Awesome! Thanks for sharing Michael!

470mm = 18 3/8" or lower than the bottom of a Chevy Tahoe or about where the driver's waistline is.

886mm = 34 5/8" or about where the driver's *ss is located!

If you wondered why it feels like the Elise rotates around you while driving, this explains it... it is!

Cheers,
Kiyoshi

 

LOL- Sounds like the car is truly centered around the driver... talk about drivng by one's seat of the pants.

 

Very cool. For those of us metrically challenged, my handy-dandy NASA derived unit converter spit out these:

886 mm = 34.882 in
470 mm = 18.504 in
18 mm = 0.709 in
75 mm = 2.953 in

 

Ok, a related question... I hope it's not too far off topic.

If the center of gravity line is across the drivers seat, does the weight of the driver change the weight distribution (front/rear) of the car?

 

Nick Adam's info said "...C of G for the Elise which is 886mm behind the front axle centre line ...."


This is impossible. The wheelbase is around 90". If cg is at this location, it means the vehicle has a front heavy bias.

Maybe he meant 889mm "ahead" of the rear axle centre line.

Joe

 

Someone asked where the center of gravity and the roll centers were for the Elise.

I asked about the CG. That was over a year ago, though, so I'm not sure if this is the thread you were thinking of:

http://www.elisetalk.com/forums/showthread.php?t=8683

Thanks in any case. I still wanted to know! :clap:

 

Nick Adam's info said "...C of G for the Elise which is 886mm behind the front axle centre line ...."


This is impossible. The wheelbase is around 90". If cg is at this location, it means the vehicle has a front heavy bias.

Maybe he meant 889mm "ahead" of the rear axle centre line.

Joe

You might be right, from the Lotus Service Notes technical data section:

DIMENSIONS
Overall length
- Elise 3785 mm
Overall width
- exc. mirrors - Elise 1719 mm
- inc. mirrors 1850 mm (approx.)
Overall height (at kerb weight)
- Elise 1117 mm
Wheelbase 2300 mm
Track
- front 1457 mm
- rear 1507 mm
Ground clearance (mid-laden)
- std. USA 135 mm
Front overhang - Elise 783 mm
Rear overhang - Elise 702 mm

- USA Elise (heaviest)
- total 912 kg )
- front 344 kg ) inc. full fuel tank
- rear 568 kg )

- 111R (lightest)
- total 860 kg >
- front 327 kg > inc. full fuel tank
- rear 533 kg >

- Exige
- total 875 kg >
- front 328 kg > inc. full fuel tank
- rear 547 kg >

By those numbers the CG should be 867.56 from the rear in the US Elise
37.72 % front 867.56 from rear axel
62.28 % rear 1432.44 from front axel

In the 111R:
38.02 % front 874.46 from rear axel
61.98 % rear 1425.54 from front axel

In the Exige (2005) toyota lump:
37.49 % front 862.27 from rear axel
62.51 % rear 1437.73 from front axel

Of course by those number you can't derive the height. So it's pretty cool information

 

For a quick check of the fore/aft CG, look under the car. The blue stickered jacking points in front of the rear wheel is pretty much the balance point...

 

Did I do this right?

Could one of the FEE graduates please tell me if I did this right.

I tried to figure out the new Cg height if I removed 10 lbs from the roof.

I assumed the 10lbs was directly over the current Cg
I assumed the current Cg was at 18.5 inches
I assumed the exige wieghed 2015lbs at Cg
I assumed Cg of roof was 41 inches above ground

My equation using RAFA from ground lvl at a point directly under the Cg.

2015(18.5)-10(41)=2005 X

X= 18.388 where X is new Cg

thus removing 10lbs from roof results in lowering Cg .112 inches or 2.84mm.

Did I do that right? Seems right. Not since college have i used RAFA.

Thanks

:shift:

 

Very cool. For those of us metrically challenged, my handy-dandy NASA derived unit converter spit out these:

886 mm = 34.882 in
470 mm = 18.504 in
18 mm = 0.709 in
75 mm = 2.953 in

Is this the same NASA that lost a space probe due to using the wrong units in the control software?

http://www.jamesoberg.com/mars/loss.html

ed

 

Is this the same NASA that lost a space probe due to using the wrong units in the control software?

It happens to the best of them. Ever hear of the Gimli Glider? http://www.elchineroconcepts.com/Technology%20Folder/gimli_glider.htm

It's a good read, and even has significance with cars and autocrossing...

 

It happens to the best of them. Ever hear of the Gimli Glider? http://www.elchineroconcepts.com/Technology%20Folder/gimli_glider.htm

It's a good read, and even has significance with cars and autocrossing...

Very good read, I've never heard that story before!
Thanks for the link!

 

I don't have time right now to do some calculation, but regarding the center of gravity, the lifting point on the car is around the center of gravity without anybody in the car.

Of course, with somebody into the car, the center of gravity is moving forward, and since the car is mid weight (light weight is lower than an Elise for me), the driver and passenger weight have an important effect.

I did some measurement on my Europa, when I am into the car, the weight distribution is around 45/55. And when the car is empty, I can lift the front of the car by myself (without a jack).

By the way, the center of gravity is not indicating inertia of the car. If you take a big BMW, the center mass is around 50/50, but the engine weight is important, and the transmission is located at the rear. Typically, this kind of configuration is giving a good weight distribution, but in other hand, the dynamic inertia around the center of gravity is higher.

On the elise, the engine is a transaxe, and the weight is mainly at the back of the car. The front end have a lot of stuff, impact zone (not heavy, but at the end), big brake, direction... The center of the car is empty, and the frame should weight like nothing overthere, but you have the driver weight. That's main that the car have probably a medium inertia, not high of course, but not low also.

The Europa, and mine per example, equipped with a heavy roll cage, with the total weight of the car of 1450 pounds, the mass is more at the center of the car, and the inertia is probably better than the Elise. And in fact, with a Renault engine of 150 hp, it eat the Elise on the track. But, and to honest, many modification on my Europa...

The Elise is a great car, I like it, and the car have probably a big potential.

Another small point, when a companie is supplying the power/weight ratio, it never take the driver weight in the calculation, marketing... and for a light car or worst, a motorbike, the driver weight should be into the calculation. Imagine a bike, 375 pounds, 155 hp at wheel, good ratio, and take a driver of 200 pounds, oups... the ratio is slightly change.

 

For a quick check of the fore/aft CG, look under the car. The blue stickered jacking points in front of the rear wheel is pretty much the balance point...

As long as you don't remove the front wheels on a lift. =)

rotfl

 

As long as you don't remove the front wheels on a lift. =)

rotfl

Hey, I typed that long before Qball's adventure...