Baby template car for DARKO 2016

[Xist]

When did you get your first crack on this windshield?

[freebeard]

...Bonneville speed run...

Do go on.

[gumby79]

Originally Posted by Xist

When did you get your first crack on this windshield?

3winters ago. This will be the 4th curent count is 8. 1 with it on 2 this week aftre removing the bug shield.


Pavement is 92.5mph with or without my Aero Tonto . Governor is set for 2500RPM x .69 OD x 3.55 R&P x 31.7" tire =96mph minus torque converter slip. =92.5 MPH (GPS ) 95 gage.
Time trap confurms the neaddle was installed 2.5mph high , error is 2.5 at all speeds.

[freebeard]

Without a functioning odometer and with an optimistic speedometer, the most I got out of the trip was that the left lanes are 5-6mpg more expensive than the right lane.

Data-wise. The after-party in the motorhome was priceless. And name-dropping Ben Davidson.

[aerohead]

*Total trip miles,4,687
*Total fuel consumed,147.324 gallons
*Average trip fuel economy,31.814 mpg
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*3,418 miles @ 65 mph maximum = 32.798 mpg average
*1,269 miles @ 70 mph maximum = 29.435 mpg average
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*Total all-up travel weight = 4,280- lbs
*Front axle = 2,280-lbs
*Rear axle = 2,000-lbs
*Weight distribution,F/R,53%/47%
*Frontal area 29.0 sq-ft
*Cd 0.345 (from DARKO)
*CdA 10.005 sq-ft
*Front downforce @ 65 mph,22.7-lbs
*Rear lift @ 65 mph,48.8-lbs
*Projected fuel economy with GDI,37.717 mpg
*Projected fuel economy with Diesel TDI,42.637 mpg
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Spirit 'EV',cab/bed gap sealed,Dodge Viper windshield/cowl block:
*Cd 0.297
*Cd 0.287 'camera' truck (mirror delete)
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Component drag measurements:
*Dodge Viper windshield & cowl-block, -Cd 0.005
*SCCA race mirrors (2), +Cd 0.010
*Features drag (cut lines,small gaps) Cd 0.000
*Truck cab/bed gap, +Cd 0.016
*Cooling system, +Cd 0.027
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Baby Template car:
*Uncorrected drag force measurements @ arbitrary 3.0 sq-ft frontal area,(Long-tail)produce
--------------------------- Cd 0.132
--------------------------- Cd 0.150
--------------------------- Cd 0.139
--------------------------- Cd 0.1403 average
*Uncorrected short-tail measure
--------------------------- Cd 0.1725 average
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Measurements corrected for actual 3.4795 sq-ft frontal area produce
--------------------------- Cd 0.1209 average,long-tail
--------------------------- Cd 0.1487 average,short-tail
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Baby's road load aerodynamic power requirement @ 200-mph = 26-hp
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Spirit with Baby's body,@ 65 mph:
*43.493 mpg
*50.017 mpg with GDI
*56.541 mpg with Diesel TDI
*130.479 mpge with EV drive
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Remarks:
*The T-100 has never achieved over 30 mpg without some sort of tail.
*I couldn't finish what I started,so I tested what I had.No tail.
*Almost all of the belly was missing.
*The new hood blister additions and aero-shell side fairings appear to have helped compensate for the lack of belly and boat tail.
*If Elon Musk did an EV pickup with aero shell,it would be easy for him to see Cd 0.22.
*I'll try for a return trip in 3-years to finish the Spirit project.
*Baby has 'real' tires and place for taillights and license plate,unlike Jaray's,Lay's,Kamm'/Fachsenfeld's,and Buchheim's pumpkin seed models.
And while she's not as low drag as Cambridge University's CUER (Cd 0.11),she would represent a D.O.T.-legal design.
*It looks like the 1994 Accord,with Baby's body would handily do 32-mpg @ 100 mph,or 100 mpg @ 55 mph.
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My brother has suffered perhaps an irreversible disability from an adverse reaction after receiving an immunization from Kaiser Permanente.He shot smoke-flow video of Baby at DARKO,but I'm not gonna bug him about it until we find out his long-term prognosis.
PS
AeroStealth posted a 15-minute video about Baby on You-Tube.If you're not familiar with this project it will help bring you up to speed.
Thanks again to Gumby79 and Freebeard for all the helping hands at DARKO.I feel like we got a lot accomplished in a limited amount of time.

