Hello Guys land Dolls, As some of you already know I took over a project
from Eric Pitts over the summer. I think that I might be the fifth owner of
this project and there have been many changes from owner to owner. This is a
unique project that was started by Dr. Dean about 16 years ago now. So there is
no blame to be found here just observations on how a plane can weigh a ton (
not really an exaggeration). When I got it home I took every assembly and
cataloged and weighed them. I then started to evaluate how I wanted this plane
to turn out and then evaluated what weight reductions could be done. To be
very fair there are many very well built assemblies that I well use pretty much
as is. The first and largest was the fuselage on gear. (too many little
items included or not included for anyone to make a comparison) This weighed in
at 150#. I have removed a lot of epoxy runs and spills. The use of flox while
in the right places was 2 to 3 times what was needed for fillets and edge of
foam filling. Wood blocking from different configurations of systems was all
still in place, even though not used anymore. The result so far is a reduction
of nearly 10# from just this assembly. I still see another 3# in lightening
holes and a couple more things to remove. (Like tail wheel support) The seat
had a much smaller yield but still gains to be had. It started at 8.5# and with
just sanding extra flox out came down to 8# even. There are a couple
things that I am trying to share here in thinking about where you might be able
to build a part a bit lighter. One item is in blocking. If you are trying to
use a block of wood for a gusset or support and is is being used or glued on
two sides consider it being a triangular piece instead of a square piece. Half
the weight for free. In most cases just epoxy is enough on the surfaces that is
in contact. Flox fillets are likely over kill and just more weight. (Yes,
ounces add up to pounds) Also if it is a long blocking situation think if it is
needed full length or if one or several short pieces would do the same job.
Clean up extra epoxy runs and spill overs. Use peel ply as much as you can.
Again it does make a difference on ever part. Be careful of the edge depth that
is filled with flox on every part. I think the rule of thumb is a 1/4" and it
could be a triangular 1/4" if the edge is over 1/2" wide. If the edge is that
wide or more I might suggest that the flox edge still only be the 1/4"
triangular edge and and a layer of glass to cover the surface with peel ply to
take out the excess epoxy. Lightening holes are another very efficient
way to to save weight. I made two new mounting brackets for control stick
assembly out of aluminum angle. I was able to reduce the weight of each bracket
by exactly half with lightening holes with no loss of structural integrity. The
brackets weighed about 3 ounces each so basically I got 2 for one weight wise.
Not a lot but again ounces make pounds and I will not have another 700 plus
pound KR. Give your bird a free Christmas present by saving weight.
Remember you save fuel forever for every ounce that you don't need to drag into
the air. Think before you beef up a part that has served as is for 40 years of
KR's. Think if it really does need to be thicker. Think if it needs to be steel
instead of aluminum. Think if it really needs another layer of glass. Think if
you really need heavy electric motors instead of light flap or trim hand
operated. Look at every part you make and wonder if it is the lightest way that
it can be completed.All my best,Joe Horton
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