This video kinda inspired me to design another racer 

Here is a (rough) chassis drawing (side view)

Side impact bars (top view)

This racer will be made out of 1" HREW (hot rolled electric welded) steel tube

...so, we have (2) base rails, 4 side impact bars & the roll cage that will make up most of the chassis

...& only weigh ~25 lbs.

FYI: That CUSA rules update video was made by Challenge USA Electrathon (seems to be a "spin off" of the original/national Electrathon America program)
ChallengeUSA - Electrathon

I think the 6" side impact bar spacing rule, is a good idea
...so, when setting up a chassis "jig", I made sure to space the side impact bars ~5 1/2" apart 

For reference
8. Frame members on the side of vehicles must be designed to help prevent another vehicle
from intruding into the drivers compartment in the event of a crash. No spacing larger
than 6 inches is allowed on the frame of the vehicle around the front and sides of the
drivers compartment and the battery box(es), as tested with a 6 diameter disc. The 6
disc must be prevented from intruding into the driver compartment by 1 OD (square or
round) tubing.

Another view

Did anyone notice the front axle in the last couple of pics?

The main criteria for this design was just to be simple & light weight 

Here's a rough drawing

Parts

...(1) 32" piece of 1" x 14g. steel tube 

...(2) pieces of 1" x 1/8" steel strips

...& a little bit of shaping 

Assembled

Installed on chassis

* Also, made it bolt on/removable 
...so, it's easily replaceable if necessary

Spindle mounting brackets

Reinforcement

Spindle bracket temporarily mounted on the spindle mounting bracket with a screw

...to help hold 'er in place while setting the Castor (~2.5* to the negative) 

* Setting the Castor a little bit to the negative

...helps to center the steering

...which helps the racer go down the track straight(er) 

** Be-aware that adding too much negative Castor

...makes the racer go down the track really straight

...but also, makes the steering a lot harder to turn 

Here is the spindle bracket "tacked" in place (using small welds) on the spindle mounting bracket

...then, after double checking accuracy

...remove the screw

...& weld 'er on, good-n-strong 

For this racer I'm thinking' about trying/using some standard 6" go kart type wheels
...with probably ~13" tires
...which have a side wall of ~3"

* The rule book mandates that the "ride height" must exceed the height, of the sidewall, of the tires.

So, I'm using a 2 x 4 (set on edge) to help establish a ~3 1/2" "ride height"

In the rear, I'm going set the "ride height" at ~4"
...because, while doing research on Aerodynamics, I learned that "they" (whoever "they" is) recommend that the floor of the vehicle be set, on a bit of an angle.

** A secondary reason that I mentioned ride height & the floorboard angle
...is because it can/will affect the Castor angle
...so, you have to incorporate "it" into the mix

Because, if you set the Castor angle while the chassis/floorboard is setting level
...& then, "angle" the floorboard up in the rear
...it would negate or cancel out the Castor angle, that you previously set

Functional Artist wrote:

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* The rule book mandates that the "ride height" must exceed the height, of the sidewall, of the tires.

So, I'm using a 2 x 4 (set on edge) to help establish a ~3 1/2" "ride height"

 

I do not think this is true anymore. At some point the rules were revised to a specific ride height test (over a milled board) rather than getting into the question of at what tire pressure you measure sidewall. Here is what I find in the rule book:

 

10 WHEELS and TIRES

1. Tires must be a pneumatic (inflatable) type.

2. Wheels and tires of any diameter or width may be used.

3. The minimum ground clearance is to be judged by the cars ability to roll over a 2x2 that is milled to be 1½ x 1½. This is to prevent the vehicle from sliding on the ground in the event of failure of any or all of the tires.

4. While in driving position the driver's body must not be able to come in contact with tires, wheels or spokes.

 

The other issue to consider is that a lower center of gravity normally allows the tires to generate more grip in the corners allowing the driver to carry more speed. We run the Super Coupe as close to the ground as legal.

 

Functional Artist wrote:

In the rear, I'm going set the "ride height" at ~4"
...because, while doing research on Aerodynamics, I learned that "they" (whoever "they" is) recommend that the floor of the vehicle be set, on a bit of an angle.

