Does a square drop lower air resistance much?

[McFish1951]

At 73, I need a 6 ft height at the rear to stand in and to enter. I don't want a Rouser style box; the MPG penalty seems like too much. If I put a 4 ft height at the front, 3 ft along the length; then slope the height up 2 feet so the rear is 6 ft tall. So the rear of the trailer has an area 3 ft long by 6 feet high, and 6 ft wide. The door is in the rear wall. The 2 ft slope in the middle helps to spill the wind; hopefully enough to lessen the overall drag. I'm open to input. TIA

[Pmullen503]

That large flat back will have a lot of drag. Since the front of the trailer is in the slipstream of the TV, the back really matters.

That said, you can always go slower or closer to home or just pay more for gas. Your comfort's important.

[tony.latham]

Yes, that flat back will cause drag.

A teardrop-shaped camper, as you may know, is an airfoil. With some roof vent fans, the lift provided by the camper's shape pulls the vent lid up and causes a low-pressure zone inside, which can cause water ingress through window vents if it's raining. (There's a fix for it.)

There's a reason they pull easy.

To get in and out of a teardrop, you do it the same way as in your bed. You sit on the edge and swing your legs up. It's simple and easy --and I'm 73 too. You might try to find a teardrop you can test for a few minutes.

Tony

[working on it]

I have a squareback trailer with a 45 degree slope on front, and a flat back hatch. Basically a 4Hx8Lx4W square box, with the front cut down. I angled the front to match the height of my wife's old Cobalt's rear end (with factory rear spoiler), so she could tow it when camping (she never did, and I made it mine, after that). Of course, it ended up being heavily modified, over-stuffed, and exceptionally overweight, because that's what I do.

The trailer, being flat at the rear, needed something to break up the vacuum caused by the airflow over the flat roof. As a motorsports afficianado, ex-dragracer and car builder (mostly an assistant to a master mechanic/fabricator), I was aware of the use of various airfoils, wings, spoilers, splitters (etc) that could be used to change the behavior of the airflow. But, being cheap, and also unconcerned about the MPG incurred by towing a flat-backed trailer (because my tow vehicle gets 11 MPG towing any trailer, or none at all), I just used a simple raised bump (a rounded "Gurney flap "spoiler, if you will) atop the rear hatch (a folding piece of stiff conveyor belt, that also covers the open gap caused when the hatch is lifted), to break up the vacuum effect. After years of use, I've found that the rear hatch stays clean (a sign that the vortex behind the trailer isn't pulling in dust/dirt, which happens when the drag is high), so it must be working.

As for your design, I wish I had made mine the same, instead of the way it is now. I have to enter head-first, and exit feet-first, as my door is too far forward,and there's an overhead shelf over the 36" high door, so I must duck in. It wasn't too difficult when I built it at 61-63 y.o., but now, at almost 75, with bacd back, knees, and sciatica on both sides, I have to use grab handles to go in or out (or even to rise up from sleeping position). That's one of the reasons why I seldom camp anymore.

To avoid problem with an overhead vent, I chose to use steel, waterproof, two-piece vents fro etrailer.com, mounted in four places: two for cabin ventilation, one for supplying air to the rear storage area "galley" (and for cooling the interior mouted A/C unit), and the fourth for the exhaust of the A/C unit. I use the galvanized version of this vent

Polar steel vent.JPG (60.06 KiB) Viewed 1057 times

now at $47 each, they were about $20 each IIRC, in 2012

I added bug screen mesh on three of the vents, and leave them partially open at all times, even in the garage at home. The one use for the A/C exhaust is basically a covering for the exhaust duct, and is lifted up when in use. The two vents for the cabin have 120mm Corsair computer case fans (that swing-away, if not needed) that can be switched to either pull air in or push it out, as needed. The vents have proven to be totally waterproof over the last decade+.

[McFish1951]

Tony; thanks for the thought. I have tried a "normal" teardrop; with 2 issues. 1) the doors are not wide enough to sit in while putting on shoes, and the bottom of the door digs into my thighs. 2) Not tall enough to get dressed inside. Yes, a dressing tent outside can do double duty; an outside bathroom and a dressing area. My hope is the sloped design might be more aerodynamic than a Runaway Rouser design, and lighter, while still affording some stand up room.

[tony.latham]

1) the doors are not wide enough to sit in while putting on shoes, and the bottom of the door digs into my thighs.

I can't help you with the door width, but here's how I explained your other issue in my book:

The location of the bottom of the doorframe is also critical. You want to sit on the mattress, not the doorframe. The bottom of the wall also needs to support a portion of the mattress. Thus, the bottom of the door opening must be located about halfway up the mattress.

It works.

Tony

[OP827]

Did you consider lifting roof options? I know the build is more complicated, but I think it worth it if you value the standing comfort and still want to go long distance without too much thinking of the cost. Just a thought.