Teardrop Walls

[Paddy Shepherd]

Hi all,

Newbie to the forum here, and to teardrops. Haven't actually started building one but here's the background:

For a college project I am designing a multi-purpose teardrop camper/cargo trailer.
The chassis will be a bought-in Erde CH751 motorcycle trailer (the rails are removable to allow ATV carriage, bicycle carriage, or flatbed trailer etc, so this fits with the multi-purpose theme of the project). The teardrop shell will be designed to be removable, mounted to the chassis via bolts and quick-release fastenings. Keeping the weight low is MASSIVELY important here. My weight limit for the trailer is 750kg's Gross. The chassis weighs 125kg meaning I have 625kg to spare for the shell.

The shell will be very basic, but will be available with multiple options.
For example, the spec that I am modelling will consist of 1 large rear hatch (normally where the galley would be - there isn't a "galley kitchen" on this shell. Cooking equipment will be camping-esque and stored inside), a single mattress giving space for bicycle storage inside, and one large shelving unit at the closed end, and a skylight in the roof. No electrics are necessary, but will be optional, as the bought in chassis comes inclusive of all lighting requirements for the UK.

Before starting the college project I'd already considered doing this due to the fact we already own one of these chassis'.

I am currently modelling the teardrop. My plan so far has been to use two sheets of ply for each side, 5mm with a 40mm void between them for thermal insulation board (for example: click here).

Obviously in my base I have lateral supports and in the roof for the roof skins to attach to. However, I am unsure of how much support I will need in my sidewalls, as I imagine the composite construction will be fairly strong. As there are many many ways to construct a teardrop, I'm finding it difficult to find information about this online.

The teardrop shell will stand at 2600mm long, reaching a total height of 1300mm at tallest, and 1400-1420mm wide.
It will be a flat front construction, curved roofline to a much smaller, flat rear.

I will add screenshots of it so far later on. In the meantime any advice on the sidewalls issue would be massively appreciated.

Cheers,
Paddy

[Paddy Shepherd]

Here's the model assembly so far. As you can see at the moment the walls are hollow and still to be detailed.

[rowerwet]

I have no idea what a kg feels like, but if you want light and strong, you can't beat a foam I. Best of all it can't rot.
I built with 1/4" skins and 1x2 sticks making each wall a kind of I neam. 3/4" foam board in the voids keeps it cool or hot like I want, however it still is heavier than it could be if I just used foam board as the inside of the tear and 1/8" ply as the outer skin.
Now I would just build with 2" foam board and painted canvas as the skins.

[Paddy Shepherd]

Thanks for that.

For reference, 1Kg = 2.2lbs.

So in that case, would you imagine that a sandwich of 2 5mm sheets of ply filled with thermo-board foam would be adequate for sidewalls, bearing in mind that they don't take a massive load?

[rowerwet]

With the foam and ply fully glued together, it would be almost indestructible. 1/2" or 10 or so mm of plywood is overkill, 1.5" of foam board would be strong enough by itself.
Look into the weight of a cubic cm of wood vs foam. One sheet of 5 mm ply will weigh 60 or so kg. Weight builds up fast.

[Paddy Shepherd]

Not quite sure where you got that 60kg from buddy but thank you for the info on the strength.
I just looked at some marine ply (although I will probably just use normal) and the weight of that for a 4' x 8' sheet in 5mm (3/16") thickness was 16lb according tho the specs, which is approximately 7.5kg.

[dales133]

Just make sure the ply you use is exterior rated.ie exterior rated glue and preferably hardwood

[ctstaas]

Hi Paddy, Whats up?
A few suggestions from me; Some take 3/4" sheets and cannabalize them and add insulation to the cut outs and thin sheeting to the inside and out before skinning the outside in Al. Mine is just 3/4" marine grade plywood with no insulation in the walls. When you cut your outside shape do them together so no matter the final shape they will both be the same. It will really help later in the build. When I rolled the cabin onto the frame I was thinking " I could make it detachable and have a multi-use trailer", but that thought didn't last long. For you, Oh yeah, consider light and fender placement and your good.
I would move my galley opening back farther. You could fit five kegs in your proposed galley. Five kegs is the right amount of beer but you need some space inside the cabin so its a trade off. Really, My galley barely fits my icechest with the hatch closed so I dodged a design bullet there, so my advise is to make your galley space accommodating for you essentials but be gracious for you sleeping quarters, it might rain.
I love TD's because they provide super function with high design attributes. I'm sure you'll get an A on your project.
Enjoy, Chris

[rowerwet]

Not quite sure where you got that 60kg from buddy but thank you for the info on the strength.
I just looked at some marine ply (although I will probably just use normal) and the weight of that for a 4' x 8' sheet in 5mm (3/16") thickness was 16lb according tho the specs, which is approximately 7.5kg.

