drathbun and son race results for 2013 Pack derby

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drathbun
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drathbun and son race results for 2013 Pack derby

Post by drathbun » Sun Jan 27, 2013 1:30 pm

We had our derby yesterday. This year, unfortunately, we did not have much time to work on cars. My son (Web II) started his last Saturday during our pack workshop hosted at my house. He designed and we cut out a wavy pattern. He didn't decide how he wanted to paint it until about Tuesday, at which point he decided he wanted to use the wave pattern and make a flag. Since his older brother had already done a US flag, he did a Texas Flag, going for the pack "Lone Star" design trophy. We had a bit of a rush job, so the paint job wasn't stellar, but it did look like the flag, and he did win the desired design trophy.

This year for the outlaw class I wanted to do something fun, so I ordered a ducted fan kit from one of the supporting vendors here. It took about 15 minutes to put together, and that's because I painted the base. The instructions were very clear and the car went together perfectly. I took some axle rejects that were already polished (but maybe not as perfect as some others) and slapped on some wheels and was ready to go. I tested all of the electronics, but could not test the car, so I had no idea how it would perform until race day.

On Wednesday night I made a super-thin wedge style car using one of Sporty's topics as a baseline for how to use the tungsten cubes. My block before weight was 0.8 ounces, the wheels (standard wheels and axles) added 0.48, and all of the rest of the weight was tungsten cubes crammed into the back, both in front of and behind the axle. I painted it black, with an overcoat of metallic silver, finished with a transparent purple. It looked okay, but considering the entire car - including all four coats of paint - was done in one night I wasn't complaining.

On race day I kept the fan car under wraps; very few people knew that I was doing it. My older son helped me decorate a shoe box with radioactive symbols and big danger signs, and we had a major unveiling when the car came up in a race in our outlaw division. The scouts thought it was great and even the parents were getting into it. A reall good time on our track is 2.28 or 2.27. Most scouts come in about 2.3, some of the faster parents who have been building cars for a while have hit 2.25. I think the track record is 2.24. The fan car hit 1.8! It was fantastic fun.

Ultimately my son (Web II) with the Texas Flag car took first in his den (by the slimmest of margins) and first overall in the pack (first time for our family) by an even slimmer margin. Our cars have almost always been competitive, but we've never done quite enough to get to the top of the pack. This year despite the late start and limited time to work, we did make it, and to be honest I believe the difference maker was some derby graphite from the same supporting vendor that I got the fan kit from. When we put the graphite on, I could tell immediately how much smoother it was than the hardware stuff stuff we've been using all of these years. As I watched my sons car race, it was clean coming down the slope, smooth through the transition (our pack has an older wooden track) and at the very end of the track (32') seemed to surge ahead by just a fraction. I believe that's because the graphite was allowing him to preserve that extra tiny bit of speed. It wasn't that his car was surging ahead, it was that the other cars were starting to fall off.

I think if we had a 40' track instead of 32' that his margin of victory would have been a bit wider, but as it was the races were extraordinarily exciting! I will go back and pull up some race times and post them to show how close.

Ultimately if you're on the fence between using local store-bought graphite or getting some of the "fancy" stuff from some of the supporting vendors, I now believe that the graphite does make a difference.

My "standard" outlaw car took first place in the outlaw division. Obviously the fan car was disqualified. ;) It was great fun to watch though. My purple wedge car was made to scout standards and that's what we ultimately used to qualify who won the race.

Pictures to come...



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Re: drathbun and son race results for 2013 Pack derby

Post by drathbun » Sun Jan 27, 2013 2:43 pm

Texas Car - First in Webelos I, First in Pack, and winner of the "Lone Star" Design trophy. We used the slots. Weight was flat tungsten applied in front of and behind the rear axle. I think it was around 2 ounces in front and one ounce behind the axle. Even though we used the slots I drilled them using the standard alignment tool before inserting the axles to make it easier to insert and stay straight. A trick I picked up from reading this board. ;)

Image

Ducted fan car that "blew away" the competition :lol:

Image

My regular outlaw car:

Image

The underneath side of my outlaw car, showing the tungsten weight placement. There were 28 cubes in front of the rear axle and 26 cubs in back. There is a tiny bit of lead tape added during check-in time to bring it up to exactly 5.00 ounces.

Image

The total time for my son's car for the grand finals was 9.1260, an average of 2.2815 per run. The second place car had a total of 9.1330, and average of 2.28325. Over four races, the Texas Flag won by an average margin of only 0.00175 seconds. :shock:

My outlaw car ran four races in 9.0570 for an average of 2.26425. My wedge from last year, which used cylinder tungsten inserted from the rear of the car ran 8.9640, and average of 2.241, which stands still as the track record. Other than the fan car... ;)



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Re: drathbun and son race results for 2013 Pack derby

Post by Curse You Red Baron! » Mon Jan 28, 2013 1:05 pm

Interesting that you attribute the improvement to graphite. I'm not used to seeing that much change between graphite sources. I've always used hobe lube with an overlay of Max - V and still have chatter. However, we recently used FS home-made guage design to ensure consistent diameters on our wheels, and polished and waxed the wheel hubs - now I know the meaning of 'quiet'! I believe the last two factors had a huge impact.



