Guppy Trailer, part 1: the basic concept

This summer Lizzie wants to go on a grand-loop road-trip around the U.S. with the kids. We have thought about various ways to do this, and we have decided upon building a teardrop-type trailer which we will tow behind our VW Golf (a.k.a. Glove). Why? 1. We need something convenient to camp in. At first I was not sure that I was going to go on the trip (I tried to get back to Kabul for August), and Lizzie wanted a secure place to sleep. 2. Buying another vehicle would have cost far more, even if it were an ancient VW Microbus.

I researched teardrop trailers online, and found out two important things. First: teardrop trailers emerged during the Depression, as families could not afford to stay in hotels. So our choice to build a teardrop is historically consistent. Second: it is very difficult to get plans of a teardrop trailer (for free). However, these trailers emerged at about the time that plywood became available, and for many D.I.Y. families, the 4′ x 8′ module of the plywood sheet was the standard-unit basis for the design. Here is my version:

TrailerSectionDesign

Initially my design had a simple sloped back like other teardrops, the shape that gives them their name. Then I decided to add a swallow-tail to the galley hatch to separate laminar airflow over the trailer from backdraft turbulence behind it. Most recent cars have some version of this lip, so my hunch is that this will work better. Sophia looked at the new design-shape and said it looked like a guppy. And so this design was named!

But what would the Guppy sit on? I was not familiar with trailers, but our neighbors are. We took a look at a flatbed trailer parked nearby, made by Carson. From the manufacturer’s labeling on the trailer I realized that the flatbed has a VIN, and is engineered to comply with DOT standards. Essentially, the steel flatbed trailer is the vehicle, and the Guppy is merely the cargo, or payload that sits on the trailer. So I ordered a ‘flatbed mini’ from Carson, with a 4′ x 8′ frame, and an axle assembly rated at 2000 lbs. For this trip to work, the Guppy must weigh far less that 2000 lbs; maybe 300 lbs max. Part of the reason to design and build my own is to make it as light as possible.

And how would we tow this trailer with a Golf? We had to order a trailer hitch. Fortunately JC Whitney sells Curt trailer-hitch frames that fit a 1998 Golf, at $225. Installation was a pain, because the Golf is a unibody construction so there is no chassis nor any pre-made attachment points. I had to bore out 3/8″ bold-holes on some very irregular, compound-curve surfaces to mount the hitch frame.

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