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

Hello all.I've had a little time to devote to the trailer project.The complex curves make it a challenge for me to visualize my goal so I did some primitive Photoshop work to help my pea brain.The image is from an actual photo of a Viking fiberglass speedboat a neighbor gave me atop it's cut-down trailer.The inverted-prow is deceptive in the photo and when viewed from the rear,the hull comes to a complete point,ten feet behind the tailgate of the truck.This agrees with the aero template from Jaray and Lay's work.Most of the gray area at the lower part of the trailer body is fairing for the wheels.The underside of the trailer follows a line rising 2.5-degrees and is a continuation of the line established from the underside of the T-100.Between the truck and leading-edges of the trailer will be four movable gap-fillers which hinge at the truck back and ride on the forward surface of the trailer on rollers,held in tension against the trailer by a tension cable which itself rides over pulleys below the panel elements,with a simple spring maintaining tension.---------- The boat hull is far from ideal but using it will save hundreds of man-hours and should help settle my curiosity about such a contraption.Maybe 40-mpg HWY,we'll see.P.S.,the trailer is large enough to serve as a rigid tent,for car-camping.

mating
 

Now that the spring rains have hit,the flying insects are attempting to mate with it!

aerohead -

Ha ha, that reminds me of the lovebug couples that used to cover Houston in the summer.

CarloSW2

I totally missed this thread the first time around. Very nice! Think you could get some more pictures from different angles? It looks very interesting.

pictures
 

I have some shots of it from before I cut the pull bar down to its final length,which puts the axle way aft and I didn't include 'em.I'll slap the thing back behind the truck and get better shots and post those.Everyone does need to see those views to get a proper feel of the form.Hang on,and I'll get it done.

I am curious about how it turns. Do the sides slide into the trailer?

I love it. But my wife said she'd be more embarrased to drive it than our current aerotricked Echo ;-)

What do you figure the overall MPG improvement to be?

turns
 

The 4 articulated gap-fillers are hinged at the truck's back.They "ride" on rollers on the face of the trailer,which is a wedge.As the rig corners,the panels displace outwards to clear the pivoting trailer face,and then,as the trailer straightens,a spring-tensioned cable,riding on pulleys attached under each panel,pulls the panel back to it's "stowed" position.The longitudinal edges of the panels are chamfered at 45-degrees,and it is hoped,will not bind.

The truck is getting 36-HWY/32 -Interstate.With the trailer,I'm given to understand from the formulas,that the trailer could push the mpg to 40-HWY/36-Interstate.There's no way to know without attempting it.--------------------- The trailer would only be used for out of town travel.------------ With the 2-wheel trailer behind the CRX,I pulled an average 50-mpg.There were no gap-fillers, no lower sides or belly to the 2-wheeler,and no real boat-tailing.------------------From Los Angeles to Denton,with a quarter-ton of batteries in the trailer,I still pulled 50-mpg.The rig weighed 3,300 pounds(the weight of my T-100 empty).

I also missed this thread first time around. Another interesting project, Phil.

Darin,I've been wanting to do this since 1991,when I went to the Solar 500 in Phoenix.Two teams drove from L.A.to Arizona,with EVs pulling "range-extender" generator trailers(The DEMI CRX and Volvo).They didn't understand about streamlining the trailer for extra range.So maybe something like this could go behind FrankenSwift to make it a "hybrid."

2 extra photos of trailer
 

I've got a couple extra shots of the trailer from different perspectives to get a better feel of the tail.These were taken before I shortened the trailer frame,so the axle will not be in the proper position,but you'll be able to "see" what the air is going to see.

