[aerohead]

Weather forecasters predicted decent weather for May 26,so I took advantage of the weather window in between tornadoes.
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The Viking was road worthy again,although with pre-existing damage from the December 2009 wreck.
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Test weight was 4,570-LB, within 1% of December,2009.( 1,250 LB over orig. curb weight).
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I performed a 20-mile warm-up @ 60 mph ( 2-miles short of SAE recommendation) then headed for LOVE's Travel Stop,elevation 703-feet,PUMP#7 to top-off the tank.
* Weather:CLR, 70 F,RH 55%,Baro. 30.03",wind north @ 7 mph ( headwind)
* I departed northbound,accelerated to 65 mph on I-35 and cruised at a steady 65 mph until road construction forced traffic down to 62-63 mph for about 10-miles.
* I exited at Oswalt Rd,# 21,elevation 1,053', @ 52 miles out,stopped,made the U-turn,and re-accelerated into the construction traffic,southbound,with a 9 mph tailwind,then gaining to 65 mph as we left the construction area.
* At Milam Rd. I made the exit.Stopped.Crossed the bridge to LOVE's,exited into their driveway and drove back to PUMP#7 to top-off.
* At 104 miles for the round trip the T-100 took 3.128 Gallons to fill to top of filler neck,with fuel standing motionless at the top.
*Weather @ end-of-test:CLR, 75 F,48% RH,30.00",wind north @ 9mph.
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* Mileage works out @ 33.24 mpg @ 62 ave.moving speed ( GARMIN Nuvi 1300),4.321 mpg higher than December,2009.
* Seasonal mileage gain was predicted be 31.497 mpg.
* I believe the 1.743 mpg discrepancy owes to the new nose airdam mod ( which gave me 'boat-tailed' mpg on last September's trip to Bonneville and RENO).
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* @ 33.24 mpg the Cd vs MPG relationship yields a drag coefficient of Cd 0.242.
* However,the extra 1,250 Lb would create an approx. loss of 1.5 mpg owing to the additional R-R.
* Allowing for the added weight,the Drag coefficient would have to be Cd 0.198 to explain the 33.24 mpg at 37.65% overweight.So Cd 0.198 seams reasonable.
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* Presently,the gap has a wake turbulence volume of 45 cubic-feet( approx. 41% of total wake volume)
* According to Hucho and Chevrolet Truck Division of General Motors Corp.,the 'gap' is responsible for a 19%-20% drag increase.
* Abbott and Von Doenhoff show a mid-chord slotted Clark-Y airfoil at a 23.5% drag penalty.
* The science suggests that the gap-filled trailer will have about Cd 0.159 and 34.56 mpg ( gasoline)
--- 38.36 mpg ( Diesel )
--- 40 mpg ( TDI )
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*If I restore the bellypan diffuser with tire fairings the mpg should go up
* If I repair the broken fairings on Viking the mpg should go up more
* If I complete the leaf-spring fairings the mpg should go higher
* If I fair in the truncation for Bonneville we might see Cd 0.12,as did MG EX -181 and Solaraycer.
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I will do a tuft test and photos as the trailer is configured at present for later comparison as mods evolve.
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It appears that the science supports the notion that the gap-filled trailer will ADD mpg when pulled.Viking is over-length and over-weight as a pop-up camping trailer.If reduced to simply a streamlining add-on device at minimum weight,the concept should register a net gain when pulled.We hope to demonstrate this with the Prius project.If I actually make it to the Salt Flats and not blow the engine,the top speed data,plus trip mpg data should be another way to verify the drag coefficient.We'll see.