Thursday 21 July 2022

Cross struts

 21 July 2022

Simplicity=Repeatability.

Traditional layout construction is to lay out the longest and main structural parts (such as leading and trailing edges, upper and lower longerons), pinned out on the building board and then cut the struts to fit in between the outer frame.

There's usually a left and right side to be constructed and be identical.

The problems/difficulties:

  • not a good fit
  • not at identical position

Solve it by:

  • Trace a working plan by positioning left and right fuselage together, typically the upper longerons are against each other, draw in the longerons and struts.
  • Pin over long strips on the building board over the working plan. When pinning, leave enough space so that straight edge can be placed over the cut lines of the struts so that the straight edge can guide the guillotine cutter.
  • Chop the struts, lay the longerons and glue in place.
The fit will be better and the struts will be in identical positions. It is easier to making accurate angle cuts. The number of cuts is the same. We may waste a few inches of strut material in total, but that's not a deal breaker.

Wing construction can be the same if there is no 'airfoil' ribs. For smallish model where curve plate airfoil is used, the ribs can be treated as struts in the fuselage example. Then need some water/template/rolling pin to get the flat plate to become a curved plate.

Pin strut material on board