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

[aerohead]

Originally Posted by orbywan

Those are great illustrations, aerohead, do you have any dimensions for the various arms? Those might be of interest for towing the boat behind the boat tail.

My RV boat tail is coming along pretty well. So much for building a quick prototype to see what kind of gains it achieves. This is such a big structure I decided to buy some steel and go for it, I don't know how else to do it. The three trim pieces for the rear cap were all damaged and cracked and they want about $350 for new trim so I figure if this works that money is well spent towards the modifications. The frame is about 80% done so far and weighs a little over 60 pounds. I’m impressed with how strong the structure is, even with no skin yet.

I'm going to cover it in coroplast to do some testing, if it proves to be sufficiently beneficial I'll probably recover it with aluminum. This summer heat is slowing things down a little but I can’t wait to test this out.

orbywan,The illustrations are purposely vague on account of the fact that everything would need to dialed in on a vehicle case specific basis.
I built a chipboard and push-pin model of the mechanism and ran it through the full range of motion without trouble.It appears to function okay for something home-built.
In production,something like this would last beyond a normal human lifetime,working into the future,moving from vehicle to vehicle as the tow vehicle reached its useful lifespan.Like a B-52 or DC-3/C-47.
I'd like to have something like what is used on Disneyland's Monorail and some transit buses.But that sort of thing is hard to construct at home.

[aerohead]

Here are two shots taken from the fire-escape.I could not get directly over the rig,but you can get a sense of the plan-taper of the trailer body and how it transitions into the boat-tail.And of course,the 'Gap' which will be sealed by the movable panels.

[aerohead]

I got underneath the truck recently and removed the forward 3-sections of bellypan for scheduled oil and filter.
I took the opportunity to reconnoiter the driveshaft safety loop install.With a peek underneath,I realized that the front seat would have to come out,and that would allow the switchover to the seat frame/racing seat/racing harness.
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I pulled the seat ( now it's the cats ),measured,marked,and drilled the cabin floor for the Summit Racing' driveshaft safety loop,and assembled/installed the loop.
I swapped to the new ( recycled) T-100 seat frame which of course,just bolted right in.Onto that went the blow-molded racing seat ( recycled ).And this allowed reconnoitering of the Simpson Racing 5-point harness ( recycled ).
A subframe is in the works,which will allow attach points for the fire-extinguisher,GPS,Airspeed indicator,and parachute release mechanism.
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I constructed a 'Gap-Seal', from SAE Papers #s 801402 and 801403,by McDonald & Palmer of Purdue University,and Berta & Boris of FIAT.
It's a simple panel which spans the longitudinal gap between tailgate and prizmatic trailer nose ( this is not the gap-fillers,which are still in the works ).
I used some aluminum extrusion C-Section and flat stock,plus some of the polyurethane floor pad material,machine screws,nylock nuts,a few machine screws and fastnuts.
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This morning,the winds were forecast to be light,so I did 2-runs,back to back,without,and then with air conditioning.
It was the same 104-mile round-trip as test#2.
* Baro :29.98"-30.01"-29.99"
* R.H.: 67%-38%-38%
* Wind: S-3 mph,S-W 7,S-15
*Temp: 84 F-90F-95F
* Target speed : 65 mph
* Elevation 683' - 934' maximum
* Road temp: 88F- 115F
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RUN# 3
I pulled 31.44 mpg w/o AC
Moving ave.= 62 mph
Max speed ( passing) 71 mph
Airspeed: 62- 78 mph
Cabin Temp: 84F-104F
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RUN# 4
26.510 mpg
Moving ave.= 58 mph ( holiday gridlock over 7-miles of construction zone)
Max speed ( passing ) 73 mph
Airspeed: 58-88 mph
Cabin: air conditioned full-time
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I didn't come close to RUN # 2,however the absence of the forward section of the bellypan ( it will be off until September ) would negate the presence of what was left on the truck.
The 1.8 mpg difference on # 3 is in range of the contribution lost by the missing pan.
The 6.73 mpg difference with RUN #4 may be explained as follows:
* 7 miles of traffic
* full-time air conditioning ( I never test with AC )
* defeated bellypan
* 15 mph headwind on return leg ( 80 mph airspeed ) with passing bursts to 88 mph
NOTE: From the vehicle logbook,from April,2008 and September,2009,the T-100 returned between 26.369-26.767 mpg @ 80 mph,when tested in the Trans-Pecos region of West Texas.
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SAE's 'Gap-Seal' demonstrated a 4% drag reduction on a semi-trailer.This would equate to a little over 2% mpg,which could easily be lost in the 'noise' of real world testing.
I'll retest with the pan sometime.I'm not discouraged.The more data the better and it's good to get all the seat time I can get pulling the trailer.
I would like to be acquainted with all its idiosyncrasies before I head out to Utah.
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PS,my workmate flew out to Europe for a 3-week tour blowing trumpet for the Blues brother's Band.I'll get the 3-weeks to blow low drag into the rig.

[aerohead]

Here are pics of safety loop,new seat setup,and SAE's 'Gap-Seal'

[tomauto]

I saw you out on I-35 today just South of Gainesville! I wanted to leap out of my Insight and say hi. Hope all is well with you Phil. Thanks for posting up your progress.

[MetroMPG]

Originally Posted by aerohead

Here are two shots taken from the fire-escape

I chuckled at the shadow of the guy leaning waaaaay out over the edge to get the cool photo!

[MetroMPG]

Originally Posted by COcyclist

orbywan, This deserves it's own thread. Great to see some modding on a large vehicle and please post the results. I hope you were careful not to go too steep on your angles. Good for you for diving in on this project.

Agreed on all points!

orbywan, If you like, I can copy your posts in this thread to a new thread which we can title to reflect the specifics of your project.

LOTS of people have talked about modding big RV's for improved aero; not many have tried it (that I have seen). Hope the shape is optimized!

[Cd]

Originally Posted by euromodder

Looks complicated.

How about a rounded-off front, and spring loaded side panels ?

.

I was thinking the very same thing. Actually, the first thing that came to mind was the panels used by NASA on its semi truck aero study. They simply had them on a hinge mounted to the cab.

[Cd]

Phil, she looks great.
From the high shots it looks like the angles on the sides are too steep. Is this an optical illusion ?

[aerohead]

Originally Posted by Cd

Phil, she looks great.
From the high shots it looks like the angles on the sides are too steep. Is this an optical illusion ?

Cd,22-degrees( as per W.A.Mair's research findings ) is the largest angle on the trailer.
The Japanese Automotive Research Institute(JARI) uses a telecamera,at 100 meters from a vehicle for frontal area measurements.MIRA,in the UK uses a similar strategy.
One might presume that their 'factory' photos are obtained this way.This would help compensate for optical distortion of an image.
I was only shooting from about 36-feet above the rig with a 'normal' lens.It's apt to guarantee a distorted view.