Wednesday, June 1, 2011

Nice Curves...The Lower Longerons that Is...

Curvy Fuselage Bottom
Clamping tool used by many builders
The lower longerons go in pretty easy per plans.  The key is to make the necessary relief cuts for each curve of the lower fuselage side so the longerons fit well.  You will want plenty of clamps to hold the longerons down in the curves while it cures well.  Be sure to use the nails per plans to hold it in the proper location and then the clamps to hold it against the side while curing.  These two things working together made this easy.  It would be also helpful to make some small wooden tools (here we go again :-)  )  for the clamps to mate well to the top of the longeron stock vice trying to clamp the points of the triangular longeron.  In the pics, you can see the wooden clamp tools made from a spare 2x4.  As always, click the pics to enlarge.  My first one came out great.  I don't have enough clamps to do both at once so I'm waiting for the right side to dry now.
Clamping the Lower Longeron
TIP: I do want to mention something that the plans does not discuss and may cause you a pause.  Assuming you have done everything to plan, you may find that the lower longerons will overhang anywhere from .1" to .3" at the aft half of each fuselage side when placed in the appropriate location.  (see graphic below)   When I encountered this, I wasn't sure whether to go ahead and place them per the measurements from the upper longeron or line them up with the edge of the foam and just make sure they were the same on each side.  The plans clearly says to place the longeron at the specific measurements, but you know you start to second guess the meaning.
Click to Enlarge

Well, I found in the archives someone mentioning the same issue.  The answer was basically, don't worry about it.  Place the lower longerons at the proper measurements and let them overhang.  In a future chapter, when you shape the bottom of the fuselage, some of the bottom longeron will get sanded away anyway.  If there are any gaps left in the foam at that point, just fill it with pour foam, shape, and move on.  Below is a drawing I made to describe the problem to the Cozy Email Group before I found it in the archives.



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