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Here is my latest creation. I won't post all the details, please visit http://mocpages.com/moc.php/428357 in terms of how it works, details, etc. Briefly, I sought to create a funnycar that would propel itself. Because it would be propelling itself, it would have to be fairly large (enough air for short burst of speed), but at the same time light. limiting the coefficient of drag would also be very important. Thus the ungainly looks of the thing. But..... funnycars aren't built for looks, rather for acceleration... right? Kinda inspired by 42050....but I wanted to create something with an engine sound, fast, and help true to the funnycar name. The drivetrain was incredibly simple but effective. Neutral… and one forward drive gear. This is the gear set-up for most drag racers. This can get complex though, with many sophisticated models allowing a type of clutch that limits slip and only allows a certain amount of torque to be applied at different RPM levels. But for all intents and purposes, for this model, all I wanted was neutral and drive. This certainly tested Lego gears, changeover catch, and drive rings. But incredibly, there was no skipping. This was quite amazing given the amount of torque that was applied to the drive train. This is similar to real drag racers. I remember a documentary I watched a while ago stating that the gears in a real drag racer only last 2-3 races before needing replacement because of the tremendous torque, heat, and stress applied. The goal of the drive train was to have a neutral gear so that the engine (which is from lpepower.com, Thanks Alex! I love this engine!) could first rev up. Although the engine is quite powerful in and of itself, the fact that it was already running at approximately 1500 RPMs before the gears engaged really resulted in the car’s speed. The whole set-up looked like what is below. To explain the picture you have the arrows pointing in opposite directions representing the tendency of the drive ring to want to pop out of place because it was trying to engage a set of gears where moving at different speeds (well, one was moving and the other was stationary) and the rubber bands acting against it. Initially, when the engine was started I had an axle placed in the hole where the left arrow is to hold it in place. Placing the axle here would stretch the bands back and disengage the drive. So I would first start the engine, let it rev to approximately 1500 RPMs, put the axle, the bands would pull the catch, engage the drive ring into the receiving gear and….. we were off! The “fuel” that was used was simply air. The air tank was the only thing in this model that was not 100% Lego. All else was. The setup was something that I had built before, just on a smaller scale (one liter bottle). Details can be found here but here are some photos. The 1 liter bottle I used I obviously blacked with spray paint. Simply cut out the nozzle from a bike tube and used very strong epoxy-type glue to seal it all. Worked great. Thanks for taking a look. Hope you enjoyed!