Hello from Holland

[graham17457]

Hello, I recently discovered teardrops and immediately fell for them! They're ideal for behind my Reliant three-wheeler. Because this car is so light (400 kg), the maximum weight I can tow with an unbraked axle is 50% plus 50 kg, so that's 250 kg (550 lb). This means I'll be using lighweight construction, and there'll be no fitted galley kitchen or cupboards inside - just nets. It'll measure 2400 x 1200 mm (8 x 4 foot).

Below is my provisional design, based on a profile 'borrowed' from www.aussieteardrops.com. I'm thinking of sides from 18 mm (3/4") ply cut to a skeleton frame, and skinned with 3 mm (1/8") ply on the outside and 3 mm white coated board on the inside. Insulation foam from a spray will fill the cavities (flame retardent). An external aluminium (0.7 mm) skin with a hammer finish would be nice. Roof will be 5 mm flexible ply with a fine fiberglass tissue and polyester coating. Inner ceiling will be the white coated board. I also plan to make the complete caravan detachable from the chassis (storage consideraration). A removeable tongue box for a mini fridge (if weight allows) to finish.


The chassis is made from stainless steel (50 x 50 x 3 mm and 50 x 25 x 2 mm section tubes), and weighs about 45 kg (90 lb) excluding axle and wheels. I had this made before I realized the weight restriction for unbraked axles- so I'm going to have to be careful. I could go for a braked axle but this significant increases the cost and is not really necessary for such a light trailer.

For those interested, the towing vehicle is a Reliant Rialto van from 1983. The Rialto was built as saloon, estate, hatchback and van from 1982 until very late in the nineties. It has a polyester body and galvanized steel chassis, and a simple 4-cylinder 850cc all-aluminium engine. Easy to work on, and my son (aged 12) and I are having a great time rejuvenating it.
Reliant started in 1935 making three-wheeler vans based on a motorcycle front fork, and introduced three-wheeler cars in 1953. They were a regular sight on British roads up until 2000 when it became no longer financially viable to hand-build small cars in polyester, and European regulations got too strict for a car with its design roots in the sixties! However there are many fans keeping the flame alive. Holland was a good export market for Reliant, although mine is a UK (steering wheel on the right ) model. The Robin is perhaps the most famous Reliant model, and the Bond Bug the most extreme.


Great forum, I wish I'd discovered it before making the chassis! I'm sure I'll be back with many questions along the way. Regards, Graham

[BillandMarijo]

Welcome to the forum.
Enjoy,
Bill and Marijo

[Classic Finn]

Hello Graham and Greetings from Finland.

Welcome to the forum. Glad to have you onboard. Looks like your off to a very nice start on your teardrop.

Very nice profile you have chosen as well.

Best regards

Classic Finn and Family

[Mark McD]

Welcome to the forum and good luck with your project. There are a few ultralight threads ongoing...search "ultralight" and pico-light at the top of the page using the search function.I'd post the links myself but I'm using a Mac right now and I'm not Mac literate.

[TPMcGinty]

Welcome! Good luck with your build. Your trailer design reminds me of a "Little Guy" trailer. They make one of the lightest tears out there.

[Mini Renegade]

Welcome to the Forum.

I have been building a Generic Benroy for the last 2 years which has a galley with no cubboards and only 2 cupboards inside. I used 9mm ply for the sides and made every part of the trailer structural for strength. I had a custom chassis made that weighs around 30Kg. The whole trailer weighs around 200Kg so it can be done. I intend pulling it with a 998cc Mini clubman estate.

Are you not painting your van dirty yellow with Trotters independant traders on the side

[Rigsby]

Welcome to the forum, mate. If you want to go a little heavier, you could always get another reliant back axle and springs, and use them, with the handbrake cables coupled to a overrun hitch
steve

[graham17457]

Thanks for the welcome and tips.

...Are you not painting your van dirty yellow with Trotters independant traders on the side

The van will stay green! Delboy had a Regal van - I love the replicars but later Reliants in Trotter livery look a bit naff. Some people would probably say that all Reliants look a bit naff, but I like 'em. Simple, a bit eccentric, and quite cheap. And lots of smiles per mile - mine and onlookers!

I've been working on the detailing of the tear. Not there yet, but here is the progress so far. It's less tear-shaped than the first concepts, but I needed a short flat area for the roof vent and for the rear lights. The figure is 1.83 m (6 ft) for reference. My door will be a hatch as used for campers (600 x 800 mm) as I can get one quite cheaply (without inner panel).

[Mark McD]

Do you think the weight savings gained by not outfitting galley will be offset by the three ply lamination sidewall construction? If your overall intent is to design light you could probably do it lighter and equally as strong with single wall construction or a laminated frame/1/8" skin construction like Mike's ultralight or perhaps Andrews Superleggera?. Andrew and Mike's designs are perhaps as light as one can be.

[graham17457]

Do you think the weight savings gained by not outfitting galley will be offset by the three ply lamination sidewall construction? If your overall intent is to design light you could probably do it lighter and equally as strong with single wall construction or a laminated frame/1/8" skin construction like Mike's ultralight or perhaps Andrews Superleggera?. Andrew and Mike's designs are perhaps as light as one can be.

I'm reading through the ultralight thread now, and there are some interesting solutions. My side wall proposal is 15 mm plywood cut down to a skeletal frame with inside and outside skins (both 3 mm thick). However, what about the outside skin being just aluminium - or is this too vulnerable?

I'm already thinking of cutting off the rear chassis cross-member and part of the side rails . This could save quite a few kilograms. And does anyone know if alloy wheels are significantly lighter than steel? The axle I plan to use has a 100 mm PCD 4-stud pattern (Opel), so plenty of cheapish wheels available.

[Rigsby]

How about making a camper out of another Rialto van?

[Mark McD]

Graham,
I'm going to go outside and weigh a sheet of 1/8 laun and a piece og .032 H5052 aluminum. I'll post back in a few.

[graham17457]

How about making a camper out of another Rialto van?

I know of a couple of Reliant vans that have raised the roof (with half a skibox bonded on) and an estate that's been turned into a trailer/caravan. The camper versions have to trade in one front seat to get the length for a bed, and the trailor versions are not particularly space efficient inside. The floor is quite high and not flat, the transmission tunnel is intrusive and so on. It would take quite a bit of remodelling the shell to get it right inside. And the shell, chassis and rear axle are quite heavy - not sure I could get it down to 250 kg.

[Mark McD]

Okay... I was sidetracked in the garage.

4' x 8' x 1/8" luan plywood = 10 lbs , approx
.032 H32 5052 Aluminum - .46 lbs per square foot

You can see the amount of weight aluminum cladding adds on is significant considering you would clad two sides and the top. That would probably average out to about 70-80 square feet of cladding to cover a "typical" tear adding weights up to 40 pounds, conservatively, when you factor in mouldings,windows, vents, etc.
If I was going to clad the outside "skeleton" frame with aluminum, I don't think I 'd use anything thinner than .025 aluminum, which weighs in at .36 lbs per sq foot, still hefty but a considerable weight savings over.032 given the fact that you'll save 20 pounds by not cladding the sides and the proportionate amount if you don't skin the top.

I've ripped apart my fair share of pop-ups and not one had any exterior skins under the aluminum, so this type of construction is not atypical.
The siding was contact cemented directly to the foam insulation and sub frame.

[Miriam C.]

to the playground Graham. Have you thought of leaving off the inside ceiling. You can save close to 20 pounds. Also I am glad you are removing some metal. Beautiful work on it though.........

Have you found Roly's Stacker? I think it weighs in about 250 pounds.

Good luck and great CAD work too.