Pickup Truck Streamlining
 

I remembered to bring the camera and hope Al will be able to post images before the store closes at 4:00 PM.
I'll go ahead and briefly explain the latest mods to the T-100 which went on the last trip:
(1) The nose was re-configured more like the half-zeppelin profile of the 'Template',kicking the air over and around rather than allowing to flow underneath.
(2) Both front wheel arches received for the first time,a rear radius which integrates into rocker panel fairings.Short of full skirts,this is an attempt to clean up the flow here a bit.
(3) As mentioned above,the truck received rocker panel fairings to integrate flow coming from the new wheel arch radii.
(4) The hood blister finally got the plex wing fairing for the driver' side.The T-100 has a fairly mediocre windshield and the blister with wings attempts to 'soften' the pressure gradients present before,around,and over the windshield.The proper solution would be a $3,000 GTP compound-curve laminated safety glass windshield and re-engineering of the cabin,both outside the scope of the project.
(5) Driver-side cab/Poco-Loco integration fairing.Finally,after 5-years waiting,I finally have a fairing to eliminate the locked-vortex which occupied this area adjacent to the back of the cab and forward section of the aero-shell "Poco-loco" named from the sailboat from which it is derived.
(6) Passenger side Poco-Loco side window.No aerodynamic benefit but a great safety addition while backing out of parallel parking spaces into traffic.
(7) Rear windshield for Poco-Loco.Again,no aero benefit however I get rear vision for the lane I'm in and vision while backing.The dimensions of the fenestration are the bare minimum for vision,while minimizing the volume of the locked-vortex created by the new void.
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OBSERVATIONS:
Without the 24-inch boattail, missing 2-sections of the bellypan,and missing the diffuser section entirely,over the recent 4,100-mile trip the truck performed close to the 2005 performance which included the tail,full belly and 1st-gen trashcan nose.
At a trip average of 31.3 mpg and mileage ranging from 28-36 mpg it appears that the new mods are allowing 'long' truck mpg from the 'short' truck.
It should only get better from here.
On a velocity-weighted basis,using the MPG data through the 'back door' of GM Lab's Cd/MPG relationship,the truck's mpg would indicate approximately Cd 0.20 compared with the original Cd 0.44.
If things fall together over this next year we may finally know if the trailer can push the Cd even lower.

Excellent! You might try putting some radius on the front of the bed wedge. Or install some filler between the bed and and the cab.

Keep sharing.

Did you make any runs with it at Bonneville?

Any details on how you made the hood blister and nose modifications? They appear to be sheetmetal that was formed and riveted in place?

Mike

venturi
 

Hey Phil,
does your hood tilt forward like a vette? is there a practical purpose to the gap between the rearmost top of the cab and the bed fairing?
on the air/cooling intake which is frenched into the bumper i see a cone, is it part of a fixed venturi? if so what temp drop do you get on the interstate?

i have been thinking on ram air setup on my 80's 300TD wagon, removing the ugly DOT imposed "sealed beam headlights" which displaced the most powerful lights on the road in those days with barely functional candles. intead i will source the smallest (frontal area) high low beam lights i can find, place a huge ram air scoop (exclusively to feed the turbo) on one side of the radiator
and an intercooler on the other side. i feel strongly about feeding turbos and keeping the compressor side cool, therefore the desire to use a venturi.
however, as air velocities change i feel a venturi of that size needs to be variable much like the cones in the SR71, if only they could have found a way to syncronise them, in the time they took to actuate pilots fopund themselves 11 miles off course. back on the ground, do you have any ideas on making one variable, and, a way of acuating it:eek:
oops, forgot to mention i also want to do pre turbo misting (h2o) i can make tiny drops which wont hurt the compressor vanes, so its placement will either complicate this design or could possibly create symbiosis - if the misting head can be placed within the cone of the venturi...

- dig your stuff. dont ever stop!

How much difference is there between the radiused wheel arch and a full wheel fairing? If you extend the middle of the wheel fairing down to cover the the rim would you still need moon covers?

I also want to know how you made the airdam/nose.

well aerohead, I have to say, you are a huge inspiration to me.
looking at the mileage your getting with that tank (;)) makes me believe Im going to achieve my 30+mpg mark with relative ease :)

I wanted to ask, have you considered a basic wind tunnel for the engine bay ?

