what will this car do?

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davet
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what will this car do?

Post by davet » Sat Oct 06, 2018 9:33 pm

We had our 2nd Annual derby workshop at church today in prep for the race on Oct 20th. I had some helpers with no building experience working with me so you already know I was busier than a one-armed paper hanger on a windy day.

I was tuning cars on the tuning table and was brought the last car of the day. It's a MN Vikings car with balsa horns stuck to the sides on the rear. Very cool car. BUT, the helper cut it out with the slots on opposite ends. The car was done and I discovered we had .07 oz on the DFW. That's darn near a zero COM.

We did some work on it and I was able to get it to .58 oz on the DFW. Will this car behave the same as a standard car with the same weight on the DFW or will it act lighter on the front?

It weighs 4.95 oz now. I'm tempted to add some putty under the front end.

Thanks all.
Last edited by davet on Sat Oct 06, 2018 9:51 pm, edited 1 time in total.



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davet
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Re: what will this car do?

Post by davet » Sat Oct 06, 2018 9:50 pm

Also, I gave it 4.5" of steer in 4' because of the light front.



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Re: what will this car do?

Post by Speedster » Sun Oct 07, 2018 5:21 am

Where does the car balance?



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davet
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Re: what will this car do?

Post by davet » Sun Oct 07, 2018 7:34 am

I didn’t check that specifically but I know that an extended wb car with .62 oz on the Dfw is between 5/8 and 3/4” and very stable.



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Re: what will this car do?

Post by davet » Mon Oct 08, 2018 9:31 am

Balances at 5/8” ahead of rear axle line. We usually had our extended wb cars at 5/8” and one even a hair under. I’m not sure how “tippy” this design will be with the same com.
Will it be more susceptible to the front getting light off the transition since the rears are more forward.



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Re: what will this car do?

Post by Speedster » Tue Oct 09, 2018 4:57 am

You should be OK and that is the Maximum I would ever go. If you can add more weight to the front I know 3/4" is safe on the Best track. Our Girl Scouts raced on a really rough wood track last year but fortunately even when they bounced they remained on the track.
Let us know how the car does.



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Re: what will this car do?

Post by davet » Tue Oct 09, 2018 8:03 am

Thanks Speedster. I went and picked it up from church. Took the measurements and found the 5/8 com. I removed some rear weight and added some putty ahead of the front axle. It’s now got .63 oz on dfw but com didn’t change noticeable. This dfw weight on our extended wb cars would be a com of 5/8”. Those cars were very stable but I’m confident in your “should be OK” remark. We’ll test run it prior to race and if I have to add weight to make it stable it will just be overweight and will run anyways.



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