Compact III -- New Modification w/ front galley

[vtx1029]

Can't you mount AGM batts on their side? May give u more clearance. Sectioning that box wouldn't be very hard. Or just make your own box using 1"square tubing and angle. I would think mounting it to the axle would be a bad idea could put extra stress on the axle along with work hardening the battery cables.

6" of clearance I would think would be fine if it was near the axle.

Ya know you could make a box with hinges on one side welded to the frame and bolt the other side up so it would swing down for easier removal.

[myoung]

I think I will purchase the battery and gas bottle before chassis construction begins and then I can lay things out more precisely with my ace fabricator.

I'm leaning in favor of welding a trapezoidal shaped floor beneath the A-frame. It would have a bent up front extending a few inches above the center of the A-frame so it could act as an anchor for the tongue box. It would also extend 3 or 4 inches underneath the front of the trailer body as well. The cables and hoses would then be anchored to the A-frame floor, run out the gap in the back, and then up thru grommets under the counter for distribution to the places they would be needed.

I don't see much problem putting a partition, perhaps of 1/4-inch ply between the bottle and the battery. I've checked with a friend in the risk management/fire safety biz and he says the danger of explosion is minimal to non-existent with AGM batteries.

[S. Heisley]

Regarding the battery, one thing that I haven't seen discussed here is where your charger or converter is going to reside. (Did I miss it?) That could make a difference as people normally want their battery to be near that.

When charging my AGM battery, I did notice a very small amount of a gaseous odor. It wasn't offensive or enough to cause breathing problems, though. (Residing in a special battery box that is vented to the outside very near the door, the vented gas may have been wisping back through the door opening.) Because AGMs are used with wheelchairs, a person can supposedly sleep right next to them without a problem. They can be tipped and jostled without incident. However, I don't know about permanently laying an AGM on its side. I'd check with the manufacturer to be certain that that is okay to do.

[myoung]

Regarding the battery, one thing that I haven't seen discussed here is where your charger or converter is going to reside. (Did I miss it?) That could make a difference as people normally want their battery to be near that.

Interestingly, perhaps, in our Airstream the converter and the 2 AGM batteries are about as far apart from one another as physically possible.

I have considered placing the converter below the set of drawers to the right of the sink alongside the partition. This location would be quite close to the battery on the A-frame and right near the fuse and distribution panel that I'll probably place on the front wall above the Porta Potti.

With a 22-inch counter depth defining the depth of the partition, there should be plenty of room for the distribution panel and master cutoff switch and probably a few other items I have yet to think about like the fire extinguisher, for example.

[Cliffmeister2000]

My battery tender is in the galley, and my battery is on the tongue. Been like that for 2 years, no issues yet.

[myoung]

... I have modified the tongue box a bit. I have put a floor under the box welded to the underside of the A-frame and extending under the body of the trailer by about 5 inches. This leaves a gap between the floor and the cross brace angle for snaking the hose and cable up thru the floor and still accessible. The gap is a vent at the bottom of the box too. Also, there is a partition between the battery and gas bottle shown, but not detailed yet.

This probably isn't a big deal, but putting the floor under the A-frame rather than over it, lowers the center of gravity of the battery and gas bottle by more than 3 inches.

I noticed that there seem to be more heavy items on the port side than on the starboard side. So, to reduce the possible listing of my vessel, I swapped the battery (52 lbs) and gas bottle (12 lbs dry, 32 lbs full) locations. That also puts the battery closer to the converter and the gas bottle closer to the fridge and water heater. A good move all around, I'd say.

I'll put the pots and pans and the converter all in the same plane to the right of the center line. Also, to balance out the weight port and starboard, I'll put the fresh water tank beneath the sink and as far to the right as possible. I'll opt for a tall, narrow, deep tank.

For my final balancing act, I'll wait until nearly all the equipment and interior construction is completed before deciding on the final location of the grey water tank. There is room to shift it off center to the right if the extra trim is needed.

[myoung]

The changes here are few. I just started playing around with tiling a diamond tread plate pattern on the drawing. Got to redo it with something a little more to scale and lacking in the gradient tinting. Oh, I've got to find some tire and wheel images, too.

[S. Heisley]

The diamond plate will probably be extra effort but it will help protect your hard work and will definitely look nice.

[angib]

Mike asked me to post the results of my (off-forum) checks on the strength of the tongue of this design, for general discussion:

It looks like you've got 37" from the front of the front body support/angle to the front of the frame. I've added 3" for the distance to the hitch ball so that gives a tongue length of 40". My feeling is that only the tongue strength matters - if it's strong enough there, it's strong enough everywhere else.

