Milling weight pockets video

[Cubscout Dad]

If you are referring to me....

These are the three that we built this year. 1/8" center sections, with a 1/4" rear on the cubed car, and 3/16" rears on the canopy cars.

Yes that is what I was looking for, I think it is kind of neat. How did they run ?

 

[Gtdhw]

Yes that is what I was looking for, I think it is kind of neat. How did they run ?

First year running this design, and our pack race isn't until March 18th. It's a design borrowed from someone else, who apparently did extensive testing with it, and has had much success with it. I'm pretty exited to see how the cars do.

 

[Kinser Racing]

...who apparently did extensive testing with it, and has had much success with it.

What kind of testing and success where? Thanks!

 

[Gtdhw]

What kind of testing and success where? Thanks!

This is a "Sporty" chassis design, and read that it's had good success at MA. Some wind tunnel testing involved I'm told as well.

 

[microbrush]

Nice Video Bulldog! The dremel King.

 

[microbrush]

A thinner body would move less air, no? I've cooked up something similar.

 

[bracketracer]

A thinner body would move less air, no? I've cooked up something similar.

If you have to drag a row of 1/4" cubes through the air, does it really matter how thin the body is?

Not trying to start an argument. Just curious.

 

[microbrush]

I'm not an aerospace engineer. My thought is the less air you have to move and DISPLACE the better. I thinned mine down to 1/16th". Have not been able to test it. Yes the back end is 1/4", but that is about 1.5" long so there is a good 5 plus inches where it is 1/16th; have to raise slightly for the front axles. I think of the air as I do water. Why are there less variables in times in the bearing class? Less air is displaced?

 

[bracketracer]

Why are there less variables in times in the bearing class? Less air is displaced?

I believe the smaller standard deviation in the Unlimited class is fully due to the bearings. I tested six bodies for Choo Choo last week using my wide, 2g bearing wheels. SD for each car was .0002 or less. With normal 2g wheels and axles I'm usually .0005 or so.

 

[Gtdhw]

If you have to drag a row of 1/4" cubes through the air, does it really matter how thin the body is?

Not trying to start an argument. Just curious.

Just a scout Dad here, not an event competitor, like most of you guys. This is our 5th year (my oldest just crossed over, and my Tigers first year), so I decided to do a lot more reading/research this year, to see if we could "up" our game for this next 4 years. My oldest made it through his cub years undefeated in three different packs, but never could place better than 3rd in the districts.

I found this body style, and was amazed at how easy it was (with the change from cubes to a canopy) for a 1st or 2nd year scout to build. One cut on the band saw, and one hole popped through the top with the drill press for the canopy bung. MUCH easier than the 3 3/8" holes popped in the side design. So that's why we went with it.

My oldest, who can't compete this year, wanted to build for the sibling race, so we collaborated on the cubed car. From my limited experience, I couldn't get 24 cubes in this type chassis, unless it was shaved to 1/8" in the middle. We can't use lightened wheels, so getting the body to 11g's was the ticket to getting the 24 cubes in, and still leaving room/weight for a light coat of paint. No way that we found, to get the body to 11g's, without the 1/8" chassis. Leaving it at 1/4" thick, it was simply too heavy, only allowing for 22/23 cubes (ladder was an option, but my oldest and I are thinking of trying our hands at that next year, but that design is just not feasible for a tiger/wolf)

So in short, the 1/16" body was required for us to get 2 rows of 12 cubes, regardless of the higher/thicker rear of the car. Full length 1/4" chassis (not laddered) was just too heavy to accept the 4.0oz of cubed weight. (which is what I read, before we started). I wasn't there, so I can't speak of the "wind tunnel testing", but what I read sounded very feasible, and just saw it as a plus.

 

[microbrush]

I believe the smaller standard deviation in the Unlimited class is fully due to the bearings. I tested six bodies for Choo Choo last week using my wide, 2g bearing wheels. SD for each car was .0002 or less. With normal 2g wheels and axles I'm usually .0005 or so.

I thought that people's times were more similar with and without of traffic in the bearing class. This is what I was referring to as well. If this is not true than maybe I am completely off the mark.

I still think a thinner body will be less affected by "dirty air". I also like that fact that it displaces less air. The theory sounds good in my mind. I have no facts or skill set to search it out. Plus it is a lot of fun to grind a body down on that ridgid sander! A lot more fun than trying to rout out the body on a drill press. I may have to try Bulldogs technique.

 

[B_Regal Racing]

So in short, the 1/16" body was required for us to get 2 rows of 12 cubes, regardless of the higher/thicker rear of the car. Full length 1/4" chassis (not laddered) was just too heavy to accept the 4.0oz of cubed weight. (which is what I read, before we started). I wasn't there, so I can't speak of the "wind tunnel testing", but what I read sounded very feasible, and just saw it as a plus.

Interestingly, doing the math and calculating volume, it appears that a ladder body would be lighter and be more readily able to accept 24 cubes. Consider a distance of 4" between the axles. You could either have a 1/16" x 1 3/4" x 4" for a thin solid plank, or two rails between the front and rear axles being 1/8" wide x 1/4" high by 4" long (2 x 1/8" x 1/4" x 4"). It does however, take some practice to develop the skill to build a BASX type car accepting 24 (or more) cubes.

Interesting thought about the dirty air and a thin car though. Might warrant some investigation....

 

[Gtdhw]

Interestingly, doing the math and calculating volume, it appears that a ladder body would be lighter and be more readily able to accept 24 cubes. Consider a distance of 4" between the axles. You could either have a 1/16" x 1 3/4" x 4" for a thin solid plank, or two rails between the front and rear axles being 1/8" wide x 1/4" high by 4" long (2 x 1/8" x 1/4" x 4"). It does however, take some practice to develop the skill to build a BASX type car accepting 24 (or more) cubes.

Interesting thought about the dirty air and a thin car though. Might warrant some investigation....

I would agree that a laddered 1/4" car would/should/could be made lighter, but as a Tiger Scout car, it just was never an option for us, as it is just too far beyond my Tigers ability at this point. This chassis accomplished the same goal for us though, as it was light enough (11g) to accept 4.0oz of added weight (3.5oz canopy & 2 1/4oz tungsten rounds glued in from the bottom in recessed holes, behind the rear axle). We were able to accomplish a 17/32" COM (might even of been 1/2" if we would've moved the front wheels back). That is a pretty good accomplishment, and a good number IMO, for a car that a young cub scout can build. Not sure what other "one cut" chassis can off this?