Full-boat-tail trailer with gap-fillers for Toyota T-100 pickup

[groar]

Originally Posted by aerohead

KB,it's just a baby.
It was a 3-sheets of plywood project with 3-sets of professionally fabricated constant-area turning-vanes and a recycled 115-VAC HVAC air-handler embedded inside,on casters.
It is a full-recirculation type with open nozzle/test-section.
She produces a 'wind' of only 23-mpg ( 37 km/h ) and can't even produce proper Reynolds number.
It does give you a clue though with tuft-testing and the 'students' love it.
Some 'jump' when they try to hold a parachute against the airstream! Fun.

Sorry to insist on this subject (may be a dedicated thread could be great )

What are the size of the plywood sheets ?
What is the ratio of reduced models you can test in ?
What is the wind speeds you can simulate ?

IIRC : Lets say these are 4x8 feet sheets. You can have reduced models inside 1x1x2. For a 6 feet wide car, this is a 1:6 ratio for the reduced model. Such ration need winds 6 times faster than the 1:1 ratio, so the 23mph is simulating speeds of 4mph.

Don't hesitate to correct me

Denis.

PS Thanks a lot for all the information you share on this forum.

[aerohead]

Originally Posted by groar

Sorry to insist on this subject (may be a dedicated thread could be great )

What are the size of the plywood sheets ?
What is the ratio of reduced models you can test in ?
What is the wind speeds you can simulate ?

IIRC : Lets say these are 4x8 feet sheets. You can have reduced models inside 1x1x2. For a 6 feet wide car, this is a 1:6 ratio for the reduced model. Such ration need winds 6 times faster than the 1:1 ratio, so the 23mph is simulating speeds of 4mph.

Don't hesitate to correct me

Denis.

PS Thanks a lot for all the information you share on this forum.

Denis,I'm having trouble with the SD card in my camera.As soon as that is resolved I will capture some images and post in a separated thread.
I don't like to rely on memory any longer,but here are some data about the tunnel which are accurate:
* 3- 4-foot by 8-foot sheets of 13mm plywood were used in the project,two to form the sides,and third,plus cut-offs to cap it off.
* I'll get accurate dimensions for nozzle and return inlet.
* no drag force measurements can be produced,only flow visualization.
Al's closing shop,will catch uo asap,Phil.

[KamperBob]

Originally Posted by groar

Sorry to insist on this subject (may be a dedicated thread could be great )

What are the size of the plywood sheets ?
What is the ratio of reduced models you can test in ?
What is the wind speeds you can simulate ?

IIRC : Lets say these are 4x8 feet sheets. You can have reduced models inside 1x1x2. For a 6 feet wide car, this is a 1:6 ratio for the reduced model. Such ration need winds 6 times faster than the 1:1 ratio, so the 23mph is simulating speeds of 4mph.

Don't hesitate to correct me

Denis.

PS Thanks a lot for all the information you share on this forum.

Dittos!

[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.

[euromodder]

Keep up the good work, Phil !

[MetroMPG]

Phil - nice results. I think it would blow most "regular" folks' minds to noodle the concept of pulling a trailer that can increase overall fuel economy!

Looking forward to seeing your gap-filler ideas on this & the Prius trailer.

Darin

[orbywan]

Neat project Phil, I just found this thread. Do you have any updates on it? How did it do for mileage? You should have told the guy's wife, if you're worried about looking a little strange, don't mess with aerodynamics.

[orbywan]

Opps! I posted this above before I realized I wasn't at the end of the thread. Still getting the hang of navigating.

[aerohead]

The good news: Al is swamped with work here at Copy Pro,and it will be a profitable summer for him.
So it will be next week before I can post the schematics for the gap-filler mechanism(s).
My workmate has a 3-week European music gig with the Blues Brothers Band coming up in 3-weeks so I'll have three straight weeks to do fabrication on the rig.I'll just stay home and weld and slam fiberglass.
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Also,I scoped out a high-rise fire escape on the old opera house building in Denton this A.M. and I think I can use it as a photographic platform for some plan view shots of the rig.I can't get directly above the thing,but everyone should be able to get a sense of that curvature from the T-100 onto the trailer when viewed from above.One of the members asked about this kind of photo.Hope it's okay.
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I continue to data mine my library for ancillary info.If I owned a Nissan Leaf,I know exactly what I'd do to it.
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PS I'll get the tuft study photos asap and post them as well.I just need some 'calm' weather.

[KamperBob]

Originally Posted by aerohead

The good news: Al is swamped with work here at Copy Pro,and it will be a profitable summer for him.
So it will be next week before I can post the schematics for the gap-filler mechanism(s).
My workmate has a 3-week European music gig with the Blues Brothers Band coming up in 3-weeks so I'll have three straight weeks to do fabrication on the rig.I'll just stay home and weld and slam fiberglass.
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Also,I scoped out a high-rise fire escape on the old opera house building in Denton this A.M. and I think I can use it as a photographic platform for some plan view shots of the rig.I can't get directly above the thing,but everyone should be able to get a sense of that curvature from the T-100 onto the trailer when viewed from above.One of the members asked about this kind of photo.Hope it's okay.
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I continue to data mine my library for ancillary info.If I owned a Nissan Leaf,I know exactly what I'd do to it.
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PS I'll get the tuft study photos asap and post them as well.I just need some 'calm' weather.

Phil, your fire escape perch for overhead pix got me thinking so I'll have to watch for similar photo ops. Perhaps the far side of the vehicle could be jacked so the roof is more normal to the camera. A high overpass and helper (one drive, one shoot) also springs to mind.