Northern Lite Traveler

[alaska teardrop]

• This sketch is from a series drawn in the winter of 2006 under the Northern Lights in a small cabin on a ridge above Goldstream Valley, Alaska.

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• The plan envisioned a light weight chassis, riveted aluminum cabin construction, strength, durability, low maintenance & a reasonable aerodynamic profile to be pulled with a small car.

• Well, I finally made the mechanical drawings & built it in Greenville, Michigan. It came in at 525#. 900# GVW. Allowing 375# for gear. Hitch weight 90#. Ride height 10". Tire track 62".

• Overall length 10'-4", width 5'-9", height 5'

• Interior length 80-1/2", width 45-1/2", height 42-1/2", footwell height 20"

• Door with slider window 26"x36". Window with slider 30"x20". Tailgate 18"x46".

• Edit: added mechanical drawings on page 4.

• Sharing the experience:

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• Fred

 

[alaska teardrop]

• The chassis & cabin floor frame were welded on a flat metal table with a 220A MIG welder. It was then sand blasted, acid dipped & powder coated. The cabin floor is .063" (1/16") aluminum tapped with VHB & riveted to the floor frame & two cross members.

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• More on the chassis in this thread.

• viewtopic.php?f=35&t=12220

• Fred

 

[alaska teardrop]

• The cabin is constructed using: .063" (1/16") 3003-H14 sheet aluminum. 16 gage (1/16") x 1" 6063-T52 square tubing. 1/8" x 1" angle cleats. 3M 4919F VHB tape. 3/16" *closed end* aluminum structural rivets (575# shear - 840# tensile).

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• The walls are made on the work table, outer film protected surface down. The side plan is layed out on the inner face of the sheet. The curve of the roof, window & door openings are cut. The rivet holes are punched or drilled. The hoop is cold formed by hand over a wooden buck. The tube framing is cut & secured in place with tape. The cleats are installed. The assembly is turned outside up. The tubing is drilled through the premade holes in the outer sheet & riveted with a pneumatic riveter.

• The walls are installed to the steel floor frame with tape & rivets along the bottom. The ten vertical wall frame members are cleated to the top of the floor frame.

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• The cross ribs are attached to the hoop with three cleats at each end.

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• The ribs are inset to allow for complete insulation sheathing of the front wall & roof.

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• Fred

 

[GRY GHST]

nice looking trailer

 

[alaska teardrop]

• The walls are fitted with one inch of *EXTRUDED* polystyrene insulation. The front & roof are fitted with one inch between the ribs & another inch of continuous insulation over the ribs. The floor has two inches of continuous insulation on the top side of the aluminum floor.

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• It doesn't have to be freezing, but anytime the inside temperature is greater than the outside, moisture created inside will migrate to the cold side. *EXTRUDED* polystyrene doesn't absorb water. The surface & edges are a vapor barrier in & of itself. With the seams & openings taped with *made for* vapor barrier tape, the moisture barrier is complete.

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• Fred

 

[alaska teardrop]

• The ceiling is barrel bend birch & the walls are 1/8" birch ply.

• The side panels were matched to the outer walls on the work table.

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• Both sides of all the panels are coated with a sealing primer. The interior sides are finished with three layers of hand rub polyurethane.

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• As an additional thermal barrier, all of the interior panels have an extruded polystyrene underlayment attached to the back sides.

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• All the wall panels have a no glue rubber edge trim. The interior is installed in place with large head aluminum rivets.

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• The flooring is 'lay flat/no glue' vinyl on top of the 2" insulation.

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• Note: In case of damage, the interior can be removed by drilling out the rivets & replaced.

• Fred

 

[alaska teardrop]

• The galley & cabin shelving is made with 3/4" birch ply. All the pieces are routered on one side in a pattern to half depth in order to reduce weight. Assembled on the bench.

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• The assembly is secured to the wall framing with riveted aluminum angle.

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• Note: Air flow over the top of the dividing wall if the tailgate is open & 2 1/2" double screened vents on both sides for cabin make-up air.

• Fred

 

[alaska teardrop]

• The tailgate has a powder coated 16 gage steel perimeter frame with an aluminum piano hinge. The aluminum on both sides & outer trim are attached with VHB tape.

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• It closes against a 1/8" x 1 1/2" aluminum angle outer frame with a 1" rubber 'D' seal.

