Episode 198: JATO Rocket Car: Mission Accomplished?

Air Date: May 1, 2013

An airman strapped a jet assisted take off (JATO) unit to his Chevy Impala, rocketed across the desert at 300 mph (480 km/h), and soared through the air for over a mile after hitting a bump.

busted

All five MythBusters joined forces to test this myth and to commence their 10th anniversary season. This was the first myth ever tested on the series and it was still not fully resolved after two previous attempts (in Jet Assisted Chevy and Supersized Myths).

To begin, the Adam and Jamie tore out the inside of a Chevy Impala and welded in an extensive steel mounting system for the rockets. They used five rockets with 2,000 pounds (900 kg) of thrust each, for a total 10,000 pounds (4,500 kg) of thrust. Extra weight was also added to the front of the car to help balance it. Grant then modified the car to be driven remotely by adding controls for the steering, throttle, brake, and shifter. Kari and Tory modified a large dump truck to be used as a mobile bunker during the rocket tests. They protected the cabin of the truck with a thick steel cage and polycarbonate blast shields.

To conduct the rocket tests, the team traveled to a dry lake bed in the Mojave desert. A blast-resistant steel building was trucked in to protect the crew from any rouge rocket cars. A line of 50 pound (23 kg) sand bags was used to create a berm for the car to hit. Adam drove the Impala from within the mobile bunker and Kari fired the rockets at the appropriate moment. The approach and ignition were clean; the car accelerated to about 200 mph (320 km/h) before hitting the berm. After hitting the berm the car quickly tumbled wildly out of control, destroying itself. At this point the MythBusters decided they had replicated the conditions of the myth as perfectly as possible and declared it busted.

In an attempt to replicate the results of the myth by any means possible, the MythBusters used a second Impala with a total of six rockets attached for a total thrust of 12,000 pounds (5,400 kg). Instead of a berm, they built a large ramp out of prefabricated roof trusses. The ramp was 65 ft (20 m) long and 11 ft (3.3 m) high. With Jamie controlling the Impala this time, the car hit the ramp dead-on and briefly launched into the air. The car then tumbled forward and bounced off the ground again before smashing itself. It traveled a total of 600 ft (180 m) after hitting the ramp.

19 Comments

  1. gunner says:

    lets put fins on that car just to see how far it will go, come on guys lets show what it takes :) we all want to see a car fly

  2. Josh says:

    While watching this episode, I noticed something that I personally feel is the problem. The rockets on the car are arranged in a VERTICAL line. This design helped produce the notorious “fishtail”, to which it also resembles. Due to this design, a slight change in horizontal direction is greatly increased. However, if the the rockets were arranged in a HORIZONTAL line, there would be less of a adverse reaction in the case of a sudden change of direction. In addition, this design would be more beneficial to the lift, as the rockets would lift/push the entire car, not just the center. Also, the rockets would be more fluid with the original shape of the car, instead of a vertical “fin”. But again, that’s just my personal logic.

    • SomeDude says:

      Your point is very valid, and things like that could change the whole results of the test. Looks like MythBusters will have to revisit this again if they want to get it right.

      Also the multi-task episode is not very valid either due to the tasks having a bias to them, having each person do the things they almost never do(Aka having no redefined skills of a specific task) would be more valid.

      • SomeDude says:

        They(MythBusters) sometimes get caught up in the daily action of releasing episodes and stuff, don’t worry, just inform, once they notice a flaw, I’m almost 100% positive they’ll make it right. :D

    • OiamondBack says:

      I think they already said that they don’t want to alter the car in anyway because it would jut be a car shaped rocket rather than a car with a rocket on its back

  3. gdp says:

    “gunner” and “Josh” each have it “half right.”

    There are two requirements for stable aerodynamic rocket flight:

    1.) The “line of action” for the total thrust must pass through the vehicle’s center of mass — or equivalently, the engines must not exert any net torque on the vehicle. One may most certainly ensure this criterion in a multi-engine rocket by aligning each engine such that its center axis (line of thrust) points through the vehicle’s center of mass — which is why the central axes of each of the three Space-Shuttle Main Engines appear to splay slightly “outward” from the Orbiter’s longitudinal axis.

    2.) The “center of pressure” for the vehicle must be located _behind_ the center of mass. This criterion may be ensured by adding “fins,” which is why many rockets have fins.

    Unless both of these criteria are simultaneously met, the rocket will “pinwheel” — as indeed the “JATO Car” and nearly every other rocket the Mythbusters have built has “pinwheeled” after launch…

  4. Bob says:

    After watching the replay of the “launch” from the side view, it was apparent that the ramp geometry is the issue. While the height of ramp may be fine to achieve the desired distance, the ramp transition is the culprit. The momentum of the car had to drastically change due to the abrupt angle change. The added rocket thrust only compounded the problem. If the ramp had been curved, like a skateboard quarter pipe, the momentum and attitude of the car would have been preserved. Small scale testing and calibration would have certainly borne this out.

    • Stephen Myers says:

      YES I agree, so much of the momentum went into effectively crashing into the ramp. I wonder if the front is nose heavy? They may have to rethink the ballast at that launch angle.

  5. Bobby says:

    Its seems as if this case may have needed some new viewings… Or maybe Jamie and Adam purposely mist up, so their could be another TV Episode about this!

  6. Adam says:

    @Bobby: You’re right! That’s what we’re trying to do. Stay tuned to MythBusters!

    • Josh says:

      That sounds like a ptrety bad elevator accident, and I’d imagine that things like mining elevators and temporary construction elevators see much higher accident rates than the regular commercial service elevators I was talking about, especially since some of them are open, which could lead to amputations and falls. Even in that story, however, it sounds like there was some kind of initial disaster a collapse of the elevator shaft itself before the elevator fell. They really are remarkably safe.

  7. Adam says:

    Sorry, I wasn’t being serious just now.

  8. Adam says:

    I am really not Adam from MythBusters. Sorry for joking around…

  9. nikolas says:

    do you vrite slovakish?

  10. nikolas says:

    please ansver me

  11. nikolas says:

    I want to ask you something

  12. John says:

    Dokážem písať slovenskom, ale ja si ju prečítať =:0)

  13. Rob says:

    You guys are trying to create a rocket. They were doing a myth about a guy who strapped a rocket to the top of his car. Not redesigned his car to make it a rocket.

  14. Jay says:

    I saw the episode again and it is so clear what went wrong. The car nosedives. Had they not added the weight in the front of the car, it would have flown so much futher. They should revisit that :)

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