Diamonite Electrathon America Racer

[Whitetrashrocker]

Your force will vary along your height also due to the non parallel sides.

 

[Edwin Spangler]

Is that foam similar to the foam used in pipe insulation or pool noodles? It looks identical. Ive used that material for years as a pad for my foot on my sim's dead pedal. I hold some pretty firm pressure on that stuff (10kg ish? Estimating by reference of the 50kg I put into my brake pedal) and it holds up really well. It was originally supposed to be temporary as I didnt expect it to last more than a week. Well, after about 5 years of daily kickings, I have made just enough of a dent that I can feel my foot print. You cant see it, but my foot feels it.

 

[Functional Artist]

Is that foam similar to the foam used in pipe insulation or pool noodles? It looks identical. Ive used that material for years as a pad for my foot on my sim's dead pedal. I hold some pretty firm pressure on that stuff (10kg ish? Estimating by reference of the 50kg I put into my brake pedal) and it holds up really well. It was originally supposed to be temporary as I didnt expect it to last more than a week. Well, after about 5 years of daily kickings, I have made just enough of a dent that I can feel my foot print. You cant see it, but my foot feels it.

Hey ES,

Yup, same stuff as Pool Noodles
...& "if" the "pressure" (from your foot)
...was "spread out" across the entire "pad"
...it would/should last for...quite a while...longer (maybe even indefinitely)

Thanks for adding to the discussion

 

[Functional Artist]

Do you have a hydraulic press?

You can find your foams "spring rate"

We do this with valve springs and landing gear springs, but im sure you can modify for the compression rate for the foam.

Put an analog bath scale on the floor of the press. Then compress the spring usually one inch and read the weight on the scale. Some spring manufacturer data has this, some dont.

Its a good way to compare springs within a set.

Not sure how much that closed cell foam will hold and how fast is the rebound?

Got up early (for some reason)
...& been thinkin' about this

Now, after ~4 hours
...& 2 pots of coffee...time to do some "jabbering"

I don't have a full-size hyd press (just my mini-press)
...but, I figured that I could maybe use a drill press (for your recommended test)

Just put the bath scale on the "table", of the drill press
...& put the piece of closed cell foam "pad", on the scale

Then, place/use a spreader plate, on top of the pad
...& then, using the handle, of the drill press
...apply pressure, to the "pad"

The "depth gauge" (on the drill press) could be used to measure the distance traveled
...as the bathroom scale, read & displayed the amount of pressure, that was required to depress the "pad"
&
I could also visually observe the amount of time required, for the "pad' to "spring back"
...&/then, maybe do some "guess-ti-mating"
...but, the "spring-back" would probably be (IMO) too quick, for me to try-n-measure

***(Please forgive me...as I'm NOT trying to be argumentative)***

But, I'm having a hard time understanding "why" this info would be helpful &/or necessary?

Where I'm coming from (theoretically) is:
..."if" a 1" x 10" x 10" piece of wood was used, as the "pad", we would have a really hard (virtually no) suspension. Let's call it a (0)
...& "if" a 1"x 10" x 10" piece of (let's say) couch foam was used as the "pad", we would have a really soft suspension. Let's call it a (3)
...but, ideally we want a (2) something in the middle

*More back-story
Way-back-when, while "floating around" in "free thought" & thinkin' about this
...I thought about how (lets say) a brand-new TV is "suspended" in the box, with Styrofoam "packing", for protection
...& "if" the box is bumped, jostled &/or dropped, the "packing" is to help "insulate" the TV, from impacts
&/so
I was thinking that for a racecar, this type of "insulating properties" could be beneficial
...as opposed to a "hardtail" or no suspension...at all
but,
A bit more suspension "travel" would be helpful
...as would, some spring back...too
&
This where I thought about using some closed cell foam, as a suspension component or "springy-insulator"
&
I think I mentioned, that I've used this 1" foam, for DIY mini-vehicle seat cushion material before

Once I made-up a seat using (2) layers of this 1" closed cell foam
...on a 1/2" piece of plywood
...& tested it

During testing, I noticed the seat was good-n-stiff (supported my weight well)
...& seemed to absorb most of the "bumps in the road" pretty good
...but, it wasn't very comfortable (like a bit too stiff)

Next, I made-up a seat using (1) layer of 1" couch foam
...& a piece of 1" closed cell foam
...on a 1/2" piece of plywood
...& tested it

I found this configuration to be "the best of both worlds"
...as this seat still absorbed "bumps in the road" pretty well
...but, now it was much more comfortable too

 

[Whitetrashrocker]

No offense taken. Im just feeding your thought process.

My theory was to use a square inch or so slug to push on the foam and see what kind of pressure it takes to make it give.
Then you could use this psi measurement to help tune in your cantilever lenghts.

