List,
You asked for a new topic Keith. Please bear with me list as I explore
what I think I know and what I do not know about SCTA & ECTA rules - which
is where the list comes into its own .............
The 'chopping of the roof' of a quite modern vehicle that could run in comp
coupe is permitted (indeed encouraged), but I am confused that much of the
rule book relates to two dimensional measurement and views, but we are
dealing with a three dimensional matter.
The A (front), B (middle or door) and C (rear) pillars of modern 4 seater
cars will lean back and forth (A & C), to angle the two main screens, but
they also all lean inwards a little so as to angle the upper sides and
windows of the car. The roof plan area is decreased when compared with,
say, the shoulder height (when seated) of the passenger area.
The 'chop' to a comp coupe has to be equal front and back - therefore wedge
shaped cuts when viewed from the side do not appear to be allowed. If
'equal' at the front there has to be symmetry when looking at the front
elevation - both A pillars cut down the same (although why you might wish
to wedge left to right, or vice versa, would seem to me to be unusual). No
problems at this point.
The front 'vertical' height of the screen (no doubt measured by projecting
the upper edge height forward, to come to a virtual point above the lower
screen edge) has to equal or exceed the minimum dimension stated. No
problem with this either.
The roof surface 'angle' in relation to the body has to remain unaltered.
Presumably another rule to prevent creating a wedge shape by displacing the
cuts on the A pillars lower than the C pillar ones, that would otherwise be
'equal'. No problem here either.
The bodywork of the vehicle has to be remain unaltered in surface 'contour'
- this is bringing me to the limit of my understanding or correct
interpretation.
As the roof is lowered to the screen height figure, the A pillars not only
need to lean further back, to meet with the roof and the C pillars further
forward to re attach to the roof ........ but all three side pillars (A,
B, C) will need to lean inwards - because the roof is smaller than the
'hole' over the passenger compartment.
The leaning of front screens is allowed - by reference to looking at many
comp coupes, particularly those based on 30's bodies. So it appears that I
do not need to lengthen the roof. Do I forget abot the rear pillar lean
too?
But ........... can the sideways lean be considered acceptable within the
maintaining of the 'contours' wording?
The only way to correct the side lean would be to widen the roof, but that
in itself would alter the contour of the roof - assuming that it is
considered bodywork of course and that appears not to be allowed by the
rules.
So do I forget about any changes to the roof size and just accept that all
pillars will lean further inward - (towards the vehicle's front to rear
centreline) more?
In view of the complexity of correcting a roof chop at a later date, it
needs to be right from day one.
Did any of you Comp Coupe runners follow that?
Over to the list for comment ............. please help.
Malcolm Pittwood, Derby, England
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