Episode 22: Boom Lift Catapult, A/C vs. Open Windows
- Using a boom lift as a catapult: mythbusted
- Rolling down your windows more efficient than using the A/C in a car: mythbusted (REVISTED)
Boom lift myth
This is not a myth that I've ever heard of. As the myth goes, someone was trying to lift their engine out of their car using a boom lift. The chain lifting the engine broke, and the boom lift shot up, throwing the person from the lift like a catapult.
Adam and Jamie actually gave the cool, elaborate, destructive busting to the build team to work on. Granted, they consulted on it as well, but the majority of the work was done by Scottie/Kari/Tory.
They managed to locate two free boom lifts (both had serious issues) and ended up taking the one with 'gremlins' because it had a longer boom lift (60 ft). Apparently these things cost about $50k, so getting a free lift to play with sounds like a good deal to me (I want one of my own to play with). The Mythbuster team rechristened theirs, "The Tosser."
Buster was destroyed in the elevator drop episode and was looking a lot like dismembered C3P0. With new hips and a new shoulder from Scottie he was ready to be the victim once more, but he's really starting to show wear and tear now (as if the burn marks from season one weren't enough).
Nothing happened when the dropped the engine block from the boom when it wasn't fully extended. With the arm fully extended, the boom bounced, but Buster stayed put. Scottie had the idea of hooking up Earl the Caddie to the boom arm, but that was boring as well.
In order to replicate the results (and give the viewers something more entertaining), they decided to turn the boom lift into a trebuchet using truck containers as a base and the boom lift engine as its own counterweight.
Adam's estimate: 10% falling down, 40% chance of Buster flying, 50% chance of Buster slamming into the ground
What happened was somewhat inbetween flying and getting slammed into the ground. Because they didn't design any way for the boom lift to release Buster at the ideal angle, it kept swinging around towards the ground. Because they had the boom lift suspended high enough, Buster did manage to fly a little, but it was at a 45 degree angle downward into the ground. He maybe flew somewhere between ten and twenty feet.
The Tosser's wheels broke off at the end of the throw and the entire thing collapsed down between the truck containers.
Buster got wrecked as well: both legs fell off (one broke in half) and his hand flew 65 ft on it's own.
Windows down vs. air conditioning
"Urban puzzle": it is more efficient, on a hot day, to run with the A/C on and windows up than to run with windows down (b/c of increasing car's drag).
Computer-based mpg measurements: * 11.7/11.8 with A/C on and windows up * 11.7/11.8 with A/C off and windows up * 11.3 with A/C off and windows down
So, according to the computer, it's better to use A/C with windows up.
This was too quick and easy for TV, so they decided to stage a seven hour marathon, race-til-you're-empty duel, with Jamie driving an SUV with A/C on and Adam driving an SUV with windows down. Though, once the safety inspector intervened, it was no longer a seven-hour marathon, it was a bit slower (45mph instead of 55mph), and a lot shorter (only 5 gallons each).
Jamie's A/C car ran out of gas first -- Adam's windows down SUV ran for another 30 laps -- completely contradicting the computer mpg estimate. Computer estimate based on air flow into the engine, so it would appear that it is unable to properly model the difference between A/C and windows down.