Diamonite Electrathon America Racer

[Functional Artist]

Should "go" about here
...checkin' the "fit"

The "opening" seems ta "line up"
...about where we need it ta be

Seems like we need ta do a bit more trimmin'

Back to/on the mold
...& took ~1" off of the bottom edges

 

[Functional Artist]

After makin' sure of the "fit" of the first "tunnel"
...I did some adjustin' on the "cut out lines"
...then, went ahead & cut out the second "tunnel"

...& then, there were (2)
* Custom shaped ta "hug" the sides of the monocoque

Flipper 'er over (right side up)
...double checked the "fit"
...& worked on/thinkin' about how ta do, the connectin' duct work

...& then, there were (2)
...AKA "Duals"

 

[Functional Artist]

Made sure the front roll bar still mounts properly
...& "clears" the "tunnel"

Yup, looks good!

CAD duct work

Looks like the "piece(s)" we would need are ~10" - 12" long

...& ~4 1/2" at the widest part

I'ma thinkin' that the "tunnel" molds may be useful for makin' these "pieces"

Yup, looks like we can get a ~10" - 12" piece off of it

Even the narrowest part of the mold is ~4 1/2"
...& there are still already coated with PVA

So, yea! I ain't gotta make more molds

 

[Functional Artist]

Also, made sure the outer sides of the "tunnels"
...would align with the outer body panels/sides

Another view

Also, cut some FG cloth, for the next procedure

 

[Functional Artist]

Layed down (3) layers of 1708 (mainly left-over/scrap pieces)

Another view

Popped 'em off

Looks like this (inside)

Workin' on fittin' 'em on
...maybe something like this

 

[Functional Artist]

Anyone notice "the gap"? (Yup, that's my finger)

About "this" much "off"

I added a "filler piece" durin' installation (can't even hardly tell)

The other (gooder) side

We gots us some...Side Pipes

 

[Functional Artist]

An (inverted) view of the "air channels"

Since we added all of this stuff "hangin' down"
...let's make sure everything is nice-n-even with the bottom of the racer

Air Intake area

Throat area

The Tunnels

Flipped 'er back over

* Notice the "nose" is ~1" higher than the actual floor of the racer
...for even better unobstructed air flow
...into the under car aero system

 

[Functional Artist]

I put the front wheels on & leveler 'er out
...ta check on ground clearance

Looks like the bottom will "ride" just under 2" off of the ground

On ground clearance, the EA rule book states:
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 be1½”x1½”. This is to prevent the vehicle from sliding on the ground in the event of failure of any or all of the tires. (page 8.)

So, we look ta be "in compliance"

Here is a view of the front ground clearance
...with the wheels on

A view of the air intake area
...from up/underneath
...as it will "ride down the road"

 

[Functional Artist]

The venturi principle described above is exclusive to a closed system, or pipe. Half of this "pipe" is open to the atmosphere, so different rules apply.

Hey Ez,
I've been thinkin' about your comment, a bit more
...&/so, have some "jabberin' ta do"

Because "part" (not half, due to the roadway) of the "pipe" is "open to the atmosphere"
...I guess this situation could be referred to as a "leaky pipe"

I thought (durin' a 'bout of free thought) about the possibility of enclosing part, if not all of the air channels
...to help alleviate this "leakyness"

But/then, thought
...if any effect (like creating a low pressure area) was to occur
...it would occur inside of the enclosed pipe
&
Would NOT create a pressure difference
...between the air pressure above the racer
...& the air pressure below it

Also/then, thought about how most times when describing air flow
...most folks refer to the air as having "layers"

So, (again, while in free thought) I was thinkin' that with ~2" of ground clearance
...& an additional ~1" under the front bumper
...basically, there is ~3" of unobstructed air flowing under, the front of the racer

So/now, let's say each of them (3) "layers" are 1" thick or tall
&
When, them (3) ~1" "layers" of air flow under the front of the racer
...the bottom "layer" still just flows along, mostly unobstructed
...but, them (2) upper "layers" of air encounter the undercar aero feature
&
Get "funneled" into the air Intake
...compressed in the Throat
...& then, expands as it exits out thru the Tunnels

So/maybe the lower "layer" of air "acts" as an "air curtain"
...to help "seal" the "leaky pipe"

 

[Functional Artist]

If anyone is really interested in undercar aero
...& wants to understand why I'ma doin' all of this
...this video explains a lot of it pretty well

The video is about aerodynamic affects (& testing) on a really mini-racer (an RC car)
...but, the concepts are the same

* The good info starts about 3:00 into the video

 

[Functional Artist]

Too much?
Too deep??
Too soon???

