Aled_g
|
| posted on 5/11/09 at 02:12 PM |
|
|
Height of Centre of gravity
Does anyone know what the centre of gravity height is for a Locost roughly? very technical i know!
|
|
|
|
|
alistairolsen
|
| posted on 5/11/09 at 02:18 PM |
|
|
different for every car, Id guess about 5-6 inches from the base of the lower chassis rails through the crank, box and diff.
Wheels and brakes are blow this, bodywork, top end of engine and more than half the chassis are above it.
My Build Thread
|
|
|
steve m
|
| posted on 5/11/09 at 02:27 PM |
|
|
I would of said marginly lower on my car 4-5 inches from the top of the bottom rail as with gearbox and diff diff on that mark, and 1/2 an engine
above,
with out the engine there isnt much weight above the lower rails anyway
It would be intresting to actually find out, but how ?
|
|
|
blakep82
|
| posted on 5/11/09 at 02:31 PM |
|
|
i would say (as a complete guess) almost somewhere around the line of the crank/gearbox/prop. perhaps slightly above
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
|
|
|
Breaker
|
| posted on 5/11/09 at 02:40 PM |
|
|
quote:
Originally posted by steve m
It would be intresting to actually find out, but how ?
You can define the COG yourself by hanging your car up at 1 point. Then you should draw a (virtual) line from your "hanging" point
vertically to the ground. This test should be repeated several times (f.e. hang your car by each wheel) and determine the virtual line. These lines
should all cross in 1 point and this will be the COG.
Please post some pictures after doing this test 
Apparently this is my 100th post !!! 
[Edited on 5/11/09 by Breaker]
|
|
|
dhutch
|
| posted on 5/11/09 at 03:28 PM |
|
|
100posts? Get back to work.....
But no, i two would imagine it to be about where most have stated.
- Another way to work it out crudely would be measure the mass and location of the center of mass all key items, Engine/Gearbox, Diff, Chassis, etc
and then calc.
- Although without a lot of work and attention to detial you could proberbly imagine simular to simular accruacy.
Another way to measure the hight of the CG if you have a set of scale (ideal four, that are fairly accurate) is to measure the corner weights of the
car, then to raise one side (or the front/rear) 2ft or simular (a known amount anyway) and remeasure the corner wieghts. Then calculate your heart
out.
Thats what they do at JCB for there diggers.
Daniel
|
|
|
Breaker
|
| posted on 5/11/09 at 03:34 PM |
|
|
quote:
Originally posted by dhutch
100posts? Get back to work.....
But no, i two would imagine it to be about where most have stated.
- Another way to work it out crudely would be measure the mass and location of the center of mass all key items, Engine/Gearbox, Diff, Chassis, etc
and then calc.
- Although without a lot of work and attention to detial you could proberbly imagine simular to simular accruacy.
Another way to measure the hight of the CG if you have a set of scale (ideal four, that are fairly accurate) is to measure the corner weights of the
car, then to raise one side (or the front/rear) 2ft or simular (a known amount anyway) and remeasure the corner wieghts. Then calculate your heart
out.
Thats what they do at JCB for there diggers.
Daniel
Pfff, my empirical test is more accurate... Of course, if someone wants to calculate it; you can find the formula's here:
Wikipedia linky
Enjoy !
[Edited on 5/11/09 by Breaker]
|
|
|
Peteff
|
| posted on 5/11/09 at 04:44 PM |
|
|
I don't know where it is, what baffles me is why anyone would want to know 
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
Macbeast
|
| posted on 5/11/09 at 05:11 PM |
|
|
To design suspension for minimum roll ?
I'm addicted to brake fluid, but I can stop anytime.
|
|
|
Richard Quinn
|
| posted on 5/11/09 at 05:39 PM |
|
|
I think mine's with all my 13mm sockets and 3mm allen keys somewhere in the garage. I'll find it one day!
|
|
|
Bob C
|
| posted on 5/11/09 at 05:55 PM |
|
|
balance the car on the 2 wheels of one side & take a photo from the front.
Do the same on the other side - take another photo.
Measure the angles with a protractor.
Seemples
Actually I've been meaning to do this with mine ever since I built it...... maybe one day ;^)
you need to know height of CG to work out your braking properly & if you want to calculate roll couples & stuff...
[Edited on 5/11/09 by Bob C]
|
|
|
Cousin Cleotis
|
| posted on 5/11/09 at 06:36 PM |
|
|
http://www.longacreracing.com/articles/art.asp?ARTID=22
Paul
|
|
|
Confused but excited.
|
| posted on 5/11/09 at 08:55 PM |
|
|
Pfff, my empirical test is more accurate... Of course, if someone wants to calculate it; you can find the formula's here:
Wikipedia linky
Enjoy !
[Edited on 5/11/09 by Breaker]
I think you will find that that only applies to two Locosts orbitting about a fixed point in space and gives the centre of mass, not the C of G of one
car.
Tell them about the bent treacle edges!
|
|
|
Steve Hignett
|
| posted on 5/11/09 at 11:06 PM |
|
|
quote:
Originally posted by Aled_g
Does anyone know what the centre of gravity height is for a Locost roughly? very technical i know!
Do you actually want to learn what everyones Locost CofG is, or would you rather learn where the Roll Centre of each axis is of certain Locost'
(type race cars for eg)?
[Edited on 5/11/09 by Steve Hignett]
|
|
|
v8kid
|
| posted on 6/11/09 at 02:42 AM |
|
|
300mm measured on my car using corner weight scales. I went to silly extremes to get it low so it might be a little higher on a
"standard" locost
|
|
|
procomp
|
| posted on 6/11/09 at 07:34 AM |
|
|
Hi
It is in general quite a bit higher than most are thinking it is. And remeber that you have to include the drivers weight unless building a remote
control version. And full roll cages espesialy the 45mm ones make a huge difference to the outcome.
Cheers Matt
|
|
|
skinned knuckles
|
| posted on 6/11/09 at 02:34 PM |
|
|
I'm with procomp on this one, cog is a hard one to call in a cr that weighs so little and the driver can make a massive difference.
are you looking at this from a racing point of view? what type of roll cage will you have? a full 4 leg cage will raise your GOG massively, a 2 leg
not so much but still significant, how much do you wiegh? what size fuel tank will you have and how low can you get away with mounting it?
really every home built car, cobbled together from different parts and assembled for different porposes will have significantly different COGs. how
long is a piece of string?
A man isn't complete until he's married, then he's finished
|
|
|
kb58
|
| posted on 6/11/09 at 09:16 PM |
|
|
Indeed. My tube frame, composite shell, mid-engine Mini was at 16" for CG.
One thing people need to keep in mind is that CG isn't about what stuff weighs, it's about where it's distributed. A plastic hollow
model shell of a car that weighs 1kg has the same CG as one made of lead.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
|
|
|
