general ground clearance calculation (math)

[Bucks]

I am trying to figure out a ground clearance question... For example, say I have an RV and I know the center of front wheel to center of rear wheel is 144" in length and has a ground clearance (from ground to underbelly) of 26" (of course hypothetical). Is there a way to calculate the minimum ground clearance based on this information if I stretched that RV to have a wheel base of say 192"? Can I just extrapolate (i.e 144/26 = 192/x) or is it just not that easy and I need more information?

 

[gorcorps]

Are you talking about basically high-centering the thing? That's highly dependent on the geometry of the hill

 

[jaedaliu]

You need more information. Ground clearance in mathematical terms is a calculation of wheel + tire size, spring rate in your suspension, and weight of the vehicle.

So, if you stretched your RV without adding any weight, your ground clearance will be identical.

 

[Bucks]

Are you talking about basically high-centering the thing? That's highly dependent on the geometry of the hill

In a sense yes, I want to assume the known information from the 144" wheelbase is at the optimal 26" height to clear any obstacle or hill it would encounter. So is there any correlation between this and an increase in RV length

EDIT: Also just noticed we have roughly the same join date, but you have 23,000 more posts than me

 

[Bucks]

You need more information. Ground clearance in mathematical terms is a calculation of wheel + tire size, spring rate in your suspension, and weight of the vehicle.

So, if you stretched your RV without adding any weight, your ground clearance will be identical.

I think this would be true on a flat surface, but what about up/down a hill, like mentioned by gorcorps and like this: http://www.youtube.com/watch?v=Mmxejm81vkI

 

[skyking]

There really is no way to make a formula for that, because each obstacle or high-center condition is unique.
For the purposes of the math problem they are probably simplifying it in a similar way as your first post.
I'd look at the distance 144 as x, and figure that triangle that is described by 1/2x.
Project that ratio out.

 

[sdifox]

I am trying to figure out a ground clearance question... For example, say I have an RV and I know the center of front wheel to center of rear wheel is 144" in length and has a ground clearance (from ground to underbelly) of 26" (of course hypothetical). Is there a way to calculate the minimum ground clearance based on this information if I stretched that RV to have a wheel base of say 192"? Can I just extrapolate (i.e 144/26 = 192/x) or is it just not that easy and I need more information?

Pythagorean Theorem should take care of that no? Assuming you know the slope you are trying to clear.

 

[Bucks]

Pythagorean Theorem should take care of that no? Assuming you know the slope you are trying to clear.

Assuming I need it to be able to handle the same inclines and declines, wouldn't it be the same to just take 144/26 = 192/x , since I think the angles would basically not factor in?

 

[sdifox]

Assuming I need it to be able to handle the same inclines and declines, wouldn't it be the same to just take 144/26 = 192/x , since I think the angles would basically not factor in?

Picture 2 triangles. First triangle is formed between the ground (the flat portion), the front wheel and the underside of the vehicle. The second triangle is formed by ground (on the slop), underside of the vehicle and rear wheel.

You changed the vehicle length. You need to recalculate the whole system and you will need to know the angle between the incline and the flat portion.

 

[Bucks]

Picture 2 triangles. First triangle is formed between the ground (the flat portion), the front wheel and the underside of the vehicle. The second triangle is formed by ground (on the slop), underside of the vehicle and rear wheel.

You changed the vehicle length. You need to recalculate the whole system and you will need to know the angle between the incline and the flat portion.

Bare with me, obviously I am a little slow but I think that is what I have done and tried to describe in the previous post but failed.

Using forming a triangle length a = 144 , height b = 26, I found Angle = Tan^-1(b/a) = 10.23

Can I then setup my triangle for the longer vehicle (a=192) to calculate b = Tan(10.23)*192 = 34.65.

Using this method I could have just done 144/26 = 192/x = 34.66. Thanks for the help so far and this actually isn't for any school assignment or anything like that, more of something I am looking into.:thumbsup:

 

[Squeetard]

Pythagorean Theorem should take care of that no? Assuming you know the slope you are trying to clear.

Trig yep. But Tangent works better. What the OP means is this I think.

Now draw a line from the bottom of the back tire to the bottom of the front. Draw a perpendicluar line from the middle of that line up to the bottom of the RV. The arctangent of those 2 lengths will tell you the radius of the curve that will clear the bottom of the RV.

 

[sdifox]

Bare with me, obviously I am a little slow but I think that is what I have done and tried to describe in the previous post but failed.

Using forming a triangle length a = 144 , height b = 26, I found Angle = Tan^-1(b/a) = 10.23

Can I then setup my triangle for the longer vehicle (a=192) to calculate b = Tan(10.23)*192 = 34.65.

Using this method I could have just done 144/26 = 192/x = 34.66. Thanks for the help so far and this actually isn't for any school assignment or anything like that, more of something I am looking into.:thumbsup:

except if your length is 144 for the 144 vehicle, you have already cleared the incline


Apparently I misunderstood... ooops.

 

[mikeford]

26" clearance and 12 or 16 foot wheelbase, Dude just don't drive over big bumps its not an offroad vehicle.

 

[Bucks]

Trig yep. But Tangent works better. What the OP means is this I think.

Now draw a line from the bottom of the back tire to the bottom of the front. Draw a perpendicluar line from the middle of that line up to the bottom of the RV. The arctangent of those 2 lengths will tell you the radius of the curve that will clear the bottom of the RV.

Yes?

 

[sdifox]

26" clearance and 12 or 16 foot wheelbase, Dude just don't drive over big bumps its not an offroad vehicle.

He's trying to go to Paradise Falls without the aid of balloons. :whiste:

 

[mikeford]

BTW if presented with a menacing hump in your path, go over it with as much of a diagonal route as you can.

 

[Bucks]

BTW if presented with a menacing hump in your path, go over it with as much of a diagonal route as you can.

Haha , i just made the numbers up. I am just trying to learnt the process.

 

[sdifox]

Yes?

Initially I thought your thing works. But actually, how can x ever be bigger than 26"? I mean the clearance is 26", how do you clear 34"?

 

[Bucks]

Initially I thought your thing works. But actually, how can x ever be bigger than 26"? I mean the clearance is 26", how do you clear 34"?

The lengthened RV (192" wheel base) would need a ride height of 34" to go over the same hill that the 144" RV could do riding at 26"?

 

[sdifox]

The lengthened RV (192" wheel base) would need a ride height of 34" to go over the same hill that the 144" RV could do riding at 26"?

ah, got it. That makes sense

It's my Silly Day. Honest.

 

[Bucks]

ah, got it. That makes sense

It's my Silly Day. Honest.

All good... I am trying to make sure it makes sense and I'm not missing anything..

 

[Squeetard]

That's the idea Bucks, I was running off to work, did a rough sketch and you figured out the rest!
But, there is no such thing as a perfect arc hill. If you have a bump in the road that both wheel bases can straddle then it is just the height of the bump that matters, wheel base will not factor in.