I mainly wanted to "make a note" of some of
...what I wasa thinkin'
...& why I wasa doin' what I'ma doin'
But/also,
To share with "the world"
..."how we got to where we are" with this project
...as "this sh*t doesn't "just happen"

Movin' on to actual "body work"

Lots of sandin'

Yup here too

 

[Functional Artist]

My arms don't like me sanding
...so, "we" made a "deal" that I would only sand for ~20 minutes at a time
&/so,
This gave me "time" to work on some other projects (in between)

Like, there is a big 'ol "gap" in between my work area/shelter & the garage
* Wow! check out this "old pic" I found of my work area, from a coupla years ago

I've been thinkin' that I could make a couplea simple brackets, to kinda "extend" the side a bit

So, this way, any rain will "run" off the shelter & "right" into the gutter, on the garage
Like these:

I also, cleaned up & painted the roll bars, while I wasa at it, too

 

[Functional Artist]

The venturi principle described above is exclusive to a closed system, or pipe. Half of this "pipe" is open to the atmosphere, so different rules apply.

Hey Ez,

Sorry, I'ma not tryin' ta "hound" ya about this
...but, still thinkin' about "if" a "closed system" is absolutely required, for the Venturi effect to occur
&
Wasa thinkin' that the "wind funnels between tall buildings" example, used in the description
1.) is not in a closed system
2.) high wind speed does not seem to be required, for the effect to occur

The Venturi effect is a phenomenon where a fluid’s speed increases as it travels through a constricted section of a pipe. This increase in velocity results in a simultaneous decrease in the fluid’s static pressure. The principle is observable in various natural and man-made environments, from the way wind funnels between tall buildings to its use in complex machinery.
&
The mechanics of the Venturi effect are illustrated using a Venturi tube, which has a wide entrance that narrows into a constricted throat before widening again. To maintain a constant flow rate as fluid passes through the smaller throat, its velocity must increase.

This relationship between velocity and pressure is explained by the Bernoulli principle. The principle states that for a fluid in motion, an increase in speed occurs alongside a decrease in pressure. In the Venturi tube, the highest fluid velocity and lowest pressure are therefore reached within the throat.

This can be visualized as a crowd moving down a hallway that narrows to a single doorway. Each person must speed up to pass through the constrained opening. Similarly, fluid particles accelerate through the throat, causing a drop in pressure. After the throat, the tube widens, allowing the fluid to slow and its pressure to increase toward its initial level.
&/also,
Think of a leaf floatin' down a stream
...& when "it" encounters a narrowed section, of the stream "it" speeds up
...while "passing thru" the narrowed area (throat)

Same with a Kayaker in a river
...just on a bigger scale

All (3) of these examples (people, leaf, kayaker)
...are not in closed systems
...& high speed does not seem to be required, for the effect to occur...either

 

[Functional Artist]

While the paint wasa dryin', I did another (rep) 20 min of sandin'
...& then, went up on the roof ta access the damage

I've been "puttin' it off" 'cause of 90+* temps
...then, the smoke
&
I've also, been kinda of obsessed with this EA racer

This is what I found

This panel is "trash"
...& that piece of cap is too

The smaller panel, further away in the pic, seems to have gotten damaged too

It's not all of that bad
...the edge got a little bit bent
...& some scuffs & scratches
But,
My father always told me "if your gonna do something...do it right"

So, yea, it's gotta go

Panel replaced
* Theys a bit dirty from storage
...but, I'ma countin' on the next rainstorm ta "wash 'em off" for me

 

[Functional Artist]

More sandin'
...& markin' "bad spots"

Then, went ta working on, installing the shelter roof extension brackets

Another view

Yup, it now "dumps" right into the gutter

 

[Functional Artist]

After "tons" & "tons" of sandin' & smoothin'
...I'ma movin' on ta "fillin' holes"

Lots of holes

They are frickin'...everywhere

 

[ezcome-ezgo]

FA, the venturi principle you describe is 100%, and I am not trying to debate it. What I am suggesting is perhaps best illustrated: If you take a funnel (which is not unlike the underside of your delightful project here) and you pour - say - oil into it. But you pour it too fast and what happens? It overflows. The air rushing into your under-vehicle funnel will follow the path of least resistance, which is not rushing through a narrow opening. I am not a scientist, so the explanation of my point is being made poorly.