Im working up a plan for directing the air flow through the bay area and out 2 side ports that I will engineer in the upper fenders of my ranger. slotted on 1 side to pull the heated air from the engine itself, while also streamlining the airflow through the engine bay.
I also have a couple of ideas rolling around through my head for smoothing my front end, (like most vehicles, its horrible with little nook and crannies) while still giving it some air flow (about 33%) as well as dropping my front wind guard down several inches. and most importantly, an aerolid and belly pan.
I'll be putting a work log up when I start any of my projects, and I would like if you stopped by the threads when I do for any advice you might have.

(ps, I also love the nose, but from reading other posts of yours, its too bad its such a pita to find that piece.)

radius
 

Varn,I taped some tufts just behind the gap where I could watch in the mirrors.They laid flat against the aeroshell and basically straight back until higher up,where they started pointing into the lower pressure coming down off the roof portion.
It appears that the air just skips over the gap and keeps on going.The guys at tech inspection at Bonneville recommended the leading edge radii also.I'll do it but I don't anticipate any measurable gain.

runs
 

I run next year,with and without the trailer.
Some of the guys really wanted me to run,I knew I was a year away from being ready ( close though ).
The big thing was to get approval for the trailer runs and we got that sorted out at tech inspection thanks to USFRA President Jim Burkdoll,who's given me the okay as long as I don't exceed 130-mph.
I have a laundry list of safety equipment to come up with over the next year and I've begun the search for tire options for the trailer.
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The blister was built on the truck using a polyisocyanurate foam board skeleton and skins that were glassed over using Bondo cloth and polyester resin from Home Depot.The wings are scaps of plexiglass attached to aluminum sheet with panel screws.There is a beam near the windshield for rigidity and I riveted an aluminum ramp to relax the angle of attack there.
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The nose is a cedar wood skeleton of formers and stringers glued and screwed and attached with steel angle brackets.The grille-block inlet is a stainless steel trashcan lid.The interior ogival valve is a commercial outdoor aluminum light fixture housing.Headlight and turn signals covers are heat-gun formed plexiglass.The new skin is aluminum sheet,screwed at the top to the original nose,the lower section to a 1/2-inch EMT bow which was bent with a tubing bender at 2-inch increments and through-bolted to the steel bumper sides.There is no 'bottom' to the new nose skin .There are only simple 2-dimensional curvature,nothing complex.
The flexible foam rubber chin spoiler is made from inter-locking foam cushion material for concrete floors sold locally at BIG LOTS.

hood/gap/cooling
 

The forward tilting hood is the ultimate objective.Right now I have to remove two handfuls of screws and the blister just to open the hood.Prototypes are like that.No convenience whatsoever!
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The cab/aeroshell gap allows clearance for frame flex inherent in the non-unibody trucks.I'll soften the leading edge of Poco-Loco at some point to help in yaw conditions but I've got bigger fish to fry first.
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The 'cone' inside the grille-block inlet is actually a 'valve' to help regulate airflow volume especially in the winter,when it will actually fully close when the truck is parked.I thought it might help conserve some engine heat,reducing 'cold-start' issues.The inlet to the radiator is air-tight and the engine runs at normal temp,although at lower load do to the reduced drag of the grille-block.So far the computer appears to be smart enough to keep the BSFC fairly constant,where a carburetored truck might suffer.
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I'm not going to be much help to you on the turbo.I'd be looking at serious race cars on that one.You almost need to get a static pressure probe and a good manometer and locate your highest pressure,whether at the forward stagnation point,or maybe even inside a wheel well.Don't know.
I think the bigger issue is rejecting the heat of compression from the compressor section.Does anyone mist the inter-cooler itself? De-ionized/de-mineralized water so zero salt buildup on the core? And no risk to the turbo if there is a plumbing problem?

Moons
 

The Moons eliminate any windage of the wheel so basically having them ( on both sides of the wheel ) would offer the lowest drag.Or something like Ford did with Probe-IV.
I don't have any specific data on the wheel arch radii other than they have been used in racing since the 1960s and on amphibious cars since 1915.Short of full skirts I think they offer a modicum of drag reduction.But I will run full front skirts at Bonneville in 2011.You get a 1/4-mile to turn there.
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I covered the nose construction in an above post,see if that works for ya.I did get some photos of some of the build which I could post at the DIY forum sometime.