Front nose of car, shape, aero, thin to win ?

[sporty]

NGyoung


I have always wondered, if the oil and lighter wheels and different rules, with the cars able TO GO FASTER. our outside of the thought process of aero, due to much more speed with some of the rules and things allowed or can be done now. when you mentioned adult racing. That was something that I wonder. Since im no math person. It would really take someone with good math skills to dig down to the real wind speed.

I think I see more fender skirts, then what I would call real fenders. A fender to me is full coverage of the wheel. going over it.

I do see allot of fender skirts and The lower air that I seen and the widening of the air. Some of the designs would help control it and keep it clean, less swirling.

I don't have time before work this morning to get into anything deeper.


Have a good day.

Sporty

[Vitamin K]

So I'm not a math or physics types (I am probably the world's worst computer science grad when it comes to mathematical aptitude), and fluid dynamics is one of those extremely scary areas of study, so I can't really speak authoritatively on the matter. What I have observed is that 'teardrop' shapes seem to do well when it comes to passing through a medium with a minimum of resistance, and that it seems like you would want a fender to completely encase a wheel (front and back) to effectively route the airflow around.

I get the impression that the 'side-fender' design is not terribly popular in the adult league racing, because a larger fender adds more weight to the car, which makes it harder to hit that sweet spot of COM that the pros crave.

That said, check out this video for the NPWDL's August "Street Stock Pro" race. The winner, Lightningboy's X3, uses a 'side-fender' design that's slimmed down pretty impressively, but still provides coverage for the front and rear of the wheels.

https://www.youtube.com/watch?v=SxVNrIxg7fA#t=1m

Might be on to something, possibly?

NGyoung


I have always wondered, if the oil and lighter wheels and different rules, with the cars able TO GO FASTER. our outside of the thought process of aero, due to much more speed with some of the rules and things allowed or can be done now. when you mentioned adult racing. That was something that I wonder. Since im no math person. It would really take someone with good math skills to dig down to the real wind speed.

I think I see more fender skirts, then what I would call real fenders. A fender to me is full coverage of the wheel. going over it.

I do see allot of fender skirts and The lower air that I seen and the widening of the air. Some of the designs would help control it and keep it clean, less swirling.

I don't have time before work this morning to get into anything deeper.


Have a good day.

Sporty

[FatSebastian]

That said, check out this video for the NPWDL's August "Street Stock Pro" race. The winner, Lightningboy's X3, uses a 'side-fender' design...

The video is almost 18 minutes. Can you reference a frame number / time which clearly shows the design being described?

[Vitamin K]

That said, check out this video for the NPWDL's August "Street Stock Pro" race. The winner, Lightningboy's X3, uses a 'side-fender' design...

The video is almost 18 minutes. Can you reference a frame number / time which clearly shows the design being described?

I tried to put the timestamp in the video link. The car in question is in the first heat, which starts at approximately 1 minute in. Of course, it runs in several heats, so you'd have to skip around to see them all.

[ngyoung]

That said, check out this video for the NPWDL's August "Street Stock Pro" race. The winner, Lightningboy's X3, uses a 'side-fender' design...

The video is almost 18 minutes. Can you reference a frame number / time which clearly shows the design being described?

You can skip to the end where the finals are. He was a translucent blue where you can see the "ladder" style showing through underneath.

As for aerodynamics and tear drop it was but it was discovered that a flat back or Kamm tail can actually offer less drag.

"The Kamm Tail
It was once thought that a long tapered profile to the tail of a vehicle would provide the most aerodynamic configuration in terms of the lowest possible drag co-efficient. However, Wunibald Kamm, a German Professor of fluid dynamics, discovered that the length of the tail end section would have to be so long as to make the vehicle impractical. Moreover, there would also be an increase in surface area which would also create its own frictional drag. The solution, Kamm found, was to cut the theoretically long tail in half: the resultant profile gave the vehicle both good aerodynamics and minimal surface drag. Thus this distinctive, sharply cut-off, rear end style has thus been named the "Kamm Tail.""

[Vitamin K]

Quite interesting. I guess the real trick is being able to calculate the angle for what makes a 'good' shape as opposed to a poor one, in terms of calculating airflow.

As for aerodynamics and tear drop it was but it was discovered that a flat back or Kamm tail can actually offer less drag.

"The Kamm Tail
It was once thought that a long tapered profile to the tail of a vehicle would provide the most aerodynamic configuration in terms of the lowest possible drag co-efficient. However, Wunibald Kamm, a German Professor of fluid dynamics, discovered that the length of the tail end section would have to be so long as to make the vehicle impractical. Moreover, there would also be an increase in surface area which would also create its own frictional drag. The solution, Kamm found, was to cut the theoretically long tail in half: the resultant profile gave the vehicle both good aerodynamics and minimal surface drag. Thus this distinctive, sharply cut-off, rear end style has thus been named the "Kamm Tail.""

[sporty]

The problem with the diagrams. Is that that air flow is correlated to being in the air.

The flow is a bit different when dealing with a bottom surface. Still nice to look at and appreciate you sharing.

[ngyoung]

The problem with the diagrams. Is that that air flow is correlated to being in the air.

The flow is a bit different when dealing with a bottom surface. Still nice to look at and appreciate you sharing.

A lot of automobiles incorporate the Kamm tail in their design.

[sporty]

The video is almost 18 minutes. Can you reference a frame number / time which clearly shows the design being described?

I tried to put the timestamp in the video link. The car in question is in the first heat, which starts at approximately 1 minute in. Of course, it runs in several heats, so you'd have to skip around to see them all.

Its a nice well made video, I like the slow motion action, without looking like slow mow. I could not see the shape well enough. So I cant speculate.

