CG height
Khaled Mostafa
K
Leon van Dommelen
>does anyone know the cg height of a '90 mazda miata?
Maybe Mazda does, for a *specific* loading, options, spring
heights, fuel, passengers, ... Since I am guessing you mean the
cg of *your* Mazda Miata, this may not suffice.
Fortunately, there are a number of simple ways to determine *your*
Miata cg height. Do remove the fluids from your car before trying
any of the below suggestions.
1) Assume cg is at 52% of the distance from front to rear wheels.
Balance Miata on nose. Determine vertical line and intersect with
52% line normal to car.
2) Same, but balance Miata on either side.
4) Same, but balance Miata on tail pipe.
4) Do not balance Miata but simply put vertical on nose.
Determine time until Miata comes crashing down. Compare with
computed values of crashing time versus cg position using
an assumed radius of gyration of Miata.
5) Put Miata on left-right divided scales, raising one side compared
to the other by letting out the air from the tires at one side,
and blowing them up to 100 psi at the other side. The change in
left and right weights due to the tire air change will indicate the
height of cg. Do not forget to correct for the change in tire buoyancy
when doing the computation.
6) Using a torque wrench on the crankshaft pulley bolt or similar,
determine the ratio of torque to angular deflection of your Miata.
On skid pad, drive circles at the limit of friction and determine
angular deflection. Compute height of center of gravity assuming
0.8 to 1 g traction depending on tires mounted. Make sure you
only exert a torque on the torque wrench, of course; don't force
it.
7) Similar, but use your big mother in law on the hood to
estimate torque versus angular deflection around the door-to-door
axis. Brake hard while using a G-tech to determine braking g. (Many
who used this method with a bubble level to determine car deflection
reported inconsistent but satisfactory results.)
8) Take Miata to moon. Center of gravity will be the same as on earth,
but lack of buoyancy simplifies computations.
9) Take Miata to tiny black hole. Center of gravity will be at the point
closest to black hole.
10) Weld tiny black hole to bottom of car and return to earth. Both
center of gravity and center of mass will be at bottom of car. As will
be much else.
I worked hard on this, but still, do feel free to ask for more help if
these suggestions are not enough for you.
Leon
--
Leon van Dommelen :) Bozo, the White 96 Sebring Miata .)
REMOVE THE "z"s -> domm...@zmiata.net www.dommelen.net
EXIT THE INTERSTATES (Jamie Jensen)
Matthew Russotto
Leon van Dommelen <domm...@zmiata.net> wrote:
>"Khaled Mostafa" <khal...@hotmail.com> wrote:
>
>>does anyone know the cg height of a '90 mazda miata?
>
>Maybe Mazda does, for a *specific* loading, options, spring
>heights, fuel, passengers, ... Since I am guessing you mean the
>cg of *your* Mazda Miata, this may not suffice.
>
>Fortunately, there are a number of simple ways to determine *your*
>Miata cg height. Do remove the fluids from your car before trying
>any of the below suggestions.
Leon, I tried the black hole trick, but the black hole evaporated before
I got it attached. However, I have found a more practical way
11) Attach a cable to the power plant frame and lift Miata (upside down)
by it. Slide cable along frame until wheels are at the same
height. This determines the front-back location of the COG. Secure
cable, swing Miata and measure period of rotation. The pendulum
equation now gives you the height of the COG. (be sure to correct
for weight of cable)
--
Matthew T. Russotto mrus...@speakeasy.net
=====
Every time you buy a CD, a programmer is kicked in the teeth.
Every time you buy or rent a DVD, a programmer is kicked where it counts.
Every time they kick a programmer, 1000 users are kicked too, and harder.
A proposed US law called the CBDTPA would ban the PC as we know it.
This is not a joke, not an exaggeration. This is real.
http://www.cryptome.org/broadbandits.htm
Dave
Dave 2000 SE II
Vasko David
full tank of fuel at 23.8 " using the method of weighing it twice, once
level and one raised. I would be curious to see what other people have
measured.