If you know it takes say, 10psi to completely smash the foam.
You figure say 100 lbs weight at the kart.
A 10:1 ratio would just bottom out pretty easily.

In your seat example your body weight is spread out over a much larger area.
So say the same 10psi foam is holding a 100lbs, but its spread over a square foot.

Now your only putting like .7psi on the foam.

There's a bunch of missing info here but you get the idea.
Sorry to ruin your sleep schedule. ☕️

 

[Functional Artist]

Hey WTR,

I cut up some test samples (1" x 1" x 1/2", 1" x 1" x 1" & 2" x 2" x 1")

...& rigged up a tester (kinda) as you suggested

Before each test, I adjusted the "impactor" (aka drill chuck)
...so, it was right up against the "spreader plate" (wood)
...& also, zero'ed the (bathroom) scale

I first tested (1) of the 1" x 1" x 1" pieces of the closed cell foam
...but, they "smashed" pretty easily
...&/so, didn't get very good data/results

Then, I tested a piece of the 2" x 2" x 1"
...& with ~1/2" of pressure applied

...the scale showed ~30 lbs.

Then, with ~1" of pressure
...the scale showed ~155 lbs.

Next, I tested a 10" x 10" x 1" piece or "pad"
...& used a bigger "spreader plate"

About the most pressure that I could apply was ~5/8"

This "just about "maxed" the scale out

 

[Whitetrashrocker]

Thats some great testing.

A few pointers?
Measure the squish from the scale. Measuring from the quill also includes the scales drop.
If your test piece was 1" thick and you pressed it 1" you achieved a scientific anomaly of making nothing from something. The opposite of women logic.
They somehow make something from nothing.

Measure the same squish.
Say 1/2". How many lbs to achieve that.
You should see a pattern then.
The 1x1 would be like 7lbs
Your 2x2 showed 30lbs. 4 times the 1x1
With that logic your 12x12 would be 144 times the 1x1 or just over 1000psi.
There might be a plateau though and anything over a certain size doesn't increase.
But im just thought experimenting here.

 

[ezcome-ezgo]

The goal of suspension in "racing" is to keep the contact patch of the tire on the surface of the earth. If it is in the air, even for a fraction of a second, that's bad. Again this is the "goal", not always 100% achievable. So to this end the "bounce-back" of the spring is very important.

 

[Functional Artist]

Thats some great testing.

A few pointers?
Measure the squish from the scale. Measuring from the quill also includes the scales drop.
If your test piece was 1" thick and you pressed it 1" you achieved a scientific anomaly of making nothing from something.

Hey WTR,

Thanks for suggesting a "test procedure"
...helping me "think this thru"
...& for complimenting the effort too (as it was only like ~30*, in the garage, during these tests)
&
Good catch
I was concentrating on, getting test results at 1/2" & 1" of "spring travel"
...& didn't even think about the test piece only being 1" tall

So, I would think the results from the 1/2" test (of ~30 lbs.) were pretty accurate
...mainly because1/2" is within the springs (up to) 1" of travel range
&
I agree the 1" test results (of ~155lbs.) had to be "flawed"
...because when 1" of "travel" was applied to the 1" sample"
...the sample got "maxed out"
&
Once "maxed out" the pressure was just being "transferred"
...thru it
...directly to the scale

I also agree the "travel" measurement should have been done at the scale
...to eliminate "it" from the equation

* This is a great example of sharing a unique idea/concept
...& having it "reviewed by a group of peers"
...where "like minded" folks look over
...& examine each others "work"
...& then, offer helpful tips, suggestions, testing ideas & even critiques

**Yea, the same basic concept as DIYGK
...just "we" B goin' a bit "deeper"

 

[Functional Artist]

The goal of suspension in "racing" is to keep the contact patch of the tire on the surface of the earth. If it is in the air, even for a fraction of a second, that's bad. Again this is the "goal", not always 100% achievable. So to this end the "bounce-back" of the spring is very important.

Hey Ez,

Yup, I agree.

AFAIU ideally when a vehicle is cruising along
...& a wheel "hits" a bump
...we want the suspension & wheel to "give" (move upwards)
...& then to "spring back" or bounce back (return to its neutral position) ASAP
&
While this "suspension/wheel to bump, engagement" is happening
...we don't want the chassis to even "know" that it happened
Because
If the impact from the bump, is transferred up thru the suspension, to the chassis
...the weight of the chassis is "thrown upwards" a bit which:

1.) what goes up must come down (mean 'ol Mr. Gravity, joins the party)
...so, the motion from the vehicle, going upwards
...then, travels back down, thru the suspension
...potentially causing a "bouncing effect" of the wheel
&
2.) could potentially cause overall control issues, of the entire racer
&
As you so eloquently pointed out:
"The goal of suspension in "racing" is to keep the contact patch of the tire on the surface of the earth. If it is in the air, even for a fraction of a second, that's bad."

