The name "12 Thumbs" came after I finished the design. While I was playing with my finished dragster on the cutting board (that I usually use as the background of my instructable photos). I spot that the the distance between the front and rear wheelbases is more or less 12" long (See photo 4, 5)
I thought about the name "12 incher" but I don't like the name. So I googgled around and came across the measurement term used in the old days, thumb, which is equivalent to an inch. (Source:http://en.wikipedia.org/wiki/English_units)
I like the word! So that's it! My dragster got it name, "12 Thumbs"
My "12 Thumbs" is the easiest of all my custom LEGO® car to build. It only used 129 LEGO® components (not included Arduino and motor controller PCB). It used the same kind of wheels and tires as LEGO® 8847 model, a lot smaller than the LEGO® 5533 "Red Fury" that used the wheel and tires of 81.6 x 34.
The "12 Thumbs" equipped with a small servo to steer the car, same type of servo (9g) that I used with my other cars, R/C LEGO® Car (& Redux), R/C Race Car, or "The Bull" Buggy, etc.
But this time, instead of using the DIY servo supporter that made out of 2x2 plates. I design LEGO compatible, 9g servo mount that is (See next Step.)
For the motor housing, "12 Thumbs" is also using my 3D Printed Motor Housing. (See details in my R/C LEGO "The Bull" Buggy, Step 1)
In the mid section of the car is a battery compartment that is big enough to fit the 9V battery (or small 7.5V rechargeable LiPo battery) into. At the rear section, is where the Arduino and motor controller PCB is located next to the motor housing.
With 7.5V LiPo battery for motor power supply, and 9V, 24mm dia. round DC motor, Arduino, and DRV8833 motor controller IC (Details in Step 8), my "12 Thumbs" just flew out from the start line just like the real Top Fuel Dragster. On the first run "12 Thumbs" I set it speed to 3, it run so fast that I could not steer it straight, so I crashed it to the wall (See the Video in Step 10). Luckily there was no damage, the front wheels just flew off both sides.
"12 Thumbs" Dragster can be controlled wirelessly via XBee, or any other wireless radio, like bluetooth, or WIFI. In this instructable I chose to use XBee module since I have more than two XBee modules with me.
For the XBee Radio Control see R/C LEGO® Car, or Processing Controls R/C Car with XBee modules as examples.
LEGO®, TECHNIC, are property of The LEGO Group of Companies (http://www.lego.com), which does not sponsor, own, authorize or endorse this creation.
Video is available in Step 10.