Random Aerodynamic Oddity of the Day Thread

[j-c-c]

Originally Posted by Cd

Unintentional boattailing :



I was admiring the boattailing of this dump truck at work.

There is also a roll up tarp that is pulled back as seen here, so not only are the sides tapered, but the bed is also covered by the tarp.

Thanks for the clarification, I thought it was a CMV silent air brake for locales that didn't permit Jake.

[freebeard]

In case you missed it, this is a classic

www.hagerty.com/media/advice/a-few-things-to-know-before-you-steal-my-914

Dear Thief,

Welcome to my Porsche 914. I imagine that at this point (having found the door unlocked) your intention is to steal my car. Don’t be encouraged by this; the tumblers sheared off in 1978. I would have locked it up if I could, so don’t think you’re too clever or that I’m too lazy. However, now that you’re in the car, there are a few things you’re going to need to know. First, the battery is disconnected, so slide-hammering my ignition switch is not your first step*. I leave the battery disconnected, not to foil hoodlums such as yourself, but because there is a mysterious current drain from the 40-year-old German wiring harness that I can’t locate and/or fix. So, connect the battery first. Good luck finding the engine cover release. Or the engine, for that matter.

Right up there with Iowahawk's Turbonique post.

*This actually happened to me last November.

[kach22i]

Roof angle too steep to be in the other thread, but a lovely oddity.


https://forums.pelicanparts.com/off-...ures-2688.html

[kach22i]

https://forums.pelicanparts.com/off-...ures-2687.html

[kach22i]

https://forums.pelicanparts.com/off-...ures-2686.html


https://forums.pelicanparts.com/off-...ures-2686.html

[j-c-c]

Originally Posted by kach22i

https://forums.pelicanparts.com/off-...ures-2687.html

First time I have ever seen that close up Superbird picture in action at Daytona ( I attended the race), what stands out to me mostly is the very crude duct taping of the front edge hood restraints, likely causing a lot of disruption of laminar airflow in a very critical location, and at that time it was widely known that even say dead bugs on the leading edges of airplane wings was a big no-no. I don't think the duct taping intent was to improve air flow, if it was, it was IMO rather misguided, but more to prevent hood pins from dislodging, being the duct tape pictured was a greater drag obstruction that a hood pin with a properly placed hairpin clip.

[freebeard]

Roof angle looks corrrect to me, but the broken pediemnt is a bit much.


This made my day, thank you kind sir.

[freebeard]

justacarguy visits Facebook so we don't have to:

justacarguy.blogspot.com: interesting, I wonder if it is ever used, or if they did all this work for it to be a display piece that needs dusting

[Vman455]

Originally Posted by kach22i

https://forums.pelicanparts.com/off-...ures-2687.html

These assesments are complete BS. Here's an excerpt from the SAE paper on the Charger Daytona development:

The wind tunnel development of the Daytona low form drag front end included a wide spectrum of nose configurations. The nose configurations investigated fell into two broad categories: a 9 in. extension and an 18 in. extension. Both basic shapes were developed with respect to achieving a minimum axial force [N.B. "axial force" = drag]. The results of this investigation are presented in Fig. 7. The data indicate the 9 in. extension without a front undernose spoiler is superior to the 18 in. extension without spoiler. However, the 18 in. extension with spoiler is significantly better than the 9 in. extension with spoiler. The phenomenon is probably caused by two effects:
1. The spoiler chord on the 9 in. extension is less than on the 18 in. extension for an equal distance from the nose.
2. With the spoiler installed, more air is forced over the nose surface. The upper surface of the 18 in. extension is more favorable from a drag standpoint than the 9 in. extension.
The results in Fig. 7 explain the selection of the 18 in. extension for the Daytona Aerodynamic Package.
The effectiveness of front undernose spoilers is very sensitive to front end shape. This point is illustrated in Fig. 8 where the spoiler effectiveness as a function of yaw angle is presented for the 1969 race car and the Charger Daytona. Spoiler effectiveness is defined as the force coefficient with the spoiler minus the force coefficient data without the spoiler. The incremental axial force coefficient data indicate the spoiler on the Daytona nose is 4.5 times as effective in reducing axial force as the 1969 spoiler at zero yaw angle. Similar results are seen on lift. These data indicate the spoiler-nose combination is a highly interactive aerodynamic system and must be approached and handled as such.

1. A variety of shapes were trialed
2. The engineers used existing studies on nose shape and spoilers as a starting point for their research
3. The front spoiler reduced both lift and drag--on both the 1969 blunt-nose and 1970 streamlined-nose cars
4. Nose design was just one part of a 5-part approach to a complete aerodynamic package to improve the Charger

[j-c-c]

It does seem at first reading drag reduction took precedent over any lift/df numbers, which can be easily contributed to the aero on track knowledge/goals at that time. Am I correct that front spoiler was a later version than first used, and apparently much more robust in design and effectiveness? Most early pics of Mopar Aero car's spoilers show something approx 1/4? that size if I remember correctly.