 

[Functional Artist]

Hey Ez,

I really appreciate ya helpin' ta expand on this discussion
...for me & for everyone else too
&
I think we are mostly "on the same page"
&/so
I gots some more jabberin'

Your first illustration
I agree, the Intake can't be too big, as compared to the Throat (or bottleneck) (kinda like what the jet does in a carb)
...or (as you describe) the (funnel) will overflow (or the engine will run too "rich"&/or "flood" the engine with fuel)

Your second illustration, seems to be describing the effect (I'm hopin' ta get from) of the Expansion Tunnels

I did some drawin' too

Some folks might not realize that
1.) the bottom of the racer is (2) separate (left & right) Venturi Tunnels
2.) the Intake is 2D (2 dimensional) (~2" tall throughout)
...while the Expansion Tunnels are 3D (3 dimensional) (going from ~4"t at the front thru ~10" at the rear)

I drew up an illustration of the left Air Channel

Notice the "channel" is ~8"w x ~2"t at its Intake
...then, narrows to ~2"w x ~2"t at its Throat
&
Then, it starts to expand to ~4"w x ~2"t at the opening of the "base" Tunnel
...& continually expands to ~6"w x ~5"t at the end of this "base" (or intermediate section) of the Tunnel

If/when, we add the Tunnel extensions
...the Tunnels will then, continually expand from ~6"w x ~5"t
...up to ~8"w x ~10"t
...while exiting out the rear of the racer

Top view

Side view
* Also, the front of the racer is ~3" off the ground
...the top of the Air Channels are ~4" off of the ground

So, there is ~1" of available expansion area, before the flowing air gets to the Throat
...& then, the expansion level "explodes" after the air flow "gets thru" the Throat

* So, the "trick" is to figure out the proper "metering" (Intake vs. Throat vs. Exhaust Tunnels)
...so, we don't "overflow" the funnel

Also, most Venturi Tunnel are illustrated as symmetrical
...but, I'ma thinkin'/it seem like an asymmetrical system may actually "work better"

Because "if" the Intake is smaller than the exit
or
Having a larger exhaust, than intake
...may help or enhance the "suction" effect

 

[Functional Artist]

the "trick" is to figure out the proper "metering" (Intake vs. Throat vs. Exhaust Tunnels)
...so, we don't "overflow" the funnel

I should have included "volumes"

The "Air Channel" is ~8"w x ~2"t at its Intake (~16 sq. in.) of volume
...then, narrows to ~2"w x ~2"t at its Throat (~4sq. in.)
&
Then, it starts to expand to ~4"w x ~2"t (~8 sq. in.) at the opening of the "base" Tunnel
...& continually expands to ~6"w x ~5"t (~30 sq. in.) at the end of this "base" (or intermediate section) of the Tunnel

If/when, we add the Tunnel extensions
...the Tunnels will then, continually expand from ~6"w x ~5"t (~30 sq. in.)
...up to ~8"w x ~10"t (~80 sq. in.) of volume
...while exiting out the rear of the racer


So, currently "we" have ~16 sq. in. of volume, coming in thru the Intake
...that will be "compressed" down to ~4 sq. in. at the Throat (a ~4:1 reduction)

Then, that ~4 sq. in. of volume starts to increase to ~8 sq. in. at the beginning of the tunnel (a ~2:1 increase)
&
Then, it continues to increase to ~30 sq. in. of volume, at the exit, of the Tunnel (a ~3.75:1 increase)
&
Then, "if" we add the Tunnel extensions
...the volume will increase from ~30 sq. in. up to ~80 sq. in.
...that is going out of the Exhaust Tunnels (a ~2.5:1 expansion)

So/basically, we have
...~16 sq. in. reducing down to ~4 sq. in.
...for a ~4:1 reduction ratio
&
Then, from ~4 sq. in. increasing up to ~80 sq. in
...for a ~20:1 expansion ratio

 

[Functional Artist]

I think (I hope) I'ma about done sandin'
...top, bottom, sides, nooks-n-crannies...everything

So, after some clean up (dust management & removal)
...I "blackened" the under workin's

Really "highlights" them Air Channels

Whilst the paint dried, I cleaned out the gutters on the garage

All spic-n-span

Also, added a light to my shelter/work area

Another view USA...USA...USA