Our race is tomorrow morning...

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Teeeman
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Our race is tomorrow morning...

Post by Teeeman » Fri Apr 27, 2007 3:37 pm

Tomorrow will be our 3rd CMB race.

Our CMB District race has the following characteristics:

1. inspection measures nothing, just a glance to see there is a seatbelt and brake handle…

2. the starting system is volunteers (Army) holding the cars by the rear axle

3. the timing system is more volunteers with stopwatches, I have observed a fellow missing a car and when asked for time he said “woops… uhhhhh… 13.2”

4. cars no longer run side/side due to the number of wrecks and collisions preventing a timely running of the race…

5. cars get together when run together as there is no separator between lanes

6. there is no functional test of steering or brakes (I have observed seatbelts consisting of rope tied together and brakes make of broom handle with no friction material added… just wood on asphalt)


We have easily won the speed category the last 2 years. But last year a couple of cars that are from our Pack caught up some with degreased and WD-40’d bearings in the wheels.

So this year we too have purchased “race” wheels… we’ll keep the other worn wheels for neighborhood tooling around (with grease seals and grease)…

the race wheels were ordered with the bearings not yet installed, seals removed, grease flushed and will be given re-lubes between runs.

This year’s car has baby smooth linkage ratio’d foot steering (adjust easily for a more maneuverable setting for tooling around the neighborhood which still is quite easy to steer).
Our brake is last year’s “twin hockey puck” brake and works like a champ.

Seatbelt is a lap/shoulder belt from a mid-80’s Celica.

We did a before and after roll test during the wheel swapout and the new wheels show significant improvement…

just letting the car roll along, it rolls much more easily and continues to gain speed quickly even on a shallow incline whereas prior it seemed to kinda find a “top speed” (in our driveway).

Anything could happen but I think if nothing breaks and the race goes off as usual, my son should collect another trophy :)


One thing other to point out: The last 2 years my son has been given 1st for Wolf then last year for Bear… the Wolf trophy says Bear (they gave us the wrong one!)… and the Bear trophy has 2005 written on it…

(laughing!)


As you can tell, what this all boils down to is the event is really more for fun and not very competitive.

It is relatively informal and much more relaxed than Pinewood for sure.

I am actually glad we don’t have a seriously competitive CMB race.

-Terry


"I dunno..." - Uncle Eddie, Christmas Vacation

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Go Bubba Go
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Re: Our race is tomorrow morning...

Post by Go Bubba Go » Fri Apr 27, 2007 3:58 pm

Any pics of this year's entry?


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sporty
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Re: Our race is tomorrow morning...

Post by sporty » Fri Apr 27, 2007 4:42 pm

Awesome,

Alot of good detailed info. Thanks for sharing the information.

Thats some good ways od running the race.


We hope to see some kewl pictures soon !


Good Luck Tommarow.

Sporty



Teeeman
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Re: Our race is tomorrow morning...

Post by Teeeman » Fri Apr 27, 2007 9:41 pm

Pics uploaded, full size... (that was a mistake but here they are)...

Image

Image

Image

Image

Image


"I dunno..." - Uncle Eddie, Christmas Vacation

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Go Bubba Go
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Re: Our race is tomorrow morning...

Post by Go Bubba Go » Fri Apr 27, 2007 11:42 pm

Teeeman wrote:...I am actually glad we don’t have a seriously competitive CMB race.

-Terry
Veeerrrrrry Nice!

Makes me wonder what you two would come up with for a "seriously competitive CMB race" LOL :shock:


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SuperDave
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Re: Our race is tomorrow morning...

Post by SuperDave » Sat Apr 28, 2007 10:20 am

As someone who has extensive Soap Box Derby experience (tho not building cars) I would urge you to think Safety.

