Episode 66: Concrete Glider

Air Date: November 8, 2006

A glider can be made out of concrete.

plausible

Adam’s glider made a flight of over 34 feet from a high of 9 feet. Jamie’s took a nose dive. Also, an expert noted that making a glider out of concrete is possible and that the Germans experimented with the idea during World War II. After the test, the MythBusters decided that making a concrete glider is possible, but highly dangerous and impractical since the brittle concrete would shatter once it hits the ground.

The vortex from a passing train can suck a person onto the tracks.

busted

Although small scale testing with model trains in a wind tunnel showed a vortex, the more dominant force when running the full size train was the air turbulence running alongside and away from the train. The force caused Ted, a dummy made of ballistics gel, to simply fall down where he stood rather than be drawn into the train’s wake, and also violently pushed around an empty stroller tethered onto the platform alongside. Despite the lack of suction, the MythBusters agreed that the turbulence was powerful enough in its own right to make standing that close to the train as it passes very dangerous.

32 Comments

  1. Kevin says:

    re: concrete glider … I recall the University of Washington developing ultra lightweight concrete which wasn’t brittle at all. They also do a “concrete canoe” competition (which appears to have grown substantially) … http://concretecanoe.org/

  2. Ray says:

    I used to test concrete. I hope they didnt add too much water when they built the concrete canoe. (Yeah, yeah, a sick sense of humour.)

  3. Andy says:

    I remembered back in my uni days that the civil engineering department at University of Sydney, Australia made a concrete hang glides and I gather it was tested. Prof Wheen (r.wheen@civil.su.oz.au) would know more. It was mention in the Uni’s 2006 prospectus. http://www.usyd.edu.au/about/publication/pub/ugprospectus/2006/prospectus06_engineering.pdf

  4. John says:

    That concrete canoe website in the link is the most poorly designed website this side of 1995

    • Troy says:

      The concrete canoe website in the link still looks like the most poorly designed website this side of 1995, almost 5 years later.

  5. Ali says:

    i think that the climax of the myth is to make a glider completely out of concrete but from what I saw they used a carbon fiber mesh as the base

  6. Steve says:

    If you watch the launch of Adam glider, he clearly compromises the flight with the string that is attached. If you watch closely, the string Adam is running with becomes tight after the launch pulling the glidder toward him. I think Jamies would have flown better if he wouldn’t have mage the last minute “nose” weight adjustment.

  7. Lee says:

    The concept will definitely work if more study in the aerodynamics of a high aspect ratio wing or foil were carried out, as well as researching additives to the concrete to make it lighter and stronger. Maybe this could be revissited?

  8. Chris says:

    I know how that dummy felt, I was walking along the side of a fairly busy road and almost got pulled into it by a passing semi. I agree that it wasn’t suction towards the road, but if you get caught off guard, you could definately have an accident.

  9. Judy says:

    As Andy wrote in July 07, Prof Rob Wheen from Uni of Sydney did make a concrete hang glider in September 1987 and it was test flown by Phil Mathewson at Kurnell sand dunes in Sydney. I have the write up and pictures of the event. Leave an email address if you want any more information.

  10. Paco says:

    With Jamies glider, it worked well when he through it in the shop. When he was testing the mith, he added a rope. It would work better if Jamie through his glider like Adam did. Then It would go alot farther than it did.

  11. This episode saved a mans life. In the above news article a 14 year old boy recalled the train episode and managed to save a mans life. Well done mythbusters.

  12. Dave Fairley says:

    During WWII Geoffrey Pyke proposed the use of a incredibly strong form of ice dubbed “pykrete” for the construction of aircraft carriers. Pykrete was a mixture of wood pulp and ice and it was believed that a ship constructed from it would be unsinkable, given its incredible strength. According to Strange Brains and Genius by Clifford Pickover a one inch column of pykrete can support an automobile. This is a WWII myth I would love to see put to the test.

  13. Myra says:

    I know I’m posting this a long time after the original air date so I should probably also post this suggestion again somewhere else if I want it to be seen BUT…
    I saw the subway vortex myth for the first time a few weeks ago, and it immediately reminded me of a myth I grew up with. As a child living near a shipping lane, I was told that the vortex behind large ships (freighter or cruise ship size) can suck a person into the propellers. My father loved scaring me with stories about swimming in the Panama Canal and fighting the suction whenever a cargo ship passed nearby. This myth is actually the reason for a phobia I have of boat propellers. Since water has such a different density than air and boats are a bit different than subway trains I’d LOVE to see this myth actually tested (and find out if my dad was just pulling my leg).

