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Old 05-11-2011, 09:16 AM   #31 (permalink)
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I'll just leave this here for the pop-top dreamers. I especially like the drill motor option. Great work guys, I can't wait to try my library for that book.

Roof Jenie | Custom Cylinders International Inc.

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Old 05-11-2011, 09:31 AM   #32 (permalink)
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A rising roof might be an option that allows low trailer height while towing, yet stand-up height when parked - but it'd take an awful lot of work to modify an existing trailer in that way and keep it structurally sound.
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Old 05-11-2011, 09:42 AM   #33 (permalink)
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It would be easier on a ground up build, I posted that for the dreamers.
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Old 05-11-2011, 12:23 PM   #34 (permalink)
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Sorry if it's been said. May have missed it....

Lower the trailer as much as possible? Most seem quite high.

Fill the gap under the trailer tongue to keep the air going under the trailer... From the truck bumper to the trailer. Could be some simple plates?
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Old 05-13-2011, 03:13 PM   #35 (permalink)
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nosecone

Quote:
Originally Posted by mateospeed View Post
That would be pretty cool! Yeah, it's probably just a dream, but it would be pretty neat. Yesterday, I saw a Honda Element cruising down the beach road with a pop-up roof, like the VW campers have/had. It made me think 2 things: 1) Cool! and 2) If they can do it, i could do it for the trailer!

Maybe one day, when I'm a big-shot manager somewhere. Or maybe not, since I don't really want to be in management.

Yes, I could enclose the tires with skirts, but the tires, wheels, and brakes are already getting warm. I'm hesitant to consider that option, since higher tire temps equate to quicker wear rates. That would quickly negate the savings in aerodynamics.


On another note, the website for NoseCone has the attached image demonstrating Cd's for several vehicles, including faired and un-faired trucks. Does that appear to match other research y'all have seen?

-Matt
Matt,sorry! trying to catch up.
*Nosecone numbers look okay.
*Hucho depicts car/trailer Cds on order of 0.45 for good configuration,using frontal area of trailer as basis.
* The inter-car/trailer gap itself can be a 10% mpg penalty by itself,or,20% drag increase over an aerodynamic singularity.
* I'm not sure enclosing the wheels is an issue.If doubtful,NACA submerged inlets and flex-duct could be positioned for dedicated cooling,along with shark-gill outlets.
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Old 05-13-2011, 03:31 PM   #36 (permalink)
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images

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Originally Posted by mateospeed View Post
Got it. Imageshack saves the day, once I coverted it to a JPG. They're different sizes, I'm not sure why, but click the first one to see it full size. It is 2 sheets, not the same image.





Enjoy my amazing drawing skills. Yes, I know, I should've been an artist. I'm flattered that you think so!
Matt,in your elevation view from the side,I would recommend you lower the radiussed face of the trailer down to belly level.
In the plan-view image,I suspect that the flairing to the sides will cause what Hucho refers to as 'overshoot',where the flow is kicked out further than what is necessary to make the jump without aggravating the wake between car/trailer.
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Old 05-13-2011, 03:41 PM   #37 (permalink)
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inter-library loan

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Originally Posted by mateospeed View Post
I don't have a scangauge, or anything like it. I'm hesitant to buy one, since I'm planning to ditch this Tow Vehicle and go to a diesel manual when possible. I'm assuming the scangauge will not transfer to a diesel, but this might not be a good assumption. I've been doing my best to judge the load on the truck, whether or not to unlock the coverter ascending hills, etc. Transmission temp never seems to change much, perhaps because it has a giant cooler, and is a 3/4 ton to start with. I very rarely use cruise control, btw. It almost always throttles up, drops into 3rd and unlocks the converter when starting uphill, whereas I would rather not, unless it's a very long, steep hill.



Perhaps I'm not being clear on the way I'm approaching the problem. I'm considering 2 different thought paths: one of seperate truck and trailer bodies, and one with a connected truck and trailer.

If considering seperate truck and trailer, its seems a viable thought path to consider the trailer to have a Cd of near 1.0, but only be partially wetted, if that makes sense. If it this is simply an incorrect way of thinking, then that's acceptable, and I'll drop it. When adding a bed cap, you would effectively reduce the "effective" frontal area of the trailer.

Now, all that said, I've come to a realization: none of that makes sense. All vehicles have some gaps in them; even the truck has a gap b/w cab and bed. The seperate vehicles and effective frontal area approach does not follow accepted aerodynamic principles. I will indeed drop that thought path. Thanks for helping me get there!

SO, what I'm looking at are different ways to reduce the Cd of the entire rig, by smoothing the transition from one frontal area "block" to another. That makes more sense. Now, where's the smiley with a lightbulb?!



My library is pathetic. "we don't have it." Is about all I'm getting. No response to "can you get it," "is a transfer possible," or any talk like that. They looked at me like I was completely out of line for suggesting such a thing. Perhaps I approached it from the wrong angle... time to send in the hot wife:-)

-Matt
Your librarian should be able to do a inter-library loan in which you just pay for the postage to mail the book back and forth,unless the book is strictly a 'reference' item,which,if so,cannot leave a library.
If that's the case,they should be able to locate the nearest library which has the book.
If 'reasonably' close,travel there,and use the library's copy machine to reproduce the materials you need.I did this with Fachsenfeld's book.
If those people have a degree in library science they should be stumbling all over themselves to help you.If not,you may contact your city manager or mayor and suggest that those personnel are under-qualified for their taxpayer-supported job.
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Old 05-14-2011, 04:13 PM   #38 (permalink)
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car/trailer photo

Mateo here is an image to look at
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Old 05-23-2011, 07:51 PM   #39 (permalink)
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Nice image. Note that European trailers are not set up for use with weight distribution hitches, and that the Rabbit is nose-high.

Deflectors -- when used over a large gap -- are generally derided as "bug line" indicators. They may well work with a fifth wheel enclosed trailer (travel-type, horse trailer, etc; where pickup cab and trailer are close), but does anyone have "proof" of their working over a larger gap than what both CUMMINS and KENWORTH indicate is beyond the effective 24-30" gap between tractor & trailer for commercial vehicles?

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Old 05-26-2011, 08:11 AM   #40 (permalink)
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What speed do you drive?

My Econoline gets it's best mileage at 52-53 mph. About 1600 rpm. It is a 5.4 v8. Below that it is worse and above it is worse. I take a couple of miles to get up to speed.

Do you have a fuel economy gauge?

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