Nissan takes a brave leap in Le Mans

[kach22i]

I just had to share this little find.

Random TRANSPORTATION pictures - Page 706 - Pelican Parts Technical BBS


No new ideas under the sun?

[Frank Lee]

Originally Posted by theycallmeebryan

I wouldn't drive that at high speeds.

It's backwards, in terms of aerodynamic efficiency and stability.

Welcome to the home of the VIGILLANTE

If trikes can kick handling arse, near trikes should be able to.

[Sven7]

I'll wager that if this batmobile is a success the racing bodies will ban it from competition, just like the fan car and rotary engine.

Originally Posted by kach22i

Is that the blue car which you post once in a while?

I cannot seem to find information on it.

Google search Panhard LM64. 64LM indeed does not find much!

[niky]

Originally Posted by kach22i

On a 911, braking torque cause by the front wheels shifts the center of inertia to a 50/50 weight balance during hard braking (entering a turn).

They also have the weight in the back for traction for powering out of a turn.

I'll post the simple diagram illustrating this, which I recall - once I find it.

Here is a thread on the topic:
Weight transfer vs brake bias - Page 2 - Pelican Parts Technical BBS

On the DeltaWing, the COG is so far back that even under braking, the rear tires do most of the work.

Apparently the long nose acts like a lever arm, with such a long arm pivoting around the rear tires, very little force needs to be applied to turn the front end. Similar to a 911 in steady-state cornering (that pendulum thing)... only even more extreme.

[kach22i]

Originally Posted by Frank Lee

Welcome to the home of the VIGILLANTE.

This one is new to me, thanks for posting it.

I'm a big fan of 3-wheelers.

Originally Posted by Sven7

Google search Panhard LM64. 64LM indeed does not find much!

Thanks, I thought it was that one.

Originally Posted by niky

On the DeltaWing, the COG is so far back that even under braking, the rear tires do most of the work.

You mean like this?
http://www.ivy50.com/story.aspx?sid=10/26/2006

If the Segway team was like a rowing team, then the coach was none other than Dean Kamen, the legendary inventor of the Segway who holds 440 patents and invented the first wearable medical infusion pump while still an undergraduate.

[NeilBlanchard]

The Cg on a trike projected as a 45 degree cone to the ground forms a circle, and that circle *must* be within the triangle formed by the tire contact patches. This DeltaWing is technically not a trike, but it might as well be. Under hard braking and hard cornering at the same time would really threaten the stability of this layout.

It is odd that *both* the stability and the aerodynamics would be better if the two (widely spaced) wheels were in the front. Then the wheelbase could be shorter because the weight shift under hard braking and hard cornering would move the Cg closer to the wide track wheels and this would be far more stable.

[kach22i]

Originally Posted by NeilBlanchard

The Cg on a trike projected as a 45 degree cone to the ground forms a circle, and that circle *must* be within the triangle formed by the tire contact patches.

I'm having a difficult time visualizing this, do you have a diagram?

I found some related information here:
http://www.deferredprocrastination.c...cle-stability/

[tortoise]

Originally Posted by kach22i

I would have assumed that a shorter, or more conventional wheelbase would be more stable, but still unstable.

As your plan view triangles show, the lengthened wheelbase puts more lateral distance between the center of gravity and the line between the two wheels on one side, thus giving the same benefit in reducing weight transfer to the outside wheels in cornering that you would get from a wider track.

I can't imagine why you would think a shorter wheelbase would be more stable. Dragsters and land speed record cars, which only want to go straight, run long wheelbases

The reason for a dragster's length is the torque and counter moment arm of the length to balance it, right?

The longer the ratio of wheelbase to CG height, the less weight transferred from the front to rear wheels at a given acceleration rate. Thus a longer wheelbased dragster can run a higher percentage of static weight on the rear wheels without wheelying.

[tortoise]

Originally Posted by NeilBlanchard

The Cg on a trike projected as a 45 degree cone to the ground forms a circle, and that circle *must* be within the triangle formed by the tire contact patches.

This assumes a 1 G maximum cornering speed, and neglects aero downforce. The principle is correct, though.

This DeltaWing is technically not a trike, but it might as well be. Under hard braking and hard cornering at the same time would really threaten the stability of this layout.

True, but you don't need to do that.

It is odd that *both* the stability and the aerodynamics would be better if the two (widely spaced) wheels were in the front. Then the wheelbase could be shorter because the weight shift under hard braking and hard cornering would move the Cg closer to the wide track wheels and this would be far more stable.

If the widely spaced wheels were at the front, and the CG were near the rear, your 45 degree cone would fall outside the triangle. If the CG were near the front, you'd need FWD or AWD for any sort of decent acceleration.

As to the aerodaynamics of widely spaced rear wheels, if you assume a single, eenveloping body, you're right. If you think of the main body and each rear wheel as separate teardrops, then the wide space rear wheel setup looks pretty good.

[tjts1]

Originally Posted by NeilBlanchard

It is odd that *both* the stability and the aerodynamics would be better if the two (widely spaced) wheels were in the front. Then the wheelbase could be shorter because the weight shift under hard braking and hard cornering would move the Cg closer to the wide track wheels and this would be far more stable.

This is incorrect.