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Homemade Rocket Hits Record-Breaking 2,723 Feet Using Only Water and Air

posted by cmn32480 on Sunday October 11 2015, @06:17PM   Printer-friendly
from the damn-thats-high dept.

Phoenix666 writes:

There's a fairly robust community that builds and launches water rockets. You know, regular rockets in pretty much every way except for the fact that they use pressurized water and air to launch into the sky. One such water rocket from a South African team of students​ at the University of Cape Town just broke the world altitude record with it's most recent attempt.

The university team managed to grab the record thanks in part to an extremely lightweight frame. The rocket's frame weighs just over three pounds counting the on-board camera, parachute system, flight computer, and carbon fiber skeleton. The team had tried for the record two times before but had been plagued by equipment failure and air leaks. The third time took.​

The group launched their rocket, which clocks in at around nine feet in height, two different times on August 26th to get an average between the two. The first made it to 2,740 feet and the second to 2,707 feet for a world record of 2,723 feet, averaged. That handily beat the previous 2,044 foot record, set in 2007 by a U.S. group​.

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  • (Score: 1, Informative) by Anonymous Coward on Sunday October 11 2015, @06:40PM

    by Anonymous Coward on Sunday October 11 2015, @06:40PM (#248127)

    And then DHS descended on them.

    • (Score: 2) by Runaway1956 on Sunday October 11 2015, @07:03PM

      by Runaway1956 (2926) Subscriber Badge on Sunday October 11 2015, @07:03PM (#248133) Homepage Journal

      DHS has offices in South Africa? Do you have their local phone number?

      --
      Abortion is the number one killed of children in the United States.

      • (Score: 0) by Anonymous Coward on Sunday October 11 2015, @07:18PM

        by Anonymous Coward on Sunday October 11 2015, @07:18PM (#248136)

        They have agents everywhere.

      • (Score: 2) by davester666 on Sunday October 11 2015, @07:53PM

        by davester666 (155) on Sunday October 11 2015, @07:53PM (#248144)

        They have jurisdiction EVERYWHERE, punk!

  • (Score: 2) by Username on Sunday October 11 2015, @08:26PM

    by Username (4557) on Sunday October 11 2015, @08:26PM (#248153)

    I can go anywhere in Colorado/Utah/Wyoming and launch a rocket that will reach a true altitude at least 300 feet higher than 2723.

    • (Score: 0) by Anonymous Coward on Sunday October 11 2015, @10:51PM

      by Anonymous Coward on Sunday October 11 2015, @10:51PM (#248182)

      Estes "D" engine? Want more fun? Get a Tripoli license and fly Aerotech Consumer Aerospace motors, much more fun but expensive.

      • (Score: 2) by Hyperturtle on Monday October 12 2015, @06:09PM

        by Hyperturtle (2824) on Monday October 12 2015, @06:09PM (#248538)

        Launching those D engines without the actual rocket to surround them in -- that's fun! And dangerous as all get out (which makes it more fun...)

        Also fun is launching water rockets sideways. Maybe not a rocket of that size... but everyone gets wet and those things are really hard to aim and don't hit hard when you're using a $10 toy store model.

  • (Score: 2) by frojack on Sunday October 11 2015, @08:57PM

    by frojack (1554) Subscriber Badge on Sunday October 11 2015, @08:57PM (#248156) Journal

    I wonder if there is any amount of water too heavy to lift by any amount of pressurized air via water rocket technology given the limitations on the capabilities of available containment materials.

    --
    No, you are mistaken. I've always had this sig.

    • (Score: 2) by mhajicek on Sunday October 11 2015, @09:56PM

      by mhajicek (51) Subscriber Badge on Sunday October 11 2015, @09:56PM (#248169)

      I'd say a black hole's worth would definitely qualify.

      --
      The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek

    • (Score: 3, Informative) by khallow on Monday October 12 2015, @01:05AM

      by khallow (3766) Subscriber Badge on Monday October 12 2015, @01:05AM (#248228) Journal
      Water-air rockets are governed by the rocket equation - delta v is proportional to the log of the mass fraction used (starting mass divided by final mass) and the exhaust velocity of the propellant. So if you can achieve a certain final velocity with your rocket, given 90% of the rocket's mass is used up, then you can get double the final velocity with 99% of the rocket's mass used up and triple the final velocity with 99.9% of the rocket's mass used up. If the exit velocity is low, you end up with a ridiculous mass fraction to get the desired final velocity. For example, a kerosene-LOX engine has an exhaust velocity of around 3000 m/s. Reading around, I see a calculation for one water-air rocket of 20 m/s. That means that for the same mass fraction consumed, the water-air rocket in question would reach delta v less than 1% of the delta-v of the kerosene-LOX engine. There probably isn't enough water in the world at that exhaust velocity to put a 3 pound rocket into orbit. Maybe I'll calculate it later.

      • (Score: 3, Informative) by hankwang on Monday October 12 2015, @07:27AM

        by hankwang (100) on Monday October 12 2015, @07:27AM (#248306) Homepage

        20 m/s delta v for water sounds rather low. The exhaust speed is sqrt(2p/rho) with p the pressure and rho the density. With p in bar, it's Dv=14 [m/s] sqrt(p/[bar]). The pressurized air takes negligible mass and you surely can get more than 2 bar air pressure in a lightweight container.

    • (Score: 2) by PartTimeZombie on Monday October 12 2015, @02:23AM

      by PartTimeZombie (4827) on Monday October 12 2015, @02:23AM (#248255)

      Completely non-technical answer, but I have a water rocket kit I bought for one of my kids. We've had a lot of fun messing about with it, and found that if we fill the bottle almost to the top, it takes off very slowly, and doesn't get much height, which makes for great slow-mo videos.

  • (Score: 3, Insightful) by BK on Sunday October 11 2015, @09:55PM

    by BK (4868) on Sunday October 11 2015, @09:55PM (#248168)

    I don't think that word means what you think it means...

    --
    ...but you HAVE heard of me.

  • (Score: 2) by cnst on Monday October 12 2015, @07:33AM

    by cnst (4275) on Monday October 12 2015, @07:33AM (#248308)

    What's "2,707 feet"? I thought South Africa was a developed nation, do they still measure stuff the ancient way?

    • (Score: 4, Informative) by cnst on Monday October 12 2015, @07:36AM

      by cnst (4275) on Monday October 12 2015, @07:36AM (#248309)
      Actually, the original source cites proper measurement units. http://www.uct.ac.za/dailynews/?id=9389 [uct.ac.za]

      A team from the University of Cape Town's Industrial Computational Fluid Dynamics (CFD) Research Group has successfully broken the longstanding Class A water rocket world altitude record by a massive 33%, achieving a height of 830m.

      Wow, 830m, now that's impressive!