project update
 

I've got 26.5 man-hours into the trailer project and thought I'd post an update.The critical dimensions are fixed now and completion will be a matter of integrating all the bits together.I've made many concessions now(compromises)which I don't think will sacrifice performance terribly,although the final product will be far from ideal.-------------- The trailer required a 6-inch (150mm) gooseneck offset to the tongue for the two "bellys" to plane out on the bottom.------------ The shackle/leafspring/axle/wheel orientation does not allow the trailer bottom to follow the diffuser angle of the truck without moving the C.G. higher,something I'd rather not do.Anyway,the bottom will be more level,with adequate approach/ramp/and breakover clearance.----------The stinger is at 12-feet from the back of the truck.Aerodynamically,it's much longer than needed,however,I made some concession to "swing" space and interior volume,as I may be "living in there" on the road.--------------I removed my 2-inch ball and moved the smaller ball hitch to truck center.--------------- This morning I purchased 48 linear feet of new 16-gauge square mild steel tubing to begin the boat hull-to-trailer integration.-------- I also hit some thrift stores and yard sales before the copy center opened,and scored some in-line skates (to rob the wheels off of for the movable gap-fillers) and also two aluminum pot lids to make smaller versions of MOON covers for the trailer wheels.-------------- My deadline for testing is in the third week of September.Both "World of Speed" at Bonneville and" World Human Powered Speed Championship" at Battle Mountain,Nevada will be happening almost simultaneously and I'll shuttle between the two,with digital camera,tape measure and hoy batteries.------------- I'll be able to visit friends and family,racking up mileage to the West Coast and back.---------- By the time I get home,I should have a good real-world data set to share with everybody.I'd love to see 40 mpg HWY and 36-mpg Interstate.-------- Going for an LSR is out.At 300,000 miles on the engine,and needing the truck for work,I'm just not in a position to risk blowing the thing up,and so very far from home.I should be able to deduce the theoretical top speed from the mileage data.Should the Bureau of Land Management be looking the other way,the rig could accidently find its way onto the salt at WOT for a "handling-run."But I never said that!

Project Update #2
 

Hello all.Short work day so got to come look at internet.Last Sunday,I logged my 67th man-hour on the trailer project.The complete forward outline is now defined in steel,and back to the rear of the trailer frame.------------- The front is prismatic,and will provide the "facets" which the gap-filler panel guide-wheels will contact for turn articulation.A "closet" will be provided for a spare tire,lug wrench and jack.This will also give me some tongue weight for stability.-------------- The whole nose will be clad in fiberglass panels recycled from the remnant of the Viking hull.----------- I purchased enough aluminum sheet a few years back in anticipation of skinning the underside of the trailer.------------- Fairings will be constructed for the axle,both leaf-spring/shackles,and both wheels.The designs are from Hoerner's book,and specifically from Messerschmitt research on bomb pylons,wing-tanks,and faired landing gear.I will also mimic the forward wheel fairings of the Honda Dream-2.------------ A frame must be fabricated to take the place of the existing tailgate which will support the four movable gap-fillers,and of course the panels themselves.------------------- Also,the rear of the hull ( the prow ) is too "fast" and will require side extensions to slow the exit architecture to 22-degrees,respecting Mair's work.This will help provide an alcove for the license plate and running lights.----------------- I'll look for off-the-shelf wheelcovers,but should that be a dead end,I've got some aluminum cookware that can be adapted.------------------ I've had good results "bending" the 1.25-inch square tubing by making kerf cuts with the metal chop-saw,bending to match the hull outline,then tack-welding to "fix" the shape.The 1/2-inch Square tubing I inserted into a heavy wall pipe,then slipped a "cheater" pipe over to make incremental bends at about 4-inch centers.--------------- All the final welding remains.Electrical.Body and Paint.--------- September will be here soon! I'll get some shots of the rig posted this coming Saturday.-------------- I've run numbers as best as I can.To my knowledge no one has published data on such a device,as not surprisingly,no one has been crazy enough to try it.Best I can tell,along with the kit already on the truck,the trailer is good for a 95% drag reduction for profile drag and the T-100's road horsepower will be about half of it's original.I'll collect what I've come up with and share that,but I want to post the material on the "mirror-imaging"for the "template" first.If there is enough time,I'll do both Saturday.

Good stuff. But you ought to know that, in the South, it's called a "cheeta'" pipe.

Have photos but deadlocked
 

I was hoping to download some more current photos of the trailer project but I think I've overwhelmed my capacity and will have to get help before I can post.

do the tallight lenses flip up or down to eject the parachute(s)?!

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

LOL

lenses
 

They actually rotate out to expose the barrel of the 20-mm Vulcan canon.------ Sorry,couldn't resist!

boats
 

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

Photo-update #1 "FrankenViking"
 

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.

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.

amenable
 

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!

PROJECT UPDATE#3 (Theory behind invention)
 

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.

Project-update#4 ( Specifications)
 

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.

PHOTO-Update# 2-A ( T-100 tuft study )
 

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.

PHOTO-Update#3 (FrankenViking taking form)
 

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.

Project Update #5 (transparent trailer technology)T-3
 

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.

Project Update #6 (better rolling)
 

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.

Project Update # 6 ( Plan-B )
 

My departure date came,I left,but without trailer,and only went as far as Las Cruces,New Mexico.---------- With 186 man-hours into the project I wasn't anywhere near completion and now have moved my new deadline to Christmas holiday season.---------- I have a week and a half before I go back to work.With liberal scratching of my pin head,I guestimate an additional 120-150 man-hours to pull everything together.--------- I did do a 1,349-mile baseline run with the new "racing" tires and altered gearing to help me nail down "trailerless" performance which will help separate out future numbers with the trailer in tow.The T-100 hit a new high for highway mpg,I'll post a new thread on that.Looks like 40-mpg is doable under best conditions.

