When I was 10 years old, my best friend and I built a rocket-powered Lego car. We came up with the idea on our own, two boys killing a summer afternoon with a bin full of bricks and a pack of Estes model rocket engines. There was no internet. No YouTube. No parental supervision. We were just into Legos and rockets and thought it’d be fun to combine the two. And good Lord was it ever.
Little did we know that after pressing the launch button, the drag racer we built would scream up the driveway, smoke spewing everywhere, and blow sky high raining Lego down all over the yard. We were beside ourselves with glee. I still tell the story 30 years later, and it brings me nothing but joy.
Turns out, we failed to take into account the small charge at the top of the engine that ejects the parachute on a traditional model rocket. We had locked the engine in so tightly with bricks that when it fired into the car mid-run, it proceeded to demolish the whole vehicle. We learned from our mistake, gave the engine a little more space on the next build, and it easily completed a full run across the school parking lot without incident. We also learned that building a rocket-powered Lego car was a damn fun (and super easy) project, although it’s hard to imagine any kid doing so unsupervised these days. Nonetheless, here’s how to make one in three easy steps.
What You’ll Need:
- Enough Legos, including axels and wheels, to build a car (or at least a platform) that rolls. There’s no need to buy an actual Lego car kit, but it can’t hurt ⏤ just realize that the heat/exhaust from the engine could damage some of the bricks.
- An Estes model rocket engine and remote launcher.
- A driveway or parking lot. The wider the better, as there’s no steering involved and the car can careen in various directions.
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Step 1: Build the Car
Again, the actual vehicle can be as simple or complex as you want, just as long as it rolls freely and there’s a secure compartment in the back for the engine. The bigger or heavier the car, obviously, the bigger the engine you’ll need. With Estes engines, ‘A’ is the smallest, ‘F’ the largest. You could probably experiment with two smaller engines if need be (maybe one atop the other) but you’ll need to fire them close enough together to keep the car driving straight.
Step 2: Insert the Engine
In terms of fitting the engine, again, we secured the engine flush against a wall of bricks. Don’t do this. Make sure it’s locked into the vehicle on the sides, and there’s room behind the engine when the delayed ejection charge fires. Some people also fit the engine at a 10-degree angle and leave the floor open ⏤ you won’t get as much thrust firing slightly upward, but the ejection charge will fire harmlessly into the ground.
Step 3: Launch
There were no GoPro cameras in the mid-1980s, but if there were, attaching one would have been pretty awesome. If you do strap one on the front, make sure to do a test run before needlessly putting your camera in harm’s way. After the car is built and the engine locked and loaded, insert the starters and fully extend the wires of the electronic launcher so you’re a safe distance away. From there, insert the key, count down, and fire away.
While we didn’t record our car exploding with a giant VHS camera, here are a few fun videos on YouTube to give you an idea of how it looks in action.