Baby template car for DARKO 2016

[aerohead]

Originally Posted by gumby79

Am I understanding correct?
1)
If there's no change in frontal aera the a-b comparison will both be skued the same amount? Making the % of change an acaccurate a-b test. But the actual CdA # would be illegitimate.

Eg. Leave the Headache Rack on for ab cap test (the red part ) because it adds 15*2" of surface. 114*2" aera.79*2'
This shot is from a slightly elevated angle making the increase look larger. The lower bar is below the cab . Ecept in the center its 1/2"T ×6" W above. With ~ 7°pinch for & aft . The 3"W ×1/8"T is dead flat to the air.

The plan is for this to have an air curtain affect. To settle the disturbance from the cab/ cap gap. A less functional more aerodynamic design,has been suggested by many people , would be to eliminate this cab protection feature.

2)the Dodge advertised CdA (have you beenable to locate one yet?not me )compaired to the DARCO naked. Would this yield a value to the amount of skue?
I think the anwser is :
A) there is a variant from tunnel to tunnel so not comparable


3)
The removal of the headache rack (red part ) would alter the %of blockage resulting in a different skue ? A naked test could not be compaired to a headache rack test(different Aera/skue)?

* The large frontal area creates local acceleration of the airflow to velocities which exceed the 'infinity' velocity of the tunnel (76-mph).
* This 'super-velocity' causes a thicker boundary layer on the truck,tunnel floor,walls,and ceiling,which chokes the flow causing buoyancy effects which can't be eliminated.
*It's this buoyancy effect which trashes all the data.
*There is absolutely no way to know how much the 'actual' values are being skewed.
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*With a constant frontal area,none of the coefficients can be trusted,and even with A-B-A testing the absolute numbers cannot be trusted.We'll only be able to see 'trends'. Which I think will still be valuable on their own.
* To complicate things,if you remove the headache rack,whatever numbers are produced must be taken in light of the lower frontal area.
*We can only say that the 'observed' overall drag went up or down.
*But that's valuable data in itself.
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* There are some published Cds and frontal areas from Dodge.I'll try and dig out what I have.
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*A 'naked' Cd from Dodge,compared to a 'naked' Cd at DARKO would be valuable.It WOULD infer an amount of 'skew'.
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* There IS a tunnel-to-tunnel variation in coefficients when a standard NACA-profile calibration model is tested from location to location.A number of tunnels have been evaluated,and a standard deviation has been established.
*Unfortunately,both the A2 and DARKO are too new to have been included.Same for Gene Has' new rolling floor tunnel.
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*As to the cab-bed gap,I'm gonna try and test,sealed,and 'normal' to measure any difference on the T-100.2-years ago,the smoke blew over the gap as if it wasn't there.I'd like to know what difference it makes.

[aerohead]

Originally Posted by freebeard

Let me try to make this on-topic.

On Saturday BRING had a 50%-off-everything sale and, among other things, I picked up two more wakeboard control arms, including the one that's 8ft long. I partially dismantled it and lashed it to the roof rack and bike rack. long enough to take some pictures. Their both now dismantlated down to the curved tubes.



It needs to set about 4" lower. Thinking about how to grip the external drip rail and transition to a round tube, I'm currently onto taking a piece of bicycle inner-tube and stretching it into the shape I need and injecting JB Weld into it to solidify the shape with a bonus rubber coating.

I have six in total and a plan that involves tabs in slots. So what I'm saying is if it takes a while to regroup and reschedule, that's good for me.

Could you steal,and reproduce the drip rail attachment design from the existing roof rack and use that to morph into the aluminum tubing ?
On the VW Bus I drilled through the rails,but I'd never recommend that.

[freebeard]

Thanks. I have three or four sets of roof rack clamps, but they all want to resist pull at right angles to the drip rail, not tangent to it. I'll drill eventually, probably for fender skirts or something. I want this to drop into the bike rack sockets and clamp to the drip rail. I could also lose the stock deck lid and use it's mounting points to be really solid.

Four tubes will define the DLO, two will lay along the drip rail and some extra straight pieces will bring up the rear. I've curved some composite panels for filling down to diffuser level. Possibly 18" extensions to a trailer hitch for the bottom since I have one.

Keep me posted on the rescheduling; I'm almost out of debt [again].

[aerohead]

Originally Posted by freebeard

Thanks. I have three or four sets of roof rack clamps, but they all want to resist pull at right angles to the drip rail, not tangent to it. I'll drill eventually, probably for fender skirts or something. I want this to drop into the bike rack sockets and clamp to the drip rail. I could also lose the stock deck lid and use it's mounting points to be really solid.

