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Vacuum Process Results

The oven has eight 600-watt coiled heaters, with each pair of heaters connected in series to give 600 watts per pair (total of 1200 watts), or in parallel to give 4800 watts.

I ran the oven to 210ºF in the series connection. A Zote representative suggested this lower temperature because the oven took about 30-40 minutes to get to temperature. Normally Zote molding is done around 275-300º because the sheet of Zote is placed in an oven for a few minutes, which is at temperature, removed and placed between male female molds and quickly formed. The time at temperature is short.

This shows the inside of the Zote cooling down just after vacuum forming. It is sitting on the oven with vacuum still applied until thoroughly cooled. The little black spot on the inside of the Zote is a patch over the weld joint that had failed on a earlier attempt. The patch is HD80 material contact cemented. The contact cement does not hold at 200º, but the vacuum pulled the patch down over the hole well enough to apply 10” of vacuum to the Zote. I purposely limited the amount of vacuum to 10” anyway to prevent excessive compression and thinning of the Zote. Part of the Zote rigidity comes from its thickness.

This is the inside of the left half of the shell. The long black lines are the main U-shaped foam stiffeners. The lower one runs along the bomb bay doors and seat. The middle is the bottom of the entry door. The upper black line is the separation of the canopy and turtleback line. I'm experimenting with a tongue and groove slot arrangement in which the canopy will drop into the entry door (the same for the turtle back).

Up at the nose is a 4" wide black HD80 section glued to the edge of the shell. This increases the shell width to accommodate the pedals, handlebars, and shoulders. The perpendicular curved black pieces are the stiffeners around the door opening.

The little black alignment blocks are along the separation line of the tail to main shell. With a removable tail the vehicle can fit inside a car, and if the rear wheel has a flat the tail is simply removed instead of removing the entire bike. Also that separation line is where the limit of the Zote foam sheet occurs.

This shows the tail pulled away from the main shell. The two small U-shaped internal braces on the tail plug into the larger U-shaped internal braces. There will be a latch on each brace and one on the turtleback line pulling the tail onto the main shell. The little black blobs are holding the dividing line; they keep the tail from moving inward or outward.

The main shell weighs 2 lbs. 9 oz. and the tail is 13 oz., for a total of 3 lbs. 6 oz. Both halves might come to 7 lbs. with additional stiffeners around the canopy. Another 1 lb. for the mounts will bring this to 8 lbs., a bit heavier than my OFS (Orange Foam Shell), but this one is 95" versus 80" long. Also, the OFS is made of LD45 rather than this LD60, which is a bit denser.

The main shell is quite stiff just by itself. It will be even stiffer when mounted on the bike. I probably could have started with 0.55" instead of 0.6" material. I guess the middle center section may be about 0.4" thick. I will find out when I cut the door opening. It does feel uniform, though.

The outside foil shape is pretty uniform. Because the mold has minimal curving around the middle center section, there is a slight tendency to be flat here. It looks concave in respect to the surrounding convex surfaces, even with the longitudinal stiffeners. I might have to add vertical rib stiffeners here, and luckily there is enough internal room. I am concerned that toes, heels, and handlebars will have enough clearance. It all depends on how accurate my drawings are.

Here I have glued the right half of the shell to the left half. The tail is not on. The side view shows the black center section back as far as the beginning of the canopy. That black HD80 is very stiff and has a lot to do with controlling the shape.

You can see a slight amount of surface ripple on the side. This could be from the breather blanket. It's very slight, so I don't think it will affect the airflow. This is a turbulent model, not laminar.

Here is the nose foil shape. It's pretty uniform, a bit blunt, but it has to clear the wide Q from the triple crank. This shape nose is primarily what makes it a turbulent model.

Next section: Mounting the foamshell on the LFWD