E.T. Foam Home ...

[GPW]

Just another drawing for a simple (larger) camper trailer . All straight lines , non curves , no kerfing. Yet should be almost as streamline as a rounded one .
The size is easily adjustable for Larger or smaller. The foam , depicted in two colors, is only to show the use of whole sheets of foam .

[GPW]

And the 8’ version if desired...

[GPW]

... and "dressed” ...

[Fred Trout]

Lots of compound angles to fuss with, which I am not looking forward to

[GPW]

Lots easier than kerfing , trust me ... The angles are easy to measure and cut ... Just like woodworking ... sorta’

Fred, since you don’t know me yet , let’s just say a Drawing escapes every now and then .... It’s what I do ... Just an idea up for discussion ...

Goodness knows if I built every one I drew , I’d have a yard full of trailers .... and be Divorced too ...

[Fred Trout]

I have no idea if what they are doing with cargo trailers these days with the V-nose is completely aerodynamically effective but looks like a good enuf idea for me to use it on my build. Decided to just close the front of mine all up, cover with canvas, move the battery into the galley area and put shelves up in the narrow part of the nose - eventually. I might even forget the continuous front angle and just do the V-nose like from the 1 foot drop since that's already cut.

[GPW]

You have to do what makes You happy !!!

[KCStudly]

...I’d have a yard full of trailers ...

Um, don't you already have a yard full of trailers?

[GPW]

KC, I have a BIG yard .... plenty of room for trailers , just don’t tell the wife ... she doesn’t quite understand our obsession...

But I’ve been good .... we’re down to 4 trailers now ... two built , two awaiting a cabin.. ( or foam boat )

[GPW]

Well you know we built the FoamStream , and although Perfect for our needs , it wasn’t the easiest thing for this old guy to build ... Having to cut sheet foam to thickness from blocks (which didn’t always come out exactly the same ) Then requiring CNC cut ribs , which not everybody has access to ... And then all that kerf cutting , which was a real labor and bigger mess.
Further thinking was (in this case ) to emulate the good properties of the FS without all the complicated hassle (and weight and expense) of construction... What we wanted to retain is the sort of “tubular” ( ish ) structure that would give the whole cabin a lot of strength and rigidity without exotic framing or extra weight... Good standup headroom , the ability to sleep sideways for more efficient floor space , and have an efficient streamline nose that didn’t require sculptural skills ...

I believe this one could do that , uniform sheet foam , with angle cuts made on a table saw... (they’re just not that difficult ), the pop the whole structure together , glue , cover ... and Bob’s your ....
Note : the term E.T. is regrettably not a reference to a cute little alien creature.... It means "Escape Trailer"... for those times when you just have to get away ...

[Fred Trout]

A quality table saw has always been a desirable garnish to the DIY salad. Too bad it needs so much permanent-more-or-less open space. For some reason, a table saw has always been the difference between a serious wood shop tinkerer and a once in a while weekender.

[GPW]

All we have for a table saw anymore is one of those little Cheapo Chinese table saws .. Not much for cutting wood , but it does cut Foam easily ...

[loaderman]

angled fronts are not streamlined. Rounded are. And a taper to the back that causes the air to push you forward as it goes over.
Now the question I have not yet found the answer to is this - is a angled nose more aerodynamic then a flat nose.

[GPW]

LDM , I beg to respectfully disagree a little bit ... No they are not as fully efficient as completely rounded noses , but are Much better than flat noses . We proved that years ago when aero-modeling and experimenting with “Diamond" airfoils.
And we must admit , it does look better than a V front ( like on a cargo trailer), and possesses (somewhat) the structural qualities of a rounded surface (tubular) ... It’s all a compromise ...

... and we’re still not quite sure on the back end pushing the air moving you forward thingie’ .... so then why do hi-performance cars have flat backs ... (ish' )

Good fodder for discussion eh ?

Here’s one we had great success with ... (see Pic)

[KCStudly]

It is not a matter of "pushing you forward" (greater pressure in the rear than the front... that's not going to happen) so much as it is a matter of not pulling so hard backwards (big void space = lower pressure = relative vacuum compared to front = turbulence in the rear). If you can get the airstream to reintegrate without creating turbulence the pressure balance is better and the difference from front to rear is reduced. Same at the front; if you can split the air and get it to move to the sides and top without damming it up or changing its direction abruptly, it takes less energy to move it out of the way and less pressure will build up.

My guess on the flat backed race cars is, that GPW is referring to NASCAR cars where there is a highly regulated rules package that keeps the cars all on the edge of control and drafting is king. Without the flat back and high spoiler, the cars would all be strung out (like F1 and Indy cars) with limited opportunities to pass and much fewer wrecks.

If you look at F1, Indy cars, or even LMP, the back of the bodies (pods really) are extremely streamlined and taper to a virtual point at the gear boxes (disregarding all of the down force generators and canards). The side pods are like inverted wings in a tunnel.

If we are talking GT, like a Corvette or Mustang, they can have a flat back appearance, but what is really going on is that they have belly pans and rear diffusers, making the whole body into some what of an inverted wing, pulling air from under the car up to the spoiler and improving down force.

Our trailers don't need down force for turning and braking traction (force redirection that takes energy = drag). For that matter I hope they never go fast enough to generate enough lift to be of any concern. Side wind toppling is a valid concern in severely windy weather and beveled or rounded roof edges certainly helps there, as would less overall side area (= less area for the wind force to act upon), a wider footprint and/or lower side wall heights (= less leverage against the CG compared to the reaction point).

I respectfully agree with GPW, any tapering or rounding is better than a flat nose.

All that being said, on my own build aerodynamics was only given minimal consideration; the cabin width is about the same as both boxy SUV TV's; the front profile radius starts below the roof lines of both TV's; and the cabin height is not much higher than the TV's. The rear hatch profile is more about optimizing galley space and aesthetics than anything to do with streamlining. I'll take my lumps.