A thought on retractable spoilers

[serialk11r]

Originally Posted by aerohead

Here is 'Kamm's' solution,bottom two images:

Yea that is obviously better, but it looks kind of ugly and I'd be concerned about damage from other people's poorly executed parking maneuvers since that would probably be implemented in cloth. If diffusers and spoilers had some seriously versatile hydraulic arms and could move all the way back you'd get a pretty good approximation with something that folds right into the body. Maybe it could be done with rear hatch/trunks that have multiple piece panels that fold outward as well, I imagine it's possible to make that look stylish.

[MetroMPG]

Originally Posted by wdb

1990's Lincoln Mark VIII had air suspension, and lowered itself at speed to improve aerodynamics.

...As does the current Dodge RAM pickup and Tesla sedan, among others I'm sure.

I think I've also seen photos of one of the Ford Probe concepts that had a dynamic air dam and "variable body rake" for best high-speed efficiency.

[botsapper]

Active-BODY aerodynamics, an oldie but goodie.

http://www.youtube.com/watch?v=EdwCap54UNk

[some_other_dave]

Originally Posted by botsapper

Active spoilers. Still like Aeromotions computer-programmed active-assistance split rear wing.

In the 60s, Porsche used a similar system on a couple of their race cars. In particular, the early 917 and one of the iterations of the 908. They had a split wing that had linkages to the rear suspension. When the suspension was unloaded and went into droop, the corresponding half of the wing tilted up into the air to push that side of the car back down. Under braking, the tail of the car tends to pitch upward, and both flaps went up, which produced more drag.

It was good for several seconds per (very long) lap at Le Mans, I believe.

"Active aerodynamics" was banned after some earlier wrecks, and Porsche agreed to fix the wings in place on the 908 but was able to get a one-year exemption for the 917.

This is a long way of saying: You don't have to control it with a computer, and it's already been done.

-soD

[botsapper]

Originally Posted by some_other_dave

In the 60s, Porsche used a similar system on a couple of their race cars. In particular, the early 917 and one of the iterations of the 908. They had a split wing that had linkages to the rear suspension. When the suspension was unloaded and went into droop, the corresponding half of the wing tilted up into the air to push that side of the car back down. Under braking, the tail of the car tends to pitch upward, and both flaps went up, which produced more drag.

It was good for several seconds per (very long) lap at Le Mans, I believe.

"Active aerodynamics" was banned after some earlier wrecks, and Porsche agreed to fix the wings in place on the 908 but was able to get a one-year exemption for the 917.

This is a long way of saying: You don't have to control it with a computer, and it's already been done.

-soD

The first active aerodynamics use was the 1955 Mercedes 300 SLR, who was concerned about Jaguar's effective disc brakes so Mercedes added a huge air brake to assist slowing down their SLRs.

http://www.youtube.com/watch?v=x83rE8jE2MA

The first active split wing was Nissan's R381, winner of 1968 Japanese Grand Prix.

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

Jim Hall and the Chapparals had moveable rear wings that feather out when going on straights for top speed - as well as shutting off the front nose ducts! OnInnovation: Cars as Wings with Jim Hall

Porsche 917 had moveable winglets controlled strictly by the suspension. Uneven road suspension loading and high speed transitions into turns made it unstable and after John Wolfe's fatal crash caused Porsche to remove the flaps and resorted back to fixed wings.

[aerohead]

Originally Posted by serialk11r

Yea that is obviously better, but it looks kind of ugly and I'd be concerned about damage from other people's poorly executed parking maneuvers since that would probably be implemented in cloth. If diffusers and spoilers had some seriously versatile hydraulic arms and could move all the way back you'd get a pretty good approximation with something that folds right into the body. Maybe it could be done with rear hatch/trunks that have multiple piece panels that fold outward as well, I imagine it's possible to make that look stylish.

It doesn't matter how the elongation and taper is executed,but the trailing edge must to be continuous and airtight,wrapping all the way around as Kamm has done,or as with a sealed box-cavity.Any 'hole',anywhere, will allow lower pressure are to bleed into the space and adulterate the pressure increase you're trying for,netting low to zero gain.It's not negotiable.

[serialk11r]

Originally Posted by aerohead

It doesn't matter how the elongation and taper is executed,but the trailing edge must to be continuous and airtight,wrapping all the way around as Kamm has done,or as with a sealed box-cavity.Any 'hole',anywhere, will allow lower pressure are to bleed into the space and adulterate the pressure increase you're trying for,netting low to zero gain.It's not negotiable.

Oh right, this thing again (I remember you saying this about spoilers too). Well, I'm sure the wing in question can be designed to sit flush with the bodywork to form a box-cavity maybe with the help of some deployable flaps on the bumper.

[freebeard]

It doesn't matter how the elongation and taper is executed,but the trailing edge must to be continuous and airtight,wrapping all the way around as Kamm has done,or as with a sealed box-cavity.Any 'hole',anywhere, will allow lower pressure are to bleed into the space and adulterate the pressure increase you're trying for,netting low to zero gain.It's not negotiable.

I'm not sure what you're saying here. Holes to the upstream exterior, or to the interior?

Open box-cavities OK?

[some_other_dave]

I didn't know about the air-brakes on the Benzes, nor the Nissan split-wing--thanks!

Originally Posted by botsapper

Porsche 917 had moveable winglets controlled strictly by the suspension. Uneven road suspension loading and high speed transitions into turns made it unstable and after John Wolfe's fatal crash caused Porsche to remove the flaps and resorted back to fixed wings.

Interesting--Ludvigsen's "Excellence Was Expected" cites rules as the reason for the winglets' removal. But the car was marginally undriveable with or without the winglets until the redesign for the 1970 season.

-soD

[aerohead]

Originally Posted by serialk11r

Oh right, this thing again (I remember you saying this about spoilers too). Well, I'm sure the wing in question can be designed to sit flush with the bodywork to form a box-cavity maybe with the help of some deployable flaps on the bumper.

Yes,if the flaps sealed between spoiler and diffuser you'd be golden.