Question about kamm extensions.

[MetroMPG]

Originally Posted by Christ

You wouldn't have a visual of the rear view anywhere stashed away, would you? Would you liken it to looking through a rear window that had louvers on it?

I believe Phil had just the one "step" in his bed cover for rear vision (plus one at the top for the center mounted brake light).

You can sort of see it here:



From: http://ecomodder.com/forum/showthrea...ding-1280.html

So you can't see through plexi when it's at the right angle for a Kamm... same with lexan.

I'm fairly sure I asked basjoos about the rear visibility through his boat tail, and he said it was OK.

[aerohead]

Originally Posted by MetroMPG

I believe Phil had just the one "step" in his bed cover for rear vision (plus one at the top for the center mounted brake light).

You can sort of see it here:



From: http://ecomodder.com/forum/showthrea...ding-1280.html

I'm fairly sure I asked basjoos about the rear visibility through his boat tail, and he said it was OK.

I'm having to cut these into "poco-loco," the boat hull on the T-100.The blind spots are wicked and the new trailer is completely invisible from the cab so I'm adding a small dorsal fin to it with red light so I will know it's back their and hasn't headed for Kansas.I'll do the cut for the 3rd brake light also.Motorists act spooky enough,I need all the safety edge I can get.

[Christ]

I was actually referring to a shape more like stairs, but keeping the upper edges of the 90* "steps" on the same 10-13* slope

So it would have several 2" "clear steps" that are vertical and appreciate in distance from the rear window, and have horizontal "slats" connecting them, which also appreciate in distance from the rear window, starting from top to bottom.

If I have to find a pic, I will.

[cfg83]

Christ -

Originally Posted by Christ

I was actually referring to a shape more like stairs, but keeping the upper edges of the 90* "steps" on the same 10-13* slope

So it would have several 2" "clear steps" that are vertical and appreciate in distance from the rear window, and have horizontal "slats" connecting them, which also appreciate in distance from the rear window, starting from top to bottom.

If I have to find a pic, I will.

You mean like this? :



CarloSW2

[Christ]

Precisely. Obviously, there would be mini-swirlies in each step, but you'd still be able to see... but then again, maybe there isn't really a visibility issue with Kamm extensions?

[orange4boy]

Polarized glasses to the rescue.

During the day you could wear polarized sunglasses to eliminate most of the reflections on an angled plexi kamm. At night these reflections are reduced but you can get non tinted polarized glasses as well. I wear polarized sunglasses to reduce the reflections of my dash on my windshield. Works fantastically well. Don't know how I would live without them now.

[aerohead]

Originally Posted by cfg83

Christ -



You mean like this? :



CarloSW2

I wish I could slam image stuff like that out on the net.It's exactly what Christ is talking about,and anyone looking,will come immediately up to speed on the discussion.------------- Each of those steps will have a locked-vortex over which the surrounding air will flow.You will lose some energy due to the circulation,however there should be a net drag reduction.---------Continuum Dynamics did this sort of thing with an 18-wheeler,and with single panels.The more panels,the smaller the steps.At an infinite number of panels you have the smooth curve.------ This step thing will be heavier but will be very simple to construct.Thanks much for the image!

[cfg83]

aerohead -

Originally Posted by aerohead

I wish I could slam image stuff like that out on the net.It's exactly what Christ is talking about,and anyone looking,will come immediately up to speed on the discussion.------------- Each of those steps will have a locked-vortex over which the surrounding air will flow.You will lose some energy due to the circulation,however there should be a net drag reduction.---------Continuum Dynamics did this sort of thing with an 18-wheeler,and with single panels.The more panels,the smaller the steps.At an infinite number of panels you have the smooth curve.------ This step thing will be heavier but will be very simple to construct.Thanks much for the image!

I just did these here :

http://www.youtube.com/watch?v=aElwpzC4QUY

http://www.youtube.com/watch?v=8PJOI9TNsVs

This was the original "staircase" I did, but the steps were too small to see any vortex action :

http://www.youtube.com/watch?v=-MobBDsznZE

Here are the inputs I used for each run :

Re =2,500,000
dt =0.01
movie length, sec = 40
width = 256
height= 128
visual cutoff level = 40

CarloSW2

[Christ]

It seems like the larger steps made the oscillation of the wake slow down to a lower frequency... I didn't count frames to find out, but it looks that way at a glance... anyone verify this?

[FastPlastic]

What about strait out the back like the lamborghini has? It would be a little like looking through a venetian blind.