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

[Cd]

Originally Posted by aerohead

With the low power I need all the distance I can get to the mile trap.

What is the goal of the run ? To get the top speed of the truck with the aeromods ? Couldn't you get a good estimate of that by finding the Cd of the rig ?
Also, what about swapping out the gears for a short course ?

Originally Posted by aerohead

have reason to be going to Alpine,Tx for astronomy and may go by the Texas Mile just to look,but I really can't see it as a resource for what I'm doing.

Eventhough you might not get to the trucks top speed, wouldn't the information from a mile run be helpful to estimate some sort of acceleration curve ? At the very least it would be a fun day at the track !

Originally Posted by aerohead

,I am now very interested in buying some wind tunnel time at GM.The road-testing is extremely problematical for data acquisition,and each year I appreciate the value of large-scale tunnels,even at $2,000/hour.

What about the A2 tunnel ?
From what i have read in the past, there is always a huge waiting list for testing at the large scale tunnels. Texas Tech has one, but im not sure its large enough to fit a full size vehicle.
And $2,000 an hour ? I thought it was many times greater than that - if they even let individual hobbyist in. You are referring to the A2 - no ?
Why not save some serious money and hassle and drop by the A2 ?
A2WT HomePage

http://www.youtube.com/watch?v=mqi6wo8bVrs

I'd love to see your truck and the AeroCivic tested here. That would be awesome.

[orbywan]

Originally Posted by aerohead

I'll add data as time permits.
She's still an unknown quantity,but the 47.9 mpg run illustrates the relative importance of streamlining.Getting the Cd down lower will be the same as a continuous tailwind when on the highway.See you all later.

I can't imagine why you would be burned out after all of that. Your log is the perfect example of why it is so hard to get definite numbers as to what is 'signal' (accurate data) and what is 'noise' (inaccurate numbers due to wind, hills, road surface, crap).

I'm curious Phil, have you shopped around at all to see what facilities, if any, are available nationwide for wind tunnel testing besides the $2,000 an hour guys?

While we're on the subject, just for fun, what do you think it would cost to build a wind tunnel big enough to test your truck and trailer in? I'm talking an econo version, not so cheap the data would be suspect, but a cost effective version that would still yield useful numbers.

Second thought; what do you think it would cost to build a wind tunnel just big enough for a compact car, glass on all sides so you can observe smoke testing?

What would something like that use for a wind generator?

[aerohead]

Originally Posted by Cd

What is the goal of the run ? To get the top speed of the truck with the aeromods ? Couldn't you get a good estimate of that by finding the Cd of the rig ?
Also, what about swapping out the gears for a short course ?




Eventhough you might not get to the trucks top speed, wouldn't the information from a mile run be helpful to estimate some sort of acceleration curve ? At the very least it would be a fun day at the track !



What about the A2 tunnel ?
From what i have read in the past, there is always a huge waiting list for testing at the large scale tunnels. Texas Tech has one, but im not sure its large enough to fit a full size vehicle.
And $2,000 an hour ? I thought it was many times greater than that - if they even let individual hobbyist in. You are referring to the A2 - no ?
Why not save some serious money and hassle and drop by the A2 ?
A2WT HomePage

I'd love to see your truck and the AeroCivic tested here. That would be awesome.

*Top speed for the rig will allow reverse-engineering of the Cd.It must be the terminal velocity to work.
*MPG numbers will help me learn the Cd also if I can account for wind,grades,weather,etc..Real rocket science!
* I'm not willing to change anything about the rig except the shape.It can be the only variable.Otherwise I'll never be able to figure anything out.
*Acceleration data won't help
*Not to be disrespectful,but I would have to seriously investigate the A2 Tunnel before I would be comfortable trusting their numbers.The test section does not respect blockage effect parameters.
*The Texas Tech tunnel is for scale models only,nothing full-scale.
*I think someone posted an article about GM renting out their tunnel at $2,000/hour.That would be cheap! Lockheed Marietta was $1,800/hr in 1991 when I went by there on the way home from the Chrysler Proving Grounds.

