Center of Gravity Height

Ian Curtis

Ian Curtis

Senior Member
Does anyone know/have measured the height of the CG of their Model A?

Google doesn't seem to know. I found a thread from a couple years ago where some had measured the fore/aft location which agreed pretty well with rules of thumb, but not the height. I did find a Model T thread which had a picture which seemed reasonable, but just wondering if anyone knew more exactly.

https://www.mtfca.com/discus/messages/118802/158063.html?1283701871
 
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Center of gravity is Weight X Arm = Turning Moment. I've done a lot of W&B on different aircraft and it's really not that complicated but a person needs a good set of scales and measurements for longitudinal and lateral arm locations for weigh points and for the datum which is generally at the front most location of the vehicle. The datum is basically the zero point.

When a person refers to a vertical center of gravity then it gets more complicated. This is considered irrelevant in aviation since they have wings or rotor blades that control the center of lift so vertical CG doesn't come into play. An automobile has the centerline of the axles and spindles that bear the weight of all parts above them. Boats and ships have buoyancy in the water but that changes depending on the load that the boat is carrying. They can roll over in rough seas if the vertical CG is too far above the line of buoyancy. Motor vehicles can also be susceptible to roll over if there is a lot of weight mounted too far above the frame. Big tractor-trailer rigs have more difficulties in this respect due to loading and what can happen in emergency avoidance moves on the roadway. A strong wind can even blow some trailers over at times. I don't really know of a reason to try and measure the vertical CG but the Weight X Arm = Turning Moment still applies but it's figured vertically instead of longitudinally and laterally.

Ford was rather unique in their chassis design in the way they tried to have as much unsprung weight as they could get down low. This helps with body roll. They eventually put stabilizer bars on there but that wasn't till 1940 or so.
 
Look at the factory assembly line photos that show the body drop. The body support at the drop will give you the horizontal balance point. The CG will reside on vertical plane below the body support point. The CG will vary for each body style.
 
Your question is kind of confusing … ;)

What exactly are you wanting to know ?

Are you wanting to know the height of a
specific vehicle from grade ?

Based on personal experience transporting
over 450 Model T’s and 250 Model A’s
of just about every configuration,
I can tell you that each is slightly different
due to wear and suspension and tires
(among other things) …

I towed custom built enclosed trailers for
many years that had 8 foot clearances
at the rear door until covid hit - then I
switched to an all aluminum trailer with
a rear door clearance that weighed 50%
less when empty …

Every vehicle I transport is measured
before I pick up for height and width and length
to make sure it will fit inside my trailer.


Jim
Transporting To Travel
Traveling To Share
Stories From The Road
 
Steve Smith put a book out years ago called "Advanced Race Car Suspension and Design" if I remember properly. It has everything you want to know about suspension and designing it properly. I think later on it was available on a CD that you could put n the numbers and it would do the calculation.
 
I put all my weight and balance work ups into the Excell so that all I have to do was add the operational weights such as passengers, baggage, and fuel and it would give me an instant weight and CG.

To do a vertical W&B the car would have to be weighed while on it's side using special fixtures to do the different weigh points that would tell where the CG would be. It's not a real practical thing but it could be done. Fixtures and wood blocks for the scales are considered as tare which can be subtracted from the scale readings for calculation purposes.

Model A passenger cars don't have much steel in the roof since most were covered with poultry netting and several layers of fabric & cotton padding. The heavier one would be the big package van types with the fully stamped steel roof such as manufactured by The Budd Company.
 
I just thought of a really oddball question in the 5,000,000 model A.'s that were produced I wonder how many feet of paultry netting was used???
 
I think there maybe a sales pitch there somewhere these eggs are from homeless chickens as opposed to free range or caged chickens!!!
 
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