Four tubes will define the DLO, two will lay along the drip rail and some extra straight pieces will bring up the rear. I've curved some composite panels for filling down to diffuser level. Possibly 18" extensions to a trailer hitch for the bottom since I have one.

Keep me posted on the rescheduling; I'm almost out of debt [again].

I've got one more brake disc replacement/wheel bearing clean-pack just to get back where I was 12-days ago.I'll do that tomorrow,then I can get back to mods.I'll be into another income cycle before long,which will help.
Deadlines only seem to create unnecessary stress,so I'm gonna just work 'til I'm within spittin' distance of being ready, then we can talk to Layne at Darko and see what their schedule looks like there.
Gary has warned me about snow issues,since I'll be doing a bunch of mountain passes.Gumby's got to get in from Montana.No telling what you'll see comin' in from the Pacific NW! Wyoming got snow the other day!
Nobody needs to be sliding off the road.
And I don't want to really do any snow-plowing with the aero mods.
I'll see what I can get done over the next 2-weeks.It's a lot of time for fabrication if I don't have to back-track again.
PS I hope your brakes don't look anything like mine after Bonneville! I had to use a angle grinder with metal cutoff discs for an hour to separate the 1st disc from the hub. It looked like a Civil War relic dug up from Gettysburg!

[skyking]

Phil, if you don't make it this year, the upside is I may join you next year with beetle, kamm, trailer and wheel covers to play with.

[freebeard]

I hope that was a particularly bad year at Bonneville. If it was always soup like that nobody would ever come back.

My solution was to total it on black ice. The whole front end has been replaced. All said and done, it was probably the steering gearbox being bound up that let it get away from me. When I had the muffler replaced, that was as you describe.

Realistically, it will be spring before my boat tail is finished.

[aerohead]

Originally Posted by skyking

Phil, if you don't make it this year, the upside is I may join you next year with beetle, kamm, trailer and wheel covers to play with.

I'd like that,but I will probably skip next year to build up the budget again,plus maybe get that concrete,and some other small improvements done to the shop.
If you can wait,I'd like to join up then.
I could have the Insight up and running by then,and we could get a DARKO number for it,to compare to CAR and DRIVER's numbers from the A2 and GM wind tunnel.
That would help us understand more why Gary's Prius registered Cd 0.285.

[aerohead]

Originally Posted by freebeard

I hope that was a particularly bad year at Bonneville. If it was always soup like that nobody would ever come back.

My solution was to total it on black ice. The whole front end has been replaced. All said and done, it was probably the steering gearbox being bound up that let it get away from me. When I had the muffler replaced, that was as you describe.

Realistically, it will be spring before my boat tail is finished.

The worst I've seen was 1990,when the whole dry lake was under water.
But 2014 was really wet leaving out from the access road,with submerged moguls,which tore the diffuser off the truck.Oncoming traffic produced waves which really raised the water level hitting the mechanicals.
Layne said,this year,salt conditions were perfect.Thin,but perfect.
Black ice,gotta love it!
Don't set a deadline for yourself,for getting the tail done.It will be enough work by itself without the added stress of a clock and calendar barking at you day by day.
It will be fun to see at 'work'!

[aerohead]

All the brake issues are resolved.I had to cut the second disc off as well.She stops good,she no longer pulls to the left,and a 60-mph vibration went away,all due to the single warped rotor.I can't complain.Those were original rotors and calipers that failed at 22-years/396,000-miles of service.And they failed close to home rather than out on the West Coast or something.
I took a load a trash to our dumpster, and carried stuff to recycling on the way to town,and then ordered a new set of OEM-sized,215 75R/15 Hankooks for the truck once I got to town.
They said to check back after 3:00 PM today to see if they came in.
I need the tires on the truck to know about all the actual clearances around them.I'm going to use the foam floor padding material to tightly close the gaps around the tires,letting the foam ablate from tire scrub to produce the minimum gap.
I've got an idea about the 'hour-glass' openings around the steering wheels as well that I want to play around with.
The hood vents worked out,cooling-wise,although they may have disrupted the airflow.That will be something to test for at the tunnel.
So,it's back to fabricating and real mischief!

[freebeard]

From this point forward, if I invest in drums and/or rotors again, they will routinely be sent off to Cool Rotors for cryogenic tempering. I'm liking the result so far.

Have you seen the FiberFix ad where they roll the Metro down the 140ft cliff? I'm thinking I could use long-fiber body filler and wrap that with hemp tape for the joins. I have tab-and-slot scheme for inlaying the composite panel in the tube frame. The top panel might be redwood strips covered in fabric like an old woody.

You mention 'hour-glass opening' just after 'abating foam'. It will be interesting to see what turns up.