Converted the wrong way... oops

[Ron Dickey]

if you made the back square you could have a swing out kitchen.

https://www.pinterest.com/pin/209135976418924130/]
then there are camping boxes
http://www.google.com/search?q=camp+box ... &oq=&gs_l=

does you trailer have tie downs inside.
http://www.google.com/search?q=trailer+ ... &oq=&gs_l=

some offer swing away or fold up beds
http://www.google.com/search?q=trailer+ ... &oq=&gs_l=
while others just have removable furniture

hope this helps
Ron

[Paddy Shepherd]

Hi Paddy, Whats up?
A few suggestions from me; Some take 3/4" sheets and cannabalize them and add insulation to the cut outs and thin sheeting to the inside and out before skinning the outside in Al. Mine is just 3/4" marine grade plywood with no insulation in the walls. When you cut your outside shape do them together so no matter the final shape they will both be the same. It will really help later in the build. When I rolled the cabin onto the frame I was thinking " I could make it detachable and have a multi-use trailer", but that thought didn't last long. For you, Oh yeah, consider light and fender placement and your good.
I would move my galley opening back farther. You could fit five kegs in your proposed galley. Five kegs is the right amount of beer but you need some space inside the cabin so its a trade off. Really, My galley barely fits my icechest with the hatch closed so I dodged a design bullet there, so my advise is to make your galley space accommodating for you essentials but be gracious for you sleeping quarters, it might rain.
I love TD's because they provide super function with high design attributes. I'm sure you'll get an A on your project.
Enjoy, Chris

Long time no visit gents. Thank you for your comments, I'll take that info on board.
The galley hatch has been designed that way due to the fact that there won't be a "galley" as such. Unlike many of the TD's on here I do not intend on having a fixed kitchen in the back. Instead, the rear hatch is the main access hatch and there will be shelving at the head end to store utensils, gas stove etc, with the cooking done outside under shelter of the hatch (with an option to extend using an attached awning). This allows for a large interior area without the impedance of a kitchen, but also allows the trailer to be used as an enclosed cargo trailer if the interior is removed (which is all designed to be) as well as the option to remove the shell for a flat bed trailer. In my case, I don't need to worry about light/wheel arch positioning as the chassis I am using (prepurchased, it's a 3-motorbike or 1 atv trailer, further adding to functionality) comes complete with lights, wheels and fenders. I hope this is making sense. In the event that it isn't, there's an image below of how the teardrop could be used (be gentle, the model hasn't been rendered yet!)
NB: there will be insulation inside the roof lining etc, but this will be in the form of insulation matting (loft insulation stuff) rather than the rigid insulation foam that I've idealised for the walls.
Chris - I've taken on board what you've said about the walls without insulation, and may do this if I come to build it - however, it's too late in the design to change it purely for this project purpose. There's a long justification process where you need to evaluate why you've chosen a certain method, and it's too late to start going back through this).

Thanks all!

[S. Heisley]

Hi, Paddy. I think you're smart to want to park your bike inside your teardrop. There are gangs that are stealing bikes at unheard of rates, all over the nation. If they can't get them off the bike rack, they steal the rack too. Last fall, police found an area, in a canyon behind a local hospital, that contained parts from 2,000 presumably stolen bikes.

[Paddy Shepherd]

Hi, Paddy. I think you're smart to want to park your bike inside your teardrop. There are gangs that are stealing bikes at unheard of rates, all over the nation. If they can't get them off the bike rack, they steal the rack too. Last fall, police found an area, in a canyon behind a local hospital, that contained parts from 2,000 presumably stolen bikes.

Bike thefts have picked up at an astonishing rate over here in the UK too unfortunately, if they can see it, they'll take it. Recently a professional cyclist had his house broken into in broad daylight by 2 youths, who then rode off on their bikes with his 3 race bikes over their shoulders. Thankfully CCTV at his house was able to find them, but it just shows the thieves will stop at nothing to get their hands on bikes!!

[Paddy Shepherd]

Thanks to all of you who helped out with advice, suggestions and ideas. I handed in my project a few weeks ago and have been awarded distinction level. This is the highest possible level for the project unit, so I'm massively grateful for all the help I received on here.

Maybe one day I'll actually get round to building the thing...