[Merlyn2220]

If I'm reading the truck data correctly:

Cd = 0.435 with everything and the joints taped up on the bed cover (aka Tonto)
Cd = 0.458 as above without the tape (+5.3%)
Cd = 0.357 removed the bug deflector (-22.1%)
Cd = 0.338 removed the air dam (-5.3%)
Cd = 0.450 stock (no Tonto, bug deflector, airdam) (+33.1%)

Is that an accurate summary of the truck data? I ask because there's a prevailing sentiment that the front end geometry isn't as important as the rear end geometry. I recall reading a post about Bonneville testing where they said that extensive front-end changes made little to no difference in speed. The bug deflector seems to be a huge hit to Cd performance, negating the advantages of all the other aero details. So clearly the front end matters a lot. I wonder how bad it is with the bug deflector and nothing else...

Maybe the right way to look at front vs rear is, "don't do anything really bad on the front, or you'll lose all the work you've done on the rear."

[aerohead]

Originally Posted by Merlyn2220

If I'm reading the truck data correctly:

Cd = 0.435 with everything and the joints taped up on the bed cover (aka Tonto)
Cd = 0.458 as above without the tape (+5.3%)
Cd = 0.357 removed the bug deflector (-22.1%)
Cd = 0.338 removed the air dam (-5.3%)
Cd = 0.450 stock (no Tonto, bug deflector, airdam) (+33.1%)

Is that an accurate summary of the truck data? I ask because there's a prevailing sentiment that the front end geometry isn't as important as the rear end geometry. I recall reading a post about Bonneville testing where they said that extensive front-end changes made little to no difference in speed. The bug deflector seems to be a huge hit to Cd performance, negating the advantages of all the other aero details. So clearly the front end matters a lot. I wonder how bad it is with the bug deflector and nothing else...

Maybe the right way to look at front vs rear is, "don't do anything really bad on the front, or you'll lose all the work you've done on the rear."

Layne printed the entire data set for me.So here's a stab.
Looking at the raw data,the changes reflected:
*Taped gaps = delta 3.03%
*Bug deflector delete = delta 14.92%
*Airdam delete = delta 2.79%
*Tonto delete = delta 15.34%
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From worst-case,to best-case,there was a 15.35% delta CdA,using 36-sq-ft frontal area and the reported Cds of 0.7815 vs 0.6615.
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The Chevrolet C-10 from the same era was reported @ Cd 0.535 if you reverse-engineer from the 1986 body-in-white C-1500.The JEEP Comanche pickup was Cd 0.55.Some messengers will have you just estimate Cd 0.50 for this time period,as these values weren't offered freely in the press.
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Gumby's Dodge shares some of the liabilities that my '62 has.Erupting windshield weatherstripping, inset side glass,plus exposed rain gutters,and windshield header overhang conspire to frustrate attached flow around the greenhouse area.
The mid-80s new truck designs addressed these shortcomings.Cd 0.55 goes to Cd 0.45,then to around Cd 0.35 for today's RAM 1500 with tonneau and grille-shutters.The GM Holden Ute of late is Cd 0.309 ( more Ranchero/El Camino than a 'real' pickup).
To your point though,Hucho would probably tell you,that for passenger cars,as of the mid-80s,there was little low-hanging fruit with the forebody.The real action was in the aft-body.
Gumby's Dodge and most pickups would be an exception.
And it's a good idea to look at the drag index as well as the Cd when evaluating changes.

[freebeard]

The thing I took away from the control room was the difference between the Dodge, which bucked and quivered against the restraints at 80mph, vs the T-100 that just sat there.

I hope your brother is Okay.

[sendler]

Still asking what the difference in length is between Baby with long and short tail?

[ennored]

Originally Posted by sendler

Still asking what the difference in length is between Baby with long and short tail?

It's above:

Measurements corrected for actual 3.4795 sq-ft frontal area produce
--------------------------- Cd 0.1209 average,long-tail
--------------------------- Cd 0.1487 average,short-tail

Drag went up 23% without the full tail on it.

Unless I'm reading something wrong?