and NCTU teams so far, reaching altitudes of 10–20 km. Their plans include attempting 100–200 km altitude launch to test nanosatellites, and developing orbital launch capabilities for nanosatellites in the long run. A sub-scale N2O/PE dual-vortical-flow (DVF) hybrid engine hot-fire test in 2014 has delivered an averaged Isp of 280 sec, which indicates that the system has reached around 97% combustion efficiency. In (Germany) the University of Stuttgart's Student team HyEnd is the current world record holder for the highest-flying student-built hybrid rocket with their HEROS rockets. The Aerospace Team of the TU Graz, Austria, is also developing a hybrid-propellant rocket. The Polish Student team PWr in Space at Wrocław University of Science and Technology has developed three hybrid rockets: R2 "Setka", R3 "Dziewięćdziesiątka dziewiątka" and the most powerful of all - R4 "Lynx" with a successful test at their test stand Many other universities, such as Embry-Riddle Aeronautical University, the University of Washington, Purdue University, the University of Michigan at Ann Arbor, the University of Arkansas at Little Rock, Hendrix College, the University of Illinois, Portland State University, University of KwaZulu-Natal, Texas A&M University, Aarhus University, Rice University, and AGH University of Science and Technology have hybrid motor test stands that allow for student research with hybrid rockets. High power rocketry There are a number of hybrid rocket motor systems available for amateur/hobbyist use in high-powered model rocketry. These include the popular HyperTek systems and a number of 'Urbanski-Colburn Valved' (U/C) systems such as RATTWorks, Contrail Rockets, and Propulsion Polymers. All of these systems use nitrous oxide as the oxidizer and a plastic fuel (such as Polyvinyl chloride (PVC), Polypropylene), or a polymer-based fuel such as HTPB. This reduces the cost per flight compared to solid rocket motors, although there is generally more ground support equipment required with hybrids. In popular culture An October 26, 2005 episode of the television show MythBusters entitled "Confederate Rocket" featured a hybrid rocket motor using liquid nitrous oxide and paraffin wax. The myth purported that during the American Civil War, the Confederate Army was able to construct a rocket of this type. The myth was revisited in a later episode entitled Salami Rocket, using hollowed out dry salami as the solid fuel. In the February 18, 2007, episode of Top Gear, a Reliant Robin was used by Richard Hammond and James May in an attempt to modify a normal K-reg Robin into a