Aerodynamics ?

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Speedster
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Aerodynamics ?

Post by Speedster » Fri Feb 02, 2018 4:38 am

Are aerodynamics important in a Pinewood Derby car? You bet they are. It is the single most important thing to consider before you cut that block. When folks hear the word aerodynamics they usually think about air resistance. That's not why the car must be aerodynamic. The car must be a certain shape to start so you don't give the competition an advantage at the very beginning. After the block is cut, countless hours will be spent on each additional operation that science teaches us on how to make a block of wood go fast. Each step must be considered very carefully, starting with aerodynamics.

Design competition is a different Topic.



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Re: Aerodynamics ?

Post by Vitamin K » Fri Feb 02, 2018 5:24 am

Speedster wrote:
Fri Feb 02, 2018 4:38 am
Are aerodynamics important in a Pinewood Derby car? You bet they are. It is the single most important thing to consider before you cut that block. When folks hear the word aerodynamics they usually think about air resistance. That's not why the car must be aerodynamic. The car must be a certain shape to start so you don't give the competition an advantage at the very beginning. After the block is cut, countless hours will be spent on each additional operation that science teaches us on how to make a block of wood go fast. Each step must be considered very carefully, starting with aerodynamics.

Design competition is a different Topic.
Hmm, I think I would actually argue that weight placement is the most important factor when you determine car shape, but aerodynamics is a close second.

Fortunately, designs that emphasize good weight placement usually emphasize good aero as well! :)



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Re: Aerodynamics ?

Post by Speedster » Fri Feb 02, 2018 9:50 am

Following Science, Aerodynamics is first because the first thing you do is cut the block. You might spend a lot of time getting the block you want but at some point you need to cut it. Are you going to cut it in the best shape possible for speed following science? After the block is cut it is now how well you follow science for each activity.
I will be watching a " Hershey Bar" car this year. This is the scouts last year for the PWD. He and his father are very dedicated to this project. We will see what happens on Feb. 10.



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Re: Aerodynamics ?

Post by whodathunkit » Sat Feb 03, 2018 8:19 am

Speedster
The properties of a solid object regarding the manner in which air flows around it!

If VK's weight was attached to the out side of the car body!
How would air flow around it?
Weights embedded in the car body
that are covered have no interaction to air flow around the weights!
It's now the solid body moving through it!



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Re: Aerodynamics ?

Post by LightninBoy » Sat Feb 03, 2018 9:42 am

I love aerodynamic cars, obviously.

But when it comes to scout cars, I would never recommend aero considerations trumping the scout's desire for a certain look. It just doesn't make a big enough differences unless you are racing at very competitive levels. Several years ago we built a block car that was several car lengths faster than anything else in the pack except for our other cars.

Not saying speedster is saying anything otherwise. Just adding some context for folks that may be new to the hobby.



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Re: Aerodynamics ?

Post by Speedster » Sat Feb 03, 2018 12:12 pm

One Moment, Please.
Air flowing around the car is not why the car must be aerodynamic. It must be aerodynamic so the additional added weight (tungsten) can be placed in a certain area and can be placed where it will do the most good. "Get Rid of the Wood". I'm sorry if I did not make that clear at the very beginning.

The Design category. Here's where I think adults have failed the scouts. Absolutely, Positively every single Tiger Cub should be required to attend a seminar on the Physics of the Pinewood Derby. That's it. They now know the Basics. That's all I ask. Unfortunately, I fear what really happens is, a scout is given a book with a bunch of big, bulky cars and asked, "What do you want your car to look like ?". They're little children. They don't know any better and possibly have no one to teach them. I'm not against the Design category but I am against not sharing science with the scouts.



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Re: Aerodynamics ?

Post by whodathunkit » Sun Feb 04, 2018 7:25 am

Oh' the Science behind CoG Theory.
And how to create a desired CoG
ahead of the of the rear axle.
Through car design and weight placement!

Ok I'm with you on the science.


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Re: Aerodynamics ?

Post by bracketracer » Sun Feb 04, 2018 3:05 pm

I think that the BSA doesn’t do enough to emphasize the STEM aspects of the PWD. They are focused on model building and sportsmanship. Not unimportant goals, but it seems they could do more with it?

Not to derail the thread but if anyone has seen a curriculum that includes STEM concepts on PWD topics I’d be interested in adding it to my Pack presentation.



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Re: Aerodynamics ?

