In his most recent post (that I have received, that is) Bill Shatzner
wrote at length about the problems of relying upon published drawings.
I am in agreement with Bill and did waffle on about the subject a little
while ago in regard to scanned drawings. I my opinion, you CANNOT accept
anything as gospel unless you confirm from a number of sources. Drawings can
become distorted in the reproduction process (assuming they were correct in
the first place) and plastics probably distort and shrink
a little when they come out of the mold. The inherent assumption is that the
mold is also correct which it may not be. I feel fairly confident that there
will be a number of factors involved in the art/science of plastic
molding that will affect your model aeroplane. Perhaps someone on the list
has knowledge of the topic?
You must also remember that quality records of many of the prototypes that
interest us as modellers have not survived so the draftsman must rely upon
photographic sources. I doubt that few (if any) photos were taken with the
interests of modern day draftsmen and modellers in mind, so draftsmen have
to make estimates and occasionally revise drawings when new or better
information becomes available. You may have noticed that Ian Stair often states
that a new drawing supercedes all previous versions. I have compared some
to note the differences. Sometimes it is in the position or size of some
feature like the shape of the fin/rudder or a ventilator panel.
On the issue of dimensions, I believe that published dimensions such as overall length and wingspan can be relied upon if they come from a reputable source
such as Ray Rimel or Ian Stair but in other works I have encountered dimensions
that do not add up. That is, dimensioned drawings where the sum of
chained dimensions does not equal the quoted overall dimension.
The real issue is, HOW PEDANTIC DO YOU WANT TO BE.
Scaling up from small plans to build large R/C models can result in gross
distortions that are really obvious to someone familiar with a particular
prototype.
Scaling down to a smaller size from a larger drawing tends to hide small errors.
For instance, the scale drawings published in Aeromodeler, used to be drawn at
1/36 and were then reduced to 1/72 when published. In most cases you could
order both sizes from the MAP plans service.
I think each individual has to make a choice based upon personal desire, the
availablility of information, and whether or not the result is for personal
satisfaction or to appease some contest judge who may not know much about
you pet prototype anyway.
Regards
Paul Butler
pgb@kau1.kodak.com