Quote:
Originally Posted by JulianEdgar
When you can point to the aerodynamic testing you've done, and be able to compare that to your guesswork, we can have a discussion about the relative merits. Otherwise...
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I did have friends photograph Spirit from a chase car, while undergoing tuft testing at 100-km/h on a local highway. Those images were published here many years ago. Those may be of interest to some.
The T-100 with aero add-ons, including the inflated boat-tail was tuft-tested and photographed by John Gilkison from a cliff-side overlooking the highway near his home in New Mexico in the early 2000s, and posted here.
The 1970 Volkswagen Transporter was my senior project at Texas Tech. The particulars of that are in my unpublished 'thesis'. 27 mpg @ 55-mph, went to up to 35-mpg @ 55-mph, only aero mods and steel radials. Ala 'Crisis Fighter Pinto.'
My dad photographed tuft-testing of the Dodge D-100 pickup project from an overpass in Lubbock, Texas back in the the late 1970s. Those photos were also published here.
In 1990, after setting a land speed record at Bonneville in 1989, I assisted Kenny Lyons in getting a scale model of his record BMW-powered motorcycle streamliner tested at Texas Tech University's College of Mechanical Engineering's scale wind tunnel. It was there and then that Pat Nixon, Graduate Student Advisor, turned me on to a recent SAE publication on flow imaging and the $1,100 ( US) smoke generator used in their lab, which complemented tuft-testing, water tunnel, and water tank testing. Smoke was the only technology which allowed visual observation of vorticity, with any ease or accuracy. I 've been 'sold' on smoke ever since.
The 1984 ITworks CRX HF set a USFRA land speed record at Bonneville in 1990. All data from the California Timing Association, official timers of the FIA. Speeds are accurate to over 5-decimal places. Fuel economy data was from 'tank' mileage. Texas, to Bonneville, to California, and back to Texas @ 55-mph. ( 430,000 mile data base recorded for this vehicle ).
The 1984 ITworks CRX HF was then fee-tested at the Chrysler Proving Grounds, East Chelsea, Michigan, by third-party technical staff of CAR and DRIVER. Data reduction supervised by Technical Editor, Csaba Csere. Top speed was verified on the 8-mile oval. Coastdown testing was conducted to SAE specifications, on a tree-lined testing grounds track dedicated for that specific purpose. Skidpad testing was conducted for free. C&D brought their own weather station with them, for continuous air density monitoring during testing.
Glen Scharf of the General Motors Aerodynamics Laboratory helped me reverse-engineer a Cd 0.235 from the Bonneville, tank mpg, and proving ground data. The CRX was designed to the 'template' specification.
'Spirit' as you know, is a work in progress. One of the racing teams at Bonneville provides an on-line calculator for top speed. With the numbers from the first DARKO outing, SPIRIT is estimated at 128-mph terminal velocity. She's returned as high as 39.9 mpg on three occasions out on the open road. We have a record of all fuel consumption for the truck since day-1, when purchased new in 1994 by John Gilkison ( aka Aero Stealth ).
The second trip provided additional data for SPIRIT, as well as 'baby' the 1/3rd-scale model of the 'template.' Cd 0.1201. At under 4-sq-ft frontal area, compared to 29-sq-ft for SPIRIT', I'm unsure if 'baby's' blockage-ratio would enter into the calculus of this 'tiny' wind tunnel.
With $144,000 worth of Honeywell load cells below the floor measuring strain, their accuracy might just eclipse something I might attempt to accomplish with shade-tree engineering practice. Especially over different days of testing.