Quote:
Originally Posted by aerohead
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Roof contours steeper than Jaray's roofline are what Hucho refers to as 'pseudo-jaray'.These roof contours produce separation and very strong attached longitudinal vortices of remarkably high drag.
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When you say
steeper, I think this is a key term.
Back when I asked if the Cd of a 1/6 scale model was the same as the full scale example, I should have been asking if
the airflow was the same -
it is from what I currently understand - which is why models are used at all.
For wind tunnel testing the reason the air is accelerated for models is to equal the air pressure (lift in the case of aircraft) to scale, right?
Quote:
Originally Posted by aerohead
*For a full-scale vehicle the critical Rn will occur at 20 mph.
*1/6-scale 120 mph.
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If you think of the scale model with a roof curve being no
steeper than the full scale example, then I am on to something.
If you consider the model's roof curve to be steeper than the full scale version then my ideas would appear to be a bust, and therefore scale models hold little value for examining airflow and air attachment.
Is the measure of steepness to be measured horizontally over length? Please, no Calculus, I hate Calculus.
Or is the measure of steepness to be measured in inclination angles (scale model equal to full scale), never exceeding 22 degrees?
I have my answer to the last two questions based on what I see in wind tunnel testing photos (see BigMike's MR-2 site link:
Car Wind Tunnel Data), and the airflow over a model (not air pressure) will be similar, the larger the model the more accurate, full scale testing preferred.
What does "steeper" really mean?
Quote:
Originally Posted by ChazInMT
Your picture here with a line I added shows where you would want to put this line as a base point to work from.........
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I agree and described these sketches as following the template's highest point (center). However as Tesla pointed out the distances the arc follows at the sides on a rectangular body will have to be more "aggressive". This is where the call for a new plan view only template stems from.
To be of practical value, one could continue to use the template in profile, but not in plan view. The step to 3D and to fit typical body styles is yet another reach, for another day.
Let's get a working plan view first, and then resolve the transition from square to round.