LHD-12F
Lower Hull





    This is where it all started.  I used a cheap CAD program to design the frame, cockpit, duct work, etc.  This is the frame layout.  It was a lot of fun playing around with different configurations.  I probably went through 10-15 different ways to put'er together before I settled on this one.  Even now, I found a better way of making the frame lighter and stronger.  Oh well, as long as I can hull 2 people, I'm fine with anything.
 

    Here's the foam that will soon become the hull.  The plywood will be used to make disks for the lift duct form.

    The main stringers (lengthwise) are made from 1"X3"X12' treated pine.  The rear ribs are the same, only 5'11", and the front ribs are 1"X11/2"X5'11".  The skin is 1/8" marine grade mahogany luan.

    The first layer (from skin) is 1" foam.  The second layer will be 2" foam.  On top of that, around the perimeter, will be 4 more inches of foam, beveled outward for plow-in protection.

    And now it's all filled in.  Again, there will be 4 more inches around the perimeter, where the tack strips and landing skids will go.

    My parents bought about 2000 lbs of tile for their dining room.  Each box weighs in at 65 lbs in a 1'X1' foot print.  What great weight, I thought.  Well, it did make great weight, only I ran 2 boxes short.  I used a 120 lb vise, and myself (in the open spot) to keep the foam down while the Great Stuff cured.  Only 4 more inches to go!  You can see some of the 7 cans of Great Stuff I used to glue the foam board to the frame.

    I'm gluing together 2" foam to make 2 strips, 4" thick.  These will be angled outward, then attached on either side of the craft.  The inside skirt tack strip will be glued to them, much like the 10F.  What's unlike the 10F is the use of actual landing skids.  The tack strips won't be used to land on.   I will NEVER catch the skirt under the craft again, ripping it to shreds!

    The foam strips have been glued in place.  I should mention that before gluing the foam together, I sanded both sides to remove the smooth surface.  This gives the foam (or epoxy) something to bite onto and take hold.  After the sides set, I tried ripping it off with no luck.  I guess it worked!

    You can see the angle mentioned above.  If I loose cushion while going sideways, the sides will help keep me upright :-)  You can also see the bow foam which has just been set in place and is now curing.  I used a hand saw to rough cut the foam, then used my random orbit disk sander to smooth it out into it's final shape.  This process worked very well, and was quick and easy.  I'm yet to buy a battery charger to make a hot wire.

    A side view of the bow.  The bow foam is still rough cut.  When the foam sets, I'll sand it smooth to it's final shape similar to the side pieces.

    The Skids are in place.

    The skids are attached directly to the main stringers.  I cut slots in the skids for the stringer to sit in.  Thickened epoxy was used in the slot to hold everything together, and fill voids.  Nails keep them in places while the epoxy sets.  I hammered, smashed, sat, knelt, stood, and leaned on the skids to spread the thickened epoxy around.  This is important because if I set them down and nailed them in place, the thickened epoxy would flow out, leaving a gap between the skid and the stringer.

    If you notice, the skids are angled front and back so that in the event of a harsh landing, they will have less chance to catch on something, ripping them off, or severely damaging them and the frame.  The front skids are on either side of the lift duct, and the rear skids sit under the engine compartment.

    I originally thought that supports would be needed for the landing skids, but my method worked out great.  They seem to be very strong as is.
 
 

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