Project Update # 7 and recent photos
 

Hello all.At 250-man-hours the trailer is beginning to flesh out.The body is defined now.All electrical has been dry-fitted and tested.I've basically fixed the design for the fin.As mentioned in earlier post,the trailer is "invisible" from the cab and the fin became a necessity,as it's a bit disconcerting to go down the road when you're not sure your "load" is with you or not.----- The fin will also help balance side gust loading and add some visual "mass" for motorists approaching from behind.I recessed the fin horizontally to protect pedestrians from snagging it,should they walk by at close quarters and it has a single LED lamp to aid in after dark operations.----------- Next begins the belly,followed by fairings.--------- The "integrator" is essentially complete and ready to receive the articulated panels.----------- "poco-loco",the boat derived aeroshell gets a side and rear window.--------- I would also like to do the modified nose.We'll see.------------ Much to do.Will post as things unfold.------ The T-100 touched 39-mpg on one leg of the New Mexico return trip,my hope is that with the trailer I'll finally break into 40-mpg territory.

Phil, why not put an antenna on the end and mount a red flag back there ? You would be able to see it better, and alert motorist at the same time.
The bigger the flag the better - maybe two.

Those little moon caps on the trailer wheels are an adorable touch.

Wouldn't that cause unnecessary drag?

There was probably a touch of sarcasm in Cd's post. ;)

:D :thumbup:

Joking aside, I was wondering what you intend to do about the areas directly behind the cab*, and other areas, such as the void above the plate on the trailer.

I'd like to see some pictures of those gap fillers back on. I'm interested in seeing a picture of how they work when you turn a sharp corner,


Also, do you plan to make extentions behind the trailer wheels ? It looks like the bottom of the trailer could use a bellypan as well - I see some low hanging grapes down there.

Where did you find your 'mini moons' ?

* I know this had been brought up before, but I thought you fixed it already.

Phil, in post # 27, you have a bed cap that fills in the void behind the cab. Why the switch ?

fin/flag
 

The thing with the fin,is that it will add crosswind impact area behind the axle helping to offset the larger area and higher crosswind Cd ahead of the axle to better balance yaw forces in side gusts.Also,a red light in the top,along with strips of high-conspicuity tape will add visibility for approaching motorists so there's less chance of being rear-ended.Flags would help with visibility but wouldn't address yawing moments.

cab/voids/wheels
 

The driver's side cab fairing is still in my head and is included in the plan for the December trip.Also a side window and rear window and cut away for the 3rd brake light.------------------------ The gap-fillers are in flux and await completion of the trailer face to progress to the next phase.The facets of the trailer face are what the rollers of the gap-fillers interact with to swing the panels during turns.The upper and lower panels interact with the trailer and side panels to displace over railroad crossings/driveway ramps etc..--------------------- The trailer wheels get fore and aft fairings,as do the leaf spring/shackles and square tube axle; seven fairings in all.--------------------------- The trailer gets a full aluminum bellypan.I picked up the last piece of aluminum sheet on the way to Copy-Pro.I've spent the last two days underneath the beast and lack center-most 32-by- 36-inch section to complete belly,and about a half day's work to integrate the wheel houses for an airtight bottom.---------------------- The mini-MOONs are either cut down from real MOON covers,or fiberglass facsimiles laid up on the back side of the covers.I will be using 1/8-inch Allen socket-head machine screws,screwed directly into the rims which are drilled and tapped.------------------------ As to the void above the license plate,it will remain,will provide for ventilation when camping and there is a hand grab at the very top for maneuvering while separated from the truck.This whole chopped area constitutes 5%( 1.4-square feet ) of the original frontal area of the truck,and according to R&D conducted by Dornier Aircraft and Arado Aircraft,this area will be enveloped in a "phantom" tail,as referred to by Dr.Kamm and Dr. Korff,and will offer only a negligible drag increase.This is one of those concessions we're forced to make for a road vehicle with lights and tag.The upshot is that this is the entire wake area of the rig,for a 95% reduction,the key to drag elimination.-------------- I'll post photos as the thing evolves.Many hours of grinding/sanding/filling/primer/scratch-filling/guide-coat/and block-sanding to get ready for paint.------ A fella has agreed to do a non-toxic water based base-coat/clear-coat paint job here at the house and I get a lesson in HVLP spraying,something I've never done.