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• Edit: Corrected the size of the seal. BTW, all of the trim & seals made by Trim-Loc.

• Fred

 

[alaska teardrop]

• The two brackets & the rear of the jack mounting plate could be used to attach a storage box without drilling or welding to the tongue rails.

• The jack is a 750" Bulldog. The geared shaft retracts up flush to the frame & the wheel drops out, leaving nothing to hit on uneven ground. With the rear corners of the trailer blocked, the jack will lift the trailer tires off the ground.

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• Fred

 

[alaska teardrop]

• The tires are 195/70/14 all season radials mounted on aluminum trailer wheels run at 21 psi.

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• The aluminum fenders are riveted to the cabin framing & side walls.

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• That's all.

• Fred

 

[High Desert-TNT]

That is one heck of a nice build Fred! Thanks for sharing all the details.

 

[TJinPgh]

That is one sweet build. Of course, I do have a bias toward the reverse tears....

Amazing how light weight that is despite being all metal with all that aluminum being used.

Not an inexpensive build, I would imagine, but it should last forever.

 

[alaska teardrop]

• Thankyou John, Shaun & T.J. for your appreciation of the effort.

• Fred

 

[Greg M-TNT]

Fantastic job! I still have a printout of your original 2006 drawings in my idea file. The profile inspired my Deco tear.
How hard was bending the hoop? Did you use a full size buck or something smaller and adjust the radius as you went?

-Greg

 

[alaska teardrop]

• Hi Greg, Cool, the shape worked for you. Are you asking because you're considering aluminum next time?

• Well anyway, the tubing is 16 ga. x1" sq. 6063-T52. The buck is made of two pieces of 1/2" ply sandwiched between the one-by flanges.

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• Allowing for a cut-off, the tube is clamped at the end, pulled down by hand & clamped every 6" or so. It bends to the shape without distortion. It does spring back. If I use the buck again, I'll tighten up the radii to compensate.

• The smaller radius is 21" outside. Any lesser radius would probably require annealing.

• Fred

 

[Greg M-TNT]

Thanks for the detail Fred. Yeah, I've been thinking about doing #3 all aluminum, mostly just to learn how . Building these things is addictive.

-Greg

 

[alaska teardrop]

• You're welcome, Greg.

• Yeah, I've been thinking about doing #3 all aluminum, mostly just to learn how.

• Maybe Mike could start a 'Building with Metal' topic. There are a number of members that might contribute their knowledge.

• Fred

• P.S. This trailer is for sale.

 

[Junkboy999]

Super build

You make it look so easy. I got this log bookmarked for future ideals.

 

[alaska teardrop]

• Thanks Terry. I hope you can make use of some of the ideas in the future.

• Speaking of ideas, another friend suggested that I should explain the concepts behind the profile shape. Especially compared to the more traditional 4x8 retro streamlined teardrop shapes.

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• The cabin is 7' long to reduce weight.

• Interior volume: The flat lower front wall & taller flat rear wall increase interior volume & bed length. The interior cabin space, bed length, storage shelving & footwell are quite generous. As is the galley with the work surface tailgate down.

• Aerodynamics: The lower front wall really doesn't matter, because that portion of the front is always within the slipstream of the tow car. The only way to improve this would be to round the front corners & blend them in to the curve of roof with compound curves.

• As the tow car & trailer move through the air, the trailer strikes the air coming off the top of the tow car. The more rounded the top front, the least the resistance.

• The blue line represents the boundary layer of that air. As the roof slopes down at the back, the boundary layer is released creating a vacuum that causes drag & lowered efficiency. By keeping that slope at a shallow angle, the boundary layer doesn't release until the very back.

• At that point the flip up at the back strikes the boundary layer & turns it under, helping to break the vacuum & drag, increasing efficiency.

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• The flip up is my version of the Gurney Wicker. So called because it was developed by American racing driver & Indy car builder, Dan Gurney.

• Of course, I have no way of testing my theories other than towing the trailer down the road at high speed (which I have ). However, combined with a suspension matched to the load of the trailer & the large radial tires rated at 1356# & run at 21 psi., the trailer rides smoothly & handles well at speed.

• Fred

 

[Junkboy999]

Thanks for the explanation. I figured you made this one shorter so you have more room for your next
build in your garage.


Hey did I miss it? or did you post the weight of this camper somewhere. ??