Do the Rocker Panels help with Top Speed in a SC?

[911pcars]

I totally agree. If your ride has a similar looking body as shown in the above posts - with an engine capable of pushing the metal mass close to upper limits, then by all means address the shape of those rocker panels. Wool tufts attached to the lower rocker and a camera car recording at speed should show the air flow pattern in that region.

I recall one of Jack Olsen's threads from way back delved into that practice. Who knows, maybe Jack also conducted extensive air flow tests of that nether region. Wind tunnels are also available (at a cost) for more accurate and repeatable aero testing.

Here's a bunch:
https://www.youtube.com/results?search_query=aero+test+with+wool+tufts

Sherwood

[Bill Verburg]

[911pcars]

Bill, can you describe what the tuft angles at the rockers indicate in that photo?

[flat6pilot]

Originally Posted by VFR750

Are the Rocker panel extensions (and required rubber strip to hide the fasteners) on a G-series a good thing for Aero?

Is there any data that suggests the Rocker Panels added to the lower edge of the body help reduce drag, and hence increase the top speed of the impact bumper body?

Was there a lift reduction as well?

Mike- If they do, it's probably negligible on a street car.

I went from a narrow body to a significant widebody and my top speed was noticeably slower.





I went from ~132mph top speed at the end of the straight at my local track to about ~124mph.

This comes from wider panels, a bigger wing and wider tires that cost me (only) about 8 mph.

I would imagine the lower valance whether it was on or off wouldn't equate to much of a top speed difference, but I could be wrong.

However, I solved my problem by turning the boost up a little to compensate and I'm back to around 130mph again!

[flat6pilot]

Originally Posted by 911pcars

Bill, can you describe what the tuft angles at the rockers indicate in that photo?

The picture that shows the 'drawing' of the blue and red airflow shows there is very little turbulence going over the rockers which equates to less drag. Which means it's flowing over and under the valance smoothly.

What they're looking for is little movement of the tufts of string. If they're bouncing all over, it's indicating turbulence which could indicate increased drag.

[Bill Verburg]

Here are the drag and lift curves for a '76 Carrera 3.0, you SC will be similar





I wouldn't worry about the sides until you have addressed the front and rear

in front deeper(closer to the ground is better, extended is better

in back a wing is better than a duck which s better than nothing

best would be a bi-plane like 3.8RS used unless you want to get into the raised wings used on later cars

The difference between a 993RS wing and a 993 RS/CS(aka RSR) wing is night and day.
RS


RS/CS

[shawn908]

I'm leaving them off my car for two reasons.
One, slows down the car - its already too fast.
Two, saves weight (12lbs). Just weighed mine for this post.

[Coastr]

Originally Posted by 911pcars

Bill, can you describe what the tuft angles at the rockers indicate in that photo?

Not bill, but they show downward flowing air. Drag is caused by non laminar flow aka turbulence, as shown in the diagram.

The 993 isn’t much of a reference compared to a g-body, except in the rake of the windscreen. You can see the 993 skirts shape outwards, probably to maintain laminar flow over the rocker. The SC rockers curve inward. As such I would say they provide more turbulence than the 993 skirts or the other racing skirts of the 934/5 etc.

I doubt the SC rockers make much difference and were probably put on for appearance rather than performance. The array of tails available for SC cars was definitely motivated by what was available and sold rather than what performed the best.