30 J-3 Cub Nose
Block Scale Problem
I know I am having enough problems with this J-3
Cub without making one of my own, but the more I have looked at the front
end of the J-3 Cub, the more it doesn't look right! :O< The
picture below shows what I am talking about. See how short and flat it seems
to be.
This is another view of the short flat nose
block on the model. You have to agree, there is just something wrong with
it.
First, I checked the width of the nose block's
six laminations shown on the plans and they measured 0.75". However, the
actual six 3/32" laminations of the nose block only measure 0.56", which is
0.19" too short. This represents a 25% reduction in the thickness, which
explains part of the "dorkyness" problem.
Then I recalled the instruction supplement sheet
shown below that came with this Herr kit. Item No. 3 indicates that the nose
of the model has been made just a little wider 0.2" (1.8"
instead of 1.6"), which accounts for another part of
the "dorky" looking front end.
This 13% increase in nose block width, along with
the 25% decrease in nose block thickness, taken collectively, pretty much
explains why my J-3's front end is missing its character and I just can not
accept this. Soooo, in my quest to try and recapture the scale look of the
model's front end, I went to the J-3 Cub's profile drawing on the 3-view for
inspiration.
The fuselage is already built with the front
end's 13% increase in width. To try and change this would be disastrous and
probably result in scraping the whole J-3 Cub project. Besides, The added
width to the nose does permit room for the insertion of the 3/4" PVC blast
tube. Therefore, I had to look at increasing the nose thickness, but how
much? I decided to increasing the short 0.56" nose block thickness by the
same proportion as the 13% increase nose block width. This provides a nose
thickness of (0.56 X 1.13) = 0.85". Keeping the profile thrust line at the
same location as on the plans and using the 3-view profile shape,
I carefully sketch out the resulting nose block profile on paper. I cut out
the new profile and taped it to the front of the model's fuselage as shown
below. Guess what, the J-3 Cub will have a scale looking front end when I
make a new nose block with this profile. However, for right now, since there
is so much work involved in making a new nose block with a correct thrust
line, I am going to continue on and finish the model first, except for
covering. Then I will drop back and build this new scale looking nose
block....................Tandy