MR2 Roadster Owners Club

The Workshop => General => Topic started by: SombreroPeak on March 12, 2018, 21:26

Title: Odd aerodynamics?
Post by: SombreroPeak on March 12, 2018, 21:26
Driving home this evening I noticed that the standing water on the rear screen was being slowly blown from right to left, sideways. This didn't change going around corners or changing direction. I had assumed that the car was aerodynamically symmetrical? Is this a known, designed factor? Thought it was interesting anyway.
Title: Re: Odd aerodynamics?
Post by: shnazzle on March 12, 2018, 22:23
I've asked this befor as well and coincidentally I brought this up last week with the Mrs when I noticed that the water rolled off the back of our Superb in an almost perfect wind tunnel  fashion. In the mr2... Not so much. Perfectly horizontal..
Why?
Title: Re: Odd aerodynamics?
Post by: Call the midlife! on March 12, 2018, 22:26
More weight on the driver's side so the car doesn't sit flat causing the air to flow lopsided.


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Title: Re: Odd aerodynamics?
Post by: SombreroPeak on March 12, 2018, 22:31
 Interesting. Is that factual?  I'll be keen to get a passenger in there and see if I can tell any difference. I guess the other option might be to sit in the passenger seat and try and drive from there...I think the mirror swivels enough...cos that'll be the only problem with that option!  :D
Title: Re: Odd aerodynamics?
Post by: Call the midlife! on March 12, 2018, 22:34
Quote from: SombreroPeak on March 12, 2018, 22:31
Interesting. Is that factual?  I'll be keen to get a passenger in there and see if I can tell any difference. I guess the other option might be to sit in the passenger seat and try and drive from there...I think the mirror swivels enough...cos that'll be the only problem with that option!  :D
60% of it is 100% factual...


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Title: Re: Odd aerodynamics?
Post by: StuC on March 13, 2018, 00:01
Could also be abnormalities in the shape of the fabric roof. A little bulge here or there on an older roof might cause this phenomenon.

I wonder if there are an wind tunnel pictures floating about. <goes off to look>
Title: Re: Odd aerodynamics?
Post by: SombreroPeak on March 13, 2018, 06:43
Good point, I had overlooked the 'roof vagaries' option...
Title: Re: Odd aerodynamics?
Post by: K T M Rider on March 13, 2018, 07:15
Try taking your Sombrero off - maybe causing a mild internal vortex leading to a gentle side to side rocking motion of the rear window?  :-)

Does anyone know what happens with a hardtop fitted ?
Title: Re: Odd aerodynamics?
Post by: SombreroPeak on March 13, 2018, 18:15
I think you might be right, I'll change it for a Trump-style cap, and if that doesn't work I'll build a wall between the two...
Title: Re: Odd aerodynamics?
Post by: JoeCool on March 13, 2018, 20:20
I reckon that will be a side wind.

I got a good deal of pleasure watching the airflow blow the water off my hard top rear window last time I had the car washed and then drove it to dry it. It made lots of pretty patterns on the rear window. It was symmetrical though.
Title: Re: Odd aerodynamics?
Post by: 2 of the left on March 13, 2018, 21:26
If you have the tool bag strapped in the driver's stowage - Take it out and place centrally at the bottom of the "the frunk" and also check wind deflectors are in place ( in front of the front wheels ) ;) as well as the air deflector under the radiator intake !!