Aerodynamic Study: Spoilers & Blunt Nose and Under cover

[kats]

Hi, 

For someone who is interested in aerodynamics of our S30 cars, here is a thesis made by Nissan engineers in May 21st 1971.

Aerodynamic Study on Passenger Car Body Configurations / Michio TAKEI,   Hikota SAKAMOTO,  Kazuhiko YOSHIYUKI.  

The effects of G-nose and spoilers are quite noticeable, 7 pages of this thesis is worth to read. I'm not an engineer so some of the numerical formulas are unable to understand but the figures and illustrates work easy for me.

So, I tried to show one of their data. Those numbers in pictures are excerption from the thesis. The only thing which I am not for sure is the data of Clr for the rear spoiler only configuration. It shows 0.007, it is too small isn't it?    

By the way, Mr. Uemura told the story of naming our G-nose in his book. "Blunt-Nose", Mr. Yoshiyuki and Mr. Uemura felt it was a cool name of NASA's Blunt-Nose cone which was attached on top of the satellite. They named their nose extension kit after the NASA's Blunt -Nose but the Sales department worried about that people would not understand what it would be. Finally "Grand- Nose" was used.

Kats

 

Edited August 9, 2023 by kats

[kats]

[HS30-H]

2 hours ago, kats said:

By the way, Mr. Uemura told the story of naming our G-nose in his book. "Blunt-Nose", Mr. Yoshiyuki and Mr. Uemura felt it was a cool name of NASA's Blunt-Nose cone which was attached on top of the satellite. They named their nose extension kit after the NASA's Blunt -Nose but the Sales department worried about that people would not understand what it would be. Finally "Grand- Nose" was used.

Great data Kats. Thank you for posting.

About the 'Blunt Nose' vs 'Grande Nose' story: I think there was always a little bit of confusion mixed up with the 'Blunt' nose naming, possibly not helped by Japanese vs English language meanings. 'Blunt' vs 'sharp'.

What's the opposite of 'Blunt'? 'Sharp', right? In aero terms, we might easily think that something 'Blunt' does not cut through the air very well. That's how I think of the stock Z front end. It has a big open mouth which resists passing through the air. On the other hand, the 240ZG's front end reduced that big open mouth and channeled air over, under and around it. It cuts through the air more efficiently. So is the 240ZG's nose sharp, or blunt? Confusing, isn't it?!

In the end I think it was a good decision not to use the term 'Blunt Nose', even if I can understand the NASA_derived thinking. But still, the term DID make it into some of Nissan's factory documentation:

 

[HS30-H]

2 hours ago, kats said:

For someone who is interested in aerodynamics of our S30 cars, here is a thesis made by Nissan engineers in May 21st 1971.

Quick question, Kats. Was the thesis connected to the University of Tokyo's department of Aerodynamics and Aeronautics?

[kats]

 

4 hours ago, HS30-H said:

Quick question, Kats. Was the thesis connected to the University of Tokyo's department of Aerodynamics and Aeronautics?

Hi Alan,

I reviewed it once again to see how it was connected to the University of Tokyo's department of Aerodynamics and Aeronautics. 

I don't see it as we expected at the moment. I believe before 1969, the University of Tokyo was the only place where had a wind tunnel, but it was for 1/4 models

not for full size scale car. So early days of styling development and aerodynamics study, engineers brought their 1/4 scale models to the wind tunnel at the University of Tokyo. In 1969 Nissan built a full size scale wind tunnel at Nissan Oppama. This thesis was made by using the wind tunnel at Nissan Oppama.

Some of the engineers graduated the University of Tokyo's department of Aerodynamics and Aeronautics, so we can say the thesis was connected to it, though. 

Kats 

Edited August 9, 2023 by kats

[kats]

4 hours ago, HS30-H said:

Great data Kats. Thank you for posting.

About the 'Blunt Nose' vs 'Grande Nose' story: I think there was always a little bit of confusion mixed up with the 'Blunt' nose naming, possibly not helped by Japanese vs English language meanings. 'Blunt' vs 'sharp'.

What's the opposite of 'Blunt'? 'Sharp', right? In aero terms, we might easily think that something 'Blunt' does not cut through the air very well. That's how I think of the stock Z front end. It has a big open mouth which resists passing through the air. On the other hand, the 240ZG's front end reduced that big open mouth and channeled air over, under and around it. It cuts through the air more efficiently. So is the 240ZG's nose sharp, or blunt? Confusing, isn't it?!

In the end I think it was a good decision not to use the term 'Blunt Nose', even if I can understand the NASA_derived thinking. But still, the term DID make it into some of Nissan's factory documentation:

 

Alan,

Your explanations made me realize the real meaning of Blunt. Yes the change to "Grand-Nose" is better, even people in the sales department were not fully educated why "Blunt" is literally not suitable for the image of the extension pieces.  I think of course  Mr. Yoshiyuki and Mr. Uemura knew how NASA's Blunt

nose looked like and meaning of "Blunt", they might just wanted to barrow the image of detachable nose piece, not barrowing the meaning of "Blunt".  By the way, "Blant" is just a spelling mistake?  