Dead flat is probably the lowest drag configuration unless you are curving the floor up towards the idea of a tear drop rear. In other types of racing, we use rake (raising the rear of the car) to generate downforce but there is a drag penalty. Rake is also useful to help minimize understeer since a higher center of gravity in the rear generally leads to less grip in the rear.

Hey ProEV,

Thanks for the reply & helping to expand the discussion

A.)
I agree with you, that's what the rulebook says (page 8.)
...but, a little bit further into the rules, under Stability (page 16) it says:

STABILITY
A well-designed vehicle should be stable under all conditions and situations
that might be encountered in a race. Competition places very high loads on
a vehicle during tight cornering, even at relatively low speeds. It is therefore
very important that the center of gravity of your vehicle be located below
the axles. You need only a couple of inches of ground clearance on most
race courses. Two to three inches is usually adequate, but make sure that
you have clearance even if one, or all, of the tires are flat (this is a rule
requirement).

& also,

IIRC I read somewhere, here on the forum about recommending/needing the "ride height" to be a bit higher than the sidewall of the particular tire, that the racer was running
...because "if" the tire went flat, it potentially wouldn't be touching the ground anymore
...& "if" the tire wasn't touching the ground anymore (basically, suspended in the air) it can't "get a grip" which affects control
...& loss of steering (or "grip" of the rear wheel ...even) could cause the race car to slide (uncontrollably) on its bottom 

B.)
I partially got the "idea" about the upwards "rake" in the rear, from in a caption, in the "Airfoil" illustration (on the same page) it says
Close to the ground the ideal shape
looks like this in side view
&
I also, remember from some of the aerodynamic research, that I've done
...something about having an upwards rake, towards the rear, of the vehicle helps the air to escape, out the rear...easier 

* Please, do me a favor & respond more often, to help further these discussions...even more 

Functional Artist wrote:

---

A.)
I agree with you, that's what the rulebook says (page 8.)
...but, a little bit further into the rules, under Stability (page 16) it says:

STABILITY
A well-designed vehicle should be stable under all conditions and situations
that might be encountered in a race. Competition places very high loads on
a vehicle during tight cornering, even at relatively low speeds. It is therefore
very important that the center of gravity of your vehicle be located below
the axles. You need only a couple of inches of ground clearance on most
race courses. Two to three inches is usually adequate, but make sure that
you have clearance even if one, or all, of the tires are flat (this is a rule
requirement).

 

 

As you and I have discussed before, the manual needs editing and updating. There was a rule that involved deflated tires but that rule was changed (by vote) to the current rule specifying ride height and how it is measured. The Vehicle Design section is recommendations, not required.

 

'It is therefore very important that the center of gravity of your vehicle be located below the axles.'

I would argue that the center of gravity should be as low as possible to encourage stability. Where the tire meets the road is where the pivot point is established, not where the axle is located.

 

Functional Artist wrote:

---

 

& also,

IIRC I read somewhere, here on the forum about recommending/needing the "ride height" to be a bit higher than the sidewall of the particular tire, that the racer was running
...because "if" the tire went flat, it potentially wouldn't be touching the ground anymore
...& "if" the tire wasn't touching the ground anymore (basically, suspended in the air) it can't "get a grip" which affects control
...& loss of steering (or "grip" of the rear wheel ...even) could cause the race car to slide (uncontrollably) on its bottom 

 

Most teams run bicycle tires. These tend to come off the rim when the inner tube pops. My concern would be that the rim digs in and the car flips. When I blow a tire, the car slides on its floor with the other two tires giving me some steering control. A sliding car stops quickly and damage is normally limited to replacing some rivets that wore off.

 

Functional Artist wrote:

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* Please, do me a favor & respond more often, to help further these discussions...even more 

 

But then I won't finish my car in time for the next race.

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I made up some inner, body panels (&/or scatter shields)
...& painted them "watery" blue

Winter has arrived (currently ~34* & light snow)
...so, this project is mostly "on hold" til' spring