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Re: drathbun and son race results for 2013 Pack derby

Post by sporty » Mon Jan 28, 2013 4:43 pm

Congrats and a nice little read.


Ya, Im not sure what you were using in the past for graphite. but there is 3 / 4 very popular graphites that work well and the others, are often not recommend.

in no order.

Max-v
hodges.
hobb-e-lube
greasem

the other I can not mention the vendor.

Most use the lube in a combination forum for best results.

Now, Thanks for mentioning my name as a idea based style of car. i would mention, that I do not know what the weight would be, or balance point with using the 1/8th cubes. I have always used the 1/4 cubes. I did see you mention more weight forward, then rearward, but not much.

I would be curious to know what your bore prep method is, and if you use pin gauges to check the wheel bores and if you know the run out or o.d. of the wheels ?

Sporty



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Re: drathbun and son race results for 2013 Pack derby

Post by drathbun » Mon Jan 28, 2013 11:15 pm

sporty wrote:Im not sure what you were using in the past for graphite.
Whatever I got at Wally World. :)
Max-v
That's what we used this time.
Now, Thanks for mentioning my name as a idea based style of car.
I roughly used the concepts mentioned here.
I would be curious to know what your bore prep method is,
Don't do any. :)
and if you use pin gauges to check the wheel bores
Nope
and if you know the run out or o.d. of the wheels ?
I added graphite, gave the wheels a good spin, and with a very informal testing method (one-mississippi, two-mississippi) got somewhere in the area of 17-18 seconds. I was quite pleased to see that. Also the wheels seem to run quieter but that may have been totally unrelated to the graphite selection.

To be honest, I like making cars with my boys, but I'm not a total speed freak. No offense intended to anyone here, it's just not that cutthroat in our pack. :) When BSA came out with the newer style wheels that don't have the mold mark on the tread and are already lighter and already have coned hubs (to a degree anyway) I quit worrying about any sort of wheel prep whatsoever. I do polish my axles and do work to get a reasonably straight alignment as I install the wheels. That seems to be good enough that even with slots we can make a car that's fast enough to be respectable in our pack. There has only been one year that one of my sons didn't place in his den, and while we don't always win the pack I really don't want to set that as an expectation anyway. It's better for my sons, and better for the rest of the pack, to see different faces at the top each year. When my older son was a Webelos II I worked more with him to try to go out on top, and we placed second in the pack. He was cool with that, and happy for the winner. I had planned on doing the same with my younger son next year; he just got there a year early. :)

But I do believe that the switch to a higher quality graphite definitely had an impact on our cars this year.
Last edited by drathbun on Tue Jan 29, 2013 1:18 am, edited 1 time in total.



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Re: drathbun and son race results for 2013 Pack derby

Post by Noskills » Mon Jan 28, 2013 11:24 pm

Really like the color on the purple. Nice effect with the three coats!
You did some ghost flames like that once right?
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Re: drathbun and son race results for 2013 Pack derby

Post by sporty » Tue Jan 29, 2013 12:04 am

Thanks for answering my questions and the indepth over view. And being honest how you feel and where you are at.

I have much respect for anyone, that can be honest, and say, hay we are not into going super fast, it's okay. I try and not shove it down anyone and Hope I do not come across that way to anyone here.


Thanks

Sporty



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Re: drathbun and son race results for 2013 Pack derby

Post by drathbun » Tue Jan 29, 2013 1:16 am

Noskills wrote:Really like the color on the purple. Nice effect with the three coats!
Thanks!
You did some ghost flames like that once right?
Similar, yes. I used a metalic purple over a regular purple. The flames on that car were a lot more work! This was more of a rush job.
sporty wrote:Thanks for answering my questions and the indepth over view. And being honest how you feel and where you are at.
You're quite welcome, I have taken many, many points and suggestions away from the regulars on this board and have a ton of respect for all that y'all do.
I try and not shove it down anyone and Hope I do not come across that way to anyone here.
Certainly not to me. :) That's why I tried the "no offense" line in my last post, trying to get across that I certainly get why you were asking, but also tried to explain why we didn't do anything more than slap the wheels on.

It's all good. :thumbup:



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Re: drathbun and son race results for 2013 Pack derby

Post by drathbun » Tue Jan 29, 2013 1:30 am

The purple ghost flames car was mentioned here and the purple paint used in my outlaw car this year was another transparent paint like I used (green) here. The transparent paints are designed to be painted over silver, and from my experience (I have used red, blue, green, and now purple) they come out looking really nice. The red is by far my favorite, followed by the green. By painting with black primer, then masking off a pattern and painting the undercoat of metallic silver, you can get a design that shows through the final transparent color. The cat eyes that I did this year I picked because it was a relatively simple design to cut out and apply. I was initially trying a lightning bolt but for the life of me could not get it straight!

