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Old 03-11-2012, 01:11 AM   #241 (permalink)
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Driving home from my friend's shop today, I was thinking about suspending a 5' boat tail off the back of my tuck, complete with tail lights and backup lights. Thanks for giving me a little hope for that idea.
A proper aeroshell will hit my tailgate at about 50" or so on template. Carry it out another 5' makes it tasty indeed. 5' of taper won't hurt things either.

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Old 03-12-2012, 06:35 PM   #242 (permalink)
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Originally Posted by slowmover View Post
Great stuff, aerohead!!

Planning those trip legs (time & distance between stops) just became that much more important. Planning the stops so that one has no traffic devices between the standing start and highway entrance seemed obvious. Now it has given the time spent with some satellite images of the "stop" an impetus it didn't have before (for those of us, at present, with fixed configuration trailers and hitch rigging) to kill as much RR problem as possible. Then the problems of aero are a bit more clear. Possible potential gains after as much noise eliminated as planning can make it.

.
Yeah,until we can get those tires made from unobtainium we've got to watch our weight.
The stoplight to stoplight is the other killer.I can't tell you how many un-synchronized traffic lights I hit on my trip.Running 1,300-lbs over stock weight really showed in the logbook.Lots of mountains too!
Between Fachsenfeld,Hucho,Hoerner,and NASA I'm seeing repeating number sets for comparative anatomy in trailers.
It appears that,as of 1935 or so,the concept of a mpg-adding,range-extender trailer had already moved from theoretical abstraction,to fully-proved off-the-shelf technology.
Looks like it's just languished since then,buried on the shelves of libraries.
Constructing a trailer of Cd 0.05 today looks to be a no-brainer,which completely eliminates the turbulent wake.Up to a Cd 0.11 drag reduction for any squareback configuration,be it van,suv,motorhome,tongue-pull,or 5th-wheel/gooseneck.
It's an interesting proposition certain to meet with mass disapproval I'm sure.
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Old 03-12-2012, 06:53 PM   #243 (permalink)
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Driving home from my friend's shop today, I was thinking about suspending a 5' boat tail off the back of my tuck, complete with tail lights and backup lights. Thanks for giving me a little hope for that idea.
A proper aeroshell will hit my tailgate at about 50" or so on template. Carry it out another 5' makes it tasty indeed. 5' of taper won't hurt things either.
In the images posted earlier for the railroad boat-tailed tailcar,all the boat-tailing was done in plan-view.
The length of the tail is 1.74X the body width for the full stinger.It's within 2.5% of the template,so it's going to just slide in between Mair's 22-degree,and Emmelmann's 23-degree max slope angle protocol for attached flow.The base drag is completely eliminated.Which would be the lion's share of road load for a light truck on the highway.
The locomotives,self-powered railcars,and buses all show higher drag without the 'trailer.'
At 9" ground clearance,the ideal self-powered railcar comes in at Cd 0.08.NUNA territory.
We may not be able to go that low with ground clearance without active suspension,but nobody has said that we can't streamline the wheels.
The caveat is,that we can't have all the excressences like awnings and rooftop AC units,'n such scraping the sky as we go.These sorts of things must be better integrated into the body,as orbywan is doing on his rig.
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Old 03-13-2012, 12:38 AM   #244 (permalink)
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I looked at that mess up there on the trailer and realized the only way to go was clean slate.
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Old 03-13-2012, 12:11 PM   #245 (permalink)
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This is just great stuff. Knew that there was a lower number, but not that one could potentially "zero out" a trailer. The assumption (the workable one, today) is a minimum 30% loss from best solo mpg. Only 20% would be fantastic (for a trailer from which one could live or work). A 40% loss (sometimes more) is the norm.

The caveat is,that we can't have all the excressences like awnings and rooftop AC units,'n such scraping the sky as we go.These sorts of things must be better integrated into the body,as orbywan is doing on his rig

The utility trade-off. How long owned, how many miles, how many nights of use (or similar Q's for business trailers). Don't forget solar. Where and how to place those panels is a big deal. The overall independence of a trailer -- business or personal -- is vital, barely second to being roadworthy. Solar electric has become central to that independence, itself barely third after water storage/use, and propane (or other fuel).

One needs to be able to use what is aboard the trailer along any mile traveled, not just at designated waypoints. So, the antenna farm is another consideration. Building a roof for constant access is a backwards step (set-up and take-down) and removes utility. Doesn't matter if I'm setting up a roadside stand, or am traveling a gypsy route with family aboard. Anywhere, anytime.

