This could be roof mounted on a removable roof rack. He shows a fast back vehicle towing a caravan, with a large roof mounted deflector showing the lowest drag.

[PaulB2]

Something more stable,would be to split a 8" PVC pipe and attach the halves to the upper edges of the trailer face.

Hard to do since the front face has a curve in it.

That's a pretty small car towing that trailer, heh.

Those roof racks are interesting, but we aren't seeing what is happening at the trailer sides, with a cross wind, etc.

Isn't it true that almost any trailer shape generates lift? The way those streamers look in those pictures are similar to what happens with a wing. Added speed of air over the top causes reduced pressure, which means lift...

[freebeard]

Almost any typical trailer but not almost any conceivable trailer.



This is a Luigi Colani Bonneville car that obtained massive downforce without add-ons. Except the fenders are sort of add-ons. Flat on the top and convex on the bottom. Translated to trailer terms — sort of an upside down Airstream.

maybe aerohead will come along and say whether Airstreams have any lift to start.

[Hersbird]

Originally Posted by PaulB2

Hard to do since the front face has a curve in it.

That's a pretty small car towing that trailer, heh.

Those roof racks are interesting, but we aren't seeing what is happening at the trailer sides, with a cross wind, etc.

Isn't it true that almost any trailer shape generates lift? The way those streamers look in those pictures are similar to what happens with a wing. Added speed of air over the top causes reduced pressure, which means lift...

I think any lift generated is just a tiny fraction of the weight. We aren't talking lightweight aircraft, and we aren't talking aircraft speeds. An airstream is actually a heavy trailer compared to some of the stuff made today.

I used the sheetmetal ductwork for my edges. If it were a curved surface you could cut some relief cuts in it to let it bend. They could just be simple cuts almost all the way across just leaving an inch in the center intact then they will slide inside themselves like an armadillo skin as it makes the bend.

[freebeard]

Hard to do since the front face has a curve in it.

The center 80% in lightly curved. If you have an half-pipe and spread the center or pinch the ends, it curves. On the ends if you don't want to use Hersbird's pie cuts, crimp the edges. There is a dedicated hand tool. But you can just grab the edge with a fork[-like object] and twist. That's how panel beaters start, then they hammer the crimps flat again.

[aerohead]

Originally Posted by PaulB2

Hard to do since the front face has a curve in it.

That's a pretty small car towing that trailer, heh.

Those roof racks are interesting, but we aren't seeing what is happening at the trailer sides, with a cross wind, etc.

Isn't it true that almost any trailer shape generates lift? The way those streamers look in those pictures are similar to what happens with a wing. Added speed of air over the top causes reduced pressure, which means lift...

In road vehicle aerodynamics,lift is a function of flow separation,and the low pressure over the vehicle induced by low pressure present at the separation line.It has nothing to do with the displacement of the streamline filaments.
In the image below,the top vehicle would be extremely unstable at speed,whereas the bottom vehicle would be especially stable.

Streamlined bodies are incapable of generating lift,as they have zero separation,or recover with reattached flow.