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

[aerohead]

Originally Posted by gascort

Phil, I really love the literalness of the BOAT TAIL! Neat project.

Yeah,and it eventually dawns on you,that any current boat-maker could be manufacturing really low-drag composite trailer bodies.

[aerohead]

Al scanned 4-images of the trailer project for me.The tail is already out of date as I got 6.5 hours in on it last Sunday.I'll get pics of that soon.--------------------------------- The outline is basically defined now in steel.After final welding I can begin to add skin to nose,belly, and sides, as well as panel in the new 22-degree Mair tail.I've run plumb-bobs,levels,straight-edges and protractor over the whole thing.Nowhere does the geometry of the body exceed critical angles.-------------------- The exit wake comes in at 1.4-square feet compared to 29 for the standard truck.Flow was clean with the boattail,so should be clean coming onto the trailer body.------------------------- Everything else gets fairings.--------------------------- The numbers are getting scary.I've been turning over every rock I could find to find supporting research in fluids to help extrapolate what the crazy thing might do.Even if I do very conservative doubling of Cds for axle,wheels,leaf-springs,the truck/trailer combo comes in below Probe-V,and by a margin.------------------- Road load at 70-mph is 19.369-horsepower compared to 43.413 for the T-100.---------------------- September seems to be racing at me.Time will tell what sort of state-of-completion I achieve by roll-out.----------------------------------- Sorry! I've used my 1.10MB of space and no capacity for any more attachments,so it may be another week before I can get help.

[Big Dave]

With the economy the way it is a lot of boat builders are sitting around because boats aren't selling. You'd think they'd be amenable to a bit of product diversification.

[aerohead]

Originally Posted by Big Dave

With the economy the way it is a lot of boat builders are sitting around because boats aren't selling. You'd think they'd be amenable to a bit of product diversification.

Yeah,I'd be turning over every rock to keep my workforce busy.And with their "wet-look" gel coats and fabulous craftsmanship,these folks could remake their industry.Probably SBA grant money from DOE available too for MPG-related products.Weird!

[aerohead]

Al's busy so I'll tap the keys with additional netsam.Hope to have photos up shortly.----------------------------------- I've been turning over many rocks for the "science" of trailers,and there is nothing so far in the public domain for what I'm attempting but let me share some of the things I've come across to explain the trailers theory of operation: (1) the trailer shape is matched specifically to that of the towing vehicle. (2) there is no drag-creating "distance" between the vehicle-trailer combination. (3) there is no frontal area penalty due to the trailer's symtechotic( symbiotics of machines?) full-draft,wake-filling architecture. (4) there is no trailer nose aerodynamically-induced pitching moment to affect vertical tow-bar loading. (5) trailer leading-edge radii are increased to infinity,as they forward across the gap-filler bridge,continuing along the flanks of the towing vehicle all the way to the vehicle's nose,prohibiting trailer-nose-induced yawing moments during crosswind driving. (6) the "full","air-tight" articulated gap-fillers eliminate interference-drag between vehicle-trailer,customarily found in conventional "gap" configurations by providing a unitary and un-broken continuous flow support surface from the tow-vehicle nose rearward to the trailer tail. (7) The unitary configuration allows all the benefits of "slipstreaming," "draughting," "drafting," "formation-driving," and "convoy-driving," reducing drag of both the towing vehicle as well as the trailer. (8) the "pumpkin-seed" form achieved by the vehicle/gap-filler/trailer combination virtually eliminates profile drag ( form-drag ) by preventing any aftbody boundary-layer flow separation-induced turbulent wake formation. (9) the remaining 5% wake area obviated by the inclusion of tail lamps and license plate establishes the "phantom-wake" boat tail terminus,as reported on by Kamm,Korff,Morelli,Heinkel,Arado,etc.. (SUMMARY) The gap-filler/full-boat-tail trailer combination provides one avenue to explore the far reaches of the low-drag universe and energy efficiency obtainable when drag coefficients approach orders of Cd 0.12 in the real world.

[aerohead]

Al's still busy so here's some quanta on the trailer at 89.5 man-hours into the project: [ Height = 43-inches (1075mm)], [ Width = 72-inches (1,800mm )], [ Length = 139.75-inches (3,439.75mm)], [ Frontal Area = 12.363-square feet (1.144 square meters)], [ Fineness-ratio (gross) = 3.25:1, 1.625:1 (free-air).---------------------------------------- Drag (pounds force at 70 mph) as estimated from Technical Aerodynamics,Wood: (a) faired axle = 0.69825, (b) faired wheels = 4.028, (c) faired leaf-springs = 1.113, (d) inverted-reversed hull with Mair' 22-degree boat-tail addition = 16.998.------------------------------------------- Total aerodynamic drag force at 70-mph = 22.837 pounds * ( this is for the trailer going through the air by itself with no vehicle in front,or in a wind tunnel by itself )--------------------------------------------- Rolling Resistance Force of trailer @ 500-pound design weight,70-mph,bias-ply 50-psi tires (4.80 X 8 ),from F= [ 0.0148 w + 0.000442(v-66)w] = 7.40 pounds.------------------------------------------ Total drag of trailer ( aero and RR) = 22.837 + 7.40 = 30.237 pounds at pull-bar.------------------------------------NOTE: A 65% "weight gain" to the CRX cost 2-mpg on the highway.The FrankenViking constitutes a 15% weight gain to the T-100.------------------------------------------------------------- Drag coefficient,T-100 ( with present kit) Cd 0.235(estimated from GM Aero Labs protocol.Drag coefficient of T-100 pulling a "conventional trailer, Cd 0.156 ( from Hucho: NASCAR-draft research.------------------------ Drag coefficient of FrankenViking, Cd 0.128,as per Technical Aerodynamics protocol and doubling Cds for ground-effect. Drag coefficient of FrankenViking as a "towed" structure, Cd 0.051,as per Hucho.----------------------------------- Presently the T-100,without boat tail,has a clean exit aperture of 59% Af,about 17.12 square-feet of turbulent wake.The addition of gap-fillers and trailer reduce the wake area to under 1.5 square-feet,a 95% wake reduction compared to the stock T-100.----------------------------------------------- The original Road Load Horsepower for the T-100,at 70 mph is approximately 43.413-HP at the drive wheel.With the gap-filler trailer,the road horsepower is estimated to drop to 21.997-horsepower ( 50.67% of original power).------------------------------------- If fuel consumption follows road load power,then the addition of streamlining package and gap-filler trailer theoretically could translate into a 50% mpg improvement at 70-mph over the stock pickup,perhaps 36-mpg interstate/38-mpg HWY.Barring the unforeseen,I should know something by mid-September.