The adult racing is at such a high level and pushing the very edge of things. As I mentioned earlier. The rules for adult racing, is far more different, then say our local packs or council races.

So much more speed is there, with different axles, lighter wheels, the wax/oil process. I am re mentioning what I would like to know. The scale speeds with correlation to scale air flow that it creates.

I certainly feel side skirts, fenders, if done right, can widen the air flow and effect the car next to it. But real speed increase from it. I don't think so.

A great builder and heavy involved racer, is going to be a great competitor.

Sporty

[sporty]

The problem with the diagrams. Is that that air flow is correlated to being in the air.

The flow is a bit different when dealing with a bottom surface. Still nice to look at and appreciate you sharing.

A lot of automobiles incorporate the Kamm tail in their design.

My edit of the photo, is what I seen, minus the rear end can't be narrowed due to rules and track guide rail.

I removed some of the air flow lines, to show what I really seen.

The problem with many pictures and displays of air flow. are showing massive air flow. power / air speed that can do that and does in much higher speed and wind in the air.

The issue, is with pinewood derby, no wind in the air and I don't feel the speeds with typical stock axles and graphite cars and 5oz, a standard track and typical 2.2 gram wheels are getting anywhere close to the speed to the typical diagram, image of the ones out there.

Sporty

[bracketracer]

So much more speed is there, with different axles, lighter wheels, the wax/oil process. I am re mentioning what I would like to know. The scale speeds with correlation to scale air flow that it creates.

Sporty, I can tell you that my typical adult league car, a NPWDRL Street Stock, that runs around a 2.98 time is going 15.432098 ft/sec at the bottom of the hill on a Besttrack set to 27.1 degrees, or about 10.522 mph actual speed. If I assume a 1/25 scale I believe that's around 263 mph scale speed at it's peak? It finishes a 42 foot track running 14.576772 ft/sec or 9.939 mph actual or 248 mph scale speed.

[sporty]

So much more speed is there, with different axles, lighter wheels, the wax/oil process. I am re mentioning what I would like to know. The scale speeds with correlation to scale air flow that it creates.

Sporty, I can tell you that my typical adult league car, a NPWDRL Street Stock, that runs around a 2.98 time is going 15.432098 ft/sec at the bottom of the hill on a Besttrack set to 27.1 degrees, or about 10.522 mph actual speed. If I assume a 1/25 scale I believe that's around 263 mph scale speed at it's peak? It finishes a 42 foot track running 14.576772 ft/sec or 9.939 mph actual or 248 mph scale speed.

Oh thank you, thank you very much.

This information is a delight. !

This info would confirm, what I have learned and was understanding on it. I just didn't have good numbers / math reference, speed correlation in non scale.

Now, what this means to me, From the talk I had with a aero space guy a few years ago, wow, 4 years plus now. lol.

He said that aero does not come into play until min of 17 miles per hour. But I felt he was on the conservative side. Because he was trying to explain some factors. that can get lengthy of typing to go into. lol. but easy to understand once explained.

Its huge to me, because it so much tells me, what I thought I seen and learned from the wind tunnel was not far off. that I was not way off track.

I feel at 12 or 13 miles per hour, non scale. aero starts, but not very effective or consistent. But does start. where as the Aero space guy said 17 miles per hour.

I figured with the talk I had with him, that size and mass was a factor and a pinewood derby car being much smaller, that the number would be a tad lower.

So I wonder the other classes, that (street stock you mentioned) (I don't know the rules or what is typically can for that class).

But other classes that are faster then the street stock class. Very well could be right there on the edge of that 12 to 13 miles per hour and aero would be at the beginning stages of a real factor.


And again thanks for the info.

It's so hard for me, because Some are fast and win with fenders and swear by them and even been videos showing faster with, then without. And I had questions back then about the video that upset people. and that was never my intent.

I still feel that what I seen in the wind tunnel. that the wind is not powerful enough to stay up and is not reaching the rear wheels. Not to be confused, cuz I know its going low and off the sides.

That's why my bodies had slanted , flared lower sides. Its not going far out and away much.

But that was with a single car and single lane in the wind tunnel. I would have loved to had access to a bigger professional wind tunnel machine that could have two lanes or even 3 lanes inside of it with two or three cars.

One of our tests was even finger spinning the wheels and then closing it up and turning it on real quick to see, how the aero / wind effected the wheel spin. We could not see anything at lower speeds. I think kind of needed a slow motion camera too.
It was hard to see when the air effected it, initially. had to turn up the wind speed to see it effect it which was around 18 to 22 miles per hour.

thanks again,

Sporty

[LightninBoy]

That said, check out this video for the NPWDL's August "Street Stock Pro" race. The winner, Lightningboy's X3, uses a 'side-fender' design...

The video is almost 18 minutes. Can you reference a frame number / time which clearly shows the design being described?

Here's a picture ...

[gpraceman]

He said that aero does not come into play until min of 17 miles per hour.

I don't buy that, as there have been several people, myself included, that have done experiments that have showed that aerodynamics do have an effect at PWD speeds. Just take a thin car, make several runs and note the times. Then add an index card cut to simulate the cross sectional area of a larger car and do several more runs. The car with the smaller cross sectional area will be a bit faster, all other things kept the same. Is it a big effect, no. Other factors have a larger effect on a car's speed.

[sporty]

The video is almost 18 minutes. Can you reference a frame number / time which clearly shows the design being described?

Here's a picture ...

Very nice love it ! that is a great shape, I love the mid section, between the wheels. the inside by the wheels. nice work.

Very nice and good design. thanks for posting a much better picture.

Sporty