Kats

Edited August 9, 2023 by kats

[SpeedRoo]

Is the whole report available to view @kats Should make interesting reading. Does it make any reference to aero imbalance due to the large differences between front and rear lift coefficients?

[SpeedRoo]

I didn't realise the 240Z was such a draggy shape in both standard and modified forms. For such a small front area it creates a lot of drag. Blunt noses can actually be very aerodynamic, the problem is the openings at the front, whether blunt or sharp, they have the biggest influence of the drag and lift figures. Would be interesting to see if they tested the car with the radiator intakes closed off and the effect. 

 

[SpeedRoo]

To give you an example of blunt nose aero, this car has a Cd of 0.326, CLf of 0.92 and CLr of 0.60. It also has a much larger frontal area with a width of 6 foot. The blanking plate to reduce the opening was key in reducing the drag.

 

[HS30-H]

4 hours ago, kats said:

Alan,

Your explanations made me realize the real meaning of Blunt. Yes the change to "Grand-Nose" is better, even people in the sales department were not fully educated why "Blunt" is literally not suitable for the image of the extension pieces.  I think of course  Mr. Yoshiyuki and Mr. Uemura knew how NASA's Blunt

nose looked like and meaning of "Blunt", they might just wanted to barrow the image of detachable nose piece, not barrowing the meaning of "Blunt".  By the way, "Blant" is just a spelling mistake?  

Kats

I totally get why they would have been going with the 'Blunt' nose name for the more aero-efficient 240ZG front end, following on from NASA's use of the term and their pioneering research which they would have been referencing (yes, I think 'Blant' is just a typical Katakana-linked mistake) but I think it is counter-intuitive.

I'm kind of glad that they went with 'Grand' (I have often seen it spelled as 'Grande' in period Nissan documentation) as I think it is an apt descriptor.  

 

[kats]

5 hours ago, SpeedRoo said:

I didn't realise the 240Z was such a draggy shape in both standard and modified forms. For such a small front area it creates a lot of drag. Blunt noses can actually be very aerodynamic, the problem is the openings at the front, whether blunt or sharp, they have the biggest influence of the drag and lift figures. Would be interesting to see if they tested the car with the radiator intakes closed off and the effect. 

 

Hi Roo,

Me neither, and also engineers were shocked when they saw the results of Cd and Cl at that time. I will upload the remaining pages. Before that I will try to explain

that Mr. Miyazaki told me about how bad the opening front end of S30 was. Just like you proposed, it was the issue of S30 which engineers had to deal with.

I will draw a picture by hand, Mr. Miyazaki said S30 front end is so wide that it leads too much air coming through the radiator. Then the air can't go through under the engine because the air was blocked by the air stream which is flowing underneath of the car. At the end, the pressure of inside of the engine bay becomes positive, it pushes the front end. The higher front end gets more Cd worse. This story I think it relates the story of 15mm lower front end of Europe model (except Portugal model). 

And Mr. Miyazaki even told me there was a test  car which had a factory air conditioning coupled with Z432!! (Z432 was not able to make a choice of air conditioning from the factory). During the test of aerodynamics, one day he was wondering why one car had a better value than other cars. The better one had an air conditioner condenser in front of the radiator. Less air gave less lift. That was a Z432.

Kats   

  

Edited August 9, 2023 by kats

[HS30-H]

10 hours ago, kats said:

 

Hi Alan,

I reviewed it once again to see how it was connected to the University of Tokyo's department of Aerodynamics and Aeronautics. 

I don't see it as we expected at the moment. I believe before 1969, the University of Tokyo was the only place where had a wind tunnel, but it was for 1/4 models

not for full size scale car. So early days of styling development and aerodynamics study, engineers brought their 1/4 scale models to the wind tunnel at the University of Tokyo. In 1969 Nissan built a full size scale wind tunnel at Nissan Oppama. This thesis was made by using the wind tunnel at Nissan Oppama.

Some of the engineers graduated the University of Tokyo's department of Aerodynamics and Aeronautics, so we can say the thesis was connected to it, though. 

Kats 

I believe that, after their merger, Nissan had use of the ex-Prince research facilities at Ogikubo, which was linked to Tokyo Daigaku's Aerospace department? I also remember reading that Prince, and subsequently Nissan, had sponsored students in Tōdai's Aerospace department around that period via a bursary scheme. Nissan took over Prince's satellite-launching rocket program, I think?

Here are a few stills from one section of the Maru Z Keikaku Suishin Iinkai films. I had believed that this impressive array of research equipment was either part of the full-size Nissan wind tunnel that came on stream in 1969, or was part of the facilities at Ogikubo. We can see both full-size (silver pre-production car?) and scale model research taking place. Maybe the filming even took place at both locations?