Soul Help (Spoiler/Kammback)

[Soulster]

Way to windy to test this yet, but does anyone think removing this spoiler will help anything?







And yes, it was a PITA to get off! For some reason Kia bolted and glued it on!

Then with that removed...







Is this the right angle?

[Weather Spotter]

When I made it that was the angle the cardboard wanted to hold, I think it is a bit steep off the top, ideas?

I need help with the sides too. I do not want to mess up the visibility of the lights so I put the Kammback in from the sides. Will this help or hurt?

I know I need to round the sides, but that is tricky in cardboard w/out a frame to support it.

For attaching the Kammback I was going to make a fame bolting to the 4 holes the OEM spoiler used. Run that along the front and sides to about where the glass bottom is. I was going to have it just rest on the hatch with some rubber. I would also make a second support ridge on the back edge, starting from the same lower spot. I would attach this to the first one via a front to back brace. Will this keep it held onto the car?

If you have not figured it out yet Soulster and I are brothers. He made lots of negative comments about my car (like "I will never do that to mine") but the 4+ MPG gain got him thinking

[Soulster]

yah about that bro! Your car looked FUGLY!!! until you finished the mods... and now it just looks sorta ok. My car is sweet to start with and should look funky modern with the mods...

[skyl4rk]

I would say flatter and longer. Try to start at the point where the flat roof meets the radius headed downward.

[Weather Spotter]

Originally Posted by skyl4rk

I would say flatter and longer. Try to start at the point where the flat roof meets the radius headed downward.

How long would you go?

I went with this length as that was the size cardboard I had.

[cfg83]

Weather Spotter -

Originally Posted by Weather Spotter

When I made it that was the angle the cardboard wanted to hold, I think it is a bit steep off the top, ideas?

I need help with the sides too. I do not want to mess up the visibility of the lights so I put the Kammback in from the sides. Will this help or hurt?

I know I need to round the sides, but that is tricky in cardboard w/out a frame to support it.

For attaching the Kammback I was going to make a fame bolting to the 4 holes the OEM spoiler used. Run that along the front and sides to about where the glass bottom is. I was going to have it just rest on the hatch with some rubber. I would also make a second support ridge on the back edge, starting from the same lower spot. I would attach this to the first one via a front to back brace. Will this keep it held onto the car?

If you have not figured it out yet Soulster and I are brothers. He made lots of negative comments about my car (like "I will never do that to mine") but the 4+ MPG gain got him thinking

Yeah, because the roof is so flat, I think the angle becomes pretty shallow. I am guessing about 7 degrees :



At first I thought the sides should also taper in. But now I am thinking that if the mount point is the same as the cardboard example, the air will flow off the side of the car and "connect" with the side of the Kamm/spoiler. In that case I am guessing that the goal would also be 7 degrees.

CarloSW2

[Weather Spotter]

So, if I did my trig right, for a 24" Kammback a 7 degree angle produces a 2.9" drop front to back.

Should the sides come in that far too? if so where to measure off of, car edge or start of Kammback (inner side of lights)?

[cfg83]

Weather Spotter -

Originally Posted by Weather Spotter

So, if I did my trig right, for a 24" Kammback a 7 degree angle produces a 2.9" drop front to back.

Should the sides come in that far too? if so where to measure off of, car edge or start of Kammback (inner side of lights)?

I think the idea is attached flow, so it would be from the side of the car. However, there are practical considerations for the Soul. Soulster needs to maintain visibility of his high-up rear lights, and it's easier to "frame" the hatch in a Kamm-spoiler than to have it extend out (right?!?!?!). That's why I think the air would be ok with this compromise :



For your Matrix, you already have a roof that is sloping downwards. That allows you to push your center of max roof camber forward, so you can have a steeper slope :



But I guess that 8 degrees isn't much different than the Soul. Since the Matrix isn't tapering to the back like a tadpole, it would be 7 or 8 degrees on the side.

But as I've said before, wait for other aero-smarties to chime in. I am just stating what I *think* I have learned from them.

CarloSW2

[Weather Spotter]

Originally Posted by cfg83

Weather Spotter -



I think the idea is attached flow, so it would be from the side of the car. However, there are practical considerations for the Soul. Soulster needs to maintain visibility of his high-up rear lights, and it's easier to "frame" the hatch in a Kamm-spoiler than to have it extend out (right?!?!?!). That's why I think the air would be ok with this compromise :



CarloSW2

The issue is the lights, I think that if I can keep it in the hatch area (or just out to the inside side of the lights) I can make it work.

Nice diagram!

I think that the side gaps (by the lights) will have detached air flow, but it should rejoin in time to come off the back at the right angel. Will this help much or would it be better to remove the sides altogether and just have the top piece?

I *might* be able to make a cover over the lights that is clear (Plexiglas) but I will have to see how badly it distorts or refracts the light. It would also add to the complexity of the build (two materials, joints, not being able to hide the supports as well, etc). But it would allow us to go out to the edge of the car.

[skyl4rk]

Originally Posted by Weather Spotter

How long would you go?

As long as you can without blocking views. Try starting at 3 feet and adjusting until you can see and the lights can be seen.