Tungsten Puma Weighta

[whodathunkit]

My understanding Nellie Faye fenders are no longer sold or available thru derby evolution.

That's bad news! I liked how the Nellie Faye fenders gave the car a Corvette look.

[sporty]

I'm hoping there will be some transparency and flexibility. And someone with a laser machine, plasma cutter, will make and offer them. The kit ones, I really like.
So I am hoping here, mfg and vender deal can be made here.

[whodathunkit]

That would be cool if someone did!
I see you can still get the pinewood fenders for around $ 8.00
and the balsa fender kit for around $ 3.00 kind looks like a close out.. like you say.

Well anyway Sporty after seeing your car.. And waiteing for Tungsten Puma weights from Joe.
I can't waite to try the weights out on this 2nd mini I'v been working on.
Hope this is not bad for pinewood and Basswood!

[sporty]

Cool. Nice..

If u click on item upper right. Will say not available. So no buying.

[Laserman]

That would be cool if someone did!
I see you can still get the pinewood fenders for around $ 8.00
and the balsa fender kit for around $ 3.00 kind looks like a close out.. like you say.

Well anyway Sporty after seeing your car.. And waiteing for Tungsten Puma weights from Joe.
I can't waite to try the weights out on this 2nd mini I'v been working on.
Hope this is not bad for pinewood and Basswood!

Hi Mark,
Those little minis crack me up every time I see them.

I like the way you notched the fenders/ body!

Sorry for the delay on the weights
Things never seem to slow down for me.

Will get them to you ASAP

That is terrible news about the NF fenders!

Perhaps I can help out.

[Derby Evolution]

Guys,

While I won't be offering Nellie Faye fenders in the future, I will have a replacement for them that has shown an improvements in times.

[ngyoung]

I think the NF fenders were more popular for their style over their performance. I like them for how they make an otherwise Hershey bar body look more like an import super car. When are you going to unveil your new design?

[Johnscooling]

Are they faster?

[davet]

Back to the weights. We'll be making a thin car and when you put the Puma weights on doesn't it mean you have to put more weight further forward to keep the COM reasonable? If you pack all the weight around the axle with Puma weights then add weight further forward to keep COM from being too aggressive what is the benefit over 10 cubes behind and the rest ahead of the axle and no Puma weights?
Your green car has only one row of cubes behind the axle. Wouldn't it be faster with more cubes further back and not using the Puma weights?

[Vitamin K]

Back to the weights. We'll be making a thin car and when you put the Puma weights on doesn't it mean you have to put more weight further forward to keep the COM reasonable? If you pack all the weight around the axle with Puma weights then add weight further forward to keep COM from being too aggressive what is the benefit over 10 cubes behind and the rest ahead of the axle and no Puma weights?
Your green car has only one row of cubes behind the axle. Wouldn't it be faster with more cubes further back and not using the Puma weights?

My only theory is that the wider placement of the weights might improve stability and allow for a more aggressive CoM. But that's purely speculation.

Need some experimentation!

[Laserman]

Hi Davet,

The Puma Weights circle the rear axles. This means that half the weight of the Puma Weights is in front of the axle (1.3oz)
and the other half is already behind the rear axles (1.3oz)


If you put an additional 10 cubes ( 1.72 oz) behind the rear axle then you are at about 3oz behind the rear axles while maintaining a body that is 1/4" thick.

Additionally, the weights make for a quicker rotational moment of inertia at the transition of the track.

As Vitamin K pointed out: By pushing the weight to the outsides of the car it also increases the car's stability by slowing the moment of inertia from the car rocking side to side.

All of this helps make for a faster, more stabile car that can have a very aggressive COM but avoids the wiggles.

Beyond that, the weights fill the wheel void to make the rear wheels more aerodynamic and with less turbulence on the wheel.

[davet]

Hi Davet,

The Puma Weights circle the rear axles. This means that half the weight of the Puma Weights is in front of the axle (1.3oz)
and the other half is already behind the rear axles (1.3oz)


If you put an additional 10 cubes ( 1.72 oz) behind the rear axle then you are at about 3oz behind the rear axles while maintaining a body that is 1/4" thick.

Additionally, the weights make for a quicker rotational moment of inertia at the transition of the track.

As Vitamin K pointed out: By pushing the weight to the outsides of the car it also increases the car's stability by slowing the moment of inertia from the car rocking side to side.

All of this helps make for a faster, more stabile car that can have a very aggressive COM but avoids the wiggles.

Beyond that, the weights fill the wheel void to make the rear wheels more aerodynamic and with less turbulence on the wheel.

If I run 12 cubes behind the rear aren't I getting more weight behind the rear axle than 10 cubes with Puma weights? Would 12 cubes behind axle AND Puma weights be too much to overcome in keeping a 5/8"-3/4" COM". Maybe another cube would need to be added 1"-2" ahead of axle to get the COM and DFW weight targets. I'll have to lay out some weights trying to duplicate the Puma weight and see how COM is affected. My boy is still deciding on a design for the car so I have some time.

I live in MN and we have about 10" of snow where I'm at. Good thing you guys aren't at my door trying to sell me snow because I'd probably buy some. You make good arguments for the Pumas. I'm not sure if I know enough about the moment of inertia point to be able to decide based on that. Maybe I'll epoxy a few 3/16" cubes to the side of the body inside the wheel cavity. With the new Webelos plan this will be our last year so I hate to spend the money on those things.

[DerbyAddicted]

I would LOVE to try the Puma weights, but I'm afraid that it would cause issues. Even though they would technically be legal, I think there would be major griping.

[Laserman]

Lol! Yes. I have heard that folks gripe about the winner of the PWD!
The smart move is to come in second.

[DerbyAddicted]

I think everyone would be convinced they were some kind of washer/bushing/bearing and blow a gasket! At a minimum, it would probably result in a tear down (a pack first).