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Old 09-29-2008, 05:57 AM   #21
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Trailer: 2007 19 ft Escape 5.0 / 2002 GMC (1973 Boler project)
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Hi: Reace... We already know about Slope nose aerodynamics. Almost everyone who sees our 5.0 says it looks "So Sleek"!!! In a trailer where every inch counts you must strike a ballance between interior storage space and exterior aerodynamics. I thought you already had... but you can always try to squeeze out some more. Just don't ruin the "Glassic" look of your trailers to be trendy!!! My 2c worth.
Alf S. North shore of Lake Erie
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Old 09-29-2008, 10:22 AM   #22
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Applying this shape to a travel trailer with, say, 7 feet of headroom in the middle in exchange for having only 5 feet right at the back, might not be such an impossible idea.
I like that idea.
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Old 09-29-2008, 10:33 AM   #23
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Trailer: LittleGuy Classic Teardrop ('Baby Osmo') (Previously 13 ft Scamp Custom Deluxe)
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Poor Reace -- he would have loved to have a nice 95% consensus, one way or the other! However, we can see two distinct camps emerging -- the first focuses on efficiency, the second on convenience.

The efficiency group probably already leaves behind the things they don't need, because un-needed items add the other gas-mileage killer - weight. This group can generally make do just fine in whatever storage space happens to be there, and the loss of just one or two cubic feet of storage won't negatively impact them.

The other group places a higher priority on convenience, and will pack any and every available storage space with items that add to the comfort or peace-of-mind. The loss of even one cubic foot of storage is a significant set-back to the enjoyment of their camping style.

It is interesting, too, that the cabinet in question is a FRONT cabinet, which translates into pure tongue weight. This translates directly into tow-vehicle capacity, and therefore, to some degree, economy. For instance, my tow vehicle (which isn't Escape-class) is rated for 1500# of trailer, and for 150# tongue weight. However, the suspension can't really carry that much tongue, so front cabinets are a major negative to me in whatever I tow. My tongue capacity keeps my towing capacity down to about #1200, based on the 10% rule.
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Old 09-29-2008, 11:03 AM   #24
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Trailer: Casita Spirit Deluxe 17 ft 2001
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I agree a windtunnel would be great if the funding was there! Hey....election coming up....maybe the govt want to chip in for a good cause!

Peter you make great points on the front and rear and I think this is where the Oxygen had a great aerodynamic design. I didn't want to go that far tho.

We are in the process of building a new 17' mold and angling the front end was something that came up after touring the local RV show this past weekend. There are some goofy looking 'stickys' trying to save fuel....but today it is something to look at.

Reace
Reace dont do a sharp angle front , this is ugly ,"sticky" hit the air like a wall! They have the Cx of a 40' contener! Your Escape is perfect like it is....Maybe one complain...Give us a bigger battery box! G...I wish you give anough space to carry 2 T-105 6Volt in your new 19' because we need them! Old time is gone we are in futur and we carry more power ungry luxury Item, Radio/TV/DVD Sat receiver and solar system just to name a fiew. We need power!

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Old 09-30-2008, 02:12 AM   #25
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Aerodynamics
The complexity of this topic is massive, and altogether exciting to look at. The simple solution that you have come up with, will in all likeliness not improve anything.
You guys need to watch some Bill Nye!

But in all seriousness... (from my understanding), Most of drag that makes trucks and campers so inefficient is the back of the vehicle. As you are running down the road, you are displacing air, that you are running into (at the speed limit I hope). The issue is that the air has to be replaced (you are in effect creating a vacuum behind your vehicle), and air has to be filled/replaced into your wake. This replacement in your wake, is what slows you down, and it actually pulls you back. It also makes your engine work harder to overcome. Slowing down actually improves your aerodynamic efficiency...

Enter the teardrop shape. As you may know this shape is very aerodynamically efficient. The reason is, it allows the air to be replaced in the rear more effectively, and removes a lot of turbulence.

EDIT: Also consider the "cool" wing that many vans/cars use on the back of their vehicle. The idea has a scientific basis. The purpose is to redirect a stream of air behind your car, filling the void/vacuum that you are creating...

