Get Rid Of The Kammback.

[Autoxdriver]

I have to admit I don't understand the aerodynamics of the Kammback. Everything I have ever seen from airplanes to boat-tailed rifle bullets says the the rear should be tapered. Just look at any typical subsonic airplane fuselage, like a jet airliner for example.

Maybe it has to do with the proximity to the ground?

 

[goofyone]

I have to admit I don't understand the aerodynamics of the Kammback. Everything I have ever seen from airplanes to boat-tailed rifle bullets says the the rear should be tapered. Just look at any typical subsonic airplane fuselage, like a jet airliner for example.

Maybe it has to do with the proximity to the ground?

It's called the Kamm effect and it is a way to get most of the effect of a full taper without spending money on building the entire shape.

"While the realities of fluid dynamics dictate that a teardrop shape is the ideal aerodynamic form, Kamm found that by cutting off / flattening the streamlined end of the tear at an intermediate point, and bringing that edge down towards the ground, he could gain most of the benefit of the teardrop shape without incurring such a large material, structural, and size problem. The airflow, once given the suggestion of the beginning of a turbulence-eliminating streamlined teardrop tail, tended to flow in an approximation of that manner regardless of the fact that the entire tail was not there."

 

[Autoxdriver]

It's called the Kamm effect and it is a way to get most of the effect of a full taper without spending money on building the entire shape.

"While the realities of fluid dynamics dictate that a teardrop shape is the ideal aerodynamic form, Kamm found that by cutting off / flattening the streamlined end of the tear at an intermediate point, and bringing that edge down towards the ground, he could gain most of the benefit of the teardrop shape without incurring such a large material, structural, and size problem. The airflow, once given the suggestion of the beginning of a turbulence-eliminating streamlined teardrop tail, tended to flow in an approximation of that manner regardless of the fact that the entire tail was not there."

And now I know! Thank you.

 

[jrm_cr_fl]

Just back from Daytona and seeing the P4. I was told that the rear passenger area is now actually smaller than on the P3, which conflicts with my previous statement, but they are still tweaking the design. I was told they are going to move the windshield 2" forward and raise the roof line (again), which will then give more room to the rear passenger. So I guess P4 is not the final production model I heard it was. I also was told that it currently is about $280 over budget for target price, but they are still working on bringing that back into budget. Those Elio guys at Bikefest were a wealth on info. Just ask them. I did.

 

[zelio]

It's called the Kamm effect and it is a way to get most of the effect of a full taper without spending money on building the entire shape.

"While the realities of fluid dynamics dictate that a teardrop shape is the ideal aerodynamic form, Kamm found that by cutting off / flattening the streamlined end of the tear at an intermediate point, and bringing that edge down towards the ground, he could gain most of the benefit of the teardrop shape without incurring such a large material, structural, and size problem. The airflow, once given the suggestion of the beginning of a turbulence-eliminating streamlined teardrop tail, tended to flow in an approximation of that manner regardless of the fact that the entire tail was not there."

That does make sense. Now that I think about it I can't imagine the airflow suddenly dropping "over the cliff" like water does over a dam simply because part of the tail is missing. Thank you for sharing that knowledge. I am going to know more about my Elio than I have any other car I have ever owned. That makes the wait worth it because knowledge is power. Z

 

[Craig]

In the video the pink represents the part of the car (point of the tear drop) that is cut off. Now look at the blue green passing over the top, notice that it dose not pour over the end of the car. That is what you want. If the blue green air passing over the top of the car spills down over the end it will causes a turbulence in the pink area that has a tendency to suck the car backwards. The pink area represents the Kamm effect.
　
http://www.youtube.com/watch?v=6b36ZP3PGis

 

[Brian1362]

Pick up trucks are designed to be driven with their tailgate up or off, not down. I saw one in a wind tunnel that showed why. Similar concept with the kammback.