This is might be genius, convince me that I’m an idiot.

[t76410d]

What if I were to build a standard foamie/pmf build (with no galley), but after I did my pmf layup I glued a narrow (3”x3” ?) spine of foam down the center of the roof, and then laid a another layer of canvas over the roof? Basically create a “tent” of pmf canvas over the roof.

Why would I do this?
- A pocket of air could be very useful in moderating the temperature. If the air gap wasn’t effective, you could stuff it with insulation.
- I don’t have to worry as much about water intrusion for any holes in my envelope, like ventilation.
- A sloped roof would shed water more effectively, possibly increasing the lifetime of the roof.
- Would be more resilient to hail/rocks/etc. Like wrapping yourself in a trampoline.
- Makes the roof replaceable? I’d imagine you could cut the “Tent” off and put a new one on – you wouldn’t damage the actual structure of the TD.
- Awesome 50’s styling


Why shouldn’t I do this?
- Am I creating a giant snare drum, destined to turn every hail storm into a traumatizing experience?
- Not sure how PMF would perform when not backed by foam, or at the potentially vibrating union of the 2 layers.
- Would the “spine” create a long point load across the center of the roof, causing it to split? Could be mitigated by using an inverted “ T ” of foam down the center to spread the load.
- Would this create a pocket of “dead air” around any ventilation openings? I guess I could just use side vents instead, but then I lose one of the advantages. And it wouldn’t look as cool.
- This might not look cool.


Possible configurations:

- Sealed front and back – no worries about weird aerodynamics, no potential water ingress/mold factory. Couldn’t use air vents under it, maybe creates weird pressure differentials with temperature or elevation, kinda lame.

- Open front and back – I assume airflow helps cooling, air vents may get enough airflow to be passive (wouldn’t want to have to rely on a powered air vent if there’s a potential for dead air), least worry about potential mold factory. Potential weird aerodynamics (Could the front scoop create weird uplift or suck rainwater/roadspray through? Could airflow vibrations at the scoop cause delamination? Would it sound like a vuvuzela going down the highway?).

- Sealed front open back – Less worries about weird aerodynamics, no worries about front edge durability, still able to “breathe”, you could run air vents underneath (probably paired with vents outside the “tent”). Creates large open area I couldn’t access (mold, insects, whatever), potential airflow vibrations causing delamination at back.

- Open front sealed back – Stupid.


I'm really tempted to do this, in the sealed front open back configuration. Can someone explain why this is a terrible idea?

[t76410d]

I got impatient and posted this on r/teardroptrailers last night, and someone suggested doing the tent in fiberglass and/or incorporating some sort of backer board to support the "tent."

Sound like a pretty good idea to me - could help with expansion/contraction, vibration, etc.


Somebody also mentioned using it for storage, which wasn't my original intent but it might be a place to store a couple things for easy access in camp, like a jacket or whatever.
Putting some lights up there could create a cool effect too... or look dorky.

[Squigie]

I don't see much benefit to the multi-layered roof.
Just add the peak to begin with. Make it solid.

[printer]

How about these?

[DrewsBrews]

Sounds like alot of pain for not much gain. I wouldn't say you're an idiot. All ideas start from somewhere. Porsche wouldn't be what they are today if they didnt stick with a subjectively bad idea (rear engines) until they figured out how to make it work well.

You'd also need a method to maintain tension as the fabric stretches out otherwise it would probably reach a point of flapping so badly that it destroys itself. With that in mind I don't see much reason for it to be permanently affixed.

[troubleScottie]

So many different ideas.

Air is a poor conductor of heat, but does conduct heat. Think forced air heating/cooling systems. So insulation is needed. Some people use wood/plywood/solid walls. It has a low R factor but better than air.

Not sure why one might think a tent is stronger than a wooden roof. Most structures' roofs survive hail, strong wind, fierce rain without issue. Not sure about a cloth awning. In addition, you need to take this down the road, literally. Again hard top trailers/cars/trucks/buses do quite well.

If you are afraid of damage to the outer shell, you can add epoxy/fiberglass/carbon fiber?? to cover the roof.

The classic teardrop is a half wing with little or no horizontal areas. Water will run off. Obviously any holes or obstructions can reduce that.

Even assuming all your assumptions are true, as previous post states, not clear if there is a benefit over a standard plywood or foam construction.

[popper]

I think this could work with a backer plate of 'something.' My gut tells me it wouldn't work well without a backer plate. I'd love it if somebody would try just to see.

I quite like this idea, but then again I like a lot of ideas that don't work. By the time you add up the money and time.. maybe you would end up better off with 2" foam instead of 1" foam? The foam is 98% air after all. I might would try this with a backer just to see what happens. Some strong cardstock or cardboard maybe.

[Terra6]

Unsupported pmf has limited durability by itself without a supporting layer has been my experience with building a dropcloth and TB2 cot. Dents and penetration on my rig same with over a dozen coats of paint on top.
Fwiw, my experience.