[aerohead]

I've got some pics of the trailer I'll try to post today but wanted to put this up first.I posted this also at the aerodynamic template thread. The photo was taken a couple years ago.What's important to the trailer project,is that the articulated gap-fillers take the place of the boat tail,providing the "bridge" between the truck/trailer( 20% drag for a conventional trailer ).---------- Theory suggests that if the flow can follow onto the trailer without separation,and then continue to the end of the boat tail,then there will be no wake.--------------- From the photo,you see fully attached flow to the back of the boat tail.That's all you could hope for.With the streamlining kit and trailer,the wake is reduced from 29-square feet,to 1.5-square feet,a 95% reduction.

[aerohead]

Here are a few recent pics of the trailer.Remember that the nose will be "enclosed" within the gap-fillers.Space frame will be paneled with foam and glassed.Seven fairings.

[aerohead]

I pulled the rig up to nearby cul-de-sac for critical measurements,as I have no concrete surface to work off of yet.----------The startling thing was that I couldn't see any of the trailer.That's a good thing aerodynamically,it was the entire premise for the project.But it gives you the Willies not being able to verify it's presence.---------- So I'm cutting into "poco loco," the boat hull which has been serving as the bedcover for the T-100.I'll create a rear windshield,have already cut away for the side window,and will restore the alcove for the 3rd brake light at the back of the cab,all of which I had in the original shell which has gone to sleep with the goats.---------- Also,I'm going to add a rear dorsal fin and integral red running light to the trailer tail so I'll have a "glimpse" of the silly thing while pulling it.The fin will also help balance crosswind gust loads.------------ Welding is nearly complete.I'm on my second spool of wire.The frames for the side gap-fillers are created,as is the integration-frame which sits where the tailgate normally resides.---------- I was able to recycle the Viking's fiberglass fore-deck which will now make up the tails bellypan section.-------- The fiberglass fairing for the axle is ready to be bonded.----------- Paper patterns have been printed for the leaf-spring and wheel fairings.I will use cedar wood skeletons with attachment hardware already set which receives Styrofoam cut to form and glued on.After shaping these get spar varnish polyurethane blocking to allow for polyester-based body filler( BONDO) and later one layer or fiberglass cloth and resin.These will bolt through the bellypan with large fender washers and nylon locking hex nuts.------------- I installed a swing-away landing gear with wheel and welded in a spare tire mount,both to get some extra tongue weight.------------------ I'm buying brand new wheels and tires and will see about spin-balance for the little donuts.I will drill and tap the wheels in the bead area for attachment of the MOON covers.I will also run inner wheelcovers,they're composite,cast inside a MOON.------------- Some fiberglass hull will be recycled for the trailer body.Some of the body will be formed from R-MAX polyisocyanurate rigid foam insulation board from The Home Depot.These panels will get smothered in fiberglass.-------- I've purchased the lighting kit.-------- Bits and pieces are falling together.I'll get photos up when there is something to show.

[aerohead]

The new wheels and tires were deflated,metal valve stems and caps installed,then were spin-balanced using stick-on weights so the MOON covers will fit flush to the wheels.------------ I purchased a drill,tap,and special socket-head machine screws to attach the covers.------------ The T-100 has been pulling to one side.I had the alignment done this morning and we've determined that the tires are separating from pothole impacts( thanks Texas!).---------- I've ordered a set of "racing" tires for the truck.I'll be out of town early week and hope they come in for install next Saturday.The tires are from Hancook (sp?),are 215 70 HR 15 and will fit the OEM Toyota wheels.---------- I'm going to go for the 130-MPH Club,with USFRA next year at Bonneville and also see about running the trailer either at the Salt Flats or El Mirage Dry Lake,Cailifornia with SCTA.----------- The T-100's top speed is estimated at 138 mph @ sea level,she might do 130 @ Bonneville's 4,500 feet elevation.---------- The bellypan superstructure may qualify for the forward 25% driveshaft containment loop,if so,with 5-pound fire extinguisher,and new Snell-Approved helmet,I'm good to go.------------ I've cut enough of "poco-loco" away now,that I have very good side and rear vision.I've also measured for the dorsal fin height and have figured the tail for lights so I will know it hasn't gone off to Kansas without me.----------- I installed forged-steel eye-bolts either side of the hitch ball to secure the safety chains.------------ I'll be juggling multiple operations to pull everything together on time.I've only one remaining weekend to work on the project which means evenings after work each night I'm in town.My biggest challenge yet.------------- Should the silly thing perform,I might see 36-Interstate,38-HWY.-------------- I'll try and get some photos posted,but "chaos" factor might delay that 'til after trip.I want to be rested when I leave and I'm going to need every spare minute I can get.More later Phil.