It's Ended, RIP. Update 11/13/12

[GPW]

SC, you bring up some very Valid points , some things which might not be understood by the newbees'... it’s all just simple Physics huh ? I guess this is where we get down to the “science” of trailers ... mass distribution , geometry , center of gravity, leverage ...
While being new to camping trailers , we learned many years ago how to deal with a boat & trailer ... and how moving the cargo around in the boat made a Huge difference in how the trailer towed... no explanations then , it was just something you did ... tricky because of those huge Heavy outboards hanging off the back ...

It appears the very Best way to avoid any “wind damage” is to Not tow in Windy weather ... I think that applies to a lot of things besides Foamies ... I used to have Vans (my campers) , and in a crosswind on a high bridge , it got pretty Scary ...

Eagle , you worry too much ... But your Cautions have been much considered and appreciated ! And you’ve managed a good bit of camping too ...

[eaglesdare]

me worry too much?

[GPW]

I can understand you have Good reasons.... I’ve been over “that” bridge too ...

[eaglesdare]

http://www.tinyhousetalk.com/how-to-bui ... ent-288433

if you scroll down to the comments section, you will see all kinds of calculations as far as how much wind will it take to tip one over. pretty interesting if you can stay with the formulas.

[GPW]

This would probably be the “theoretical ideal” for a profile in a cross wind . No way to tip it over unless it was ridiculously high winds ...no time to be out anyway
We can go from there ...

[Wobbly Wheels]

If we're talking about a theoretical ideal, I'd put a rubber skirting around the bottom as well - just like the skirting you see on mohos, but of a heavy rubber (old conveyor belting?) to keep air from getting under the trailer and allow it to wear to the right shape.
That profile's a theoretical I know, but there would certainly have to be a vertical component to the sidewalls to make a usable interior. Since there has to be some sidewall, I wonder how to minimize its impact...

When I was thinking about the shape of mine, I cut away the corners (realizing that the tradeoff was sacrificing upper cabinets) as much as I could, but not so much that it would intrude into the floor space and cost me liveable volume: basically just to get rid of 'dead' space.
In that profile, the corners along the sides would be similar dead space, so perhaps a practical tweak to the shape would be to bring the walls up a couple of feet with a generous radius into the heavily cambered roof. That would give you sitting headroom in the center at least. If the trailer deck were a bit high, you could put in a drop-down foot well...depending on how wide your skirting was. I'm guessing you'd want both the nose and tail rounded (in plan view) which would make it look like half of a wiener sliced lengthwise...

"My trailer has a first name, it's O-S-C-A-R" ??

Interesting idea: starting with resisting sidewind rather than headwind. I wonder what the final shape would look like.

[Wobbly Wheels]

http://www.tinyhousetalk.com/how-to-build-your-own-ultra-lightweight-micro-camper-teardrop-trailer/comment-page-1/#comment-288433

if you scroll down to the comments section, you will see all kinds of calculations

I'm certainly no engineer, but I think those calculations would be for a fixed box sitting on a single point. When you are towing, it seems the dynamics would be different for a couple reasons (besides the area correction):

- Newton's First is acting on the flow over the leeward side of the trailer, resisting the force that's trying to push it over. It may not be much but, like the tipping force, it's acting over the entire leeward (downwind) surface.

- " 700 lbs. X 5.5 feet X 1/2" - this is to co-locate the Center of Effort (CE) and the CG on the longitudinal centerline of the trailer, but it's not. He hasn't allowed for the attachment at the tongue. The CE is on a line between the tongue and the wheel but the wheel (fulcrum) is to leeward of that line. That difference acts as an arc that the wind has to push the trailer 'up' and over.
That's how a sailboat's keel works to balance the CE and CG the further you heel the boat, the longer that CG arm becomes until it balances the CE.

That's not to suggest it's wrong or that I know better or anything, but I think using that as a guide wouldn't correspond with the real world results we've seen.

The UHMW roof is a good idea, except it looks bad once it gets scratched up (black would be ok) and even sealants don't stick to it so you would have to design a really good mechanical seal to survive living outdoors (or store it inside). A smoked polycarbonate might be a better material for a roof, despite the thermal expansion.

[Shadow Catcher]

Aerodynamics.
The Stanley Steamer set a world speed record of 127 mph in 1906 and unofficially 197 MPH that stood for 20 years. It was very sleekly designed but had a flat bottom, in 1907 it hit a small bump and became airborne, killing the driver and injuring the passenger. I remember seeing the engine at the Smithsonian in the 60's. It would be interesting to see what that engine could do today in a car that did not have a flat bottom.
I still think the Dimaxion design by Buckminster Fuller is interesting and something you could create easily in a foamie

[Catherine+twins]

BTW, I forgot to mention this in the destruction report, but when we started out, and the wind was calm, even my little Elantra felt very little drag behind the car starting up from a stop. And I'm maybe a bit aggressive when I accelerate. Didn't feel a thing. However, over 60 mph I did feel the air drag. I don't have cruise control on this car, but with the trailer the happy speed was definitely 60.

Just thought I would mention it. It's something to keep me working on Rev 2.

Catherine

[GPW]

My 2 cents.... towing is like being out in a boat .... you must mind the weather , and if it turns unfavorable , you must be ready to seek “safe harbour” ... Wind and rain affects how the trailer tows and stopping distances , aside from the nasty cross wind factor ... Be SAFE !!! WATCH the weather !!!! If it gets bad , pull over , better some place leeward ... ( boat talk for “out of the wind” ) .... Most any trailer is subject to being blown over , if the wind is Strong enough ...

A trick I picked up from the Glider guys was to attach a 2’ piece of yarn to the center of my windshield ... on the bottom end only ... a “crude” Yaw indicator , normal driving the yarn sticks straight up on the windshield , but in a crosswind you can see it drift right or left , opposite of the wind direction ... On my many drives/ tows from here to Texas , the straight hwy for many miles sometimes has treacherous cross winds from the nearby Gulf ... One time we rented a U-Haul Truck and it was all over the Hwy. Not Fun !!!

[atahoekid]

A trick I picked up from the Glider guys was to attach a 2’ piece of yarn to the center of my windshield ... on the bottom end only ... a “crude” Yaw indicator , normal driving the yarn sticks straight up on the windshield , but in a crosswind you can see it drift right or left , opposite of the wind direction ...

Does it also give you any indication of wind speed? More drift = higher wind velocity?

[Wobbly Wheels]

That yarn trick is exactly how the telltales on a sail work. This is what they look like on a well trimmed (adjusted) sail:


And...not so much...

[GPW]

http://www.pilotoutlook.com/glider_flying/yaw_string

[Bogo]

I still think the Dimaxion design by Buckminster Fuller is interesting and something you could create easily in a foamie

Looks like an interesting car. It would be easy to make a sleeker one now for a trailer. For the windows it would be possible to vacuform plexiglass to make curved windows. The rest could easily be done in fiberglass covered foam.
http://en.wikipedia.org/wiki/Dymaxion_car

[loaderman]

I still think the Dimaxion design by Buckminster Fuller is interesting and something you could create easily in a foamie

Looks like an interesting car. It would be easy to make a sleeker one now for a trailer. For the windows it would be possible to vacuform plexiglass to make curved windows. The rest could easily be done in fiberglass covered foam.
http://en.wikipedia.org/wiki/Dymaxion_car

It is all compound curves, pretty hard for the home builder.