Ok, so I've gotten a fair amount of foundational work done in the last week. I've had a few misgivings in general about peoples' approach to building these teardrops. I understand this is not a teardrop forum, but hey, their servers are down or slow more than they're up, so you guys get the satisfaction of reading about this build in its entirety here!
When towing with a motorcycle, there are a few design constraints that are substantially more limiting than when towing with a car. These are:
1) Height/width can result in substantial wind resistance in the forward direction, which results in a load that is a greater percentage of the overall vehicle's aerodynamic drag than would normally be perceived by a car due to the car's already-large frontal area.
2) Side profile height can act as a sail in cross winds, and since rubber contact with the pavement is very small compared to the 4-wheelers, wind is a force to be reckoned with in a bigger way than with the 4-wheelers.
3) Weight is severely limited to an upper limit of ~400-500 lbs, based on feedback from lots of folks here on the forums.
Today's post is going to identify some design philosophies that went into designing AROUND these 3 limiting factors.
Problems with most teardrop designs I've seen are as follows:
1) They add needless wood framing that replicates the underlying trailer framing. If the trailer frame is there, USE IT! Don't replicate the frame in wood directly on top of it! It adds useless weight and increases height by the thickness of the wooden frame.
2) They don't take advantage of the space inside the frame. They want to insulate the bottom of the trailer (rightly so, to keep it from sweating) and so they add a layer of foam on top of the wasteful wooden frame, thereby further increasing the height.
3) They take advantage of the full 4' width of the plywood to make the teardrop as tall as possible to give themselves as much room as possible. There is nothing wrong with this approach. It's a good tradeoff if you've got the luxury of pulling with a car. I wouldn't say this is a problem, as much as it just doesn't balance well for what we need for the motorcycle.
4) They build the walls out of 3/4" plywood or 1/2" plywood with insulation and then 1/8" ply on that insulation give it a nice finished look. This eats up space inside (and I'm building this camper for two!) and adds weight. In addition, 3/4" plywood is way overbuilt. This camper needs to support its own weight, and aero loading, and that's it. We're not placing 250 lbs of cargo on top of it.
Here's what I'm gonna do about it!
1) Lay the plywood directly on the trailer frame. See previous posts for details on that!
2) Use the space between the trailer frame members to place foam board and expanding foam insulation. In retrospect, I wish I had routed my wiring through there before doing this, or at least placed a channel to run them in, but I didn't. Oh well. Live and learn!
2" foam board (extruded polystyrene) fits nicely inside the HF trailer frame rails. Cut nicely using a PVC saw and a jab saw for drywall for getting around the wooden blocks.
In some cases, the foam board had to be split in two to fit into one of the bays because it was interfering with the hardware and structure for the leaf spring supports.
Add weight to the top and let that polyurethane glue set up overnight!
Fill gaps with expanding foam and let that foam cure overnight. I didn't and it was more of a pain than it was worth!
Slower is faster!
Now all of those gaps need to be filled with basement sealer or some other such sealer to keep moisture from getting up in there. In retrospect, I wish we had used water and ice barrier for roofing. Live and learn. Used 2 coats of basement sealer.
Here are the time-lapse videos depicting how this job!
More Foam Work:
Happy watching! Next post is about the cutting of the sides and doors! That's a scary one...big money involved and you want it to be perfect! Stay tuned...