[aerohead]

Originally Posted by orbywan

I can't imagine why you would be burned out after all of that. Your log is the perfect example of why it is so hard to get definite numbers as to what is 'signal' (accurate data) and what is 'noise' (inaccurate numbers due to wind, hills, road surface, crap).

I'm curious Phil, have you shopped around at all to see what facilities, if any, are available nationwide for wind tunnel testing besides the $2,000 an hour guys?

While we're on the subject, just for fun, what do you think it would cost to build a wind tunnel big enough to test your truck and trailer in? I'm talking an econo version, not so cheap the data would be suspect, but a cost effective version that would still yield useful numbers.

Second thought; what do you think it would cost to build a wind tunnel just big enough for a compact car, glass on all sides so you can observe smoke testing?

What would something like that use for a wind generator?

Clocks running out so I'm hurrying.
I think the GM tunnel is 60,000 horsepower.It's in Hucho's book.All of them are in there.That's what we're talking about for really good scientific numbers which would hold up to peer review.
The vehicle should not exceed 5% of the test section cross-sectional area,so they've got to be pretty 'big.'
Turbulent boundary layer and constant Cd requires at least 20 mph wind in the tunnel.
Area X velocity would give CFM.Then we need to overcome wall friction.

[slowmover]

Every time I read of this work I'm reminded that it's impressive to see from ground level what a high flyer is doing. I sure value this (and more) as "context bookends" . . what may be possible at the other end of the chart from what the high HP & heavily loaded guys are doing (commercial, mainly).

[aerohead]

Originally Posted by slowmover

Every time I read of this work I'm reminded that it's impressive to see from ground level what a high flyer is doing. I sure value this (and more) as "context bookends" . . what may be possible at the other end of the chart from what the high HP & heavily loaded guys are doing (commercial, mainly).

slowmover,is that an Airstream you're pulling? The 15 mpg sounds impressive.
Gilkison (patron saint of low-cost used T-100s) just got a 4-Runner with 5-spd auto,and 19-foot 'APEX,by Coachman.'About 61.8 ft-square frontal area,3,532-lbs dry weight.
On the first outing,at max. 65 mph,he pulled 13-mpg.
He'll do the next run w/o AC,as temps are falling now,and see how that impacts mpg.
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John is already discussing an Airstream/Argossy-style nose-type fairing to improve penetration.

[aerohead]

We just scanned and compressed some image files for the rig.
There's a shot from Bonneville( yes I got there after World of Speed had concluded) where I spent a little time at Mike Cook's 'Shootout.'
The Poteet/Main 'Speed Demon' had run 462-mph on a 1-way pass,blew the engine,and were in process of swapping engines while I was there.
Also,Terry Nish was there with the family's Royal Purple streamliner(386.387 M.P.H.).I got some boat-tail shots for another thread.
The rest of the shots are just various views,some during disassembly,showing some of the panel articulation.
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The tufts are in areas which I could see through the mirrors.
*The top panel showed very good straight-back flow in spite of the gap between panel and trailer top.
*The side panels exhibited rearward,but 'nervous' quaking of the tufts.Hucho warns that a boat-tail won't properly function unless the air to it is 'perfect,'I'm convinced.
*The underside did not allow viewing,and since the transition bellypan was incomplete,I must presume that the flow under there is also aggravated.
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Ozone has been eating all the rubber on the truck and both power-steering hoses were breaching on the trip.My apology to you all and the planet.
The upshot is that as the drops of fluid fell,the airstream painted the rearward portions of the rig.
From examination of the oil-streaking,flow attachment is surprisingly good,pushing the droplets backwards from all leading edges ( like the Corvette Stingray model in the CalTech Guggenheim tunnel).
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You can see from the photos that a 'gap' still remains for the sides/bottom/leading-edge of top-panel.Flow-fence areas on trailer will be turbulent.Tailight fenestration,without Plex. is turbulent.2009 wheel fairing damage at drivers side adds turbulence.T-100 rear wheel fairings are absent.Front wheel skirts ( planned but never fabricated) are absent.
Plenty to do,along with higher speed tests for comparison to T-100 records.
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I'm still reducing the trip data and will report on that in future post.
For 335,000-miles of database,the highest-ever recorded mpg for the T-100 has occurred with the trailer,so I guess she's worth finishing and final tests.