By extension, the utility of a road vehicle (car, truck, etc) is pretty well limited to it's beginning and end points of travel. A trailer changes that equation (and investment) entirely. Business or pleasure. Scaled-to-use is the starting point as an asset (not just a drain on assets). After all, "home" needn't be more than a sort of garage where this can be plugged in . . . and not necessarily duplicated by standard household layout (size), appliances, etc.

A vessel roaming the seas is the model.

(Okay, no more digression).

,

Last edited by slowmover; 03-13-2012 at 12:21 PM..
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Old 03-14-2012, 05:47 PM   #246 (permalink)
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utility

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Originally Posted by slowmover View Post
This is just great stuff. Knew that there was a lower number, but not that one could potentially "zero out" a trailer. The assumption (the workable one, today) is a minimum 30% loss from best solo mpg. Only 20% would be fantastic (for a trailer from which one could live or work). A 40% loss (sometimes more) is the norm.

The caveat is,that we can't have all the excressences like awnings and rooftop AC units,'n such scraping the sky as we go.These sorts of things must be better integrated into the body,as orbywan is doing on his rig

The utility trade-off. How long owned, how many miles, how many nights of use (or similar Q's for business trailers). Don't forget solar. Where and how to place those panels is a big deal. The overall independence of a trailer -- business or personal -- is vital, barely second to being roadworthy. Solar electric has become central to that independence, itself barely third after water storage/use, and propane (or other fuel).

One needs to be able to use what is aboard the trailer along any mile traveled, not just at designated waypoints. So, the antenna farm is another consideration. Building a roof for constant access is a backwards step (set-up and take-down) and removes utility. Doesn't matter if I'm setting up a roadside stand, or am traveling a gypsy route with family aboard. Anywhere, anytime.

By extension, the utility of a road vehicle (car, truck, etc) is pretty well limited to it's beginning and end points of travel. A trailer changes that equation (and investment) entirely. Business or pleasure. Scaled-to-use is the starting point as an asset (not just a drain on assets). After all, "home" needn't be more than a sort of garage where this can be plugged in . . . and not necessarily duplicated by standard household layout (size), appliances, etc.

A vessel roaming the seas is the model.

(Okay, no more digression).

,
perhaps, we can only present the data to the motoring public and let them decide whether they'll use any of it for their particular situation.
Generations of aero researchers have already lived and died without ever witnessing large scale adoption of the technology.I'm pragmatic enough to expect nothing significant within whats left of my lifetime.
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Old 03-16-2012, 02:06 PM   #247 (permalink)
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There are already quite a few people who are "mobile". Power plants, refineries, pipelines, and other large-scale capital projects requiring skilled and unskilled labor have a sea of these nearby. Today's tax situation allows depreciation (buy, use, junk) to "paper over" this central problem, which is predictable affordability outside of subsidization. So unless you are a good deal older than I have surmised, the applicability is already relevant. But, it is a DIY dilemma. For that alone there'll be those that will be thankful for this hard work shared freely (myself among them). Thanks again. It's empowering to those looking for alternatives to debt slavery and the desire for some more control over their livelihood.

"A better plow, mister, consists of . . . . "

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Old 03-17-2012, 02:43 PM   #248 (permalink)
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gap vs drag coefficient

I'll try and get a couple of images up which illustrate the impact 'gaps' can have with respect to drag coefficient.
For the stock cars drafting,the cars in solo have Cd 0.315.
For the buses,they have a solo Cd 0.50.
I'm still working on the railroad materials but have been swamped with other duties.









Last edited by aerohead; 04-21-2012 at 02:28 PM.. Reason: add 1-new table
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Old 03-24-2012, 04:22 PM   #249 (permalink)
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Sorry,no images today

I had six additional pictorial drag tables to post today,but scanner is down so it's not going to happen.
Al's swamped with work and I won't be posting the Bochum University solar car photos as well.
I'll try again next Saturday.Sorry!
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Old 03-24-2012, 09:14 PM   #250 (permalink)
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Wow, those graphics answered a question that had been rattling around in my head. Over-simplified, a car is pushing a 'bubble of air' and dragging a 'vacuum'. I wondered if there was a point where the trailing car's 'bubble' would start to fill the 'vacuum' of the leading car. This seems to be the case at around 1 vehicle length +/- .... anything beyond that and the leading car keeps its full aerodynamic drag.

I might have it all wrong in my head, but this is still very interesting information to know!

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