  14. Dennis Baile says:

    There was an incident in Flagstaff AZ where a brother and sister named Sult were pulled towards a passing freight train and the girl received MAJOR head trauma from the contact. I believe that it was in about 2000 and was reported in the local newspaper.

  15. Mr trauma says:

    In this episode there is a shot where karis skirt gets blown up by the train, is there a better angle of this event?

  16. adrianqx says:

    Have to agree the concrete canoe website ,is the worst i have ever seen, super ugly reminds of the simpsons episode when homer created a website granted hes was better looking

  17. Bertie the Bunyip says:

    In fact, not only will a concrete glider, or for that matter, a glider made of just about any material that you can get to hold together, fly, it will fly equally as well as a glider of the exact same shape made out of a much lighter material.
    The L/D (lift over drag) of any flying machine does not change with weight. in other words if you take a glider and load it up it will still go the same distance for a given altitude at the best glide speed for that weight.
    The glider will descend more quickly, but it will go faster and just as far.
    this isn’t to say a concrete glider is practical, but one made of the exact same shape as a lighter one will glide just as far.

    • Warren says:

      I am sorry but you are totally wrong. The weight is all part of the equation and the weight of a concrete glider is so much more than a light weight one it can’t glide anywhere near as far.

  18. Doug says:

    I wonder if Jamie calculated the MAC before adjusting the CG

  19. Brian says:

    What’s so special about a concrete conoe? In the late 1940′s and early 1950′s there were many concrete lighters moored on the River Medway in north Kent, UK.

  20. Brian says:

    I don’t know how Adam and Jamie could reproduce the exact set of circumstances, but an acquaintance of mine and his colleague were sucked into a passing high-speed train whilst bird watching in a railway cutting somewhere, I believe, in eastern Europe. My acquaintance was severely injured and spent many months in hospital. His colleague was killed.

  21. lyn says:

    OK. Mythbusters needs to do a follow up on this one. I know 10 & 12 year olds that weigh less than the test dummy “TED”. They use this busted mythbusters episode as an excuse to stand too close to the tracks. Every time I hear about a train vs. pedestrian in our area I fear it will be one of these kids. Adam & Jamie…Please do another episode with less weight…or at least go back and qualify what you’ve done.

  22. Toni says:

    As a young child (10-12) I stood very close to the tracks and hung on to the pole of the crossing arms. I felt the pull of the train and had to hold on for all I was worth. Never tried that again! I don’t believe they proved it a myth!

  23. nathan says:

    They should have made something with longer thinner wings(something that acually resembles a modern glider)that could be dragged behind a car and instead of supporting the concrete internally they should have wrapped it externally with carbon fiber. That way they could have made fairly large ultra thin wing and even could have made it in sections using the carbon fiber.

  24. Pryz Fytr says:

    Airspeed, airspeed, airspeed – the three things that these aircraft needed most. (Same with bamboo aeroplane.)

  25. Chris Weiser says:

    Re: Concrete Glider
    The Germans built a few hundred gliders which had steel-skin airfoils filled with concrete. The craft, dubbed Hagelkorn (Hailstone), looked somewhat like a modern high-performance glider. Its glide ratio was relatively high, and the high weight of the airframe and explosives meant it would glide at high speed (a few hundred mph).
    It was to be carried to altitude and released from the relative safety of the east side of the English Channel. A few were used, with some success.
    One example is in the Smithsonian’s National Air and Space Museum collection.

  26. Tracy says:

    This is regarding the train. Did you ever try it iin the underground. I’m sure the results would be different.

  27. Kim says:

    Try telling that to my finace’s friend. He lost his 9 year old boy from a train. They thought it was cool to sit next to the train tracks when it past by and the child got sucked under the tracks and died. The family got devastated broke up and he hold regreats for just sitting there or taking the time to have his arm around his son instead of sitting next to him. Things he thinks about what he could of done different and wishes never happened.

  28. Brian says:

    They definite;y need to test the train suction myth in a subway situation both on the edge of the tunnel by the leadining edge of the train as it exits the tunnel and by the edge of the trailing edge of the tunnel as it enters the tunnel. There should be much more of a vacuum as the air rushing on or being pushed away is limited by the size of the tunnel closing in around the train.

  29. Nathan Bowen says:

    Pond

  30. Amipo says:

    Sorry jamie, but you’ve made a mistake making your glider, when it comes to distributing weight, in fact the gravity center must be as close as possible to the lift center, and you’ve put the gravity center waaaaaaay in front of the lift center, explaining why it made a front fliip

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