Dave
"Khaled Mostafa" <khal...@hotmail.com> wrote in message
news:a7qj27$hm5$1...@nsnmpen2-gest.nuria.telefonica-data.net...
Lanny Chambers
domm...@zmiata.net (Leon van Dommelen) wrote:
> 10) Weld tiny black hole to bottom of car and return to earth. Both
> center of gravity and center of mass will be at bottom of car. As will
> be much else.
I was doing OK, really, until I reached this part. Then the coffee came
out of my nose...
Leon, does the university know that the class clown in your classes is
the professor?
--
Lanny Chambers, St. Louis, USA
'94C
the alignment page:
http://www.hummingbirds.net/alignment.html
Leon van Dommelen
>In article <e4b2auol7la6rd0to...@4ax.com>,
>Leon van Dommelen <domm...@zmiata.net> wrote:
>>"Khaled Mostafa" <khal...@hotmail.com> wrote:
>>
>>>does anyone know the cg height of a '90 mazda miata?
>>
>>Maybe Mazda does, for a *specific* loading, options, spring
>>heights, fuel, passengers, ... Since I am guessing you mean the
>>cg of *your* Mazda Miata, this may not suffice.
>>
>>Fortunately, there are a number of simple ways to determine *your*
>>Miata cg height. Do remove the fluids from your car before trying
>>any of the below suggestions.
>
>Leon, I tried the black hole trick, but the black hole evaporated before
>I got it attached. However, I have found a more practical way
>
>11) Attach a cable to the power plant frame and lift Miata (upside down)
> by it. Slide cable along frame until wheels are at the same
> height. This determines the front-back location of the COG. Secure
> cable, swing Miata and measure period of rotation. The pendulum
> equation now gives you the height of the COG. (be sure to correct
> for weight of cable)
That is good and simple. I like it.
McMahon
"Lanny Chambers" <la...@hummingbirds.net> wrote in message
news:lanny-E6C1DF....@newssvr11-ext.news.prodigy.com...
> In article <e4b2auol7la6rd0to...@4ax.com>,
> domm...@zmiata.net (Leon van Dommelen) wrote:
>
> > 10) Weld tiny black hole to bottom of car and return to earth. Both
> > center of gravity and center of mass will be at bottom of car. As will
> > be much else.
>
Did that Big Bertha Thing pin-wheel Cosmic Ray Series Possible Real World
System Constructs guy get back in here? Seems like he's been gone for a
while. Is that what this is?
He's scary.
SM
Lanny Chambers
"McMahon" <baad...@amcom.net> wrote:
> > > 10) Weld tiny black hole to bottom of car and return to earth. Both
> > > center of gravity and center of mass will be at bottom of car. As will
> > > be much else.
> >
>
> Did that Big Bertha Thing pin-wheel Cosmic Ray Series Possible Real World
> System Constructs guy get back in here? Seems like he's been gone for a
> while. Is that what this is?
> He's scary.
Nah, that's just good ol' Leon, our resident rocket scientist and token
Dutchman. He doesn't look scary at all on his web page. Just a bit
pedantic.
tooloud10
news:avf3aukq2cuu0kt5b...@4ax.com...
<snip>
> >11) Attach a cable to the power plant frame and lift Miata (upside down)
> > by it. Slide cable along frame until wheels are at the same
> > height. This determines the front-back location of the COG. Secure
> > cable, swing Miata and measure period of rotation. The pendulum
> > equation now gives you the height of the COG. (be sure to correct
> > for weight of cable)
>
> That is good and simple. I like it.
Interesting approaches...
Hey, by the way, I had never read your "Expert Opinions" page on your site
until tonight--I liked your comments regarding Automobile Magazine's 1997
All-Star award. ;)
> Leon
>
> --
> Leon van Dommelen :) Bozo, the White 96 Sebring Miata .)
> REMOVE THE "z"s -> domm...@zmiata.net www.dommelen.net
>
> EXIT THE INTERSTATES (Jamie Jensen)
--
tooloud10
Remove nothing to reply...
