Aerodynamic of the reverse tear...

[vwbeamer]

http://www.roulottesprolite.com/english/eco12.htm

Good?...bad. which way are these supposed to be pointing???

[Arne]

It looks a lot better than having the big part in the front... and it gives stand up room, which is nice.

[mikeschn]

Did anyone see any prices for those trailers?

Mike...

[vwbeamer]

Just wondering which way is more aerodynamic...

They are lite, only 750 pounds.

[mikeschn]

Just wondering which way is more aerodynamic...

Basically the same aerodynamics either way... look at the largest cross sectional area that has to displace the wind. Decrease the cross sectional area and you increase your aerodynamics...

That's the basics of it. Andrew could give you more detail...

Mike...

[bpb165]

I tend to agree about the aerodynamics. My last teardrop caused hardly a drop in fuel economy at all. It weighed in under 1000#s loaded for the weekend. My current project is a modified reverse on a 5x8 frame. It's more to your preference, keep them unique to the person that builds them or buys them.

[PaulC]

Just wondering which way is more aerodynamic...

Basically the same aerodynamics either way... look at the largest cross sectional area that has to displace the wind. Decrease the cross sectional area and you increase your aerodynamics...

That's the basics of it. Andrew could give you more detail...

Mike...

And that is all dependent on running the TD in clean air. Put it behind a tow vehicle, and in dirty air, and you can throw any thoughts of aerodynamic advantage right out the window. In a nutshell, there is none. End of story.

By the way, this has been discussed on the forum before, about a 100......................50............................or was that 150 times, before.


Come in Andrew

Cheers
Paul

[Arne]

quote: And that is all dependent on running the TD in clean air. Put it behind a tow vehicle, and in dirty air, and you can throw any thoughts of aerodynamic advantage right out the window. In a nutshell, there is none. End of story.

----------------

That is true to a degree, but the more distance between the tow and the t/d, the more turbulent the air is on the t/d.... which is why when someone says they are using a 48" tongue I kind of cringe.....

The reason they give is so the tow won't hit the tear, but how often does the t/d get 90 degrees to the tow?

Now, if you want to experiment, go down the highway and hold your hand out in the air stream and feel the resistance.. Then put your hand out holding a round plastic bottle of approximately the same size out and feel the difference....

[PaulC]

quote: And that is all dependent on running the TD in clean air. Put it behind a tow vehicle, and in dirty air, and you can throw any thoughts of aerodynamic advantage right out the window. In a nutshell, there is none. End of story.

----------------

That is true to a degree, but the more distance between the tow and the t/d, the more turbulent the air is on the t/d.... which is why when someone says they are using a 48" tongue I kind of cringe.....

The reason they give is so the tow won't hit the tear, but how often does the t/d get 90 degrees to the tow?

Now, if you want to experiment, go down the highway and hold your hand out in the air stream and feel the resistance.. Then put your hand out holding a round plastic bottle of approximately the same size out and feel the difference....

Arne, same old arguments as before, young man Put the TD 6" behind the TV and aerodynamics come into play. Use the average drawbar and forget it.
That's it from me, I am getting rather bored with repeating myself to those who fail to listen the first time.
Cheers
Paul

[angib]

Come in Andrew

Don't need to - I see you've got it covered.

Andrew

[PaulC]

Come in Andrew

Don't need to - I see you've got it covered.

Andrew

Ummm I think you just paid me a compliment

Cheers
Paul

[Arne]

ah, now if you could only get the laws of physics to agree with you...






















[/img]

[PaulC]

ah, now if you could only get the laws of physics to agree with you...


[/img]

Arne, get it right mate. All those coefficients are rated in a clean air situation, NOT in the dirty air behind a tow vehicle. Or the dirty air of a freeway with all types of vehicles around you disturbing the air.

Cheers
Paul

[Shadow Catcher]

Discussed earlier was the possible use of Airtab's http://www.airtab.com

"Airtab Press Piece Australasian Transport News (ATN)
The basic aerodynamic theory is this:

As a vehicle moves, air rushes into the space it just occupied. With the typical square and flat back of a truck or trailer, it can’t rush into that space smoothly and the problem gets worse as speed increases.

The result is turbulence, which creates drag and requires power and fuel to overcome. Any long haul operator would know of the problem which is evidenced by the turbulent mass of airborne water behind a truck in wet conditions and by the heavy build up of road grime that happens on the trailers back doors or panels."

One thing that has been left out of this discussion (more or less) is the vortexes involved. There are two, between the TV and the trailer and behind the trailer. the traditional teardrop is as about efficient as you can get and in behind a TV is likely to have the lowest drag. the back ward design just strikes me as a not great idea and you have the trailer vortex.

We have a Grasshopper design and I know there is drag and plan on putting Airtabs on both the TV and the trailer.

I have been thinking of building a wind tunnel (box with fan) to test out what is happening or finding a really dusty road next spring.

[Woody]

Drag coefficients???? aerodynamics????? fuel economy ??????? Are you kidding me. Thats why threads of this nature are never aerodynamic because they always leave lots ruffled feathers in thier wake. Thats were the real "drag coefficients" come into play here. This is one area where the "K.I.S.S." strategy never seems to be applied