The red-over-silver was used on my "spike" car that I built two years ago. It remains one of the favorite cars that I've ever put together.

Image



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Re: drathbun and son race results for 2013 Pack derby

Post by rpcarpe » Tue Jan 29, 2013 11:29 am

Nice cars, sounds like a good time had by all!


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Re: drathbun and son race results for 2013 Pack derby

Post by pgosselin » Tue Jan 29, 2013 12:32 pm

Congrats on your son's win this year. That's a memory he'll never forget.

Paul



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Re: drathbun and son race results for 2013 Pack derby

Post by Oddzilla » Tue Jan 29, 2013 4:06 pm

drathbun wrote: Image

The underneath side of my outlaw car, showing the tungsten weight placement. There were 28 cubes in front of the rear axle and 26 cubs in back. There is a tiny bit of lead tape added during check-in time to bring it up to exactly 5.00 ounces.
Just curious about something... My car in our recent PWD had the weight centered around the back axle and didn't perform nearly as well as the cars we built that had the weight spaced out further. Is it possible that rear-weighting techniques like this work better with extended wheelbases?

I don't think it was the axles because when we did the axles, when we were finished with one they went in a small bowl of isopropal alcohol before drying them off and installing them, so each car got random axles from the bunch.

I'm sure it's been talked about before, but just wanted to ask.

:D


Great looking cars, BTW!



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Re: drathbun and son race results for 2013 Pack derby

Post by sporty » Tue Jan 29, 2013 4:36 pm

Oddzilla wrote:
drathbun wrote: Image

The underneath side of my outlaw car, showing the tungsten weight placement. There were 28 cubes in front of the rear axle and 26 cubs in back. There is a tiny bit of lead tape added during check-in time to bring it up to exactly 5.00 ounces.
Just curious about something... My car in our recent PWD had the weight centered around the back axle and didn't perform nearly as well as the cars we built that had the weight spaced out further. Is it possible that rear-weighting techniques like this work better with extended wheelbases?

I don't think it was the axles because when we did the axles, when we were finished with one they went in a small bowl of isopropal alcohol before drying them off and installing them, so each car got random axles from the bunch.

I'm sure it's been talked about before, but just wanted to ask.

:D


Great looking cars, BTW!


Oddzilla,

you might have had a few things going on there. aside from the risk of getting some bad axles. but alignement, wheels and so many other reasons why that car performed bad.

I would not attribute it to where the weight was. I mean aside from me and others. we are running 2oz behind the rear and 2 oz of weight just in front. Some of us are running a 3/8th balance point and win and do very well with it.

Now, if they had to much weight and I dont know what that car looked like, the type of weight they were using, ect.

But with limited information and going loosey on some generaliztion here of trying to 2nd guess what it was. my asumption on a extended wheel base, its not likely they had to much weight, to far back. but more of a alignment issue. wiggles and bouncing off the rail allot. or wheel bore prep, so many variable to try and 2nd guess it all.

But in general, its not a known issue, with the asumption they did not add2 1/2 oz or 3 oz, behind the rear axles.

Not stock wheel bases, putting that much weight back there, would cause it to wiggle and be a mess. because the balance point for a stock wheel base cant be that extreme with out allot of hard work to tune it and dial it to run good like that.

I think the best darn stock wheel base car builders gotta be Jewkes or john or someone next in line with them. You likely dont know who that is, but league racers do.

But personally I feel, im a darn good extended wheel base builder, and thats the best reply I can give you at this time, with the information currently available.

So, if I had pictures or more information, my summary may change.

Sporty



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Re: drathbun and son race results for 2013 Pack derby

Post by drathbun » Mon Feb 04, 2013 11:24 pm

I can tell you that the purple car this year came in behind another slim wedge that I built last year that had a higher proportion of weight in front of the axle. We have a track with a very smooth curve (rather than an abrupt transition) which I believe I read means that more aggressive weight placement should be okay. But over the past several years I have observed that cars with the weight pushed a bit more forward seem to do better.

My son's car had 2/3rd of the weight in front of the rear axle and 1/3 behind it, all tungsten plates screwed on to the bottom.



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Re: drathbun and son race results for 2013 Pack derby

Post by pgosselin » Tue Feb 05, 2013 11:19 am

Sporty's right. The weight placement is acceptable.

The one thing I've noticed over the years with my building is that the closer the COM is to 1" in front of the axle, the easier the car is for me to tune. It doesn't matter whether it's spread out, concentrated, lead or tungsten. As the COM approaches 3/4", the car becomes much harder for me to tune. I can get it rolling straight as an arrow on the tuning board, but when I put it on the track, I start getting more wiggle when the car transitions from the slope to the flat portion of the track. I've never been able to completely tune out the shimmies on my more aggressive weighted cars. This isn't a problem with the weight placement, but my limited tuning ability and my ability to drill perfectly straight axle holes. The 1" center of mass is simply more forgiving when it comes to alignment, which may be why your cars are doing better with it.

Paul



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