Quote:
Originally Posted by aerohead
* September, 2020, Julian Edgar makes the comment that no ( not one! ) notchback produced since 1990 suffers separation at the end of the roof.
* In 2006, 16-years after 1990, Julian Edgar publishes, in autospeed, ' As with [many] booted sedans,... the airflow tends to separate form (sic) the body at the trailing end of the roof..... the streamline doesn't stick to the body of the roof in the roof/rear window transition but instead tends to leave at this point.'
* The statistical mean average lifespan for an automobile is 13-years.
* Statistically, 'ALL' of the 'many' notchbacks inferred by Mr. Edgar's statement would have been manufactured well beyond the 1990 cut-off date.
* Would Mr. Edgar like to address this discrepancy?
|
In 2006 in that article I was writing for the readers of AutoSpeed, and many of them still drove cars where yes, separation occurred at the end of the roof on notchbacks. An example is the 1986-1988 Commodore VL turbo, a car that (in modified form) was then still very popular with readers. That car had a roof / rear window angle that dated back to 1978. In fact, the VL Group A Walkinshaw remains one of the best aero specials ever built, and to achieve attached flow on the bootlid, they had to raise it massively.
The reason that I nominate 1990 as the date from which notchback airflow largely changed is that by that year, most manufacturers were producing cars that had much shallower angle rear windows. (Of course, that refers to cars first produced from that year, not carryover old models.) Here in Australia that included the VN Commodore and EA Falcon, and the same happened elsewhere.
And of course, rear window angles have got shallower, and boot lids higher, ever since - such that today, a notchback's airflow is often closer to a fastback.
There is no doubt that when old aero references (and they include more than just Hucho 2nd edition) describe notchback flow, they are usually describing something quite different to today's notchback cars - and to the vast majority of notchbacks of the last 30 years.