Flow Visualization on new tailcone.

[bondo]

Got out the yarn and duct tape yesterday and hit the road. We have been seeing 23 to 25 mpg in over the road testing. The air flows nice over the top. The sides, a little to be desired but did not want to eclipse the tailights. The turbulence of the wake seems to have been reduced as shown by the laziness of the tufts stuck on the very back.

This new device is held in place by the rotary latches in the lowered tailgate. To remove it, just reach under and pull the tailgate handle which releases the rotary latches.

Thanks,

Bondo

http://www.youtube.com/watch?v=Erv5in7dX1Q

[t vago]

Could you use some Lexan on the sides?

Awesome testing!

[ConnClark]

You might want to taper in the sides and the bottom to keep it from obscuring the view of the lights and license plate from an angle.

[bondo]

Originally Posted by t vago

Could you use some Lexan on the sides?

Awesome testing!

The trick is going to be how to fasten it to the truck. Would get rid of the low pressure area just inboard of the tail lights.

Bondo

[bondo]

Originally Posted by ConnClark

You might want to taper in the sides and the bottom to keep it from obscuring the view of the lights and license plate from an angle.

For view field of the tailights the sides should be angled in more. The problem is you would get less effective aero. The angle chosen was determined off a CFD simulation. Any more angle inboard would have rsulted in even less reattachment of air flow to the surface, which with the step inboard from the tail lights isn't much already.

I was tailed by an Arkansas State Policeman on the first leg of the run. He didn't pull me over so we passed the first test. You can see him at about 2:58time in the video parked to the far left in the opposite bound lanes.

The open tailgate defines the angle at the bottom so can't do much there.

Bondo

[kach22i]

Useful video, the commentary was good too.

[BamZipPow]

Since you have the tailgate down as the bottom layer of the tail cone...you can put in a rear window on the tail cone fer better rear vision!

Looks good. How do you store it?

I guess you could test some clear covers that extend from the tail lights to the end of the tail cone.

[COcyclist]

Nice work Bondo! Watching the tufts I really want to see it tested with rear wheel skirts on your rig. It looks to me like the tufts just behind the wheelwell are really disturbed. I wonder if the air would reattach to your extension if it were smooth before it left the taillights???

[bondo]

Originally Posted by BamZipPow

Since you have the tailgate down as the bottom layer of the tail cone...you can put in a rear window on the tail cone fer better rear vision!

Looks good. How do you store it?

I guess you could test some clear covers that extend from the tail lights to the end of the tail cone.

An Aerolid does need help on rearward visibility, that would be a great way to gain some.

The tailcone fits nicely inside the truck bed when not in use. basjoos had this idea figured out over two years ago. He has forgotten more than I will ever know about aerodynamics. His post is the fifth one at the link below.

While at this link, check out round.boaters up to date fuel log. He is getting much better than a 4% increase in fuel efficiency.

My new Aerolid!!!


Bondo

[bondo]

Originally Posted by COcyclist

Nice work Bondo! Watching the tufts I really want to see it tested with rear wheel skirts on your rig. It looks to me like the tufts just behind the wheelwell are really disturbed. I wonder if the air would reattach to your extension if it were smooth before it left the taillights???

You are right! That is the next step. The next flow visualization we do there will be wheel skirts over the rear wheel openings.



Thanks,

Bondo