Leon van Dommelen
>In article <ua3tthq...@corp.supernews.com>,
> "McMahon" <baad...@amcom.net> wrote:
>
>> > > 10) Weld tiny black hole to bottom of car and return to earth. Both
>> > > center of gravity and center of mass will be at bottom of car. As will
>> > > be much else.
>> >
>>
>> Did that Big Bertha Thing pin-wheel Cosmic Ray Series Possible Real World
>> System Constructs guy get back in here? Seems like he's been gone for a
>> while. Is that what this is?
>> He's scary.
>
>Nah, that's just good ol' Leon, our resident rocket scientist and token
>Dutchman. He doesn't look scary at all on his web page. Just a bit
>pedantic.
At least I stay clear of hummingbirds. Not that potty.
Lanny Chambers
domm...@zmiata.net (Leon van Dommelen) wrote:
> At least I stay clear of hummingbirds. Not that potty.
This from a guy who named his car Bozo? At least I don't publish my
students' comments about my job. What were you thinking?!
Not that I have any students--no sane person would try to learn anything
from me. :-)
Khaled Mostafa
cg height not my specific, i wanted to prove that my mazda has a static
stability factor (t/2h) way higher than 1.5 which is the highest of
passenger cars.
"Leon van Dommelen" <domm...@zmiata.net> wrote in message
news:avf3aukq2cuu0kt5b...@4ax.com...
Tony Lance
Big Bertha Thing blogs
I do not know whether you know about blogs, but I thought
you might need to know.
Blog info:-
Blogs Ping Updates
http://newhome.weblogs.com/pingSiteForm
Update your page and ping puts you on a three hour list
of new pages. (See Home link for list)
Big Bertha Thing blogs
http://tonylance.blogspot.com
Scientific cartoons from a battlefield in cyberspace.
Blogdex Weblog Index Lists
http://blogdex.media.mit.edu/linkInfo.asp?url=http://tonylance.blogspot.com/
Check your page rating and list of blogs at MIT.
Weblog Simple Sites
http://www.blogger.com
Push button web page publishing, as easy as email.
Have fun,
Tony Lance
tony...@nandomail.com
BRUCE HASKIN
You could go out and try to roll it over at 40 MPH ! If it will not
roll, try a standard car (Ford or Chev.) at the same speed. Use the
"standard car" and keep trying by adding speed until it rolls. Go try
your Miata at the same speed. If the Miata will not rollover, you can
start at that speed as one point on your chart. Now, keep adding speed
to your Miata until it rolls. This should be your other piont on your
chart. This should show that your Miata has a lower CG than the
"standard car" ! After you dust yourself off, you should be able to
chart the speed from "zero speed" to the Miata speed rollover on a graph
and plot the "standard car" speed. (Leon can tell us for sure) I think,
you should be able to show the Miata CG is lower than the "standard car"
by some number +/- some %. <G>
It's just another way to figure it !!!!!
(Hope this helps) he,he, he, he, he............
Bruce RED '91 ( I think it was the sun we had in Seattle
that did this)
Larry Gadbois
or calculatable. I suspect the cg is about 18". (Wouldn't it nice if it was
at axle height? ;-) )
"Khaled Mostafa" <khal...@hotmail.com> wrote in message
news:a7udhi$807$1...@nsnmpen2-gest.nuria.telefonica-data.net...
McMahon
"Tony Lance" <tony...@friendsmail.com> wrote in message
news:9113d514.02032...@posting.google.com...
> "McMahon" <baad...@amcom.net> wrote in message
news:<ua3tthq...@corp.supernews.com>...
> > "Lanny Chambers" <la...@hummingbirds.net> wrote in message
> > news:lanny-E6C1DF....@newssvr11-ext.news.prodigy.com...
> > > In article <e4b2auol7la6rd0to...@4ax.com>,
> > > domm...@zmiata.net (Leon van Dommelen) wrote:
> > Did that Big Bertha Thing pin-wheel Cosmic Ray Series Possible Real
World
> > System Constructs guy get back in here? Seems like he's been gone for a
> > while. Is that what this is?
> Hi SM,
> Big Bertha Thing blogs
> I do not know whether you know about blogs, but I thought
> you might need to know.