 

[Denny]

I’m not seeing a lot of travel with this type of suspension. I would think it would ride like a buckboard. The thinly padded seats only shield us from vibration not from shocks. That’s what springs are for.

 

[Functional Artist]

Thats some great testing.

A few pointers?
Measure the squish from the scale. Measuring from the quill also includes the scales drop.
If your test piece was 1" thick and you pressed it 1" you achieved a scientific anomaly of making nothing from something. The opposite of women logic.
They somehow make something from nothing.

Measure the same squish.
Say 1/2". How many lbs to achieve that.
You should see a pattern then.
The 1x1 would be like 7lbs
Your 2x2 showed 30lbs. 4 times the 1x1
With that logic your 12x12 would be 144 times the 1x1 or just over 1000psi.
There might be a plateau though and anything over a certain size doesn't increase.
But im just thought experimenting here.

Hey WTR,

I made up a (1/2" x 1" x 1 1/2") measuring "block"
...so, I didn't have to try-n-hold a tape measurer steady for each test

I re-tested a 2" x 2" x 1" sample

Pic before test/at "rest"

Pic of 2" x 2" x 1" sample with 1/2" of pressure applied
...looks ta be ~50lbs.

Pic of 2" x 2" x 1" sample with as much pressure as I could apply
...looks to be ~220lbs.

Pic of 2" x 2" x 1" sample, after springing back
...which was almost instantaneous

* Notice, only ~1/32" space (or gap) after "spring back" from being completely collapsed

 

[Functional Artist]

I’m not seeing a lot of travel with this type of suspension. I would think it would ride like a buckboard. The thinly padded seats only shield us from vibration not from shocks. That’s what springs are for.

Hey Denny,

I was wondering "where's Denny?" glad ya "chimed in" buddy

Hmmm...Denny wants ta see some travel testing

OK, pal let's test (2) of the 2" x 2" x 1" pieces, "stacked up"

Pic of "stacked' sample with 1/2" of pressure applied

The scale only shows ~8lbs.

Pic of "stacked" sample with 1" of pressure applied
...& the scale shows ~40lbs.

Pic of "stacked" sample with 1 1/2" of pressure applied

Scale shows ~190lbs.

Pic of 2" tall "stacked" sample "sprung back"
...after being compressed down 1 1/2"

 

[Denny]

So with 2” of foam it won’t even support your weight before it is compressed out? It just seems like a small coil over would do a better job. With shock loading from a bump I could see loads in excess of 1,000# happening. I think ride quality will be poor and harsh.

 

[ezcome-ezgo]

I hope you are recording all this data and extrapolating the formulas required to derive the outcomes without physical testing. Also what Denny said.

 

[Functional Artist]

So with 2” of foam it won’t even support your weight before it is compressed out? It just seems like a small coil over would do a better job. With shock loading from a bump I could see loads in excess of 1,000# happening. I think ride quality will be poor and harsh.

Hey Denny,

The 8lbs. & 40lbs. results, were from a single (2" x 2" x 4") "stacked" sample

So, I did some math (or figurin')

So, it looks like for a smallish 6" x 6" pad
...pre-load rate (not single, as listed): 72lbs. (driver getting into the racer)
...max-load rate (not double, as listed): 360lbs. (max impact rate)

For a medium 8" x 8" pad
...pre-load rate (not single): 128lbs. (driver getting into the racer)
...max-load rate (not double): 640lbs. (max impact rate)
&
For a Larger 10" x 10" pad
...pre-load rate (not single): 200lbs. (driver getting into the racer)
...max-load rate (not double): 1,000lbs. (max impact rate)

 

[Functional Artist]

Hey Denny,

As a reference, I rounded up & tested a couple of springs

They are mostly riding lawn mower seat springs
...so, they are designed to support the weight of an average size human

This spring started off at 1"
...with the scale "zeroed"

Smashed down to ~1/2"
...& the scale showed ~75lbs.

This is the biggest one
...starts off at a little over 2" tall

Smashed down to ~1 1/2"
...the scale shows ~195 lbs.

 

[Edwin Spangler]

Mr. FA... I had a realization last night. While using my own analog bathroom scale , I noticed if I centered my weight, stepped right in the middle, I had very inconsistent readings. I have to keep even pressure on the sides to get an accurate reading.

Idk, just something to look into.

 

[Master Hack]

This science shyt makes my head hurt....

 

[ezcome-ezgo]

I think that scientists and engineers have sort of set a reasonable president that closed cell foam is not necessarily a substitute for a spring/airbag/hydraulic device. I like how you think though FA, you know I love ya.