[orbywan]

Originally Posted by aerohead

We just scanned and compressed some image files for the rig.
There's a shot from Bonneville( yes I got there after World of Speed had concluded) where I spent a little time at Mike Cook's 'Shootout.'
The Poteet/Main 'Speed Demon' had run 462-mph on a 1-way pass,blew the engine,and were in process of swapping engines while I was there.
Also,Terry Nish was there with the family's Royal Purple streamliner(386.387 M.P.H.).I got some boat-tail shots for another thread.
The rest of the shots are just various views,some during disassembly,showing some of the panel articulation.
--------------------------------------------------------------------------
The tufts are in areas which I could see through the mirrors.
*The top panel showed very good straight-back flow in spite of the gap between panel and trailer top.
*The side panels exhibited rearward,but 'nervous' quaking of the tufts.Hucho warns that a boat-tail won't properly function unless the air to it is 'perfect,'I'm convinced.
*The underside did not allow viewing,and since the transition bellypan was incomplete,I must presume that the flow under there is also aggravated.
-------------------------------------------------------------------------
Ozone has been eating all the rubber on the truck and both power-steering hoses were breaching on the trip.My apology to you all and the planet.
The upshot is that as the drops of fluid fell,the airstream painted the rearward portions of the rig.
From examination of the oil-streaking,flow attachment is surprisingly good,pushing the droplets backwards from all leading edges ( like the Corvette Stingray model in the CalTech Guggenheim tunnel).
-------------------------------------------------------------------------
You can see from the photos that a 'gap' still remains for the sides/bottom/leading-edge of top-panel.Flow-fence areas on trailer will be turbulent.Tailight fenestration,without Plex. is turbulent.2009 wheel fairing damage at drivers side adds turbulence.T-100 rear wheel fairings are absent.Front wheel skirts ( planned but never fabricated) are absent.
Plenty to do,along with higher speed tests for comparison to T-100 records.
--------------------------------------------------------------------------
I'm still reducing the trip data and will report on that in future post.
For 335,000-miles of database,the highest-ever recorded mpg for the T-100 has occurred with the trailer,so I guess she's worth finishing and final tests.

Good stuff Phil. I see why it took so many hours to get it to this point. That's a lot of trial and do it over again. Sometime when you have the time I'd love to see a photo or two of the truck and trailer halfway through a turn so we can see how the panels articulate some.

I'm looking forward to towing my boat with the boat tail in place to see how it effects towing mileage, and I might try an articulated panel on either side since the side of boat is so smooth and steady for roller surfaces.

I know it's your last priority, or not at all, but when you get this combination dialed in it would be great to do a paint job with some graphics that really made the two vehicles look like one unit. Just thinking out loud.

[aerohead]

Originally Posted by orbywan

Good stuff Phil. I see why it took so many hours to get it to this point. That's a lot of trial and do it over again. Sometime when you have the time I'd love to see a photo or two of the truck and trailer halfway through a turn so we can see how the panels articulate some.

I'm looking forward to towing my boat with the boat tail in place to see how it effects towing mileage, and I might try an articulated panel on either side since the side of boat is so smooth and steady for roller surfaces.

I know it's your last priority, or not at all, but when you get this combination dialed in it would be great to do a paint job with some graphics that really made the two vehicles look like one unit. Just thinking out loud.

I'll try next Saturday for 'turn' photos.I think I have something.Never trust my memory anymore though.
And yes,wouldn't it be nice to do color-matched paint,matched body moldings and pin-stripes?
I did do some wet-sanding on a portion of the hulls acrylic lacquer, down to 1,200 grit, and hit it with 3M mico-fine finishing compound.Just like glass!

[KamperBob]

Phil, thanks as always for the continued updates on your project.
Rock on!