>
Uh, no, uh, I'm just trying to, like, you know, figure out how to replace
the plastic lenses on my Miata dash with glass ones. Don't think blogs
and/or Big Bertha Thing pinwheels are, like, uh, my thing. You know?
But, uh, Good Luck with them and all!
SM
Leon van Dommelen
>Ref. CG on your Miata.
>
>You could go out and try to roll it over at 40 MPH ! If it will not
>roll, try a standard car (Ford or Chev.) at the same speed. Use the
>"standard car" and keep trying by adding speed until it rolls. Go try
>your Miata at the same speed. If the Miata will not rollover, you can
>start at that speed as one point on your chart. Now, keep adding speed
>to your Miata until it rolls. This should be your other piont on your
>chart. This should show that your Miata has a lower CG than the
>"standard car" ! After you dust yourself off, you should be able to
>chart the speed from "zero speed" to the Miata speed rollover on a graph
>and plot the "standard car" speed. (Leon can tell us for sure) I think,
>you should be able to show the Miata CG is lower than the "standard car"
>by some number +/- some %. <G>
>
>It's just another way to figure it !!!!!
I applaud your spirit of scientific inquiry, Bruce, but I do not
think the tires have enough friction (1g) to roll a Miata. You could
of course try to drive in clay or so, but those are not reproducible
test conditions. Maybe if we put it in one of your jets in a
few g pitch-up? :)
BRUCE HASKIN
you can't roll it, then it must have a lower CG than a "standard car" !
(good thing I didn't ref. an "SUV" cause we all know what would be
like)
.....put it in a jet ? hummmmm, can't you just see that ! Don't tie
it down and do some high altitude "push overs" to get zero G. "Hey,
ya-all hang on back thare now, hear !" <G>
Thanks Leon, I think that might work.
Bruce RED '91
...............................................
On a SAD note, the Boeing flight crew just "ditched" the one & only
Boeing 307 left in the world, in the bay this afternoon ( 3 / 28 / 2002
) . All 4 crew got out without injury. The airplane is in about 10 ft.
of salt water. (7 years & $750,000) went into this restoration. Time to
start all over !
Lanny Chambers
Bru...@webtv.net (BRUCE HASKIN) wrote:
> .....put it in a jet ? hummmmm, can't you just see that ! Don't tie
> it down and do some high altitude "push overs" to get zero G. "Hey,
> ya-all hang on back thare now, hear !" <G>
Just for grins, I built a jet-powered car in X-Plane. (I wanted to try
sightseeing in traffic on the city roads.) Well, it's very difficult to
build a stable ground vehicle with airplane suspension...but once the
afterburner gets the "car" airborne, aerodynamics become important. I
had to put control surfaces on the chin spoiler and rear wing and add a
rudder, but with sufficient power I could fly under near-control, well
within the capabilities of the autopilot. Some of the bounces on landing
were truly impressive...
If you have broadband and any interest in flight sims, you must download
the X-Plane demo (http://www.x-plane.com/)
Khaled Mostafa
but anyway, NHTSA has all SSF of more popular cars.
K
"Larry Gadbois" <lgad...@earthlink.net> wrote in message
news:rKLo8.1670$Xu6.1...@newsread2.prod.itd.earthlink.net...
BRUCE HASKIN
got to fly the "full motion" sim.of the T-38. I tried an "inverted" ILS
approach to landing. At 50 ft. above the runway, I did a
"missed-approach" & the sim didn't know how to respond. So we crashed !
Big time, withall the noise & shudders. ..........ya-all be careful now,
hear?
Bruce RED '91
Lanny Chambers
Bru...@webtv.net (BRUCE HASKIN) wrote:
> Lanny, that kinda sounds like the time I was back visiting my son & I
> got to fly the "full motion" sim.of the T-38.
X-Plane will let you practice your Shuttle reentries from orbit...under
full manual control, of course. Or fly realistically on Mars, where
there's not enough air to rotate under 400 knots. One of the coolest
features: you can choose an external view that shows real-time lift and
drag vectors on all control surfaces, plus prop- or jetwash. It's an
amazing sim.