The area of doubt here is that I've said on the forum that I think teardrops can get away with frames only half as strong as the Australian trailer rules require, because teardrops are not abused like the utility trailers that the Aussie rules were written for. Now I guess that also applies to a trailer this size, but I'm not quite as sure as I am about teardrops (which can't have much extra weight added, because there isn't the space for it).

2"x2"x1/8" square tube on a 40" A-frame tongue gives a maximum trailer weight of 1560lb by the Aussie rules and so 3120lb for a 'teardrop'. So that looks just strong enough for the weight you are likely to get.

Going up to 3"x2"x1/8" rectangular tube increases the allowable weight to 2800lb by the full Aussie rules, so 5600lb for a 'teardrop'. That's clearly quite a bit more than this trailer is likely to be.

One intermediate step would be 3"x1.5"x1/8" rectangular tube which gives 2280lb by the Aussie rules, so 4560lb for a 'teardrop'. This is only 3.35 lb/ft weight (compared to 3.05 lb/ft for 2"x2"x1/8") so, as price seems to be based on weight, it's not a big jump in either weight or cost. Incidentally, I believe this is the section that Scamp trailers use nowadays for their 13ft trailer which is not a huge amount bigger than this and is lighter.

[myoung]

With Andrew's computations and suggestions, I will now refine the chassis design with 3" x 1.5" x 0.125" box sections. It is probably time to get some CAD software too. Looking at ViaCAD for the Mac.

I know that I tend not to overload trailers with too much stuff, but I must be mindful of adding unnecessary weight. I've made some preliminary calculations and figure that the tongue weight will be about 200 pounds with the axle in the current location. I would like to have perhaps 300 so that I can avoid adding stabilizers. I don't have much weight behind the axle so I'll have to consider moving it aft, but that cuts into the storage space in the sideboard and beneath the side settee.

I'm the greatest single object that the trailer will have to carry and that is about 170 pounds. I suppose I could trim that ballast a bit, but I do like to indulge while traveling. Oops.

[myoung]

Sharon and a few others building versions of pop-up tops have discussed the potential problem of lifting the top into place. Depending upon what you might put on the roof, the top might seem a bit heavy to heave. Depending upon age, height, and arm strength, the top might seem a bit heavy to heave, too.

Well, I believe David S has found the answer to the problem: 12 vdc linear actuators.

I have done a quick check on the options available and found one that may be ideal for my application, a 18-inch extension with fast activation up to 1.75 inches per second pushing 40 pounds. The model is FA-04-12-18 by Firgelli Automations and costs about $130. The motor and gearing are contained within a tube of less than 2-inches square. Way cool.

Also, quite by accident, the angle between the front of the roof and the attachment on galley counter is almost perfectly parallel with the front slope of my trailer. Now, I'm going to get CAD software to make precise calculations and plans.

It shouldn't be too difficult to make a fairly weather-proof seal around the extension tube, which is of small diameter. Since the angle between fully retracted and fully extended in my design is quite small, all that I should need is a simple rubber boot, perhaps with a slit opening if the angle proves too great.

Alternatively, I could do as Sharon is doing and extend an eve or eyebrow over the front edge of the pop-up roof. When retracted, the eve or eyebrow would sit firmly sealed on the roof behind a weatherstrip covered lip. In Andrew's original design for the Compact III, this eve or eyebrow is fixed to the roof, but then again it is at the hinged end opposite to what Sharon and I are doing.

[myoung]

It looks like the linear actuator has the capability of holding the popup firmly in place. That single point of connection in the center front coupled with the full-width piano hinge in the rear ought to be enough to obviate the need for structural support from the front and triangular side panels on the original design.

Now, I should be able to fabricate front and sides from suitable fabric with nice sewn-in screens with zippered flaps on all three sides. Very much like the VW Camper. This adds a lot of natural ventilation, reduces weight and construction complexity, and even increases the interior height when the popup is closed because the hard-sided panels won't be filling up the overhead space.

Looks like a win, win, win all around. I'm definitely going in this direction if the engineering pans out.

[vtx1029]

Personally I would look at how popups are done using ss cable and pullies, much cheaper and less things to go wrong IMO.

[myoung]

Personally I would look at how popups are done using ss cable and pullies, much cheaper and less things to go wrong IMO.

Nooo!! You're missing the whole point of self-indulgence. Expensive, easy, lazy, satisfying, way cool. Now that you bring it up, I should really opt for the remote control for the ultimate in hedonism with a pop-top.

[vtx1029]

yea but you could raise it with a cheap electric winch. Remote control no problem http://www.outletpc.com/c7265.html