What can the cars hit? No pictures of the course, but anything of that weight moving at any speed can cause a lot of damage, not the least of which could be to the kid.

and

Limit the turning ability. As shown, the car can turn so far and so fast to the right that I think it can flip over. It certainly can drive straight into a side rail and stop quite violently. If the road is straight, a few degrees is all that's needed.

and

Can the car go under a barrier and be stopped by the kids legs?


As a general rule, think Murphy. If it can go wrong it will. I've seen a SBD car at Akron flip OVER a two foot high guard rail and they're safety maniacs.


(Note: the author is a designer and vendor of tracks, timers and software. Comments by him or to him should take that into account as appropriate.)

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sporty
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Re: Our race is tomorrow morning...

Post by sporty » Sat Apr 28, 2007 11:14 am

Super Dave,


My son races SBD, Not made it to Akron though.


Sporty



Teeeman
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Re: Our race is tomorrow morning...

Post by Teeeman » Mon Apr 30, 2007 10:28 am

Car is stable actually …

good point on running under stuff, we have a standard curb at our race and nothing to get under thankfully…

the steering works amazingly well without restriction although for total speed it would probably benefit from a pin-able stop block that is easy to disengage for tooling around.

The steering gives 2:1 which reduces sensitivity and makes it easier to drive but can be swapped in 2 minutes to 1:1 for maneuverability for playing in the neighborhood.

This style of steering produces the only car I’ve seen that is controllable by pretty much anyone who gets on it.

We had a bone-simple ultralight car showup Saturday that was faster than us. There was another car that ran about the same…

3 cars recorded faster times but reviewing the video and using my own stopwatch at the race I verified that 1 car was faster, 1 car the same and 1 car was badly mis-timed (manual timing with stopwatches).

Thankfully none of the other cars for which a faster time was recorded (or that were faster) were in our Rank so we got 1st place speed for Webelos.

No looks judging this year.


Funny, the had top 4 finishers for regular and then unlimited cars… but they had no inspection…

our car is 100% legal by our rules.

But the way they handled the trophies was to give out essentially top 8 finishers calling spots 8-5 as (4-1 Cubmobile) and then spots 4-1 overall as 4-1 Unlimited… kinda unfair to the boys in unlimited because they were all regular cars (not unlimited) yet the kid who actually got 5th place gets a trophy reading 1st place, etc.

There is an open “suggestions welcome” for next year that was announced. I tried to get involved and establish communications with the race organizers the last 2 years… and volunteered to fix the things I saw wrong… no responses.

We only have 1 more year and at this point I don’t want to get heavily involved anymore.

-Terry


"I dunno..." - Uncle Eddie, Christmas Vacation

Teeeman
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Re: Our race is tomorrow morning...

Post by Teeeman » Mon Apr 30, 2007 7:35 pm

Here's the weight tech info on the above car:

The 3 wheeler data we took tonight:
(LF = Left Front, RR = Right Rear, LR = Left Rear)
(car has seat on left, weight box on right and dominant wheel on left)

Loose "items":
My son = 65 lbs
Weights = 39 lbs

CMB only
LF = 18
RR = 25
LR = 18
Total: 61lbs

CMB + Boy
LF = 22.5
RR = 55
LR = 47.5
Total: 125 lbs

CMB + Weights
LF = 20
RR = 58
LR = 25
Total: 103

CMB + Weights + Boy
LF = 26.5
RR = 70
LR = 62
Total: 158.5 lbs

Wheels are rated for 150lbs each.

Calcs for comparison:
Boy + Car = 126 lbs, close to measured 125 lbs
CMB + Weights = 100 lbs, close to measured 103 lbs
CMB + Weights + Boy = 164 lbs, close to measured 158.5 lbs
Boy = (158.5-103) = 55.5 lbs (off by 10 lbs)

I don't like the way the car jerks at the bottom of the ramp... I have gone back to the 4 wheeler camp for CMBs.

But around the neighborhood this is one fun and highly maneuverable (and easy to contorl, BTW!) car.

:)





-T


"I dunno..." - Uncle Eddie, Christmas Vacation

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