At any rate, I hope that I have added a little knowledge to your base...

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Old 09-30-2008, 09:13 AM   #26
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As always.... a wealth of information here!

Thank you all for your contributions....I will leave the design alone. I would the change the front in an effort to reduce drag and lose storage if there would be some gain over fuel economy.

Reace
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Old 09-30-2008, 09:28 AM   #27
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As always.... a wealth of information here!

Thank you all for your contributions....I will leave the design alone. I would the change the front in an effort to reduce drag and lose storage [b]if there would be some gain over fuel economy.

Reace
How about considering something with a pop up roof? It would fit into a garage, not get charged overheight on ferries, but allow plenty of headroom when camping.
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Old 09-30-2008, 09:59 AM   #28
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Close to 30 years ago my parents drove coast to coast with a 19’ stick built towed with a Ford Fairlane station wagon sporting a small V8. When they started out the rig would not go faster than 55 mph flat out on a level road with no wind. Somewhere mid country they stopped at a home center and purchased some plywood and made a simple air deflector for the roof of the station wagon. Now they could easily cruise at 65 or better.

I believe that rounding the corners of the trailer, as we have with our molded fiberglass units, would help some but the major drag reduction was to form a virtual smooth(er) shape, keeping the air form sucking back in at the back of the car (causing drag) only to hit the front of the trailer (causing more drag).

About 20 years ago I drove from SE Pennsylvania to Montana and back with 4 adults and one 18 month old in a Ford Taurus station wagon towing a small pop-up. The fuel economy averaged about 32 mpg if I am remembering correctly. This is better than I ever experienced with the car by itself. Similar but not as dramatic experience with the same pop-up towed with a full-size van. The pop-up seems to have created a much smoother transition for the air to fill in the air hole thereby greatly reducing the drag.

Reace, a roof mounted air deflector might be a very useful accessory product. A little more unusual but a removable fold up tail cone for the trailer might also reduce drag quite a bit. Just might realize significantly reduced fuel burn, good for both the wallet and ecology.

Don't give up on doing some experimenting. Many universities have small wind tunnels and are looking for student projects. You can also do some very meaningful model testing on your own.

Craig T.
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Old 09-30-2008, 10:51 AM   #29
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For a 13' footer I can't see how you could make it aerodynamic and maintain the front bunks. There is no question that the Trillium behind our Subaru is a giant wind drag - we got probably 1/2 our usual gas economy if we are traveling over 90km. However, that is offset with the overall lower gas mileage of the Subaru compared to a V6 van or truck both pulling the trailer and as my daily driver.
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Old 09-30-2008, 12:08 PM   #30
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Discussing aerodynamic trailer shapes, I thought you might like to see this amazing one-off trailer which is pretty nearly a perfect low-drag shape, I would say - rounded front corners (top and side) and rear taper in both plan and elevation. It's not perfect - those exposed fenders rather spoil it, and the roof A/C will ruin much of the excellent roof shape - but it's better than anything else around!


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Reace might like to hear you all say that you think that shape is ugly, so that the seeds of doubt aren't sown in his mind.

The trailer is built with a complete aluminium tube framework, skinned with plywood and faired..... and faired, and faired some more. However the shape would be ideal to reproduce in fiberglass.


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There are many more photos to see on the builder's original posting on the Teardrop forum: My New Trailer

Andrew
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Old 09-30-2008, 12:22 PM   #31
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While my initial impulse would be to vote for "angled" for aerodynamics - I'd want to be SURE it actually DID offer better mileage when behind a range of tow vehicles and not that it just "looked" more streamlined.

However - I'd actually be very hesitant to use the angled front in any floorplan that included a front dinette. Any remotely angled front will end up cutting into the usable seating in the front. That's something I came to appreciate in the PlayPac I rebuilt. It was fine for the kids. Likely would have been fine for me if I'd have been 6 inches shorter. But as it was I ended up feeling confined by the front wall leaning in toward me.

mkw
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