Post by Darin McGrew » Sun Feb 04, 2018 8:30 pm

Speedster wrote:
Sat Feb 03, 2018 12:12 pm
Air flowing around the car is not why the car must be aerodynamic. It must be aerodynamic so the additional added weight (tungsten) can be placed in a certain area and can be placed where it will do the most good. "Get Rid of the Wood". I'm sorry if I did not make that clear at the very beginning.
There is a big difference between "must be aerodynamic" and "get rid of the wood". And frankly, there are still much more important factors than either aerodynamics or weight distribution.
Speedster wrote:
Sat Feb 03, 2018 12:12 pm
The Design category. Here's where I think adults have failed the scouts. Absolutely, Positively every single Tiger Cub should be required to attend a seminar on the Physics of the Pinewood Derby. That's it. They now know the Basics. That's all I ask. Unfortunately, I fear what really happens is, a scout is given a book with a bunch of big, bulky cars and asked, "What do you want your car to look like ?". They're little children. They don't know any better and possibly have no one to teach them. I'm not against the Design category but I am against not sharing science with the scouts.
Huh... Tiger Cubs are in first grade, right? My experience is that kids that age are doing good to build a car that crosses the finish line, even with adult help. I wouldn't hide the science from them, but I'd certainly emphasize more important things like alignment, polished and lubricated axles, and total weight.

And if a kid wants to build a design-oriented car rather than a speed-oriented car, then I won't try to discourage him in any way.



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Re: Aerodynamics ?

Post by Speedster » Mon Feb 05, 2018 6:41 am

Hi Darin,
I absolutely agree with everything you say. All the additional things you mention are part of the science after you have the best shape for speed from that block of wood.
One of your comments about a Tiger Cub car and crossing the finish line. I do understand, I really do, There are many Grandma's helping their young scouts. I truly wish I had an answer for that.



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Re: Aerodynamics ?

Post by ciodude » Tue Feb 06, 2018 2:21 pm

I don't think it plays that big a factor except in the semi pros. :) For the average racer, wheels and weight are the biggest factors (and I'm not sure how to rate one over the other). My four girls just completed a PowderPuff Derby for Girl Scouts. It was decidedly unfair as a variety of car kits was used. In the pits I saw BSA, AWANA and others. The kits my girls got were some third party and frankly very [crummy]. Blocks were bad and the wood cracked trying to put the wheels on. Wheels were horrible and we had one that we couldn't do anything with (and no replacements).

Like many races, some people knew what they were doing, some did not.

That being said, my girls did their best, worked with what they had and while I was hoping for "just cross the finish line" they actually came in 3rd, 4th, 5th and 6th respectively in the council. (First time they competed head to head against each other) One of my 12 yo twins took 3rd place and her racer was literally the unaltered block of wood painted like a deer with some clay antlers and tail added. (I have to admit this year I didn't get her "vision") NO aerodynamics at all. The kits that beat us had better BSA and AWANA, but I'd argue if we had a better base to start from her non aerodynamic care would have beaten the others.



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Re: Aerodynamics ?

Post by chromegsx » Tue Feb 06, 2018 2:46 pm

Your not wrong that its important in the context you meant it. but just saying aerodynamics implies nothing relating to weight placement. choose words and contexts carefully. In the end I disagree that it is THE most important in your context. If I had the time, I would of liked to build a straight block car with near perfect alignment and weighted where ever for COG and run it against a cut car with weight back and bad alignment...I think the alignment would win out over aero (depending on how bad the alignment was.

To say one aspect of a build is the MOST important is foolish, when in the end its all important...the amount of importance depends on the context.



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Re: Aerodynamics ?

Post by Speedster » Tue Feb 06, 2018 3:47 pm

Your last line sums it up. If you don't start with the Best design for speed you will be at a disadvantage from that point on and you can't get it back. Doc Jobe makes comparisons starting with the words "Between 2 Perfect cars".



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Re: Aerodynamics ?

Post by Speedster » Wed Feb 07, 2018 6:05 am

bracketracer, there are many videos on you tube about building fast cars. My favorite is "Easy Pinewood Derby car Wins using science" by Mark Rober. Perhaps its main accomplishment is it instills science into the young scouts minds. As you probably know, the Ford Motor Company (and R. Lisano) have spent thousands of dollars trying to teach STEM, now known as STEAM, across the United States racing about 800 Girl Scouts. I think things are going to change as the Girl Scouts grow more and more in the Pinewood Derby. Our Program Director for Girl Scouts of Western Ohio has gotten rid of the term "Powder Puff Derby". Our Cub Scout Pack will be providing the track for racing 70 Girl Scouts on February 11 what is equal to a Cub Scout District race. I guarantee you there will be no "Powder Puffs" from our Troop Group competing. They were all at our January 6 Workshop.



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Re: Aerodynamics ?

Post by bracketracer » Thu Feb 08, 2018 9:42 am

Yes sir, I directed our pack to the video during our PWD informational meeting back in December. I thought he did a pretty good job of explaining the basics where a young person could understand. I also advised them to watch out for other videos on youtube that appear to be "how to's" but they are actually parodies. New cub parents might not know the difference!

I saw the Ford races but as far as I know, they are just for girls, the boys are left out. Which still leaves me looking for a curriculum for the boys.

Good luck with your event! Sounds like it's going to be a heckuva race!



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